Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2017	Feb. 20, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	Piedmont Office Realty Trust, Inc.
Entity Central Index Key	0001042776
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		135,065,720
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 3,044,079,292

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Assets:
Land	$ 544,794	$ 542,640
Buildings and improvements, less accumulated depreciation of $785,206 and $700,304 as of December 31, 2017 and December 31, 2016, respectively	2,418,023	2,442,178
Intangible lease assets, less accumulated amortization of $99,145 and $109,152 as of December 31, 2017 and December 31, 2016, respectively	77,805	99,695
Construction in progress	11,710	34,460
Real estate assets held for sale, net	332,410	612,719
Total real estate assets	3,384,742	3,731,692
Investment in and amounts due from unconsolidated joint venture	10	7,360
Cash and cash equivalents	7,382	6,992
Tenant receivables, net of allowance for doubtful accounts of $539 and $197 as of December 31, 2017 and December 31, 2016, respectively	12,139	26,494
Straight-line rent receivables	163,160	136,862
Notes receivable	0	0
Restricted cash and escrows	1,373	1,212
Prepaid expenses and other assets	22,517	23,281
Goodwill	98,918	98,918
Gross derivative assets	688	0
Deferred lease costs, less accumulated amortization of $183,740 and $159,531 as of December 31, 2017 and December 31, 2016, respectively	261,907	276,725
Other assets held for sale, net	47,131	58,632
Total assets	3,999,967	4,368,168
Liabilities:
Unsecured debt, net of discount and unamortized debt issuance costs of $7,689 and $10,269 as of December 31, 2017 and December 31, 2016, respectively	1,535,311	1,687,731
Secured debt, net of premiums and unamortized debt issuance costs of $946 and $1,161 as of December 31, 2017 and December 31, 2016, respectively	191,616	332,744
Accounts payable, accrued expenses, dividends payable, and accrued capital expenditures	216,653	165,410
Deferred income	29,582	28,406
Intangible lease liabilities, less accumulated amortization of $55,847 and $48,377 as of December 31, 2017 and December 31, 2016, respectively	38,458	47,537
Interest rate swaps	1,478	8,169
Other liabilities held for sale, net	380	468
Total liabilities	2,013,478	2,270,465
Commitments and Contingencies	0	0
Stockholders' Equity:
Shares-in-trust, 150,000,000 shares authorized, none outstanding as of December 31, 2017 or December 31, 2016	0	0
Preferred stock, no par value, 100,000,000 shares authorized, none outstanding as of December 31, 2017 or December 31, 2016	0	0
Common stock, $.01 par value; 750,000,000 shares authorized, 142,358,940 shares issued and outstanding as of December 31, 2017; and 145,235,313 shares issued and outstanding at December 31, 2016	1,424	1,452
Additional paid-in capital	3,677,360	3,673,128
Cumulative distributions in excess of earnings	(1,702,281)	(1,580,863)
Other comprehensive income	8,164	2,104
Piedmont stockholders’ equity	1,984,667	2,095,821
Noncontrolling interest	1,822	1,882
Total stockholders’ equity	1,986,489	2,097,703
Total liabilities and stockholders’ equity	$ 3,999,967	$ 4,368,168

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Assets:
Intangible lease assets, accumulated amortization	$ 99,145	$ 109,152
Tenant receivables, allowance for doubtful accounts	539	197
Deferred lease costs, accumulated amortization	183,740	159,531
Liabilities:
Intangible lease liabilities, accumulated amortization	$ 55,847	$ 48,377
Stockholders' Equity:
Shares-in-trust, shares authorized	150,000,000	150,000,000
Shares-in-trust, shares outstanding	0	0
Preferred stock, par value (in dollars per share)	$ 0	$ 0
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	750,000,000	750,000,000
Common stock, shares issued	142,358,940	145,235,313
Common stock, shares outstanding	142,358,940	145,235,313
Unsecured Debt
Liabilities:
Net of discount, premiums and unamortized debt issuance costs	$ 7,689	$ 10,269
Secured Debt
Liabilities:
Net of discount, premiums and unamortized debt issuance costs	(946)	(1,161)
Building and building improvements
Assets:
Buildings and improvements, accumulated depreciation	$ 785,206	$ 700,304

CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Rental income	$ 475,777	$ 459,890	$ 468,872
Tenant reimbursements	96,711	93,961	113,881
Property management fee revenue	1,685	1,864	2,016
Total revenues	574,173	555,715	584,769
Expenses:
Property operating costs	220,630	218,934	242,022
Depreciation	119,288	127,733	134,503
Amortization	75,367	75,119	60,886
Impairment loss on real estate assets	46,461	33,901	43,301
General and administrative	31,130	29,244	30,346
Operating Expenses	492,876	484,931	511,058
Real estate operating income	81,297	70,784	73,711
Other income (expense):
Interest expense	(68,124)	(64,860)	(73,998)
Other income/(expense)	657	(13)	1,565
Net recoveries/(loss) from casualty events	0	34	(278)
Equity in income of unconsolidated joint ventures	3,845	362	553
Nonoperating Income (Expense)	(63,622)	(64,477)	(72,158)
Income from continuing operations	17,675	6,307	1,553
Discontinued operations:
Operating income	0	0	84
Loss on sale of real estate assets	0	0	(1)
Income from discontinued operations	0	0	83
Gain on sale of real estate assets	115,874	93,410	129,683
Net income	133,549	99,717	131,319
Plus: Net loss/(income) applicable to noncontrolling interest	15	15	(15)
Net income applicable to Piedmont	$ 133,564	$ 99,732	$ 131,304
Per share information— basic and diluted:
Income from continuing operations and gain on sale of real estate assets (in dollars per share)	$ 0.92	$ 0.69	$ 0.87
Income from discontinued operations (in dollars per share)	0.00	0.00	0.00
Net income available to common stockholders (in dollars per share)	$ 0.92	$ 0.69	$ 0.87
Weighted-average shares outstanding - basic (in shares)	145,043,503	145,230,382	150,537,757
Weighted-average shares outstanding - diluted (in shares)	145,379,994	145,634,953	150,880,116

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income applicable to Piedmont	$ 133,564	$ 99,732	$ 131,304
Other comprehensive income/(loss):
Effective portion of gain/(loss) on derivative instruments that are designated and qualify as cash flow hedges (See Note 7)	2,479	(4,126)	(12,509)
Reclassification of previously recorded loss included in net income (See Note 7)	3,502	4,548	5,875
Gain/(loss) on investment in available for sale securities	79	21	(6)
Other comprehensive income/(loss)	6,060	443	(6,640)
Comprehensive income applicable to Piedmont	$ 139,624	$ 100,175	$ 124,664

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Cumulative Distributions in Excess of Earnings	Other Comprehensive Income/(Loss)	Noncontrolling Interest
Beginning balance, value at Dec. 31, 2014	$ 2,280,677	$ 1,543	$ 3,666,182	$ (1,396,958)	$ 8,301	$ 1,609
Beginning balance (in shares) at Dec. 31, 2014		154,324,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share repurchases as part of an announced plan	(158,860)	$ (90)		(158,770)
Stock repurchases as part of an announced plan (in shares)		(8,980,000)
Retirement of shares returned from escrow	(326)		(326)
Noncontrolling interest in consolidated joint venture	54		54
Reallocation of noncontrolling interest of subsidiary	544		1,128			(584)
Dividends to common stockholders, dividends to preferred stockholders of subsidiary, and dividends reinvested	(126,531)		(242)	(126,274)		(15)
Shares issued and amortized under the 2007 Omnibus Incentive Plan, net of tax	3,183	$ 2	3,181
Shares issued under the 2007 Omnibus Incentive Plan, net of tax (in shares)		168,000
Net income applicable to noncontrolling interest	15					15
Net income applicable to Piedmont	131,304			131,304
Other comprehensive income/(loss)	(6,640)				(6,640)
Ending balance, value at Dec. 31, 2015	$ 2,123,420	$ 1,455	3,669,977	(1,550,698)	1,661	1,025
Ending balance, (in shares) at Dec. 31, 2015	145,511,644	145,512,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share repurchases as part of an announced plan	$ (7,943)	$ (5)		(7,938)
Stock repurchases as part of an announced plan (in shares)		(462,000)
Dividends to common stockholders, dividends to preferred stockholders of subsidiary, and dividends reinvested	(122,148)		(173)	(121,959)		(16)
Shares issued and amortized under the 2007 Omnibus Incentive Plan, net of tax	3,668	$ 2	3,666
Shares issued under the 2007 Omnibus Incentive Plan, net of tax (in shares)		185,000
Net income applicable to noncontrolling interest	(15)					(15)
Net income applicable to Piedmont	99,732			99,732
Other comprehensive income/(loss)	443				443
Offering costs	(342)		(342)
Noncontrolling interest in consolidated joint venture	888					888
Ending balance, value at Dec. 31, 2016	$ 2,097,703	$ 1,452	3,673,128	(1,580,863)	2,104	1,882
Ending balance, (in shares) at Dec. 31, 2016	145,235,313	145,235,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share repurchases as part of an announced plan	$ (61,750)	$ (31)		(61,719)
Stock repurchases as part of an announced plan (in shares)		(3,133,000)
Dividends to common stockholders, dividends to preferred stockholders of subsidiary, and dividends reinvested	(193,541)		(233)	(193,263)		(45)
Shares issued and amortized under the 2007 Omnibus Incentive Plan, net of tax	$ 4,650	$ 3	4,647
Shares issued under the 2007 Omnibus Incentive Plan, net of tax (in shares)	256,628	257,000
Net income applicable to noncontrolling interest	$ (15)					(15)
Net income applicable to Piedmont	133,564			133,564
Other comprehensive income/(loss)	6,060				6,060
Offering costs	(182)		(182)
Ending balance, value at Dec. 31, 2017	$ 1,986,489	$ 1,424	$ 3,677,360	$ (1,702,281)	$ 8,164	$ 1,822
Ending balance, (in shares) at Dec. 31, 2017	142,358,940	142,359,000

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash Flows from Operating Activities:
Net income	$ 133,549	$ 99,717	$ 131,319
Operating distributions received from unconsolidated joint ventures	11	579	774
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	119,288	127,733	134,503
Amortization of debt issuance costs	1,588	1,702	1,768
Loss on settlement of forward starting interest rate swaps	0	0	(1,284)
Other amortization	73,944	74,373	61,221
Impairment loss on real estate assets	46,461	33,901	43,301
Stock compensation expense	9,196	7,928	8,789
Equity in income of unconsolidated joint ventures	(3,845)	(362)	(553)
Gain on sale of real estate assets, net	(115,874)	(93,410)	(129,683)
Changes in assets and liabilities:
Increase in tenant and straight-line rent receivables, net	(21,392)	(26,747)	(29,478)
Decrease/(increase) in prepaid expenses and other assets	384	1,437	(1,440)
Increase/(decrease) in accounts payable and accrued expenses	(1,521)	3,555	(162)
Increase in deferred income	1,016	1,441	4,613
Net cash provided by operating activities	242,805	231,847	223,688
Cash Flows from Investing Activities:
Acquisition of real estate assets and intangibles	(35,262)	(349,668)	(387,923)
Capitalized expenditures, net of accruals	(79,831)	(110,228)	(118,671)
Redemption of noncontrolling interest in unconsolidated variable interest entity	0	0	(4,000)
Net sale proceeds from wholly-owned properties	375,518	365,918	848,169
Net sale proceeds received from unconsolidated joint ventures	12,334	0	0
Investments in unconsolidated joint ventures	(1,162)	0	0
Deferred lease costs paid	(30,985)	(25,896)	(37,683)
Net cash provided by/(used in) investing activities	240,612	(119,874)	299,892
Cash Flows from Financing Activities:
Debt issuance costs paid	(132)	(264)	(1,081)
Proceeds from debt	180,000	695,000	1,301,858
Repayments of debt	(476,401)	(706,875)	(1,544,301)
Costs of issuance of common stock	(182)	(342)	(326)
Shares withheld to pay tax obligations related to employee stock compensation	(3,403)	(2,344)	(1,710)
Repurchases of common stock as part of announced plan	(60,474)	(7,943)	(158,860)
Dividends paid and discount on dividend reinvestments	(122,274)	(91,616)	(126,531)
Net cash used in financing activities	(482,866)	(114,384)	(530,951)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	551	(2,411)	(7,371)
Cash, cash equivalents, and restricted cash and escrows, beginning of year	8,204	10,615	17,986
Cash, cash equivalents, and restricted cash and escrows, end of year	$ 8,755	$ 8,204	$ 10,615

Organization	12 Months Ended
Organization	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization Piedmont Office Realty Trust, Inc. (“Piedmont”) (NYSE: PDM) is a Maryland corporation that operates in a manner so as to qualify as a real estate investment trust (“REIT”) for federal income tax purposes and engages in the acquisition, development, management, and ownership of commercial real estate properties located primarily in the Eastern-half of the United States, including properties that are under construction, are newly constructed, or have operating histories. Piedmont was incorporated in 1997 and commenced operations in 1998. Piedmont conducts business primarily through Piedmont Operating Partnership, L.P. (“Piedmont OP”), a Delaware limited partnership, as well as performing the management of its buildings through two wholly-owned subsidiaries, Piedmont Government Services, LLC and Piedmont Office Management, LLC. Piedmont owns 99.9% of, and is the sole general partner of, Piedmont OP and as such, possesses full legal control and authority over the operations of Piedmont OP. The remaining 0.1% ownership interest of Piedmont OP is held indirectly by Piedmont through its wholly-owned subsidiary, Piedmont Office Holdings, Inc. ("POH"), the sole limited partner of Piedmont OP. Piedmont OP owns properties directly, through wholly-owned subsidiaries, and through various joint ventures. References to Piedmont herein shall include Piedmont and all of its subsidiaries, including Piedmont OP and its subsidiaries and joint ventures. As of December 31, 2017, Piedmont owned 67 in-service office properties comprised of approximately 19 million square feet (unaudited) of primarily Class A commercial office space, which was approximately 89.7% leased. As of December 31, 2017, approximately 88% of Piedmont's Annualized Lease Revenue (unaudited) was generated from select sub-markets located primarily within eight major office markets located in the Eastern-half of the United States: Atlanta, Boston, Chicago, Dallas, Minneapolis, New York, Orlando, and Washington, D.C. Piedmont internally evaluates all of its real estate assets as one operating segment, and accordingly does not report segment information. However, Piedmont has provided certain information specific to each of its geographical markets that it believes may be helpful to its investors in Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations (unaudited) included elsewhere in this Annual Report on Form 10-K.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Basis of Presentation and Principles of Consolidation

Piedmont’s consolidated financial statements are prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) and include the accounts of Piedmont, Piedmont’s wholly-owned subsidiaries, any variable interest entity ("VIE") of which Piedmont or any of its wholly-owned subsidiaries is considered to have the power to direct the activities of the entity and the obligation to absorb losses/right to receive benefits, or any entity in which Piedmont or any of its wholly-owned subsidiaries owns a controlling interest. In determining whether Piedmont or Piedmont OP has a controlling interest, the following factors, among others, are considered: equity ownership, voting rights, protective rights of investors, and participatory rights of investors.

Piedmont owns a majority interest in four properties through three joint ventures. Two of these joint ventures, 1201 and 1225 Eye Street, NW Associates, which own the 1201 and 1225 Eye Street buildings, respectively, in Washington, D.C. are consolidated using the method prescribed in accounting for VIEs (see Note 6). The other joint venture, Piedmont-CNL Towers Orlando, LLC, which owns CNL Center I and II, in Orlando, Florida is an equity method investment consolidated under the voting model. Accordingly, Piedmont’s consolidated financial statements include the accounts of 1201 Eye Street, NW Associates, LLC, 1225 Eye Street, NW Associates, LLC, and Piedmont-CNL Towers Orlando, LLC .

Please refer to Note 6 for a summary of Piedmont’s interests in and consolidation treatment of its various VIEs as of December 31, 2017.

All inter-company balances and transactions have been eliminated upon consolidation.

Further, Piedmont has formed special purpose entities to acquire and hold real estate. Each special purpose entity is a separate legal entity and consequently the assets of the special purpose entities are not available to all creditors of Piedmont. The assets owned by these special purpose entities are being reported on a consolidated basis with Piedmont’s assets for financial reporting purposes only.

Use of Estimates

The preparation of the accompanying consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the accompanying consolidated financial statements and notes. Actual results could differ from those estimates.

Real Estate Assets

Piedmont classifies its real estate assets as long-lived assets held for use or as long-lived assets held for sale. Held for use assets are stated at cost, as adjusted for any impairment loss, less accumulated depreciation. Held for sale assets are carried at lower of depreciated cost or estimated fair value, less estimated costs to sell. Piedmont generally reclassifies assets as held for sale once a sales contract has been executed and earnest money has become non-refundable.

Amounts capitalized to real estate assets consist of the cost of acquisition or construction, any tenant improvements or major improvements, betterments that extend the useful life of the related asset, and transaction costs associated with the acquisition of an individual asset that does not qualify as a business combination. All repairs and maintenance are expensed as incurred. Additionally, Piedmont capitalizes interest while the development, or redevelopment, of a real estate asset is in progress. Approximately $0.2 million, $4.6 million, and $3.8 million of interest was capitalized for the years ended December 31, 2017, 2016, and 2015, respectively.

Piedmont’s real estate assets are depreciated or amortized using the straight-line method over the following useful lives:



Buildings	40 years
Building improvements	5-25 years
Land improvements	20-25 years
Tenant allowances	Lease term
Furniture, fixtures, and equipment	3-5 years
Intangible lease assets	Lease term

Piedmont continually monitors events and changes in circumstances that could indicate that the carrying amounts of the real estate and related intangible assets of either operating properties or properties under construction in which Piedmont has an ownership interest, either directly or through investments in joint ventures, may not be recoverable. When indicators of potential impairment are present, or when a sale in the near term is considered more than 50% probable, management assesses whether the respective carrying values including a proportionate amount of goodwill, if applicable, will be recovered from the undiscounted future operating cash flows expected from the use of the asset and its eventual disposition for assets held for use, or from the estimated fair values, less costs to sell, for assets held for sale. In the event that the expected undiscounted future cash flows for assets held for use or the estimated fair value, less costs to sell, for assets held for sale do not exceed the respective asset carrying value, management adjusts such assets to the respective estimated fair values and recognizes an impairment loss. Estimated fair values are calculated based on the following information, depending upon availability, in order of preference: (i) recently quoted market prices, (ii) market prices for comparable properties, or (iii) the present value of undiscounted cash flows, including estimated sales value (which is based on key assumptions such as estimated market rents, lease-up periods, estimated lease terms, and capitalization and discount rates) less estimated selling costs.

Fair Value of Assets and Liabilities of Acquired Properties

Upon the acquisition of real properties, Piedmont records the fair value of properties (plus any related acquisition costs) allocated based on relative fair value as tangible assets, consisting of land and building, and identified intangible assets and liabilities, consisting of the value of above-market and below-market leases and the value of in-place leases, based on their estimated fair values.

The estimated fair values of the tangible assets of an acquired property (which includes land and building) are determined by valuing the property as if it were vacant, and the “as-if-vacant” value is then allocated to land and building based on management’s determination of the estimated fair value of these assets. Management relies on a sales comparison approach using closed land sales and listings in determining the land value, and determines the as-if-vacant estimated fair value of a property using methods similar to those used by independent appraisers. Factors considered by management in performing these analyses include an estimate of carrying costs during the expected lease-up periods considering current market conditions and costs to execute similar leases. In estimating carrying costs, management includes real estate taxes, insurance, and other operating expenses and estimates of lost rental revenue during the expected lease-up periods based on current market demand. Management also estimates the cost to execute similar leases including leasing commissions, legal, and other related costs.

The estimated fair values of above-market and below-market in-place leases are recorded based on the present value (using an interest rate which reflects the risks associated with the leases acquired) of the difference between (i) the contractual amounts to be paid pursuant to the in-place leases and (ii) management’s estimate of market rates for the corresponding in-place leases, measured over a period equal to the remaining terms of the leases, taking into consideration the probability of renewals for any below-market leases. The capitalized above-market and below-market lease values are recorded as intangible lease assets or liabilities and amortized as an adjustment to rental revenues over the remaining terms of the respective leases.

The estimated fair values of in-place leases include an estimate of the direct costs associated with obtaining the acquired or "in place" tenant, estimates of opportunity costs associated with lost rentals that are avoided by acquiring an in-place lease. The amount capitalized as direct costs associated with obtaining a tenant include commissions, tenant improvements, and other direct costs and are estimated based on management’s consideration of current market costs to execute a similar lease. These direct lease origination costs are included in deferred lease costs in the accompanying consolidated balance sheets and are amortized to expense over the remaining terms of the respective leases. The value of opportunity costs is calculated using the contractual amounts to be paid pursuant to the in-place leases over a market absorption period for a similar lease. These lease intangibles are included in intangible lease assets in the accompanying consolidated balance sheets and are amortized to expense over the remaining terms of the respective leases.

Gross intangible assets and liabilities, inclusive of amounts classified as real estate assets held for sale, recorded at acquisition as of December 31, 2017 and 2016, respectively, are as follows (in thousands):



	December 31, 2017		December 31, 2016
Intangible Lease Assets:
Above-Market In-Place Lease Assets	$	11,935	$	25,425
In-Place Lease Valuation	$	165,015	$	183,422
Intangible Lease Origination Costs (included as component of Deferred Lease Costs)	$	250,539	$	261,075
Intangible Lease Liabilities (Below-Market In-Place Leases)	$	95,620	$	97,230

For the years ended December 31, 2017, 2016, and 2015, respectively, Piedmont recognized amortization of intangible lease costs as follows (in thousands):



	2017		2016		2015
Amortization of Intangible Lease Origination Costs and In-Place Lease Valuation included in amortization expense	$	58,467	$	58,150	$	42,278
Amortization of Above-Market and Below-Market In-Place Lease intangibles as a net increase to rental revenues	$	6,575	$	5,066	$	4,571

Net intangible assets and liabilities, inclusive of amounts classified as real estate assets held for sale, as of December 31, 2017 will be amortized as follows (in thousands):



	Intangible Lease Assets
	Above-Market In-place Lease Assets		In-Place Lease Valuation		Intangible Lease Origination Costs ⁽¹⁾		Below-Market In-place Lease Liabilities ⁽²⁾
For the year ending December 31:
2018	$	1,600	$	18,497	$	28,023	$	8,449
2019	910		14,181		23,102		7,263
2020	157		10,179		17,739		5,669
2021	104		9,013		15,685		5,468
2022	84		7,869		13,752		4,847
Thereafter	142		15,069		27,800		7,142
	$	2,997	$	74,808	$	126,101	$	38,838

Weighted-Average Amortization Period (in years)	3		6		7		6


⁽¹⁾	Included as a component of Deferred Lease Costs in the accompanying consolidated balance sheets.

⁽²⁾

Includes approximately $0.4 million of future amortization of below-market in-place lease intangibles related to our 2017 Disposition Portfolio (see Note 14) below, which is classified as Other Liabilities Held for Sale, Net, on the accompanying consolidated balance sheets. These net below-market in-place lease intangibles will be included in the gain/loss on real estate assets upon their disposition on January 4, 2018.

Investments in and Amounts Due from Unconsolidated Joint Ventures

During the year ended December 31, 2017, Piedmont sold its investment in its last remaining unconsolidated joint venture. Prior to this disposition, during the three years ended December 31, 2017, Piedmont had accounted for its unconsolidated joint ventures using the equity method of accounting, whereby original investments were recorded at cost and subsequently adjusted for contributions, distributions, net income/(loss), and "other than temporary" impairment losses, if any, attributable to such joint ventures. All income and distributions were allocated to the joint venture partners in accordance with their respective ownership interests. Any distributions were classified on the accompanying consolidated statements of cash flow using the nature of distribution approach. Any distributions of net cash from operations were classified as cash inflows from operating activities, as they were presumed to be returns on Piedmont’s investment in the joint venture. Any proceeds received as the result of a sale of an asset from an unconsolidated joint venture were considered a return of Piedmont’s investment in the joint venture and classified as cash inflows from investing activities. Due from unconsolidated joint venture represents operating distributions due to Piedmont from its investment in the unconsolidated joint venture which have been declared but not received as of period end.

Cash and Cash Equivalents

Piedmont considers all highly-liquid investments purchased with an original maturity of three months or less to be cash equivalents. Cash equivalents include cash and short-term investments. Short-term investments consist of investments in money market accounts stated at cost, which approximates estimated fair value, and available-for-sale securities resulting from Piedmont's non-qualified deferred compensation program carried at estimated fair value.

Tenant Receivables, net and Straight-line Rent Receivables

Tenant receivables are comprised of rental and reimbursement billings due from tenants, and straight-line rent receivables representing the cumulative amount of future adjustments necessary to present rental income on a straight-line basis. Tenant receivables are recorded at the original amount earned, less an allowance for any doubtful accounts, which approximates estimated fair value. Management assesses the collectability of tenant receivables on an ongoing basis and provides for allowances as such balances, or portions thereof, become uncollectible. Piedmont records provisions for bad debts as property operating costs in the accompanying consolidated statements of income, and recognized approximately $350,000, $216,000, and $22,000 of provisions for bad debts during the years ended December 31, 2017, 2016, and 2015, respectively.

Restricted Cash and Escrows

Restricted cash and escrows principally relate to the following types of items:


•	escrow accounts held by lenders to pay future real estate taxes, insurance, debt service, and tenant improvements;


•	net sales proceeds from property sales held by qualified intermediary for potential Section 1031 exchange;


•	earnest money paid in connection with future acquisitions; and


•	security and utility deposits paid by tenants per the terms of their respective leases.

Restricted cash and escrows are generally reclassified to other asset or liability accounts upon being used to purchase assets, satisfy obligations, or settle tenant obligations.

Prepaid Expenses and Other Assets

Prepaid expenses and other assets are primarily comprised of the following items:


•	prepaid property taxes, insurance and operating costs;


•	deferred common area maintenance costs which will be reimbursed by tenants over specified time periods;


•	receivables which are unrelated to tenants, for example, insurance proceeds receivable from insurers related to casualty losses; and


•	equipment, furniture and fixtures, and tenant improvements for Piedmont’s corporate office and property management office space, net of accumulated depreciation.

Prepaid expenses and other assets will be expensed as utilized or depreciated in the case of Piedmont's corporate assets. Balances without a future economic benefit are expensed as they are identified. Deferred common area maintenance costs are amortized to property operating costs as the related reimbursement income is recognized over the period specified in the respective lease. Piedmont recognized amortization of deferred common area maintenance for the years ended December 31, 2017, 2016, and 2015 of approximately $1.4 million, $1.4 million, and $2.5 million, respectively.

Goodwill

Goodwill is the excess of cost of an acquired entity over the amounts specifically assigned to assets acquired and liabilities assumed in purchase accounting for business combinations. Piedmont tests the carrying value of its goodwill for impairment on an annual basis, or on an interim basis if an event occurs or circumstances change that would indicate the carrying amount may be impaired. Such interim circumstances may include, but are not limited to, significant adverse changes in legal factors or in the general business climate, adverse action or assessment by a regulator, unanticipated competition, the loss of key personnel, or persistent declines in an entity’s stock price below carrying value of the entity. Piedmont first assesses qualitative factors to determine whether the existence of events or circumstances leads to a determination that it is more likely than not that the estimated fair value of the reporting unit is less than its carrying amount. Piedmont internally evaluates its consolidated financial position and all of its operations as one reporting unit. In conjunction with performing the annual impairment test of goodwill as of December 31, 2017, Piedmont early adopted the provisions of the Accounting Standards Update No. 2017-04 Intangibles—Goodwill and Other (Topic 350), Simplifying the Test for Goodwill Impairment ("ASU 2017-04") issued by the Financial Accounting Standards Board (the "FASB"). Beginning with the 2017 annual test of goodwill impairment, Piedmont will no longer perform a "Step 2" analysis if, after assessing the totality of events or circumstances, Piedmont concludes that the goodwill balance may be impaired for any reporting unit. A Step 2 analysis requires an entity to calculate the implied fair value of existing goodwill, as compared to its carrying amount. Instead, if Piedmont determines during the qualitative analysis that it is more likely than not that the goodwill is impaired, then Piedmont will recognize a goodwill impairment loss by the excess of the reporting unit’s carrying amount over its estimated fair value (not to exceed the total goodwill allocated to that reporting unit). There were no changes in the carrying amount of Piedmont's goodwill during the year ended December 31, 2017.

Interest Rate Derivatives

Piedmont periodically enters into interest rate derivative agreements to hedge its exposure to changing interest rates. As of December 31, 2017 and 2016, all of Piedmont's interest rate derivatives were designated as effective cash flow hedges and carried on the balance sheet at estimated fair value. Piedmont reassesses the effectiveness of its derivatives designated as cash flow hedges on a regular basis to determine if they continue to be highly effective and if the forecasted transactions remain highly probable. Piedmont does not use derivatives for trading or speculative purposes.

The changes in estimated fair value of interest rate swap agreements designated as effective cash flow hedges are recorded in other comprehensive income (“OCI”), and subsequently reclassified to earnings when the hedged transactions occur. The estimated fair value of the interest rate derivative agreement is recorded as interest rate derivative asset or as interest rate derivative liability in the accompanying consolidated balance sheets. Amounts received or paid under interest rate derivative agreements are recorded as reductions or additions to interest expense in the consolidated income statements as incurred. Additionally, when Piedmont settles forward starting swap agreements, any gain or loss is recorded as accumulated other comprehensive income and is amortized to interest expense over the term of the respective notes on a straight line basis (which approximates the effective interest method). Further, Piedmont classifies cash flows from the settlement of hedging derivative instruments in the same category as the underlying exposure which is being hedged. Settlements resulting from the hedge of Piedmont's exposure to interest rate changes are classified as operating cash flows in the accompanying consolidated statements of cash flows.

Deferred Lease Costs

Deferred lease costs are comprised of costs and incentives incurred to acquire operating leases. In addition to direct costs, deferred lease costs also include intangible lease origination costs related to in-place leases acquired as part of a property acquisition and direct payroll costs incurred related to negotiating and executing specific leases. For the years ended December 31, 2017, 2016, and 2015, Piedmont capitalized approximately $0.3 million, $0.4 million, and $1.0 million, respectively, of internal leasing and development costs.

Deferred lease costs are amortized on a straight-line basis over the terms of the related underlying leases in the accompanying consolidated statements of income as follows:


•	Approximately $50.8 million, $50.1 million, and $42.5 million of deferred lease costs for the years ended December 31, 2017, 2016, and 2015, respectively, are included in amortization expense; and


•	Approximately $4.8 million, $3.9 million, and $4.7 million, of deferred lease costs related to lease incentives granted to tenants for the years ended December 31, 2017, 2016, and 2015, respectively, was included as an offset to rental income.

Upon receipt of a lease termination notice, Piedmont adjusts the amortization of any unamortized deferred lease costs to be recognized ratably over the revised remaining term of the lease after giving effect to the termination notice. If there is no remaining lease term and no other obligation to provide the tenant space in the property, then any unamortized tenant-specific costs are recognized immediately upon termination.

Debt

When mortgage debt is assumed upon the acquisition of real property, Piedmont adjusts the loan to estimated fair value with a corresponding adjustment to building and other intangible assets assumed as part of the purchase. The fair value adjustment is amortized to interest expense over the term of the loan using the effective interest method. Amortization of such fair value adjustments was approximately $0.5 million for each of the years ended December 31, 2017, 2016, and 2015, respectively.

Additionally, Piedmont records debt issuance premiums/discounts as an increase/decrease to the principal amount of the loan in the accompanying consolidated balance sheets, and amortizes such premiums or discounts as a component of interest expense over the life of the underlying loan facility using the effective interest method. Piedmont recorded discount amortization of approximately $0.2 million for each of the years ended December 31, 2017, 2016, and 2015, respectively.

Piedmont presents all debt issuance costs as a direct deduction from the principal amount of secured and unsecured debt in the accompanying consolidated balance sheets. Piedmont amortizes these costs to interest expense on a straight-line basis (which approximates the effective interest rate method) over the terms of the related financing arrangements. Piedmont recognized amortization of such costs for the years ended December 31, 2017, 2016, and 2015 of approximately $2.8 million, $2.9 million, and $2.8 million, respectively.

Deferred income

Deferred income is primarily comprised of the following items:


•	prepaid rent from tenants; and


•	tenant reimbursements related to operating expense or property tax expenses which may be due to tenants as part of an annual operating expense reconciliation.

Deferred income related to prepaid rents from tenants will be recognized as income in the period it is earned. Amounts related to operating expense reconciliations or property tax expense are relieved when the tenant's reconciliation is completed in accordance with the underlying lease, and payment is issued to the tenant.

Shares-in-trust

To date, Piedmont has not issued any shares-in-trust; however, under Piedmont’s charter, it has authority to issue a total of 150,000,000 shares-in-trust, which would be issued only in the event that there is a purported transfer of, or other change in or affecting the ownership of, Piedmont’s capital stock that would result in a violation of the ownership limits that are included in Piedmont’s charter to protect its REIT status.

Preferred Stock

To date, Piedmont has not issued any shares of preferred stock; however, Piedmont is authorized to issue up to 100,000,000 shares of one or more classes or series of preferred stock. Piedmont’s board of directors may determine the relative rights, preferences, and privileges of any class or series of preferred stock that may be issued, and can be more beneficial than the rights, preferences, and privileges attributable to Piedmont’s common stock.

Common Stock

Under Piedmont’s charter, it has authority to issue a total of 750,000,000 shares of common stock with a par value of $0.01 per share. Each share of common stock is entitled to one vote and participates in distributions equally. The board of directors of Piedmont authorized in May 2017 the repurchase and retirement of up to $250 million of Piedmont's common stock between May 2, 2017 and May 2, 2019. Piedmont may repurchase the shares from time to time, in accordance with applicable securities laws, in the open market or in privately negotiated transactions. The timing of repurchases is dependent upon market conditions and other factors, and repurchases may be commenced or suspended from time to time in Piedmont's discretion, without prior notice. As of December 31, 2017, Piedmont had approximately $188.2 million in remaining capacity under the program which may be used for share repurchases through May 2019. See Note 19 for additional information.

Dividends

As a REIT, Piedmont is required by the Internal Revenue Code of 1986, as amended (the “Code”), to make distributions to stockholders each taxable year equal to at least 90% of its annual taxable income, computed without regard to the dividends-paid deduction and by excluding net capital gains attributable to stockholders (“REIT taxable income”). Piedmont sponsors a dividend reinvestment plan ("DRP") pursuant to which common stockholders may elect (if their brokerage agreements allow) to reinvest an amount equal to the dividends declared on their common shares into additional shares of Piedmont’s common stock in lieu of receiving cash dividends. Under the DRP, Piedmont has the option to either issue shares purchased in the open market or issue shares directly from Piedmont's authorized but unissued shares, in both cases at a 2% discount for the stockholder. Such election takes place at the settlement of each quarterly and/or special dividend in which there are participants in the DRP, and may change from quarter to quarter based on management's judgment of the best use of proceeds for Piedmont.

Noncontrolling Interest

Noncontrolling interest is the equity interest of consolidated entities that is not owned by Piedmont. Noncontrolling interest is adjusted for the noncontrolling partners' share of contributions, distributions, and earnings (losses) in accordance with the respective partnership agreement. Earnings allocated to such noncontrolling partners are recorded as income applicable to noncontrolling interest in the accompanying consolidated statements of income.

Revenue Recognition

All leases of real estate assets held by Piedmont are classified as operating leases, and the related base rental income is recognized on a straight-line basis over the terms of the respective leases. Tenant reimbursements are recognized as revenue in the period that the related operating cost is incurred. Rents and tenant reimbursements collected in advance are recorded as deferred income in the accompanying consolidated balance sheets. Property management fee revenue is recognized in the period in which the services are performed. Lease termination revenues are recognized ratably as rental revenue over the revised remaining lease term after giving effect to the termination notice. Contingent rental income recognition is deferred until the specific lease-related targets are achieved.

Gains on the sale of real estate assets are recognized upon completing the sale and, among other things, determining the sale price and transferring all of the risks and rewards of ownership without significant continuing involvement with the purchaser. Recognition of all or a portion of the gain would be deferred until both of these conditions are met. Losses are primarily recognized through impairment charges when identified.

Stock-based Compensation

Piedmont has issued stock-based compensation in the form of restricted stock to its employees and directors. For employees, such compensation has been issued pursuant to Piedmont's Long-term Incentive Compensation ("LTIC") program. The LTIC program is comprised of an annual restricted stock grant component (the "Restricted Stock Award" program) and a multi-year performance share component (the "Performance Share" program). Awards granted pursuant to the Restricted Stock Award and Performance Share programs, as well as director's awards, are classified as equity awards or liability awards based on the underlying terms of the program agreement. Awards classified as equity awards are expensed straight-line over the vesting period, with issuances recorded as a reduction to additional paid in capital. Awards classified as liability awards are expensed over the service period, with issuances recorded as a reduction to accrued expense. The compensation expense recognized related to both of these award types is recorded as property operating costs for those employees whose job is related to property operations and as general and administrative expense for all other employees and directors in the accompanying consolidated statements of income.

Non-qualified Deferred Compensation Plan

Additionally, Piedmont has a non-qualified deferred compensation plan which allows certain employees to elect to defer their receipt of compensation, including both cash and stock-based compensation, until future taxable years. Amounts deferred are invested in trading securities held in a "rabbi trust" and are measured using quoted market prices as of the reporting date. As of December 31, 2017, Piedmont held approximately $0.8 million of these trading securities. Such investments are included in cash equivalents due to their short-term, liquid nature, with the corresponding liability included in accounts payable, accrued expenses, dividends payable, and accrued capital expenditures in the accompanying consolidated balance sheets.

Legal Fees and Related Insurance Recoveries

Piedmont recognizes legal expenses in the period in which services are rendered as a component of general and administrative expense for routine corporate matters or as property operating costs for legal expenses attributable to operating properties. Insurance reimbursements related to ongoing legal matters are recorded as a reduction of legal expense in the period that the insurance company definitively notifies Piedmont of its intent to issue payment.

Casualty Losses and Related Insurance Recoveries

From time to time, specific assets may be damaged or destroyed by natural disasters. Such damages may result in significant expenses related to the destruction of fixed assets or costs to clean, repair, and establish emergency operations at the building or buildings affected by the casualty event. In addition, Piedmont may recognize expenses as a result of issuing rent abatements to tenants for business interruptions caused by the tenants' inability to access the space that they lease from Piedmont. Losses related to the above items are estimated and recorded in the period incurred without regard to whether the loss may be ultimately recoverable under Piedmont's various insurance policies. Any related insurance recoveries are recorded as income in the period that the insurance company definitively notifies Piedmont of its intent to issue payment. During the years ended December 31, 2017, 2016, and 2015, Piedmont recorded net casualty recoveries/(loss) related to Hurricane Sandy of approximately $0, $34,000 and $(0.3) million, respectively. The net casualty loss for the year ended December 31, 2015 included $0.3 million of business interruption recoveries.

Discontinued Operations

Operational results related to properties sold or held for sale prior to Piedmont's adoption of Accounting Standards Update No. 2014-08, Presentation of Financial Statements (Topic 205) and Property, Plant, and Equipment (Topic 360): Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity ("ASU 2014-08") continue to be presented as discontinued operations in the accompanying consolidated statements of income. Subsequent to the adoption of ASU 2014-08, gains and losses on sales related to properties that do not meet the revised definition of discontinued operations and the operational results of these properties are included in income from continuing operations, while the gain on sale is presented between discontinued operations and net income. These gains and/or losses, however, are included in continuing operations for purposes of calculating earnings per share data.

Net Income Available to Common Stockholders Per Share

Net income per share-basic is calculated as net income available to common stockholders divided by the weighted average number of common shares outstanding during the period. Net income per share-diluted is calculated as net income available to common stockholders divided by the diluted weighted average number of common shares outstanding during the period, including the dilutive effect of nonvested restricted stock. The dilutive effect of nonvested restricted stock is calculated using the treasury stock method to determine the number of additional common shares that would become outstanding if the remaining unvested restricted stock awards vested.

Income Taxes

Piedmont has elected to be taxed as a REIT under the Code, and has operated as such, beginning with its taxable year ended December 31, 1998. To qualify as a REIT, Piedmont must meet certain organizational and operational requirements, including a requirement to distribute at least 90% of its annual REIT taxable income. As a REIT, Piedmont is generally not subject to federal income taxes, subject to fulfilling, among other things, this distribution requirement. However, Piedmont is subject to federal income taxes related to the operations conducted by its taxable REIT subsidiary, POH, which have been provided for in the financial statements. Accordingly, the only provision for federal income taxes in the accompanying consolidated financial statements relates to POH. POH does not have significant tax provisions or deferred income tax items. These operations resulted in approximately $13,000, $415,000, and $85,000 in income tax expense for the years ended December 31, 2017, 2016, and 2015, respectively, as a component of other income/(expense) in the accompanying consolidated statements of income. Further, Piedmont is subject to certain state and local taxes related to the operations of properties in certain locations, which have been provided for in general and administrative expenses in the accompanying consolidated financial statements.

Reclassifications

Certain prior period amounts have been reclassified to conform to the current period financial statement presentation. The reclassifications relate to: (i) properties classified as held for sale as of March 31, 2017, June 30, 2017, September 30, 2017, and December 31, 2017 have been reclassified as held for sale as of December 31, 2016 for comparative purposes (see Note 14).

Accounting Pronouncements Adopted during the Year Ended December 31, 2017

As mentioned in Goodwill above, Piedmont early adopted the provisions of ASU 2017-04 on a prospective basis beginning with the annual test of impairment as of December 31, 2017. The provisions in ASU 2017-04 simplify the testing of goodwill for impairment and the implementation did not result in any change to current or previously reported information. Additionally, as of December 31, 2017, Piedmont early adopted the provisions of FASB Accounting Standards Update No. 2016-18 Statement of Cash Flows (Topic 230), Restricted Cash (a consensus of the FASB Emerging Issues Task Force) in the accompanying consolidated statements of cash flows for all years presented on a retrospective basis. See Note 15 for additional required disclosures.

Other Recent Accounting Pronouncements

The Financial Accounting Standards Board (the "FASB") has issued Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers (Topic 606) ("ASU 2014-09"). The amendments in ASU 2014-09, which are further clarified in ASUs 2016-08,10, 12, 20 and 2017-13 and 14 (collectively the "Revenue Recognition Amendments"), change the criteria for the recognition of certain revenue streams to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services using a five-step determination process. Substantially all of Piedmont's total revenues are derived from either long-term leases with its tenants or reimbursement of operating expenses, which are excluded, or expected to be excluded, from the scope of the Revenue Recognition Amendments. Piedmont's revenues which fall under the scope of the Revenue Recognition Amendments, which are effective in the first quarter of 2018 for Piedmont, include its property management fee revenues and certain of its parking and fiber or antennae fee income arrangements. Lease contracts and reimbursement revenues (provided certain conditions are met) are specifically excluded, or expected to be excluded, from the scope of the Revenue Recognition Amendments. Management has substantially completed its assessment of the impact of adoption of the Revenue Recognition Amendments and does not anticipate any material impact to its consolidated financial statements as a result of adoption.

The FASB has issued Accounting Standards Update No. 2017-05, Other Income—Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets ("ASU 2017-05"). The provisions of ASU 2017-05 define the term "in substance nonfinancial asset" as a financial asset promised to a counterparty in a contract if substantially all of the fair value of the assets (recognized and unrecognized) is concentrated in nonfinancial assets. Further, it states that nonfinancial assets should be derecognized once the counterparty obtains control. Finally, the amendments provide clarification for partial sales of nonfinancial assets. ASU 2017-05 is effective concurrent with the Revenue Recognition Amendments (detailed above), which will be the first quarter of 2018 for Piedmont. Although management continues to evaluate the guidance and disclosures required by ASU 2017-05, Piedmont does not anticipate a material change in how it recognizes, measures, or classifies the gains or losses on the disposition of real estate in its consolidated financial statements as a result of adoption.

The FASB has issued Accounting Standards Update No. 2016-01, Financial Instruments - Overall (Subtopic 825-10), Recognition and Measurement of Financial Assets and Financial Liabilities ("ASU 2016-01"). The amendments in ASU 2016-01 require equity investments, except those accounted for under the equity method of accounting, to be measured at estimated fair value with changes in fair value recognized in net income. Additionally, ASU 2016-01 simplifies the impairment assessment of equity investments, and eliminates certain disclosure requirements. The amendments in ASU 2016-01 are effective in the first quarter of 2018, and Piedmont does not anticipate any material impact to its consolidated financial statements as a result of adoption.

The FASB has issued ASU 2016-02, which fundamentally changes the definition of a lease, as well as the accounting for operating leases by requiring lessees to recognize assets and liabilities which arise from the lease, consisting of a liability to make lease payments (the lease liability) and a right-of-use asset, representing the right to use the leased asset over the term of the lease. Accounting for leases by lessors is substantially unchanged from prior practice as lessors will continue to recognize lease revenue on a straight-line basis; however, ASU 2016-02 currently defines certain tenant reimbursements as non-lease components which will be subject to the guidance under ASU 2014-09; however under proposed Topic 842, lessors may elect a practical expedient not to separate components in a lease contract provided certain components are met. The amendments in ASU 2016-02 are effective in the first quarter of 2019, and Piedmont is currently evaluating the potential impact of adoption.

The FASB has issued Accounting Standards Update No. 2017-12, Derivatives and Hedging: Targeted Improvements to Accounting for Hedging Activities ("ASU 2017-12"). The purpose of this updated guidance is to better align a company’s financial reporting for hedging activities with the economic objectives of those activities. ASU 2017-12 is effective for Piedmont in first quarter 2019, with early adoption, including adoption in an interim period, permitted. ASU 2017-12 requires a modified retrospective transition method in which Piedmont will recognize the cumulative effect of the change on the opening balance of each affected component of equity in the statement of financial position as of the date of adoption. While management continues to assess all potential impacts of the standard, Piedmont does not anticipate any material impact to its consolidated financial statements as a result of adoption.

The FASB has issued Accounting Standards Update No. 2016-13, Financial Instruments—Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments ("ASU 2016-13"). The provisions of ASU 2016-13 replace the "incurred loss" approach with an "expected loss" model for impairing trade and other receivables, held-to-maturity debt securities, net investment in leases, and off-balance-sheet credit exposures, which will generally result in earlier recognition of allowances for credit losses. Additionally, the provisions change the classification of credit losses related to available-for-sale securities to an allowance, rather than a direct reduction of the amortized cost of the securities. ASU 2016-13 is effective in the first quarter of 2020, with early adoption permitted as of January 1, 2019. Piedmont is currently evaluating the potential impact of adoption.

Acquisitions

12 Months Ended

Dec. 31, 2017

Business Combinations [Abstract]

Acquisitions

During the year ended December 31, 2017, Piedmont acquired one property using proceeds from the sale of other assets and cash on hand, as follows:



Property	Metropolitan Statistical Area	Date of Acquisition	Ownership Percentage Acquired		Rentable Square Feet (Unaudited)	Percentage Leased as of Acquisition (Unaudited)		Net Contractual Purchase Price (in millions)
Norman Pointe I	Minneapolis, Minnesota	December 28, 2017	100	%	213,851	71	%	$	35.2

Debt

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Debt

During the year ended December 31, 2017, Piedmont fully repaid the $140 Million WDC Fixed-Rate Loans prior to the maturity date without penalty and had net repayments on its $500 Million Unsecured 2015 Line of Credit of approximately $155.0 million, using a portion of the net proceeds from the sale of the Two Independence Square building located in Washington, D.C (see Note 14).

Subsequent to December 31, 2017, Piedmont fully repaid the balances of the $300 Million Unsecured 2013 Term Loan and the $170 Million Unsecured 2015 Term Loan using proceeds from the 2017 Disposition Portfolio (see Note 14) and cash on hand, as well as drawing on its $500 Million Unsecured 2015 Line of Credit.

As of December 31, 2017, Piedmont believes it was in compliance with all financial covenants associated with its debt instruments. See Note 8 for a description of Piedmont’s estimated fair value of debt as of December 31, 2017.

The following table summarizes the terms of Piedmont’s indebtedness outstanding as of December 31, 2017 and 2016, including net discounts/premiums and unamortized debt issuance costs (in thousands):



Facility ⁽¹⁾	Stated Rate		Effective Rate ⁽²⁾			Maturity		Amount Outstanding as of
Facility ⁽¹⁾	Stated Rate		Effective Rate ⁽²⁾			Maturity		2017			2016
Secured (Fixed)
$140 Million WDC Fixed-Rate Loans	5.76	%	5.76	%		11/1/2017		$	—		$	140,000
$35 Million Fixed-Rate Loan ⁽³⁾	5.55	%	3.75	%		9/1/2021		30,670			31,583
$160 Million Fixed-Rate Loan ⁽⁴⁾	3.48	%	3.58	%		7/5/2022		160,000			160,000
Net premium and unamortized debt issuance costs								946			1,161
Subtotal/Weighted Average ⁽⁵⁾	3.81	%						191,616			332,744
Unsecured (Variable and Fixed)
$170 Million Unsecured 2015 Term Loan ⁽⁶⁾	LIBOR + 1.125%		2.54	%		5/15/2018		170,000		⁽⁷⁾	170,000
$300 Million Unsecured 2013 Term Loan	LIBOR + 1.20%		2.78	%	⁽⁸⁾	1/31/2019		300,000		⁽⁷⁾	300,000
$500 Million Unsecured 2015 Line of Credit ⁽⁶⁾	LIBOR + 1.00%		2.57	%		6/18/2019	⁽⁹⁾	23,000			178,000
$300 Million Unsecured 2011 Term Loan	LIBOR + 1.15%		3.35	%	⁽⁸⁾	1/15/2020		300,000			300,000
$350 Million Unsecured Senior Notes	3.40	%	3.43	%		6/01/2023		350,000			350,000
$400 Million Unsecured Senior Notes	4.45	%	4.10	%		3/15/2024		400,000			400,000
Discounts and unamortized debt issuance costs								(7,689)			(10,269)
Subtotal/Weighted Average ⁽⁵⁾	3.43	%						1,535,311			1,687,731
Total/Weighted Average ⁽⁵⁾	3.48	%						$	1,726,927		$	2,020,475


⁽¹⁾	Other than the $35 Million Fixed-Rate Loan, all of Piedmont’s outstanding debt as of December 31, 2017 and 2016 is interest-only.


⁽²⁾	Effective rate after consideration of settled or in-place interest rate swap agreements, issuance premiums/discounts, and/or fair market value adjustments upon assumption of debt.


⁽³⁾	Collateralized by the 5 Wall Street building in Burlington, Massachusetts.


⁽⁴⁾	Collateralized by the 1901 Market Street building in Philadelphia, Pennsylvania.


⁽⁵⁾	Weighted average is based on contractual balance of outstanding debt and the stated or effectively fixed interest rates in the table as of December 31, 2017.


⁽⁶⁾	On a periodic basis, Piedmont may select from multiple interest rate options, including the prime rate and various-length LIBOR locks. All LIBOR selections are subject to an additional spread over the selected rate based on Piedmont’s current credit rating.


⁽⁷⁾	On January 4, 2018, Piedmont repaid the entire outstanding balance of the $170 Million Unsecured 2015 Term Loan and the $300 Million Unsecured 2013 Term Loan without penalty.


⁽⁸⁾	Facility has a stated variable rate; however, Piedmont has entered into interest rate swap agreements which effectively fix, exclusive of Piedmont's credit rating, the rate shown as the effective rate.


⁽⁹⁾	Piedmont may extend the term for up to one additional year (through two available six month extensions to a final extended maturity date of June 18, 2020) provided Piedmont is not then in default and upon payment of extension fees.

A summary of Piedmont's consolidated principal outstanding for aggregate debt maturities of its indebtedness as of December 31, 2017, is provided below (in thousands):



2018	$	170,882	⁽¹⁾
2019	324,014		⁽¹⁾ ⁽²⁾
2020	301,072
2021	27,702
2022	160,000
Thereafter	750,000
Total	$	1,733,670


⁽¹⁾	On January 4, 2018, Piedmont repaid the entire outstanding balance of the $170 Million Unsecured 2015 Term Loan and the $300 Million Unsecured 2013 Term Loan without penalty, which were scheduled to mature on May 15, 2018 and January 31, 2019, respectively.


⁽²⁾	Includes the balance outstanding as of December 31, 2017 on the $500 Million Unsecured 2015 Line of Credit of $23 million. However, Piedmont may extend the term for up to one additional year (through two available six month extensions to a final extended maturity date of June 18, 2020) provided Piedmont is not then in default and upon payment of extension fees.

Piedmont’s weighted-average interest rate as of December 31, 2017 and 2016, for the aforementioned borrowings was approximately 3.48% and 3.43%, respectively. Piedmont made interest payments on all indebtedness, including interest rate swap cash settlements of approximately $67.6 million, $69.0 million, and $76.4 million during the years ended December 31, 2017, 2016, and 2015, respectively.

Variable Interest Entities and Equity Participation Rights

12 Months Ended

Dec. 31, 2017

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Variable Interest Entities and Equity Participation Rights

Variable interest holders who have the power to direct the activities of the VIE that most significantly impact the entity’s economic performance and have the obligation to absorb the majority of losses of the entity or the right to receive significant benefits of the entity must consolidate the VIE. Each of the following VIEs has the sole purpose of holding land and office buildings and their resulting operations, and are classified in the accompanying consolidated balance sheets in the same manner as Piedmont’s wholly-owned properties.

A summary of Piedmont’s interests in its consolidated VIEs and their related carrying values as of December 31, 2017 and 2016 is as follows (net carrying amount in millions):



Entity	Piedmont’s % Ownership of Entity			Related Building	Net Carrying Amount as of December 31, 2017		Net Carrying Amount as of December 31, 2016			Primary Beneficiary Considerations
1201 Eye Street N.W. Associates, LLC	98.6	%	⁽¹⁾	1201 Eye Street	$	81.1	$	(6.7	)	In accordance with the partnership’s governing documents, Piedmont currently receives 100% of the cash flow of the entity and has sole discretion in directing the management and leasing activities of the building.
1225 Eye Street N.W. Associates, LLC	98.1	%	⁽¹⁾	1225 Eye Street	$	65.2	$	9.9		In accordance with the partnership’s governing documents, Piedmont currently receives 100% of the cash flow of the entity and has sole discretion in directing the management and leasing activities of the building.
Piedmont 500 W. Monroe Fee, LLC	100	%		500 W. Monroe	$	263.2	$	262.4		The Omnibus Agreement with the previous owner includes equity participation rights upon sale of the property for the previous owner, if certain financial returns are achieved; however, Piedmont has sole decision making authority and is entitled to 100% of the economic benefits of the property until such returns are met.


⁽¹⁾	During the year ended December 31, 2017, Piedmont repaid the $140 million mortgage secured by the 1201 and 1225 Eye Street properties, and recapitalized the LLCs holding each asset, increasing Piedmont's ownership from 49.5% in each of the LLCs to the amounts stated above.

Derivative Instruments

12 Months Ended

Dec. 31, 2017

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Instruments

Risk Management Objective of Using Derivatives

In addition to operational risks which arise in the normal course of business, Piedmont is exposed to economic risks such as interest rate, liquidity, and credit risk. In certain situations, Piedmont has entered into derivative financial instruments such as interest rate swap agreements and other similar agreements to manage interest rate risk exposure arising from current or future variable rate debt transactions. Interest rate swap agreements involve the receipt or payment of future known and uncertain cash amounts, the value of which are determined by interest rates. Piedmont’s objective in using interest rate derivatives is to add stability to interest expense and to manage its exposure to interest rate movements.

Cash Flow Hedges of Interest Rate Risk

Interest rate swaps designated as cash flow hedges involve the receipt of variable-rate amounts from a counterparty in exchange for Piedmont making fixed-rate payments over the life of the agreements without changing the underlying notional amount. As of December 31, 2017, Piedmont was party to various interest rate swap agreements, all of which are designated as effective cash flow hedges and fully hedge the variable cash flows covering the entire outstanding balances of the $300 Million Unsecured 2011 Term Loan and the $300 Million Unsecured 2013 Term Loan. The maximum length of time over which Piedmont is hedging its exposure to the variability in future cash flows for forecasted transactions is 24 months.

A detail of Piedmont’s interest rate derivatives outstanding as of December 31, 2017 is as follows:

Interest Rate Derivatives:

Number of Swap Agreements

Associated Debt Instrument

Notional Amount

(in millions)

Effective Date

Maturity Date

Interest rate swaps

⁽¹⁾

$300 Million Unsecured 2013 Term Loan

200

1/30/2014

1/31/2019

Interest rate swaps

⁽¹⁾

$300 Million Unsecured 2013 Term Loan

100

8/29/2014

1/31/2019

Interest rate swaps

$300 Million Unsecured 2011 Term Loan

300

11/22/2016

1/15/2020

Total

600

⁽¹⁾

In January 2018, Piedmont terminated these interest rate swap agreements in conjunction with the repayment of the $300 Million Unsecured 2013 Term Loan (see Note 5 above). As a result of the termination, Piedmont received approximately $0.8 million from its counterparties for settlement of swaps and will recognize a net, non-cash loss of approximately $1.1 million in its statement of operations for the three months ending March 31, 2018.

Piedmont presents its interest rate derivatives on its consolidated balance sheets on a gross basis as interest rate swap assets and interest rate swap liabilities. A detail of Piedmont’s interest rate derivatives on a gross and net basis as of December 31, 2017 and 2016, respectively, is as follows (in thousands):



Interest rate swaps classified as:	December 31, 2017			December 31, 2016
Gross derivative assets	$	688		$	—
Gross derivative liabilities	(1,478		)	(8,169		)
Net derivative liability	$	(790	)	$	(8,169	)

The effective portion of Piedmont's interest rate derivatives, including any gain/(loss) associated with any early settlements or terminations of swaps, that was recorded in the accompanying consolidated statements of income for the years ended December 31, 2017, 2016, and 2015, respectively, was as follows (in thousands):



Interest Rate Swaps in Cash Flow Hedging Relationships	2017		2016			2015
Amount of gain/(loss) recognized in OCI on derivatives	$	2,479	$	(4,126	)	$	(12,509	)
Amount of previously recorded loss reclassified from accumulated OCI into interest expense	$	3,502	$	4,548		$	5,875

Piedmont estimates that approximately $0.7 million will be reclassified from accumulated other comprehensive income as a reduction to interest expense over the next twelve months. Piedmont recognized approximately $0, $0, and $37,000 of net loss related to hedge ineffectiveness and terminations of its cash flow hedges during the years ended December 31, 2017, 2016, and 2015, respectively.

Additionally, see Note 8 for fair value disclosures of Piedmont's derivative instruments.

Credit-risk-related Contingent Features

Piedmont has agreements with its derivative counterparties that contain a provision whereby if Piedmont defaults on any of its indebtedness, including default where repayment of the indebtedness has not been accelerated by the lender, then Piedmont could also be declared in default on its derivative obligations. If Piedmont were to breach any of the contractual provisions of the derivative contracts, it would be required to settle its obligations under the agreements at their termination value of the estimated fair values plus accrued interest, or approximately $0.9 million as of December 31, 2017. Additionally, Piedmont has rights of set-off under certain of its derivative agreements related to potential termination fees and amounts payable under the agreements, if a termination were to occur.

Fair Value Measurements

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Fair Value Measurements

Piedmont considers its cash and cash equivalents, tenant receivables, notes receivable, restricted cash and escrows, accounts payable and accrued expenses, interest rate swap agreements, and debt to meet the definition of financial instruments. The following table sets forth the carrying and estimated fair value for each of Piedmont’s financial instruments, as well as its level within the GAAP fair value hierarchy, as of December 31, 2017 and 2016, respectively (in thousands):



	December 31, 2017					December 31, 2016
Financial Instrument	Carrying Value		Estimated Fair Value		Level Within Fair Value Hierarchy	Carrying Value		Estimated Fair Value		Level Within Fair Value Hierarchy
Assets:
Cash and cash equivalents ⁽¹⁾	$	7,382	$	7,382	Level 1	$	6,992	$	6,992	Level 1
Tenant receivables, net ⁽¹⁾	$	12,139	$	12,139	Level 1	$	26,494	$	26,494	Level 1
Restricted cash and escrows ⁽¹⁾	$	1,373	$	1,373	Level 1	$	1,212	$	1,212	Level 1
Interest rate swap asset	$	688	$	688	Level 2	$	—	$	—	Level 2
Liabilities:
Accounts payable and accrued expenses ⁽¹⁾	$	126,429	$	126,429	Level 1	$	44,733	$	44,733	Level 1
Interest rate swap liability	$	1,478	$	1,478	Level 2	$	8,169	$	8,169	Level 2
Debt, net	$	1,726,927	$	1,759,905	Level 2	$	2,020,475	$	2,027,436	Level 2


⁽¹⁾	For the periods presented, the carrying value of these financial instruments approximates estimated fair value due to its short-term maturity.

Piedmont's debt was carried at book value as of December 31, 2017 and 2016; however, Piedmont's estimate of its fair value is disclosed in the table above. Piedmont uses widely accepted valuation techniques including discounted cash flow analysis based on the contractual terms of the debt facilities, including the period to maturity of each instrument, and uses observable market-based inputs for similar debt facilities which have transacted recently in the market. Therefore, the estimated fair values determined are considered to be based on significant other observable inputs (Level 2). Scaling adjustments are made to these inputs to make them applicable to the remaining life of Piedmont's outstanding debt. Piedmont has not changed its valuation technique for estimating the fair value of its debt.

Piedmont’s interest rate swap agreements presented above, and further discussed in Note 7, are classified as “Interest rate swap” assets and liabilities in the accompanying consolidated balance sheets and were carried at estimated fair value as of December 31, 2017 and 2016. The valuation of these derivative instruments was determined using widely accepted valuation techniques including discounted cash flow analysis based on the contractual terms of the derivatives, including the period to maturity of each instrument, and uses observable market-based inputs, including interest rate curves and implied volatilities. Therefore, the estimated fair values determined are considered to be based on significant other observable inputs (Level 2). In addition, Piedmont considered both its own and the respective counterparties’ risk of nonperformance in determining the estimated fair value of its derivative financial instruments by estimating the current and potential future exposure under the derivative financial instruments that both Piedmont and the counterparties were at risk for as of the valuation date. The credit risk of Piedmont and its counterparties was factored into the calculation of the estimated fair value of the interest rate swaps; however, as of December 31, 2017 and 2016, this credit valuation adjustment did not comprise a material portion of the estimated fair value. Therefore, Piedmont believes that any unobservable inputs used to determine the estimated fair values of its derivative financial instruments are not significant to the fair value measurements in their entirety, and does not consider any of its derivative financial instruments to be Level 3 assets or liabilities.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Impairment Loss on Real Estate Assets

12 Months Ended

Dec. 31, 2017

Real Estate [Abstract]

Impairment Loss on Real Estate Assets

Piedmont recorded impairment loss on real estate assets for the years ended December 31, 2017, 2016, and 2015 (in thousands):



	2017		2016		2015
Eastpoint I & II ⁽¹⁾	$	—	$	—	$	6,195
2 Gatehall Drive ⁽¹⁾	—		—		37,106
150 West Jefferson ⁽¹⁾	—		8,259		—
9221 Corporate Boulevard ⁽²⁾	—		2,692		—
9200 and 9211 Corporate Boulevard ⁽³⁾	—		22,950		—
Disposal Group of 13 Assets ⁽⁴⁾	46,461		—		—
Total impairment loss on real estate assets ⁽⁵⁾	$	46,461	$	33,901	$	43,301


⁽¹⁾	Piedmont recognized an impairment loss on real estate assets based upon the difference between the carrying value of the asset including a proportionate amount of goodwill (because the asset met the definition of a disposed "business" at the time of measurement) and the contracted sales price, less estimated selling costs.

⁽²⁾

Piedmont, using a probability-weighted model heavily weighted towards the short-term sale of the 9221 Corporate Boulevard building in Rockville, Maryland, determined that the carrying value would not be recovered from the undiscounted future operating cash flows expected from the use of the asset and its eventual disposition. As a result, Piedmont recognized a loss on impairment of approximately $2.7 million during the year ended December 31, 2016 calculated as the difference between the carrying value of the asset including a proportionate amount of goodwill and the anticipated contract sales price, less estimated selling costs.

⁽³⁾

Piedmont elected to sell its remaining two assets and exit the Rockville, Maryland sub-market of Washington, D.C., after selling the 9221 Corporate Boulevard building in July 2016 (mentioned above). Upon management's change in its hold period assumption for the assets from a long-term hold to a near-term sale, Piedmont recognized an impairment loss of approximately $23.0 million. The impairment loss was calculated as the difference between the carrying value of the asset including a proportionate amount of goodwill and the anticipated contracted sales price, less estimated selling costs.

⁽⁴⁾

During the fourth quarter 2017, Piedmont's management changed its hold period assumption and subsequently determined that a near-term sale was more than 50% probable for a disposal group of real estate assets. Piedmont recognized an impairment loss on this disposal group (see Note 14) based upon the difference between the carrying value of the assets (which did not include a proportionate amount of goodwill because the disposal group did not meet the definition of a disposed "business" at the time of measurement) and the contracted sales price, less estimated selling costs.


⁽⁵⁾	The fair value measurements used in the evaluation of the non-financial assets above are considered to be Level 1 valuations within the fair value hierarchy as defined by GAAP, as there are direct observations and transactions involving the assets by unrelated, third party purchasers.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Commitments Under Existing Lease Agreements

Under its existing lease agreements, Piedmont may be required to fund significant tenant improvements, leasing commissions, and building improvements. In addition, certain agreements contain provisions that require Piedmont to issue corporate or property guarantees to provide funding for capital improvements or other financial obligations. Piedmont classifies its capital improvements into two categories: (i) improvements which maintain the building's existing asset value and its revenue generating capacity (“non-incremental capital expenditures”) and (ii) improvements which incrementally enhance the building's asset value by expanding its revenue generating capacity (“incremental capital expenditures”). As of December 31, 2017, after excluding the properties sold in January 2018 as part of the 2017 Disposition Portfolio, commitments to fund potential non-incremental capital expenditures over the next five years for tenant improvements totaled approximately $38.6 million related to Piedmont's existing lease portfolio over the respective lease terms, the majority of which Piedmont estimates may be required to be funded over the next three years based on when the underlying leases commence. For most of Piedmont’s leases, the timing of the actual funding of these tenant improvements is largely dependent upon tenant requests for reimbursement. In some cases, these obligations may expire with the leases without further recourse to Piedmont. As of December 31, 2017, commitments for incremental capital expenditures (exclusive of the 2017 Disposition Portfolio) for tenant improvements associated with executed leases totaled approximately $14.1 million.

Contingencies Related to Tenant Audits/Disputes

Certain lease agreements include provisions that grant tenants the right to engage independent auditors to audit their annual operating expense reconciliations. Such audits may result in the re-interpretation of language in the lease agreements which could result in the refund of previously recognized tenant reimbursement revenues, resulting in financial loss to Piedmont. Piedmont recorded reductions in reimbursement revenues related to such tenant audits/disputes of approximately $0.3 million, $1.1 million and $0.4 million during the years ended December 31, 2017, 2016, and 2015, respectively.

Operating Lease Obligations

As of December 31, 2017, the 2001 NW 64^th Street building in Ft. Lauderdale, Florida was subject to a ground lease with an expiration date in 2048. The aggregate payments required under the terms of this operating lease as of December 31, 2017 are presented below (in thousands):



2018	$	93
2019	93
2020	93
2021	93
2022	93
Thereafter	2,346
Total	$	2,811

Ground rent expense was approximately $0.1 million, $0.1 million, and $0.2 million for the years ended December 31, 2017, 2016, and 2015, respectively, and is included in property operating costs in the accompanying consolidated statements of income. The net book value of the 2001 NW 64^th Street building was approximately $4.8 million and $4.7 million as of December 31, 2017 and 2016, respectively.

On January 4, 2018, Piedmont closed on the sale of the 2001 NW 64th Street building as part of a portfolio disposition (see Note 14). The purchaser has assumed the ground lease and, as such, Piedmont will have no future operating lease obligations associated with this property. Ground rent expense for 2015 includes the River Corporate Center building located in Tempe, Arizona, which was sold in April 2015.

Litigation

Piedmont is from time to time a party to legal proceedings, which arise in the ordinary course of its business. None of these ordinary course legal proceedings are reasonably likely to have a material adverse effect on results of operations or financial condition. Piedmont is not aware of any such legal proceedings contemplated by governmental authorities.

Stock Based Compensation

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock Based Compensation

Deferred Stock Awards

The Compensation Committee of Piedmont's Board of Directors has periodically granted deferred stock awards to all of Piedmont's employees and independent directors. Employee awards typically vest ratably over a multi-year period and independent director awards vest over one year. Certain employees' long-term equity incentive program is split equally between the time-vested awards described above and a multi-year performance share program whereby the actual awards are contingent upon Piedmont's total stockholder return ("TSR") relative to a peer group's TSR. The peer group is predetermined by the Board of Directors. Any shares earned are awarded at the end of the multi-year performance period and vest upon award.

A rollforward of Piedmont's equity based award activity for the year ended December 31, 2017 is as follows:



	Shares		Weighted-Average Grant Date Fair Value
Unvested and Potential Stock Awards as of December 31, 2016	944,223		$	19.44
Deferred Stock Awards Granted	299,251		$	21.38
Increase in Estimated Potential Future Performance Share Awards, net of forfeitures	57,526		$	24.68
Performance Stock Awards Vested	(118,446	)	$	22.00
Deferred Stock Awards Vested	(305,107	)	$	19.34
Deferred Stock Awards Forfeited	(9,010	)	$	19.93
Unvested and Potential Stock Awards as of December 31, 2017	868,437		$	21.69

The following table provides additional information regarding stock award activity during the years ended December 31, 2017, 2016, and 2015 (in thousands except for per share data):



	2017		2016		2015
Weighted-Average Grant Date Fair Value of Deferred Stock Granted During the Period (per share)	$	21.38	$	19.96	$	17.59
Total Grant Date Fair Value of Deferred Stock Vested During the Period	$	5,899	$	4,806	$	4,239
Share-based Liability Awards Paid During the Period ⁽¹⁾	$	2,877	$	1,127	$	—


⁽¹⁾	Amounts reflect the issuance of performance share awards related to the 2014-16 and 2013-15 Performance Share Plans during the years ended December 31, 2017 and 2016, respectively.

A detail of Piedmont’s outstanding employee deferred stock awards as of December 31, 2017 is as follows:



Date of grant	Type of Award	Net Shares Granted ⁽¹⁾	Grant Date Fair Value		Vesting Schedule	Unvested and Potential Shares as of December 31, 2017
January 3, 2014	Deferred Stock Award	79,119	$	16.45	Of the shares granted, 20% vested or will vest on January 3, 2015, 2016, 2017, 2018, and 2019, respectively.	32,829
May 1, 2015	Deferred Stock Award	216,811	$	17.59	Of the shares granted, 25% vested on the date of grant, and 25% of the shares vest on May 1, 2016, 2017, and 2018, respectively.	66,922
May 1, 2015	Fiscal Year 2015-2017 Performance Share Program	—	$	18.42	Shares awarded, if any, will vest immediately upon determination of award in 2018.	161,005	⁽²⁾
May 24, 2016	Deferred Stock Award	232,960	$	19.91	Of the shares granted, 25% vested on the date of grant, and 25% of the shares vest on May 24, 2017, 2018, and 2019, respectively.	132,195
May 24, 2016	Fiscal Year 2016-2018 Performance Share Program	—	$	23.02	Shares awarded, if any, will vest immediately upon determination of award in 2019.	122,154	⁽²⁾
May 18, 2017	Deferred Stock Award-Board of Directors	26,187	$	21.38	Of the shares granted, 100% will vest by May 18, 2018.	26,187
May 18, 2017	Deferred Stock Award	246,671	$	21.38	Of the shares granted, 25% vested on the date of grant, and 25% vested or will vest on May 18, 2018, 2019, and 2020, respectively.	199,810
May 18, 2017	Fiscal Year 2017-2019 Performance Share Program	—	$	30.45	Shares awarded, if any, will vest immediately upon determination of award in 2020.	127,335	⁽²⁾
Total Unvested and Potential Stock Awards						868,437


⁽¹⁾	Amounts reflect the total grant to employees and independent directors, net of shares surrendered upon vesting to satisfy required minimum tax withholding obligations through December 31, 2017.


⁽²⁾	Estimated based on Piedmont's cumulative TSR for the respective performance period through December 31, 2017. Share estimates are subject to change in future periods based upon Piedmont's relative performance compared to its peers' total stockholder return.

During the years ended December 31, 2017, 2016, and 2015, Piedmont recognized approximately $9.5 million, $8.0 million and $8.9 million of compensation expense related to stock awards, of which approximately $7.7 million, $6.5 million and $7.0 million, related to the amortization of nonvested shares, respectively. During the year ended December 31, 2017, a total of 256,628 shares were issued to employees. As of December 31, 2017, approximately $3.8 million of unrecognized compensation cost related to nonvested, annual deferred stock awards remained, which Piedmont will record in its consolidated statements of income over a weighted-average vesting period of approximately one year.

Earnings Per Share

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Earnings Per Share

There are no adjustments to “Net income applicable to Piedmont” for the diluted earnings per share computations.

Net income per share-basic is calculated as net income available to common stockholders divided by the weighted average number of common shares outstanding during the period. Net income per share-diluted is calculated as net income available to common stockholders divided by the diluted weighted average number of common shares outstanding during the period, including unvested deferred stock awards. Diluted weighted average number of common shares reflects the potential dilution under the treasury stock method that would occur if the remaining unvested deferred stock awards vested and resulted in additional common shares outstanding. Unvested deferred stock awards which are determined to be anti-dilutive are not included in the calculation of diluted weighted average common shares.

The following table reconciles the denominator for the basic and diluted earnings per share computations shown on the consolidated statements of income for the years ended December 31, 2017, 2016, and 2015, respectively (in thousands):



	2017	2016	2015
Weighted-average common shares—basic	145,044	145,230	150,538
Plus: Incremental weighted-average shares from time-vested deferred and performance stock awards	336	405	342
Weighted-average common shares—diluted	145,380	145,635	150,880

Common stock issued and outstanding as of period end	142,359	145,235	145,512

Operating Leases

12 Months Ended

Dec. 31, 2017

Leases [Abstract]

Operating Leases

Piedmont’s real estate assets are leased to tenants under operating leases for which the terms vary, including certain provisions to extend the lease term, options for early terminations subject to specified penalties, and other terms and conditions as negotiated. Piedmont retains substantially all of the risks and benefits of ownership of the real estate assets leased to tenants. Amounts required as security deposits vary depending upon the terms of the respective leases and the creditworthiness of the tenant; however, generally they are not significant. Exposure to credit risk is limited to the extent that tenant receivables exceed this amount. Security deposits related to tenant leases are included in accounts payable, accrued expenses, dividends payable, and accrued capital expenditures in the accompanying consolidated balance sheets.

As of December 31, 2017, approximately 88% of Piedmont's ALR (unaudited) was generated from select sub-markets located primarily within eight major office markets located in the Eastern-half of the United States: Atlanta, Boston, Chicago, Dallas, Minneapolis, New York, Orlando, and Washington, D.C. Furthermore, approximately 1.9% of Piedmont's ALR (unaudited) is generated from federal governmental agencies.

The future minimum rental income from Piedmont’s investment in real estate assets under non-cancelable operating leases is presented below in total for properties held for use and held for sale as of December 31, 2017, as well as exclusive of properties which were held for sale as of December 31, 2017 and subsequently sold on January 4, 2018 (see Note 14 below) (in thousands):



Years ending December 31:	All properties owned as of December 31, 2017		Excluding properties held for sale as of December 31, 2017
2018	$	417,643	$	377,447
2019	401,120		361,280
2020	377,556		338,269
2021	344,991		307,008
2022	316,053		287,175
Thereafter	1,348,156		1,298,890
Total	$	3,205,519	$	2,970,069

Property Dispositions, Assets Held for Sale and Discontinued Operations

12 Months Ended

Dec. 31, 2017

Discontinued Operations and Disposal Groups [Abstract]

Property Dispositions, Assets Held for Sale, and Discontinued Operations

Property Dispositions

Since the adoption of ASU 2014-08 during the year ended December 31, 2014, none of Piedmont's property dispositions have met the criteria to be reported as discontinued operations. The operational results for periods prior to sale for properties sold since the adoption of ASU 2014-08 are presented as continuing operations in the accompanying consolidated statements of income, and the gain/(loss) on sale is presented separately in the consolidated statements of income unless otherwise indicated below. Details of such properties sold are presented below (in thousands):



Buildings Sold	Location	Date of Sale	Gain/(Loss) on Sale				Net Sales Proceeds
3900 Dallas Parkway	Plano, Texas	January 30, 2015	$	8,940			$	25,803
5601 Headquarters Drive	Plano, Texas	April 28, 2015	$	6,390			$	33,326
River Corporate Center	Tempe, Arizona	April 29, 2015	$	4,144			$	24,223
Copper Ridge Center	Lyndhurst, New Jersey	May 1, 2015	$	11,358			$	50,372	⁽¹⁾
Eastpoint I & II	Mayfield Heights, Ohio	July 28, 2015	$	(177	)	⁽²⁾	$	17,342
3750 Brookside Parkway	Alpharetta, Georgia	August 10, 2015	$	761			$	13,624
Chandler Forum	Chandler, Arizona	September 1, 2015	$	13,805			$	32,267
Aon Center	Chicago, Illinois	October 29, 2015	$	84,218			$	646,243
2 Gatehall Drive	Parsippany, New Jersey	December 21, 2015	$	162		⁽²⁾	$	50,369
1055 East Colorado Boulevard	Pasadena, California	April 21, 2016	$	29,462			$	60,076
Fairway Center II	Brea, California	April 28, 2016	$	14,406			$	33,062
1901 Main Street	Irvine, California	May 2, 2016	$	29,964			$	63,149	⁽³⁾
9221 Corporate Boulevard	Rockville, Maryland	July 27, 2016	$	(192	)	⁽²⁾	$	12,035
150 West Jefferson	Detroit, Michigan	July 29, 2016	$	(664	)	⁽²⁾	$	77,844
9200 and 9211 Corporate Boulevard	Rockville, Maryland	September 28, 2016	$	(41	)	⁽²⁾	$	12,519
11695 Johns Creek Parkway	Johns Creek, Georgia	December 22, 2016	$	1,978			$	13,827
Braker Pointe III	Austin, Texas	December 29, 2016	$	18,579			$	48,006
Sarasota Commerce Center II	Sarasota, Florida	June 16, 2017	$	6,493			$	23,090
Two Independence Square	Washington, D.C.	July 5, 2017	$	109,381			$	352,428
8560 Upland Drive	Denver, Colorado	July 27, 2017	$	3,683			$	12,334	⁽⁴⁾


⁽¹⁾	As part of the transaction, Piedmont accepted a secured promissory note from the buyer for the remaining $45.4 million owed on the sale. During the year ended December 31, 2016, the note receivable was repaid in full and such proceeds are reflected in the accompanying consolidated statements of cash flows as net sales proceeds from the sale of wholly-owned properties.


⁽²⁾	As discussed in Note 9 above, Piedmont recognized an impairment loss prior to, or in conjunction with, the sale of the property. Therefore, any gain/(loss) recognized upon the consummation of the sale consists solely of adjustments made subsequent to the sale for closing cost estimates or post-closing prorations.


⁽³⁾	As part of the transaction, Piedmont accepted a secured promissory note from the buyer for $33.0 million, and the note receivable was repaid in full during the year ended December 31, 2016. As such, the full proceeds from the sale of the property are reflected in the accompanying consolidated statements of cash flows as net sales proceeds from the sale of wholly-owned properties.


⁽⁴⁾	Property was owned as part of the unconsolidated joint venture, Fund XIII and REIT Joint Venture. As such, the gain on sale is presented as equity in income/(loss) of unconsolidated joint ventures. Amounts shown above reflect Piedmont's approximate 72% ownership.

Assets Held for Sale

During the fourth quarter 2017, Piedmont entered into two binding, non-refundable contracts with unrelated third party buyers to sell a 14 property portfolio (collectively, the "2017 Disposition Portfolio"), as detailed below, both of which subsequently closed on January 4, 2018. Therefore, as of December 31, 2017, the 2017 Disposition Portfolio met the criteria for held for sale classification, and such properties are shown as held for sale as of December 31, 2017 and 2016, respectively. For comparative purposes, any property which met the criteria to be presented as held for sale as of March 31, 2017, June 30, 2017, or September 30, 2017 was re-classified as held for sale as of December 31, 2016. The only additional property other than the 2017 Disposition Portfolio meeting this criteria was the Two Independence Square building (sold on July 5, 2017).

2017 Disposition Portfolio:



Building		Location
Desert Canyon 300		Phoenix, Arizona
Windy Point I and II		Schaumburg, Illinois
2300 Cabot Drive		Lisle, Illinois
1075 West Entrance Drive		Auburn Hills, Michigan
Auburn Hills Corporate Center		Auburn Hills, Michigan
5301 Maryland Way		Brentwood, Tennessee
Suwanee Gateway One		Suwanee, Georgia
5601 Hiatus Road		Tamarac, Florida
2001 NW 64th Street		Fort Lauderdale, Florida
Piedmont Pointe I & II		Bethesda, Maryland
1200 Crown Colony Drive		Quincy, Massachusetts
2120 West End Avenue		Nashville, Tennessee

Details of amounts held for sale as of December 31, 2017 and 2016 are presented below (in thousands):



	December 31, 2017		December 31, 2016
Real estate assets held for sale, net:
Land	$	74,498	$	127,209
Building and improvements, less accumulated depreciation of $169,116 and $244,269 as of December 31, 2017, and 2016, respectively	255,634		485,145
Construction in progress	2,278		365
Total real estate assets held for sale, net	$	332,410	$	612,719

Other assets held for sale, net:
Straight-line rent receivables	$	25,975	$	28,986
Prepaid expenses and other assets	328		374
Deferred lease costs, less accumulated amortization of $16,549 and $18,937 as of December 31, 2017 and 2016, respectively	20,828		29,272
Total other assets held for sale, net	$	47,131	$	58,632

Other liabilities held for sale, net:
Intangible lease liabilities, less accumulated amortization of $935 and $848 as of December 31, 2017 and 2016, respectively	$	380	$	468

Discontinued Operations

Details comprising income from discontinued operations are presented below (in thousands):



	Years Ended December 31,
	2017		2016		2015
Revenues:
Rental income	$	—	$	—	$	19
Tenant reimbursements	—		—		64
	—		—		83
Expenses:
Property operating costs	—		—		(1		)
	—		—		(1		)

Operating income, excluding loss on sale of real estate assets	—		—		84
Loss on sale of real estate assets	—		—		(1		)
Income from discontinued operations	$	—	$	—	$	83

Supplemental Disclosures for the Statement of Consolidated Cash Flows

12 Months Ended

Dec. 31, 2017

Supplemental Cash Flow Elements [Abstract]

Supplemental Disclosures for the Statement of Consolidated Cash Flows

Certain noncash investing and financing activities for the years ended December 31, 2017, 2016, and 2015 (in thousands) are outlined below:



	2017		2016		2015
Accrued capital expenditures and deferred lease costs	$	11,276	$	14,427	$	20,630
Change in accrued dividends and discount on dividend reinvestments	$	71,267	$	30,532	$	—
Change in accrued share repurchases as part of an announced plan	$	1,276	$	—	$	—
Investment in consolidated joint venture	$	63,026	$	—	$	—

The following table provides a reconciliation of cash, cash equivalents, and restricted cash and escrows reported within the consolidated balance sheets that sum to the total of the same such amounts in the consolidated statement of cash flows as of the periods ended December 31, 2017, 2016, and 2015 (in thousands).



	2017		2016		2015
Cash and cash equivalents	$	7,382	$	6,992	$	5,441
Restricted cash and escrows:
Real estate tax and escrowed cash	833		757		4,772
Security and utility deposit escrows	540		455		402
Total cash, cash equivalents, and restricted cash and escrows shown in the consolidated statement of cash flows	$	8,755	$	8,204	$	10,615

Amounts in real estate tax and escrowed cash represent deposits which are required by Piedmont’s lenders under certain of its debt agreements to escrow amounts for the payment of real estate taxes, and other amounts escrowed, for instance, earnest money deposited for the purchase of a property. Security and utility deposit escrows represent the cash held for tenants and/or Piedmont for lease related deposits.

Income Taxes

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Income Taxes

Piedmont’s income tax basis net income for the years ended December 31, 2017, 2016, and 2015, is calculated as follows (in thousands):



	2017			2016			2015
GAAP basis financial statement net income	$	133,564		$	99,732		$	131,304
Increase (decrease) in net income resulting from:
Depreciation and amortization expense recognized for financial reporting purposes in excess of/(less than) amounts recognized for income tax purposes	62,916			69,214			(1,717		)
Rental income accrued for income tax purposes less than amounts for financial reporting purposes	(25,432		)	(18,964		)	(12,123		)
Net amortization of above/below-market lease intangibles for income tax purposes in excess of amounts for financial reporting purposes	(6,041		)	(4,895		)	(4,614		)
Gain on disposal of property for financial reporting purposes less than/(in excess of) amounts for income tax purposes	10,068			(118,713		)	(43,493		)
Taxable income/(loss) of Piedmont Washington Properties, Inc., in excess of/(less than) amount for financial reporting purposes	176			(1,042		)	2,491
Other expenses, including impairment loss on real estate assets, for financial reporting purposes in excess of amounts for income tax purposes	49,859			42,019			54,425
Taxable income for Piedmont Office Holdings, Inc. in excess of/(less than) amount for financial reporting purposes	(28		)	648			—
Income tax basis net income, prior to dividends paid deduction	$	225,082		$	67,999		$	126,273

For income tax purposes, dividends to common stockholders are characterized as ordinary income, capital gains, or as a return of a stockholder’s invested capital. The composition of Piedmont’s distributions per common share is presented below:



	2017		2016		2015
Ordinary income	53.61	%	81.77	%	31.75	%
Return of capital	—	%	18.23	%	—	%
Capital gains	46.39	%	—	%	68.25	%
	100	%	100	%	100	%

As of December 31, 2017 and 2016, the tax basis carrying value of Piedmont’s total assets was approximately $4.2 billion and $4.3 billion, respectively.

Approximately $3.8 million of accrued interest and penalties related to uncertain tax positions was included in accounts payable, accrued expenses, dividends payable, and accrued capital expenditures in the accompanying consolidated balance sheets as of December 31, 2017 and 2016. Piedmont recognized approximately $0.1 million of recoveries of previously recorded estimated accrued interest and penalties during the year ended December 31, 2017, and no additional expense or recoveries for the years ended December 31, 2016, and 2015, respectively, related to such positions. The tax years 2014 to 2016 remain open to examination by various federal and state taxing authorities.

Tax Cuts and Jobs Act

The Tax Cuts and Jobs Act ("H.R. 1"), which generally takes effect for taxable years beginning on or after January 1, 2018 (subject to certain exceptions), makes many significant changes to the U.S. federal income tax laws that will profoundly impact the taxation of individuals and corporations (including both regular C corporations and corporations that have elected to be taxed as REITs). For example, H.R. 1 limits the ability of corporations to utilize net operating loss carryforwards and limits the deductibility of business interest for all taxpayers, subject to an exception for taxpayers that are engaged in certain specified real property trades or business who make an irrevocable election not to apply the limitation to a particular real property trade or business and to depreciate their real property investments held in such trade or business using the less favorable alternative depreciation system. To date, the IRS has issued only limited guidance with respect to certain of the provisions of H.R. 1, and there are numerous interpretive issues that will require guidance. In addition, changes made by H.R. 1 may require Piedmont to accrue certain income for U.S. federal income tax purposes no later than when such income is taken into account as revenue on its financial statements, unless the income is already subject to certain special methods of accounting under the Code. This could cause Piedmont to recognize taxable income prior to the receipt of the associated cash and accordingly, increase its distribution levels in order to maintain its status as a REIT. H.R. 1 also includes limitations on the deductibility of certain compensation paid to Piedmont's executives, certain interest payments, and certain net operating loss carryfowards, each of which could potentially increase Piedmont's taxable income and its required distributions. As described in Note 2 above, as of December 31, 2017, Piedmont has not recognized significant provisions for income tax or deferred tax assets or liabilities related to its taxable REIT subsidiary. Therefore, although management is still evaluating the effects of H.R. 1, Piedmont does not believe that H.R. 1 will significantly impact its financial statements.

Quarterly Results (unaudited)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Quarterly Results (unaudited)

A summary of the unaudited quarterly financial information for the years ended December 31, 2017 and 2016, is presented below (in thousands, except per-share data):



	2017
	First			Second		Third		Fourth
Revenues	$	148,463		$	148,679	$	137,587	$	139,444
Real estate operating income/(loss)	$	33,300		$	35,491	$	28,756	$	(16,250	)
Income/(loss) from continuing operations	$	15,154		$	17,215	$	16,617	$	(31,311	)
Gain/(loss) on sale of real estate assets	$	(53	)	$	6,492	$	109,512	$	(77	)
Net income/(loss) applicable to Piedmont	$	15,104		$	23,710	$	126,133	$	(31,383	)
Basic and diluted earnings/(loss) per share	$	0.10		$	0.16	$	0.87	$	(0.21	)
Dividends declared per share	$	0.21		$	0.21	$	0.21	$	0.71		⁽¹⁾


⁽¹⁾	On December 13, 2017, Piedmont's board of directors declared a special dividend of $0.50 per share. The record date was December 26, 2017, and the payment date was January 9, 2018.



	2016
	First			Second			Third			Fourth
Revenues	$	138,012		$	135,307		$	138,485		$	143,911
Real estate operating income/(loss)	$	26,372		$	14,791		$	2,988		$	26,633
Income/(loss) from continuing operations	$	10,396		$	(1,553	)	$	(13,065	)	$	10,529
Income/(loss) from discontinued operations	$	—		$	(1	)	$	1		$	—
Gain/(loss) on sale of real estate assets	$	(20	)	$	73,835		$	(57	)	$	19,652
Net income/(loss) applicable to Piedmont	$	10,372		$	72,278		$	(13,107	)	$	30,189
Basic and diluted earnings/(loss) per share	$	0.07		$	0.50		$	(0.09	)	$	0.21
Dividends declared per share	$	0.21		$	0.21		$	0.21		$	0.21

Guarantor and Non-Guarantor Financial Information

12 Months Ended

Dec. 31, 2017

Guarantor and Non-Guarantor Financial Information [Abstract]

Guarantor and Non-Guarantor Financial Information

The following condensed consolidating financial information for Piedmont Operating Partnership, L.P. (the "Issuer"), Piedmont Office Realty Trust, Inc. (the "Guarantor"), and the other directly and indirectly owned subsidiaries of the Guarantor (the "Non-Guarantor Subsidiaries") is provided pursuant to the requirements of Rule 3-10 of Regulation S-X regarding financial statements of guarantors and issuers of guaranteed registered securities. The Issuer is a wholly-owned subsidiary of the Guarantor, and all guarantees by the Guarantor of securities issued by the Issuer are full and unconditional. The principal elimination entries relate to investments in subsidiaries and intercompany balances and transactions, including transactions with the Non-Guarantor Subsidiaries.



Condensed Consolidated Balance Sheets
As of December 31, 2017
(in thousands)	Issuer		Guarantor			Non-Guarantor Subsidiaries		Eliminations			Consolidated
Assets:
Real estate assets, at cost:
Land	$	36,094	$	—		$	508,700	$	—		$	544,794
Buildings and improvements, less accumulated depreciation	180,886		—			2,237,437		(300		)	2,418,023
Intangible lease assets, less accumulated amortization	181		—			77,624		—			77,805
Construction in progress	85		—			11,625		—			11,710
Real estate assets held for sale, net	32,815		—			299,595		—			332,410
Total real estate assets	250,061		—			3,134,981		(300		)	3,384,742
Cash and cash equivalents	3,890		150			3,342		—			7,382
Tenant and straight-line receivables, net, and amounts due from unconsolidated joint ventures	16,891		—			158,418		—			175,309
Advances to affiliates	6,297,632		1,674,276			—		(7,971,908		)	—
Investment in subsidiary	—		3,437,299			172		(3,437,471		)	—
Notes receivable	88,810		—			144,500		(233,310		)	—
Prepaid expenses, restricted cash, escrows, interest rate swap, and other assets	5,094		2			20,222		(740		)	24,578
Goodwill	98,918		—			—		—			98,918
Deferred lease costs, net	16,611		—			245,296		—			261,907
Other assets held for sale, net	2,266		—			44,865		—			47,131
Total assets	$	6,780,173	$	5,111,727		$	3,751,796	$	(11,643,729	)	$	3,999,967
Liabilities:
Debt, net	$	1,535,239	$	—		$	424,998	$	(233,310	)	$	1,726,927
Accounts payable, accrued expenses, dividends payable, and accrued capital expenditures	20,279		104,028			93,086		(740		)	216,653
Advances from affiliates	941,494		5,277,957			1,850,712		(8,070,163		)	—
Deferred income	3,631		—			25,951		—			29,582
Intangible lease liabilities, net	—		—			38,458		—			38,458
Interest rate swaps	1,478		—			—		—			1,478
Other liabilities held for sale, net	—		—			380		—			380
Total liabilities	2,502,121		5,381,985			2,433,585		(8,304,213		)	2,013,478
Stockholders’ Equity:
Common stock	—		1,424			—		—			1,424
Additional paid-in capital	3,433,299		3,680,232			1,300		(3,437,471		)	3,677,360
Retained/(cumulative distributions in excess of) earnings	836,589		(3,951,914		)	1,315,089		97,955			(1,702,281		)
Other comprehensive loss	8,164		—			—		—			8,164
Piedmont stockholders’ equity	4,278,052		(270,258		)	1,316,389		(3,339,516		)	1,984,667
Noncontrolling interest	—		—			1,822		—			1,822
Total stockholders’ equity	4,278,052		(270,258		)	1,318,211		(3,339,516		)	1,986,489
Total liabilities and stockholders’ equity	$	6,780,173	$	5,111,727		$	3,751,796	$	(11,643,729	)	$	3,999,967



Condensed Consolidated Balance Sheets
As of December 31, 2016
(in thousands)	Issuer		Guarantor			Non-Guarantor Subsidiaries		Eliminations			Consolidated
Assets:
Real estate assets, at cost:
Land	$	38,298	$	—		$	504,342	$	—		$	542,640
Buildings and improvements, less accumulated depreciation	202,084		—			2,240,394		(300		)	2,442,178
Intangible lease assets, less accumulated amortization	725		—			98,970		—			99,695
Construction in progress	145		—			34,315		—			34,460
Real estate assets held for sale, net	33,945		—			578,774		—			612,719
Total real estate assets	275,197		—			3,456,795		(300		)	3,731,692
Investments in and amounts due from unconsolidated joint ventures	7,360		—			—		—			7,360
Cash and cash equivalents	3,674		150			3,168		—			6,992
Tenant and straight-line rent receivables, net	18,517		—			144,839		—			163,356
Advances to affiliates	6,464,135		1,315,616			—		(7,779,751		)	—
Investment in subsidiary	—		3,630,564			181		(3,630,745		)	—
Notes receivable	88,910		—			95,790		(184,700		)	—
Prepaid expenses, restricted cash, escrows, and other assets	6,173		—			20,217		(1,897		)	24,493
Goodwill	98,918		—			—		—			98,918
Deferred lease costs, net	14,776		—			261,949		—			276,725
Other assets held for sale, net	3,432		—			55,200		—			58,632
Total assets	$	6,981,092	$	4,946,330		$	4,038,139	$	(11,597,393	)	$	4,368,168
Liabilities:
Debt, net	$	1,701,933	$	—		$	503,242	$	(184,700	)	$	2,020,475
Accounts payable, accrued expenses, and accrued capital expenditures	17,365		31,230			118,712		(1,897		)	165,410
Advances from affiliates	708,340		5,071,521			2,098,146		(7,878,007		)	—
Deferred income	5,206		—			23,200		—			28,406
Intangible lease liabilities, net	—		—			47,537		—			47,537
Interest rate swaps	8,169		—			—		—			8,169
Other liabilities held for sale, net	—		—			468		—			468
Total liabilities	2,441,013		5,102,751			2,791,305		(8,064,604		)	2,270,465
Stockholders’ Equity:
Common stock	—		1,452			—		—			1,452
Additional paid-in capital	3,626,564		3,676,000			1,309		(3,630,745		)	3,673,128
Retained/(cumulative distributions in excess of) earnings	911,411		(3,833,873		)	1,243,643		97,956			(1,580,863		)
Other comprehensive loss	2,104		—			—		—			2,104
Piedmont stockholders’ equity	4,540,079		(156,421		)	1,244,952		(3,532,789		)	2,095,821
Noncontrolling interest	—		—			1,882		—			1,882
Total stockholders’ equity	4,540,079		(156,421		)	1,246,834		(3,532,789		)	2,097,703
Total liabilities and stockholders’ equity	$	6,981,092	$	4,946,330		$	4,038,139	$	(11,597,393	)	$	4,368,168



Condensed Consolidated Statements of Income
For the year ended December 31, 2017
(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Revenues:
Rental income	$	42,593		$	—		$	434,975		$	(1,791	)	$	475,777
Tenant reimbursements	11,660			—			85,525			(474		)	96,711
Property management fee revenue	—			—			18,155			(16,470		)	1,685
	54,253			—			538,655			(18,735		)	574,173
Expenses:
Property operating costs	22,805			—			216,560			(18,735		)	220,630
Depreciation	12,995			—			106,293			—			119,288
Amortization	3,049			—			72,318			—			75,367
Impairment loss on real estate assets	87			—			46,374			—			46,461
General and administrative	6,443			347			24,340			—			31,130
	45,379			347			465,885			(18,735		)	492,876
Real estate operating income/(loss)	8,874			(347		)	72,770			—			81,297
Other income (expense):
Interest expense	(56,769		)	—			(26,715		)	15,360			(68,124		)
Other income/(expense)	9,168			—			6,849			(15,360		)	657
Equity in income of unconsolidated joint ventures	3,845			—			—			—			3,845
	(43,756		)	—			(19,866		)	—			(63,622		)
Income/(loss) from continuing operations	(34,882		)	(347		)	52,904			—			17,675
Gain on sale of real estate assets	6,431			—			109,443			—			115,874
Net income/(loss)	(28,451		)	(347		)	162,347			—			133,549
Plus: Net loss applicable to noncontrolling interest	—			—			15			—			15
Net income/(loss) applicable to Piedmont	$	(28,451	)	$	(347	)	$	162,362		$	—		$	133,564



Condensed Consolidated Statements of Income
For the year ended December 31, 2016
(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Revenues:
Rental income	$	55,007		$	—		$	407,514		$	(2,631	)	$	459,890
Tenant reimbursements	14,081			—			80,378			(498		)	93,961
Property management fee revenue	—			—			16,897			(15,033		)	1,864
	69,088			—			504,789			(18,162		)	555,715
Expenses:
Property operating costs	31,967			—			205,344			(18,377		)	218,934
Depreciation	16,657			—			111,076			—			127,733
Amortization	3,715			—			71,404			—			75,119
Impairment loss on real estate assets	8,259			—			25,642			—			33,901
General and administrative	28,314			311			36,065			(35,446		)	29,244
	88,912			311			449,531			(53,823		)	484,931
Real estate operating income/(loss)	(19,824		)	(311		)	55,258			35,661			70,784
Other income (expense):
Interest expense	(49,108		)	—			(27,636		)	11,884			(64,860		)
Other income/(expense)	9,560			282			2,029			(11,884		)	(13		)
Net recoveries from casualty events	—			—			34			—			34
Equity in income of unconsolidated joint ventures	362			—			—			—			362
	(39,186		)	282			(25,573		)	—			(64,477		)
Income/(loss) from continuing operations	(59,010		)	(29		)	29,685			35,661			6,307
Gain on sale of real estate assets	31,275			—			62,135			—			93,410
Net income/(loss)	(27,735		)	(29		)	91,820			35,661			99,717
Plus: Net loss applicable to noncontrolling interest	—			—			15			—			15
Net income/(loss) applicable to Piedmont	$	(27,735	)	$	(29	)	$	91,835		$	35,661		$	99,732



Condensed Consolidated Statements of Income
For the year ended December 31, 2015
(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Revenues:
Rental income	$	67,317		$	—		$	404,460		$	(2,905	)	$	468,872
Tenant reimbursements	13,340			—			100,955			(414		)	113,881
Property management fee revenue	—			—			17,801			(15,785		)	2,016
	80,657			—			523,216			(19,104		)	584,769
Expenses:
Property operating costs	36,380			—			225,428			(19,786		)	242,022
Depreciation	20,891			—			113,612			—			134,503
Amortization	4,598			—			56,288			—			60,886
Impairment loss	6,195			—			37,106			—			43,301
General and administrative	29,645			341			35,923			(35,563		)	30,346
	97,709			341			468,357			(55,349		)	511,058
Real estate operating income/(loss)	(17,052		)	(341		)	54,859			36,245			73,711
Other income (expense):
Interest expense	(51,704		)	—			(33,540		)	11,246			(73,998		)
Other income/(expense)	12,600			—			211			(11,246		)	1,565
Net recoveries/(loss) from casualty events	23			—			(301		)	—			(278		)
Equity in loss of unconsolidated joint ventures	553			—			—			—			553
	(38,528		)	—			(33,630		)	—			(72,158		)
Income/(loss) from continuing operations	(55,580		)	(341		)	21,229			36,245			1,553
Discontinued operations:
Operating income	15			—			69			—			84
Loss on sale of real estate assets	(1		)	—			—			—			(1		)
Income from discontinued operations	14			—			69			—			83
Gain on sale of real estate assets	45,225			—			84,458			—			129,683
Net income/(loss)	(10,341		)	(341		)	105,756			36,245			131,319
Plus: Net income applicable to noncontrolling interest	—			—			(15		)	—			(15		)
Net income/(loss) applicable to Piedmont	$	(10,341	)	$	(341	)	$	105,741		$	36,245		$	131,304



Condensed Consolidated Statements of Cash Flows
For the year ended December 31, 2017
(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Net Cash Provided By/(Used In) Operating Activities	$	(18,989	)	$	5,497		$	256,297		$	—		$	242,805

Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	(1,614		)	—			(113,479		)	—			(115,093		)
Intercompany note receivable	100			—			(48,710		)	48,610			—
Net sales proceeds from wholly-owned properties	23,028			—			352,490			—			375,518
Net sales proceeds received from unconsolidated joint ventures	12,334			—			—			—			12,334
Investments in unconsolidated joint ventures	(1,162		)	—			—			—			(1,162		)
Deferred lease costs paid	(4,081		)	—			(26,904		)	—			(30,985		)
Net cash provided by/(used in) investing activities	28,605			—			163,397			48,610			240,612
Cash Flows from Financing Activities:
Debt issuance costs paid	(132		)	—			—			—			(132		)
Proceeds from debt	180,000			—			—			—			180,000
Repayments of debt	(335,000		)	—			(141,401		)	—			(476,401		)
Intercompany note payable	(14,289		)	—			62,899			(48,610		)	—
Costs of issuance of common stock	—			(182		)	—			—			(182		)
Shares withheld to pay tax obligations related to employee stock compensation	—			(3,403		)	—			—			(3,403		)
Repurchases of common stock as part of announced plan	—			(60,474		)	—			—			(60,474		)
(Distributions to)/repayments from affiliates	160,019			180,791			(340,810		)	—			—
Dividends paid and discount on dividend reinvestments	—			(122,229		)	(45		)	—			(122,274		)
Net cash provided by/(used in) financing activities	(9,402		)	(5,497		)	(419,357		)	(48,610		)	(482,866		)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	214			—			337			—			551
Cash, cash equivalents, and restricted cash and escrows, beginning of year	3,693			150			4,361			—			8,204
Cash, cash equivalents, and restricted cash and escrows, end of year	$	3,907		$	150		$	4,698		$	—		$	8,755



Condensed Consolidated Statements of Cash Flows
For the year ended December 31, 2016
(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Net Cash Provided By/(Used In) Operating Activities	$	(26,263	)	$	5,214		$	217,236		$	35,660		$	231,847

Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	(5,060		)	—			(454,836		)	—			(459,896		)
Intercompany note receivable	440			—			(71,900		)	71,460			—
Redemption of noncontrolling interest in unconsolidated variable interest entity	—			—			—			—			—
Net sales proceeds from wholly-owned properties	200,220			—			165,698			—			365,918
Deferred lease costs paid	(2,758		)	—			(23,138		)	—			(25,896		)
Net cash provided by/(used in) investing activities	192,842			—			(384,176		)	71,460			(119,874		)
Cash Flows from Financing Activities:
Debt issuance costs paid	(264		)	—			—			—			(264		)
Proceeds from debt	695,000			—			—			—			695,000
Repayments of debt	(538,000		)	—			(168,875		)	—			(706,875		)
Intercompany note payable	(9,600		)	—			81,060			(71,460		)	—
Costs of issuance of common stock	—			(342		)	—			—			(342		)
Shares withheld to pay tax obligations related to employee stock compensation	—			(2,344		)	—			—			(2,344		)
Repurchases of common stock as part of announced plan	—			(7,943		)	—			—			(7,943		)
(Distributions to)/repayments from affiliates	(312,218		)	97,016			250,862			(35,660		)	—
Dividends paid and discount on dividend reinvestments	—			(91,601		)	(15		)	—			(91,616		)
Net cash provided by/(used in) financing activities	(165,082		)	(5,214		)	163,032			(107,120		)	(114,384		)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	1,497			—			(3,908		)	—			(2,411		)
Cash, cash equivalents, and restricted cash and escrows, beginning of year	2,196			150			8,269			—			10,615
Cash, cash equivalents, and restricted cash and escrows, end of year	$	3,693		$	150		$	4,361		$	—		$	8,204



Condensed Consolidated Statements of Cash Flows
For the year ended December 31, 2015
(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Net Cash Provided/(Used In) by Operating Activities	$	(27,077	)	$	4,699		$	209,821		$	36,245		$	223,688

Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	(12,303		)	—			(494,291		)	—			(506,594		)
Intercompany note receivable	72,000			—			—			(72,000		)	—
Redemption of noncontrolling interest in unconsolidated variable interest entity	—			—			(4,000		)	—			(4,000		)
Net sales proceeds from wholly-owned properties	151,557			—			696,612			—			848,169
Deferred lease costs paid	(3,792		)	—			(33,891		)	—			(37,683		)
Net cash provided by/(used in) investing activities	207,462			—			164,430			(72,000		)	299,892
Cash Flows from Financing Activities:
Debt issuance costs paid	(575		)	—			(506		)	—			(1,081		)
Proceeds from debt	1,142,577			—			159,281			—			1,301,858
Repayments of debt	(1,438,000		)	—			(106,301		)	—			(1,544,301		)
Intercompany note payable	—			—			(72,000		)	72,000			—
Net costs of issuance of common stock	—			(326		)	—			—			(326		)
Shares withheld to pay tax obligations related to employee stock compensation	—			(1,710		)	—			—			(1,710		)
Repurchases of common stock as part of announced plan	—			(158,860		)	—			—			(158,860		)
(Distributions to)/repayments from affiliates	104,495			281,073			(349,323		)	(36,245		)	—
Dividends paid and discount on dividend reinvestments	—			(126,516		)	(15		)	—			(126,531		)
Net cash provided by/(used in) financing activities	(191,503		)	(6,339		)	(368,864		)	35,755			(530,951		)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	(11,118		)	(1,640		)	5,387			—			(7,371		)
Cash, cash equivalents, and restricted cash and escrows, beginning of year	13,314			1,790			2,882			—			17,986
Cash, cash equivalents, and restricted cash and escrows, end of year	$	2,196		$	150		$	8,269		$	—		$	10,615

Subsequent events	12 Months Ended
Subsequent events	Dec. 31, 2017
Subsequent Events [Abstract]
Subsequent events	Subsequent events Declaration of Dividend for the First Quarter 2018 On February 7, 2018, the board of directors of Piedmont declared dividends for the first quarter 2018 in the amount of $0.21 per share on its common stock to stockholders of record as of the close of business on February 23, 2018. Such dividends are to be paid on March 16, 2018. Sale of the 2017 Disposition Portfolio During the fourth quarter 2017, Piedmont entered into two binding contracts with two different buyers to sell 14 assets, each of which subsequently closed on January 4, 2018. The total gross sales price for both transactions was approximately $425.9 million (subject to an additional $4.5 million in contingent proceeds upon certain leasing activity occurring before July 2, 2018). See Note 14 for further information. Repayment of Two Unsecured Debt Facilities On January 4, 2018, using proceeds from the dispositions noted above and cash on hand, as well as a draw on its $500 Million Unsecured 2015 Line of Credit, Piedmont repaid the entire outstanding balance of the $170 Million Unsecured 2015 Term Loan and the $300 Million Unsecured 2013 Term Loan, which had maturity dates of May 15, 2018 and January 31, 2019, respectively. See Note 5 for further information. Property Under Contract for Acquisition On February 19, 2018, Piedmont entered into a binding contract to acquire, for $28 million, 501 W. Church Street, a value-add asset located in Orlando, Florida in close proximity to Piedmont's existing downtown Orlando assets, CNL Center I and II and SunTrust Center. 501 W. Church Street is an approximately 182,000 square foot, five-story office property adjacent to the Amway Center and the proposed Orlando downtown Sports Entertainment District. Share Repurchase Program Re-Authorized by Board of Directors From January 1, 2018 through February 21, 2018, Piedmont repurchased and retired approximately 7.8 million of its common stock at a weighted-average price of $18.97 per share. As of February 21, 2018, Piedmont has approximately $40.0 million of capacity outstanding under its current board-approved share repurchase authorization. On February 21, 2018, the board of directors of Piedmont re-authorized Piedmont’s stock repurchase plan to permit the additional purchase of shares of common stock having an aggregate purchase price of up to $200 million between February 21, 2018 and February 21, 2020.

Schedule III - Real Estate and Accumulated Depreciation

12 Months Ended

Dec. 31, 2017

SEC Schedule III, Real Estate and Accumulated Depreciation Disclosure [Abstract]

Schedule III - Real Estate and Accumulated Depreciation

December 31, 2017

(dollars in thousands)



					Initial Cost					Gross Amount at Which Carried at December 31, 2017
Description	Location	Ownership Percentage		Encumbrances	Land	Buildings and Improvements	Total (a)	Costs Capitalized Subsequent to Acquisition (b)		Land	Buildings and Improvements	Total (c)	Accumulated Depreciation and Amortization	Date of Construction	Date Acquired	Life on which Depreciation and Amortization is Computed (in years) (d)
1430 ENCLAVE PARKWAY	Houston, TX	100	%	None	7,100	37,915	45,015	2,050		5,506	41,559	47,065	19,653	1994	12/21/2000	0	-	40
CRESCENT RIDGE II	Minnetonka, MN	100	%	None	7,700	45,154	52,854	8,194		8,021	53,027	61,048	23,837	2000	12/21/2000	0	-	40
90 CENTRAL STREET	Boxborough, MA	100	%	None	3,642	29,497	33,139	1,462		3,642	30,959	34,601	12,361	2001	5/3/2002	0	-	40
6031 CONNECTION DRIVE	Irving, TX	100	%	None	3,157	43,656	46,813	4,422		3,157	48,078	51,235	20,502	1999	8/15/2002	0	-	40
6021 CONNECTION DRIVE	Irving, TX	100	%	None	3,157	42,662	45,819	10,545		3,157	53,207	56,364	20,118	2000	8/15/2002	0	-	40
6011 CONNECTION DRIVE	Irving, TX	100	%	None	3,157	29,034	32,191	3,283		3,157	32,317	35,474	14,126	1999	8/15/2002	0	-	40
ONE INDEPENDENCE SQUARE	Washington, DC	100	%	None	29,765	104,814	134,579	22,446		30,562	126,463	157,025	44,364	1991	11/22/2002	0	-	40
800 NORTH BRAND BOULEVARD	Glendale, CA	100	%	None	23,605	136,284	159,889	13,561		23,607	149,843	173,450	57,073	1990	12/20/2002	0	-	40
US BANCORP CENTER	Minneapolis, MN	100	%	None	11,138	175,629	186,767	18,473		11,138	194,102	205,240	71,663	2000	5/1/2003	0	-	40
GLENRIDGE HIGHLANDS TWO	Atlanta, GA	100	%	None	6,662	69,031	75,693	(16,173	)	6,662	52,858	59,520	22,040	2000	8/1/2003	0	-	40
200 BRIDGEWATER CROSSING	Bridgewater, NJ	100	%	None	8,182	84,160	92,342	(12,945	)	8,328	71,069	79,397	26,852	2002	8/14/2003	0	-	40
400 VIRGINIA AVE	Washington, DC	100	%	None	22,146	49,740	71,886	(375	)	22,146	49,365	71,511	17,594	1985	11/19/2003	0	-	40
4250 NORTH FAIRFAX DRIVE	Arlington, VA	100	%	None	13,636	70,918	84,554	10,989		13,636	81,907	95,543	26,162	1998	11/19/2003	0	-	40
1225 EYE STREET (e)	Washington, DC	98.1	%	None	21,959	47,602	69,561	8,034		21,959	55,636	77,595	19,248	1986	11/19/2003	0	-	40
1201 EYE STREET (f)	Washington, DC	98.6	%	None	31,985	63,139	95,124	5,725		31,985	68,864	100,849	21,850	2001	11/19/2003	0	-	40
1901 MARKET STREET	Philadelphia, PA	100	%	160,000	13,584	166,683	180,267	53,684		20,829	213,122	233,951	79,034	1987	12/18/2003	0	-	40
60 BROAD STREET	New York, NY	100	%	None	32,522	168,986	201,508	13,794		60,708	154,594	215,302	56,430	1962	12/31/2003	0	-	40
1414 MASSACHUSETTS AVENUE	Cambridge, MA	100	%	None	4,210	35,821	40,031	(284	)	4,365	35,382	39,747	17,288	1873	1/8/2004	0	-	40
ONE BRATTLE SQUARE	Cambridge, MA	100	%	None	6,974	64,940	71,914	(24,495	)	7,113	40,306	47,419	14,459	1991	2/26/2004	0	-	40
600 CORPORATE DRIVE	Lebanon, NJ	100	%	None	3,934	—	3,934	16,281		3,934	16,281	20,215	7,571	2005	3/16/2004	0	-	40



					Initial Cost					Gross Amount at Which Carried at December 31, 2017
Description	Location	Ownership Percentage		Encumbrances	Land	Buildings and Improvements	Total (a)	Costs Capitalized Subsequent to Acquisition (b)		Land	Buildings and Improvements	Total (c)	Accumulated Depreciation and Amortization	Date of Construction	Date Acquired	Life on which Depreciation and Amortization is Computed (in years) (d)
3100 CLARENDON BOULEVARD	Arlington, VA	100	%	None	11,700	69,705	81,405	40,963		11,791	110,577	122,368	25,520	1987	12/9/2004	0	-	40
400 BRIDGEWATER CROSSING	Bridgewater, NJ	100	%	None	10,400	71,052	81,452	(14,078	)	10,400	56,974	67,374	17,844	2002	2/17/2006	0	-	40
LAS COLINAS CORPORATE CENTER I	Irving, TX	100	%	None	3,912	18,830	22,742	(3,671	)	2,543	16,528	19,071	5,785	1998	8/31/2006	0	-	40
LAS COLINAS CORPORATE CENTER II	Irving, TX	100	%	None	4,496	29,881	34,377	(3,580	)	2,543	28,254	30,797	9,594	1998	8/31/2006	0	-	40
TWO PIERCE PLACE	Itasca, IL	100	%	None	4,370	70,632	75,002	13,334		8,156	80,180	88,336	32,194	1991	12/7/2006	0	-	40
ONE MERIDIAN CROSSINGS	Richfield, MN	100	%	None	2,919	24,398	27,317	318		2,919	24,716	27,635	5,045	1997	10/1/2010	0	-	40
TWO MERIDIAN CROSSINGS	Richfield, MN	100	%	None	2,661	25,742	28,403	637		2,661	26,379	29,040	5,419	1998	10/1/2010	0	-	40
500 WEST MONROE STREET	Chicago, IL	100	%	None	36,990	185,113	222,103	50,057		36,990	235,170	272,160	44,321	1991	3/31/2011	0	-	40
THE DUPREE	Atlanta, GA	100	%	None	4,080	14,310	18,390	877		4,080	15,187	19,267	4,524	1997	4/29/2011	0	-	40
THE MEDICI	Atlanta, GA	100	%	None	1,780	11,510	13,290	5,359		1,780	16,869	18,649	3,788	2008	6/7/2011	0	-	40
225 PRESIDENTIAL WAY	Boston, MA	100	%	None	3,626	36,916	40,542	66		3,612	36,996	40,608	9,680	2000	9/13/2011	0	-	40
235 PRESIDENTIAL WAY	Boston, MA	100	%	None	4,154	44,048	48,202	69		4,138	44,133	48,271	11,505	2001	9/13/2011	0	-	40
400 TOWNPARK	Lake Mary, FL	100	%	None	2,570	20,555	23,125	4,329		2,570	24,884	27,454	5,178	2008	11/10/2011	0	-	40
ARLINGTON GATEWAY	Arlington, VA	100	%	None	36,930	129,070	166,000	(5,596	)	36,930	123,474	160,404	15,894	2005	3/4/2013	0	-	40
5 & 15 WAYSIDE ROAD	Burlington, MA	100	%	None	7,190	55,445	62,635	2,548		7,190	57,993	65,183	9,693	1999 / 2001	3/22/2013	0	-	40
6565 MACARTHUR BOULEVARD	Irving, TX	100	%	None	4,820	37,767	42,587	(530	)	4,820	37,237	42,057	4,752	1998	12/5/2013	0	-	40
ONE LINCOLN PARK	Dallas, TX	100	%	None	6,640	44,810	51,450	1,787		6,640	46,597	53,237	6,642	1999	12/20/2013	0	-	40
161 CORPORATE CENTER	Irving, TX	100	%	None	2,020	10,680	12,700	(113	)	2,020	10,567	12,587	2,134	1998	12/30/2013	0	-	40
5 WALL STREET	Burlington, MA	100	%	30,670	9,560	50,276	59,836	(1,175	)	9,560	49,101	58,661	7,278	2008	6/27/2014	0	-	40
1155 PERIMETER CENTER WEST	Atlanta, GA	100	%	None	5,870	66,849	72,719	5		5,870	66,854	72,724	10,004	2000	8/28/2014	0	-	40



					Initial Cost									Gross Amount at Which Carried at December 31, 2017
Description	Location	Ownership Percentage		Encumbrances	Land		Buildings and Improvements		Total (a)		Costs Capitalized Subsequent to Acquisition (b)			Land		Buildings and Improvements		Total (c)		Accumulated Depreciation and Amortization		Date of Construction	Date Acquired	Life on which Depreciation and Amortization is Computed (in years) (d)
500 TOWNPARK	Lake Mary, FL	100	%	None	2,147		21,925		24,072		3,053			2,147		24,978		27,125		785		2017	N/A	0	-	40
PARK PLACE ON TURTLE CREEK	Dallas, TX	100	%	None	4,470		38,048		42,518		1,810			4,470		39,858		44,328		4,565		1986	1/16/2015	0	-	40
80 CENTRAL STREET	Boxborough, MA	100	%	None	1,980		8,930		10,910		(394		)	1,980		8,536		10,516		994		1988	7/24/2015	0	-	40
ENCLAVE PLACE	Houston, TX	100	%	None	1,890		60,094		61,984		3,756			1,890		63,850		65,740		3,591		2015	N/A	0	-	40
SUNTRUST CENTER	Orlando, FL	100	%	None	11,660		139,015		150,675		981			11,660		139,996		151,656		12,564		1988	11/4/2015	0	-	40
GALLERIA 300	Atlanta, GA	100	%	None	4,000		73,554		77,554		1,919			4,000		75,473		79,473		7,739		1987	11/4/2015	0	-	40
GLENRIDGE HIGHLANDS ONE	Atlanta, GA	100	%	None	5,960		50,013		55,973		815			5,960		50,828		56,788		5,261		1998	11/24/2015	0	-	40
CNL CENTER I	Orlando, FL	99	%	None	6,470		77,858		84,328		(303		)	6,470		77,555		84,025		4,995		1999	8/1/2016	0	-	40
CNL CENTER II	Orlando, FL	99	%	None	4,550		55,609		60,159		481			4,550		56,090		60,640		3,235		2006	8/1/2016	0	-	40
ONE WAYSIDE ROAD	Boston, MA	100	%	None	6,240		57,124		63,364		—			6,240		57,124		63,364		5,587		1997 / 2008	8/10/2016	0	-	40
GALLERIA 200	Atlanta, GA	100	%	None	6,470		55,825		62,295		(63		)	6,470		55,762		62,232		3,127		1984	10/7/2016	0	-	40
750 WEST JOHN CARPENTER FREEWAY (g)	Irving, TX	100	%	None	7,860		36,303		44,163		1,702			7,860		38,005		45,865		2,143		1999	11/30/2016	0	-	40
NORMAN POINTE I	Bloomington, MN	100	%	None	4,358		22,322		26,680		—			4,358		22,322		26,680		36		2000	12/28/2017	0	-	40
PIEDMONT POWER, LLC (h)	Bridgewater, NJ	100	%	None	—		79		79		2,740			—		2,819		2,819		676		N/A	12/20/2011	0	-	40
UNDEVELOPED LAND PARCELS (i)	Various	100	%	None	18,061		—		18,061		(1,063		)	15,914		1,084		16,998		23		N/A	Various			N/A
2017 DISPOSITION PORTFOLIO (j)	Various	100	%	None	73,285		433,351		506,636		(5,110		)	74,498		427,028		501,526		169,127		Various	Various	0		40
Total—All Properties					$	584,304	$	3,613,304	$	4,197,608	$	240,601		$	619,292	$	3,818,917	$	4,438,209	$	1,053,467


^(a)	Total initial cost excludes purchase price allocated to intangible lease origination costs and intangible lease liabilities.


^(b)	Includes write-offs of fully depreciated/amortized capitalized assets, as well as impairment loss on real estate assets.


^(c)	The net carrying value of Piedmont’s total assets for federal income tax purposes is approximately $4.2 billion.


^(d)	Piedmont’s assets are depreciated or amortized using the straight-line method over the useful lives of the assets by class. Generally, Tenant Improvements and Lease Intangibles are amortized over the lease term. Generally, Building Improvements are depreciated over 5 - 25 years, Land Improvements are depreciated over 20 - 25 years, and Buildings are depreciated over 40 years.


^(e)	During the year ended December 31, 2017, Piedmont repaid the mortgage secured by the 1225 Eye Street property located in Washington, D.C., and recapitalized the 1225 Eye Street N.W. Associates, LLC, increasing Piedmont's ownership from 49.5% to 98.1%. Piedmont is deemed to have control over the joint venture and, as such, consolidates the joint venture, including the building.


^(f)	During the year ended December 31, 2017, Piedmont repaid the mortgage secured by the 1201 Eye Street property located in Washington, D.C., and recapitalized the 1201 Eye Street N.W. Associates, LLC, increasing Piedmont's ownership from 49.5% to 98.6%. Piedmont is deemed to have control over the joint venture and, as such, consolidates the joint venture, including the building.


^(g)	As part of the acquisition of the property, Piedmont purchased an adjoining, developable land parcel of 3.5 acres for $1.0 million.


^(h)	Represents solar panels at the 400 Bridgewater Crossing building.


⁽ⁱ⁾	Undeveloped Land Parcels includes land parcels which Piedmont may develop in the future.

^(j)

2017 Disposition Portfolio includes the following properties which were reclassified as held for sale as of December 31, 2017: 1200 Crown Colony Drive, 5601 Hiatus Road, Windy Point I, Windy Point II, 2001 NW 64th Street, Desert Canyon 300, Auburn Hills Corporate Center, 1075 West Entrance Drive, 2300 Cabot Drive, Piedmont Pointe I, Piedmont Pointe II, Suwanee Gateway One, 5301 Maryland Way, and 2120 West End Avenue. Further, 2001 NW 64th Street was owned subject to a long-term ground lease; however, this lease was assumed by the purchaser upon closing. The 2017 Disposition Portfolio closed on January 4, 2018.

Piedmont Office Realty Trust, Inc.

Schedule III - Real Estate and Accumulated Depreciation

December 31, 2017

(dollars in thousands)



	2017				2016				2015
Real Estate:
Balance at the beginning of the year	$	4,800,025			$	4,725,096			$	5,267,615
Additions to/improvements of real estate	85,368				422,908				452,106
Assets disposed ⁽¹⁾	(353,911		)		(296,319		)		(926,592		)
Assets impaired	(46,461		)	⁽²⁾	(30,898		)	⁽³⁾	(40,169		)	⁽³⁾
Write-offs of intangible assets ⁽⁴⁾	(37,188		)		(11,896		)		(7,768		)
Write-offs of fully depreciated/amortized assets	(9,624		)		(8,866		)		(20,096		)
Balance at the end of the year	$	4,438,209			$	4,800,025			$	4,725,096
Accumulated Depreciation and Amortization:
Balance at the beginning of the year	$	1,058,704			$	1,019,663			$	1,182,556
Depreciation and amortization expense	145,837				155,274				155,009
Assets disposed ⁽¹⁾	(104,262		)		(95,471		)		(290,038		)
Write-offs of intangible assets ⁽⁴⁾	(37,188		)		(11,896		)		(7,768		)
Write-offs of fully depreciated/amortized assets	(9,624		)		(8,866		)		(20,096		)
Balance at the end of the year	$	1,053,467			$	1,058,704			$	1,019,663


⁽¹⁾	Includes the disposition of the 8560 Upland Drive property, Piedmont's last remaining investment in an unconsolidated joint venture.


⁽²⁾	Piedmont recognized an impairment loss on a disposal group of real estate assets as part of the 2017 Disposition Portfolio (see Note 9).


⁽³⁾	Does not include impairment loss recognized on other assets as a result of the allocation of goodwill (see Note 9).


⁽⁴⁾	Consists of write-offs of intangible lease assets related to lease restructurings, amendments and terminations.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Basis of Presentation

Principles of Consolidation

Please refer to Note 6 for a summary of Piedmont’s interests in and consolidation treatment of its various VIEs as of December 31, 2017.

All inter-company balances and transactions have been eliminated upon consolidation.

Use of Estimates

Real Estate Assets

Piedmont’s real estate assets are depreciated or amortized using the straight-line method over the following useful lives:



Buildings	40 years
Building improvements	5-25 years
Land improvements	20-25 years
Tenant allowances	Lease term
Furniture, fixtures, and equipment	3-5 years
Intangible lease assets	Lease term

Fair Value of Assets and Liabilities of Acquired Properties

Investments in and Amounts Due from Unconsolidated Joint Ventures

Cash and Cash Equivalents

Tenant Receivables, net and Straight-line Rent Receivables

Restricted Cash and Escrows

Restricted cash and escrows principally relate to the following types of items:


•	escrow accounts held by lenders to pay future real estate taxes, insurance, debt service, and tenant improvements;


•	net sales proceeds from property sales held by qualified intermediary for potential Section 1031 exchange;


•	earnest money paid in connection with future acquisitions; and


•	security and utility deposits paid by tenants per the terms of their respective leases.

Restricted cash and escrows are generally reclassified to other asset or liability accounts upon being used to purchase assets, satisfy obligations, or settle tenant obligations.

Prepaid Expenses and Other Assets

Prepaid expenses and other assets are primarily comprised of the following items:


•	prepaid property taxes, insurance and operating costs;


•	deferred common area maintenance costs which will be reimbursed by tenants over specified time periods;


•	receivables which are unrelated to tenants, for example, insurance proceeds receivable from insurers related to casualty losses; and


•	equipment, furniture and fixtures, and tenant improvements for Piedmont’s corporate office and property management office space, net of accumulated depreciation.

Goodwill

Interest Rate Derivatives

Risk Management Objective of Using Derivatives

Deferred Lease Costs

Deferred lease costs are amortized on a straight-line basis over the terms of the related underlying leases in the accompanying consolidated statements of income as follows:


•	Approximately $50.8 million, $50.1 million, and $42.5 million of deferred lease costs for the years ended December 31, 2017, 2016, and 2015, respectively, are included in amortization expense; and


•	Approximately $4.8 million, $3.9 million, and $4.7 million, of deferred lease costs related to lease incentives granted to tenants for the years ended December 31, 2017, 2016, and 2015, respectively, was included as an offset to rental income.

Debt

Deferred Income

Deferred income

Deferred income is primarily comprised of the following items:


•	prepaid rent from tenants; and


•	tenant reimbursements related to operating expense or property tax expenses which may be due to tenants as part of an annual operating expense reconciliation.

Shares-in-trust, Preferred Stock, Common Stock, Dividends

Shares-in-trust

Preferred Stock

Common Stock

Dividends

Noncontrolling Interest

Revenue Recognition

Stock-based Compensation and Nonqualified Deferred Compensation Plan

Stock-based Compensation

Non-qualified Deferred Compensation Plan

Legal Fees and Related Insurance Recoveries

Casualty Losses and Litigation Settlement Expense and Related Insurance Recoveries

Casualty Losses and Related Insurance Recoveries

Discontinued Operations and Disclosures of Disposals of Components of an Entity

Discontinued Operations

Net Income Available to Common Stockholders Per Share

Income Taxes

Reclassifications

Accounting Pronouncements Adopted and Other Recent Accounting Pronouncements

Accounting Pronouncements Adopted during the Year Ended December 31, 2017

Other Recent Accounting Pronouncements

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Property, Plant and Equipment

Piedmont’s real estate assets are depreciated or amortized using the straight-line method over the following useful lives:



Buildings	40 years
Building improvements	5-25 years
Land improvements	20-25 years
Tenant allowances	Lease term
Furniture, fixtures, and equipment	3-5 years
Intangible lease assets	Lease term

Schedule of Finite-Lived Intangible Assets by Major Class



	December 31, 2017		December 31, 2016
Intangible Lease Assets:
Above-Market In-Place Lease Assets	$	11,935	$	25,425
In-Place Lease Valuation	$	165,015	$	183,422
Intangible Lease Origination Costs (included as component of Deferred Lease Costs)	$	250,539	$	261,075
Intangible Lease Liabilities (Below-Market In-Place Leases)	$	95,620	$	97,230

Amortization Of Intangible Lease Costs

For the years ended December 31, 2017, 2016, and 2015, respectively, Piedmont recognized amortization of intangible lease costs as follows (in thousands):



	2017		2016		2015
Amortization of Intangible Lease Origination Costs and In-Place Lease Valuation included in amortization expense	$	58,467	$	58,150	$	42,278
Amortization of Above-Market and Below-Market In-Place Lease intangibles as a net increase to rental revenues	$	6,575	$	5,066	$	4,571

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense

Net intangible assets and liabilities, inclusive of amounts classified as real estate assets held for sale, as of December 31, 2017 will be amortized as follows (in thousands):



	Intangible Lease Assets
	Above-Market In-place Lease Assets		In-Place Lease Valuation		Intangible Lease Origination Costs ⁽¹⁾		Below-Market In-place Lease Liabilities ⁽²⁾
For the year ending December 31:
2018	$	1,600	$	18,497	$	28,023	$	8,449
2019	910		14,181		23,102		7,263
2020	157		10,179		17,739		5,669
2021	104		9,013		15,685		5,468
2022	84		7,869		13,752		4,847
Thereafter	142		15,069		27,800		7,142
	$	2,997	$	74,808	$	126,101	$	38,838

Weighted-Average Amortization Period (in years)	3		6		7		6


⁽¹⁾	Included as a component of Deferred Lease Costs in the accompanying consolidated balance sheets.

⁽²⁾

Debt (Tables)

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Schedule of Debt



Facility ⁽¹⁾	Stated Rate		Effective Rate ⁽²⁾			Maturity		Amount Outstanding as of
Facility ⁽¹⁾	Stated Rate		Effective Rate ⁽²⁾			Maturity		2017			2016
Secured (Fixed)
$140 Million WDC Fixed-Rate Loans	5.76	%	5.76	%		11/1/2017		$	—		$	140,000
$35 Million Fixed-Rate Loan ⁽³⁾	5.55	%	3.75	%		9/1/2021		30,670			31,583
$160 Million Fixed-Rate Loan ⁽⁴⁾	3.48	%	3.58	%		7/5/2022		160,000			160,000
Net premium and unamortized debt issuance costs								946			1,161
Subtotal/Weighted Average ⁽⁵⁾	3.81	%						191,616			332,744
Unsecured (Variable and Fixed)
$170 Million Unsecured 2015 Term Loan ⁽⁶⁾	LIBOR + 1.125%		2.54	%		5/15/2018		170,000		⁽⁷⁾	170,000
$300 Million Unsecured 2013 Term Loan	LIBOR + 1.20%		2.78	%	⁽⁸⁾	1/31/2019		300,000		⁽⁷⁾	300,000
$500 Million Unsecured 2015 Line of Credit ⁽⁶⁾	LIBOR + 1.00%		2.57	%		6/18/2019	⁽⁹⁾	23,000			178,000
$300 Million Unsecured 2011 Term Loan	LIBOR + 1.15%		3.35	%	⁽⁸⁾	1/15/2020		300,000			300,000
$350 Million Unsecured Senior Notes	3.40	%	3.43	%		6/01/2023		350,000			350,000
$400 Million Unsecured Senior Notes	4.45	%	4.10	%		3/15/2024		400,000			400,000
Discounts and unamortized debt issuance costs								(7,689)			(10,269)
Subtotal/Weighted Average ⁽⁵⁾	3.43	%						1,535,311			1,687,731
Total/Weighted Average ⁽⁵⁾	3.48	%						$	1,726,927		$	2,020,475


⁽¹⁾	Other than the $35 Million Fixed-Rate Loan, all of Piedmont’s outstanding debt as of December 31, 2017 and 2016 is interest-only.


⁽²⁾	Effective rate after consideration of settled or in-place interest rate swap agreements, issuance premiums/discounts, and/or fair market value adjustments upon assumption of debt.


⁽³⁾	Collateralized by the 5 Wall Street building in Burlington, Massachusetts.


⁽⁴⁾	Collateralized by the 1901 Market Street building in Philadelphia, Pennsylvania.


⁽⁵⁾	Weighted average is based on contractual balance of outstanding debt and the stated or effectively fixed interest rates in the table as of December 31, 2017.


⁽⁶⁾	On a periodic basis, Piedmont may select from multiple interest rate options, including the prime rate and various-length LIBOR locks. All LIBOR selections are subject to an additional spread over the selected rate based on Piedmont’s current credit rating.


⁽⁷⁾	On January 4, 2018, Piedmont repaid the entire outstanding balance of the $170 Million Unsecured 2015 Term Loan and the $300 Million Unsecured 2013 Term Loan without penalty.


⁽⁸⁾	Facility has a stated variable rate; however, Piedmont has entered into interest rate swap agreements which effectively fix, exclusive of Piedmont's credit rating, the rate shown as the effective rate.


⁽⁹⁾	Piedmont may extend the term for up to one additional year (through two available six month extensions to a final extended maturity date of June 18, 2020) provided Piedmont is not then in default and upon payment of extension fees.

Schedule of Maturities of Long-term Debt

A summary of Piedmont's consolidated principal outstanding for aggregate debt maturities of its indebtedness as of December 31, 2017, is provided below (in thousands):



2018	$	170,882	⁽¹⁾
2019	324,014		⁽¹⁾ ⁽²⁾
2020	301,072
2021	27,702
2022	160,000
Thereafter	750,000
Total	$	1,733,670


⁽¹⁾	On January 4, 2018, Piedmont repaid the entire outstanding balance of the $170 Million Unsecured 2015 Term Loan and the $300 Million Unsecured 2013 Term Loan without penalty, which were scheduled to mature on May 15, 2018 and January 31, 2019, respectively.


⁽²⁾	Includes the balance outstanding as of December 31, 2017 on the $500 Million Unsecured 2015 Line of Credit of $23 million. However, Piedmont may extend the term for up to one additional year (through two available six month extensions to a final extended maturity date of June 18, 2020) provided Piedmont is not then in default and upon payment of extension fees.

Variable Interest Entities and Equity Participation Rights (Tables)

12 Months Ended

Dec. 31, 2017

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Variable Interest Entities

A summary of Piedmont’s interests in its consolidated VIEs and their related carrying values as of December 31, 2017 and 2016 is as follows (net carrying amount in millions):



Entity	Piedmont’s % Ownership of Entity			Related Building	Net Carrying Amount as of December 31, 2017		Net Carrying Amount as of December 31, 2016			Primary Beneficiary Considerations
1201 Eye Street N.W. Associates, LLC	98.6	%	⁽¹⁾	1201 Eye Street	$	81.1	$	(6.7	)	In accordance with the partnership’s governing documents, Piedmont currently receives 100% of the cash flow of the entity and has sole discretion in directing the management and leasing activities of the building.
1225 Eye Street N.W. Associates, LLC	98.1	%	⁽¹⁾	1225 Eye Street	$	65.2	$	9.9		In accordance with the partnership’s governing documents, Piedmont currently receives 100% of the cash flow of the entity and has sole discretion in directing the management and leasing activities of the building.
Piedmont 500 W. Monroe Fee, LLC	100	%		500 W. Monroe	$	263.2	$	262.4		The Omnibus Agreement with the previous owner includes equity participation rights upon sale of the property for the previous owner, if certain financial returns are achieved; however, Piedmont has sole decision making authority and is entitled to 100% of the economic benefits of the property until such returns are met.


⁽¹⁾	During the year ended December 31, 2017, Piedmont repaid the $140 million mortgage secured by the 1201 and 1225 Eye Street properties, and recapitalized the LLCs holding each asset, increasing Piedmont's ownership from 49.5% in each of the LLCs to the amounts stated above.

- Definition

Tabular disclosure of the significant judgments and assumptions made in determining whether a variable interest (as defined) held by the entity requires the variable interest entity (VIE) (as defined) to be consolidated and (or) disclose information about its involvement with the VIE, individually or in aggregate (as applicable); the nature of restrictions, if any, on the consolidated VIE's assets and on the settlement of its liabilities reported by an entity in its statement of financial position, including the carrying amounts of such assets and liabilities; the nature of, and changes in, the risks associated with involvement in the VIE; how involvement with the VIE affects the entity's financial position, financial performance, and cash flows; the lack of recourse if creditors (or beneficial interest holders) of the consolidated VIE have no recourse to the general credit of the primary beneficiary (if applicable); the terms of arrangements, giving consideration to both explicit arrangements and implicit variable interests, if any, that could require the entity to provide financial support to the VIE, including events or circumstances that could expose the entity to a loss; the methodology used by the entity for determining whether or not it is the primary beneficiary of the variable interest entity; the significant factors considered and judgments made in determining that the power to direct the activities of a VIE that most significantly impact the VIE's economic performance are shared (as defined); the carrying amounts and classification of assets and liabilities of the VIE included in the statement of financial position; the entity's maximum exposure to loss, if any, as a result of its involvement with the VIE, including how the maximum exposure is determined and significant sources of the entity's exposure to the VIE; a comparison of the carrying amounts of the assets and liabilities and the entity's maximum exposure to loss; information about any liquidity arrangements, guarantees, and (or) other commitments by third parties that may affect the fair value or risk of the entity's variable interest in the VIE; whether or not the entity has provided financial support or other support (explicitly or implicitly) to the VIE that it was not previously contractually required to provide or whether the entity intends to provide that support, including the type and amount of the support and the primary reasons for providing the support; and supplemental information the entity determines necessary to provide.

+ References + Details

Derivative Instruments (Tables)

12 Months Ended

Dec. 31, 2017

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Notional Amounts of Outstanding Derivative Positions

A detail of Piedmont’s interest rate derivatives outstanding as of December 31, 2017 is as follows:

Interest Rate Derivatives:

Number of Swap Agreements

Associated Debt Instrument

Notional Amount

(in millions)

Effective Date

Maturity Date

Interest rate swaps

⁽¹⁾

$300 Million Unsecured 2013 Term Loan

200

1/30/2014

1/31/2019

Interest rate swaps

⁽¹⁾

$300 Million Unsecured 2013 Term Loan

100

8/29/2014

1/31/2019

Interest rate swaps

$300 Million Unsecured 2011 Term Loan

300

11/22/2016

1/15/2020

Total

600

⁽¹⁾

Schedule of Interest Rate Derivatives

A detail of Piedmont’s interest rate derivatives on a gross and net basis as of December 31, 2017 and 2016, respectively, is as follows (in thousands):



Interest rate swaps classified as:	December 31, 2017			December 31, 2016
Gross derivative assets	$	688		$	—
Gross derivative liabilities	(1,478		)	(8,169		)
Net derivative liability	$	(790	)	$	(8,169	)

Schedule of Derivative Instruments, Effect on Other Comprehensive Income (Loss)



Interest Rate Swaps in Cash Flow Hedging Relationships	2017		2016			2015
Amount of gain/(loss) recognized in OCI on derivatives	$	2,479	$	(4,126	)	$	(12,509	)
Amount of previously recorded loss reclassified from accumulated OCI into interest expense	$	3,502	$	4,548		$	5,875

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Fair Value, by Balance Sheet Grouping

The following table sets forth the carrying and estimated fair value for each of Piedmont’s financial instruments, as well as its level within the GAAP fair value hierarchy, as of December 31, 2017 and 2016, respectively (in thousands):



	December 31, 2017					December 31, 2016
Financial Instrument	Carrying Value		Estimated Fair Value		Level Within Fair Value Hierarchy	Carrying Value		Estimated Fair Value		Level Within Fair Value Hierarchy
Assets:
Cash and cash equivalents ⁽¹⁾	$	7,382	$	7,382	Level 1	$	6,992	$	6,992	Level 1
Tenant receivables, net ⁽¹⁾	$	12,139	$	12,139	Level 1	$	26,494	$	26,494	Level 1
Restricted cash and escrows ⁽¹⁾	$	1,373	$	1,373	Level 1	$	1,212	$	1,212	Level 1
Interest rate swap asset	$	688	$	688	Level 2	$	—	$	—	Level 2
Liabilities:
Accounts payable and accrued expenses ⁽¹⁾	$	126,429	$	126,429	Level 1	$	44,733	$	44,733	Level 1
Interest rate swap liability	$	1,478	$	1,478	Level 2	$	8,169	$	8,169	Level 2
Debt, net	$	1,726,927	$	1,759,905	Level 2	$	2,020,475	$	2,027,436	Level 2


⁽¹⁾	For the periods presented, the carrying value of these financial instruments approximates estimated fair value due to its short-term maturity.

Impairment Loss on Real Estate Assets (Tables)

12 Months Ended

Dec. 31, 2017

Real Estate [Abstract]

Impairment Loss on Real Estate Assets

Piedmont recorded impairment loss on real estate assets for the years ended December 31, 2017, 2016, and 2015 (in thousands):



	2017		2016		2015
Eastpoint I & II ⁽¹⁾	$	—	$	—	$	6,195
2 Gatehall Drive ⁽¹⁾	—		—		37,106
150 West Jefferson ⁽¹⁾	—		8,259		—
9221 Corporate Boulevard ⁽²⁾	—		2,692		—
9200 and 9211 Corporate Boulevard ⁽³⁾	—		22,950		—
Disposal Group of 13 Assets ⁽⁴⁾	46,461		—		—
Total impairment loss on real estate assets ⁽⁵⁾	$	46,461	$	33,901	$	43,301


⁽¹⁾	Piedmont recognized an impairment loss on real estate assets based upon the difference between the carrying value of the asset including a proportionate amount of goodwill (because the asset met the definition of a disposed "business" at the time of measurement) and the contracted sales price, less estimated selling costs.

⁽²⁾

⁽³⁾

⁽⁴⁾


⁽⁵⁾	The fair value measurements used in the evaluation of the non-financial assets above are considered to be Level 1 valuations within the fair value hierarchy as defined by GAAP, as there are direct observations and transactions involving the assets by unrelated, third party purchasers.

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Schedule of Future Minimum Rental Payments for Operating Leases

The aggregate payments required under the terms of this operating lease as of December 31, 2017 are presented below (in thousands):



2018	$	93
2019	93
2020	93
2021	93
2022	93
Thereafter	2,346
Total	$	2,811



Years ending December 31:	All properties owned as of December 31, 2017		Excluding properties held for sale as of December 31, 2017
2018	$	417,643	$	377,447
2019	401,120		361,280
2020	377,556		338,269
2021	344,991		307,008
2022	316,053		287,175
Thereafter	1,348,156		1,298,890
Total	$	3,205,519	$	2,970,069

Stock Based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of Nonvested Share Activity

A rollforward of Piedmont's equity based award activity for the year ended December 31, 2017 is as follows:



	Shares		Weighted-Average Grant Date Fair Value
Unvested and Potential Stock Awards as of December 31, 2016	944,223		$	19.44
Deferred Stock Awards Granted	299,251		$	21.38
Increase in Estimated Potential Future Performance Share Awards, net of forfeitures	57,526		$	24.68
Performance Stock Awards Vested	(118,446	)	$	22.00
Deferred Stock Awards Vested	(305,107	)	$	19.34
Deferred Stock Awards Forfeited	(9,010	)	$	19.93
Unvested and Potential Stock Awards as of December 31, 2017	868,437		$	21.69

The following table provides additional information regarding stock award activity during the years ended December 31, 2017, 2016, and 2015 (in thousands except for per share data):



	2017		2016		2015
Weighted-Average Grant Date Fair Value of Deferred Stock Granted During the Period (per share)	$	21.38	$	19.96	$	17.59
Total Grant Date Fair Value of Deferred Stock Vested During the Period	$	5,899	$	4,806	$	4,239
Share-based Liability Awards Paid During the Period ⁽¹⁾	$	2,877	$	1,127	$	—


⁽¹⁾	Amounts reflect the issuance of performance share awards related to the 2014-16 and 2013-15 Performance Share Plans during the years ended December 31, 2017 and 2016, respectively.

Schedule of Outstanding Employee Deferred Stock Awards

A detail of Piedmont’s outstanding employee deferred stock awards as of December 31, 2017 is as follows:



Date of grant	Type of Award	Net Shares Granted ⁽¹⁾	Grant Date Fair Value		Vesting Schedule	Unvested and Potential Shares as of December 31, 2017
January 3, 2014	Deferred Stock Award	79,119	$	16.45	Of the shares granted, 20% vested or will vest on January 3, 2015, 2016, 2017, 2018, and 2019, respectively.	32,829
May 1, 2015	Deferred Stock Award	216,811	$	17.59	Of the shares granted, 25% vested on the date of grant, and 25% of the shares vest on May 1, 2016, 2017, and 2018, respectively.	66,922
May 1, 2015	Fiscal Year 2015-2017 Performance Share Program	—	$	18.42	Shares awarded, if any, will vest immediately upon determination of award in 2018.	161,005	⁽²⁾
May 24, 2016	Deferred Stock Award	232,960	$	19.91	Of the shares granted, 25% vested on the date of grant, and 25% of the shares vest on May 24, 2017, 2018, and 2019, respectively.	132,195
May 24, 2016	Fiscal Year 2016-2018 Performance Share Program	—	$	23.02	Shares awarded, if any, will vest immediately upon determination of award in 2019.	122,154	⁽²⁾
May 18, 2017	Deferred Stock Award-Board of Directors	26,187	$	21.38	Of the shares granted, 100% will vest by May 18, 2018.	26,187
May 18, 2017	Deferred Stock Award	246,671	$	21.38	Of the shares granted, 25% vested on the date of grant, and 25% vested or will vest on May 18, 2018, 2019, and 2020, respectively.	199,810
May 18, 2017	Fiscal Year 2017-2019 Performance Share Program	—	$	30.45	Shares awarded, if any, will vest immediately upon determination of award in 2020.	127,335	⁽²⁾
Total Unvested and Potential Stock Awards						868,437


⁽¹⁾	Amounts reflect the total grant to employees and independent directors, net of shares surrendered upon vesting to satisfy required minimum tax withholding obligations through December 31, 2017.


⁽²⁾	Estimated based on Piedmont's cumulative TSR for the respective performance period through December 31, 2017. Share estimates are subject to change in future periods based upon Piedmont's relative performance compared to its peers' total stockholder return.

Operating Leases (Tables)

12 Months Ended

Dec. 31, 2017

Leases [Abstract]

Schedule of Future Minimum Rental Payments for Operating Leases

The aggregate payments required under the terms of this operating lease as of December 31, 2017 are presented below (in thousands):



2018	$	93
2019	93
2020	93
2021	93
2022	93
Thereafter	2,346
Total	$	2,811



Years ending December 31:	All properties owned as of December 31, 2017		Excluding properties held for sale as of December 31, 2017
2018	$	417,643	$	377,447
2019	401,120		361,280
2020	377,556		338,269
2021	344,991		307,008
2022	316,053		287,175
Thereafter	1,348,156		1,298,890
Total	$	3,205,519	$	2,970,069

Property Dispositions, Assets Held for Sale and Discontinued Operations (Tables)

12 Months Ended

Dec. 31, 2017

Discontinued Operations and Disposal Groups [Abstract]

Schedule of Disposal Groups, Including Discontinued Operations, Income Statement, Balance Sheet and Additional Disclosures

Details of such properties sold are presented below (in thousands):



Buildings Sold	Location	Date of Sale	Gain/(Loss) on Sale				Net Sales Proceeds
3900 Dallas Parkway	Plano, Texas	January 30, 2015	$	8,940			$	25,803
5601 Headquarters Drive	Plano, Texas	April 28, 2015	$	6,390			$	33,326
River Corporate Center	Tempe, Arizona	April 29, 2015	$	4,144			$	24,223
Copper Ridge Center	Lyndhurst, New Jersey	May 1, 2015	$	11,358			$	50,372	⁽¹⁾
Eastpoint I & II	Mayfield Heights, Ohio	July 28, 2015	$	(177	)	⁽²⁾	$	17,342
3750 Brookside Parkway	Alpharetta, Georgia	August 10, 2015	$	761			$	13,624
Chandler Forum	Chandler, Arizona	September 1, 2015	$	13,805			$	32,267
Aon Center	Chicago, Illinois	October 29, 2015	$	84,218			$	646,243
2 Gatehall Drive	Parsippany, New Jersey	December 21, 2015	$	162		⁽²⁾	$	50,369
1055 East Colorado Boulevard	Pasadena, California	April 21, 2016	$	29,462			$	60,076
Fairway Center II	Brea, California	April 28, 2016	$	14,406			$	33,062
1901 Main Street	Irvine, California	May 2, 2016	$	29,964			$	63,149	⁽³⁾
9221 Corporate Boulevard	Rockville, Maryland	July 27, 2016	$	(192	)	⁽²⁾	$	12,035
150 West Jefferson	Detroit, Michigan	July 29, 2016	$	(664	)	⁽²⁾	$	77,844
9200 and 9211 Corporate Boulevard	Rockville, Maryland	September 28, 2016	$	(41	)	⁽²⁾	$	12,519
11695 Johns Creek Parkway	Johns Creek, Georgia	December 22, 2016	$	1,978			$	13,827
Braker Pointe III	Austin, Texas	December 29, 2016	$	18,579			$	48,006
Sarasota Commerce Center II	Sarasota, Florida	June 16, 2017	$	6,493			$	23,090
Two Independence Square	Washington, D.C.	July 5, 2017	$	109,381			$	352,428
8560 Upland Drive	Denver, Colorado	July 27, 2017	$	3,683			$	12,334	⁽⁴⁾


⁽¹⁾	As part of the transaction, Piedmont accepted a secured promissory note from the buyer for the remaining $45.4 million owed on the sale. During the year ended December 31, 2016, the note receivable was repaid in full and such proceeds are reflected in the accompanying consolidated statements of cash flows as net sales proceeds from the sale of wholly-owned properties.


⁽²⁾	As discussed in Note 9 above, Piedmont recognized an impairment loss prior to, or in conjunction with, the sale of the property. Therefore, any gain/(loss) recognized upon the consummation of the sale consists solely of adjustments made subsequent to the sale for closing cost estimates or post-closing prorations.


⁽³⁾	As part of the transaction, Piedmont accepted a secured promissory note from the buyer for $33.0 million, and the note receivable was repaid in full during the year ended December 31, 2016. As such, the full proceeds from the sale of the property are reflected in the accompanying consolidated statements of cash flows as net sales proceeds from the sale of wholly-owned properties.


⁽⁴⁾	Property was owned as part of the unconsolidated joint venture, Fund XIII and REIT Joint Venture. As such, the gain on sale is presented as equity in income/(loss) of unconsolidated joint ventures. Amounts shown above reflect Piedmont's approximate 72% ownership.

Details comprising income from discontinued operations are presented below (in thousands):



	Years Ended December 31,
	2017		2016		2015
Revenues:
Rental income	$	—	$	—	$	19
Tenant reimbursements	—		—		64
	—		—		83
Expenses:
Property operating costs	—		—		(1		)
	—		—		(1		)

Operating income, excluding loss on sale of real estate assets	—		—		84
Loss on sale of real estate assets	—		—		(1		)
Income from discontinued operations	$	—	$	—	$	83

Assets Held For Sale and Discontinude Operations

2017 Disposition Portfolio:



Building		Location
Desert Canyon 300		Phoenix, Arizona
Windy Point I and II		Schaumburg, Illinois
2300 Cabot Drive		Lisle, Illinois
1075 West Entrance Drive		Auburn Hills, Michigan
Auburn Hills Corporate Center		Auburn Hills, Michigan
5301 Maryland Way		Brentwood, Tennessee
Suwanee Gateway One		Suwanee, Georgia
5601 Hiatus Road		Tamarac, Florida
2001 NW 64th Street		Fort Lauderdale, Florida
Piedmont Pointe I & II		Bethesda, Maryland
1200 Crown Colony Drive		Quincy, Massachusetts
2120 West End Avenue		Nashville, Tennessee

Details of amounts held for sale as of December 31, 2017 and 2016 are presented below (in thousands):



	December 31, 2017		December 31, 2016
Real estate assets held for sale, net:
Land	$	74,498	$	127,209
Building and improvements, less accumulated depreciation of $169,116 and $244,269 as of December 31, 2017, and 2016, respectively	255,634		485,145
Construction in progress	2,278		365
Total real estate assets held for sale, net	$	332,410	$	612,719

Other assets held for sale, net:
Straight-line rent receivables	$	25,975	$	28,986
Prepaid expenses and other assets	328		374
Deferred lease costs, less accumulated amortization of $16,549 and $18,937 as of December 31, 2017 and 2016, respectively	20,828		29,272
Total other assets held for sale, net	$	47,131	$	58,632

Other liabilities held for sale, net:
Intangible lease liabilities, less accumulated amortization of $935 and $848 as of December 31, 2017 and 2016, respectively	$	380	$	468

- Definition

Tabular disclosure of information related to a disposal group. Includes, but is not limited to, a discontinued operation, disposal classified as held-for-sale or disposed of by means other than sale or disposal of an individually significant component.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=65878427&loc=SL51721533-107759

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 4B
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721665-107760

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64827811&loc=d3e1474-107760

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=64827811&loc=d3e1361-107760

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721683-107760

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 3A
-URI http://asc.fasb.org/extlink&oid=84176398&loc=SL51724579-110230

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5C
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721675-107760

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 4A
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721663-107760

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84176398&loc=d3e2941-110230

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5B
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721673-107760

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 3A
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721659-107760

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5A
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721671-107760

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5D
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721677-107760

+ Details

Supplemental Disclosures for the Statement of Consolidated Cash Flows (Tables)

12 Months Ended

Dec. 31, 2017

Supplemental Cash Flow Elements [Abstract]

Schedule of Cash Flow, Supplemental Disclosures

Certain noncash investing and financing activities for the years ended December 31, 2017, 2016, and 2015 (in thousands) are outlined below:



	2017		2016		2015
Accrued capital expenditures and deferred lease costs	$	11,276	$	14,427	$	20,630
Change in accrued dividends and discount on dividend reinvestments	$	71,267	$	30,532	$	—
Change in accrued share repurchases as part of an announced plan	$	1,276	$	—	$	—
Investment in consolidated joint venture	$	63,026	$	—	$	—



	2017		2016		2015
Cash and cash equivalents	$	7,382	$	6,992	$	5,441
Restricted cash and escrows:
Real estate tax and escrowed cash	833		757		4,772
Security and utility deposit escrows	540		455		402
Total cash, cash equivalents, and restricted cash and escrows shown in the consolidated statement of cash flows	$	8,755	$	8,204	$	10,615

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Schedule of Tax Basis Income

Piedmont’s income tax basis net income for the years ended December 31, 2017, 2016, and 2015, is calculated as follows (in thousands):



	2017			2016			2015
GAAP basis financial statement net income	$	133,564		$	99,732		$	131,304
Increase (decrease) in net income resulting from:
Depreciation and amortization expense recognized for financial reporting purposes in excess of/(less than) amounts recognized for income tax purposes	62,916			69,214			(1,717		)
Rental income accrued for income tax purposes less than amounts for financial reporting purposes	(25,432		)	(18,964		)	(12,123		)
Net amortization of above/below-market lease intangibles for income tax purposes in excess of amounts for financial reporting purposes	(6,041		)	(4,895		)	(4,614		)
Gain on disposal of property for financial reporting purposes less than/(in excess of) amounts for income tax purposes	10,068			(118,713		)	(43,493		)
Taxable income/(loss) of Piedmont Washington Properties, Inc., in excess of/(less than) amount for financial reporting purposes	176			(1,042		)	2,491
Other expenses, including impairment loss on real estate assets, for financial reporting purposes in excess of amounts for income tax purposes	49,859			42,019			54,425
Taxable income for Piedmont Office Holdings, Inc. in excess of/(less than) amount for financial reporting purposes	(28		)	648			—
Income tax basis net income, prior to dividends paid deduction	$	225,082		$	67,999		$	126,273

Schedule of Characterization Of Dividends To Common Stockholders



	2017		2016		2015
Ordinary income	53.61	%	81.77	%	31.75	%
Return of capital	—	%	18.23	%	—	%
Capital gains	46.39	%	—	%	68.25	%
	100	%	100	%	100	%

Quarterly Results (unaudited) (Tables)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Schedule of Quarterly Financial Information

A summary of the unaudited quarterly financial information for the years ended December 31, 2017 and 2016, is presented below (in thousands, except per-share data):



	2017
	First			Second		Third		Fourth
Revenues	$	148,463		$	148,679	$	137,587	$	139,444
Real estate operating income/(loss)	$	33,300		$	35,491	$	28,756	$	(16,250	)
Income/(loss) from continuing operations	$	15,154		$	17,215	$	16,617	$	(31,311	)
Gain/(loss) on sale of real estate assets	$	(53	)	$	6,492	$	109,512	$	(77	)
Net income/(loss) applicable to Piedmont	$	15,104		$	23,710	$	126,133	$	(31,383	)
Basic and diluted earnings/(loss) per share	$	0.10		$	0.16	$	0.87	$	(0.21	)
Dividends declared per share	$	0.21		$	0.21	$	0.21	$	0.71		⁽¹⁾


⁽¹⁾	On December 13, 2017, Piedmont's board of directors declared a special dividend of $0.50 per share. The record date was December 26, 2017, and the payment date was January 9, 2018.



	2016
	First			Second			Third			Fourth
Revenues	$	138,012		$	135,307		$	138,485		$	143,911
Real estate operating income/(loss)	$	26,372		$	14,791		$	2,988		$	26,633
Income/(loss) from continuing operations	$	10,396		$	(1,553	)	$	(13,065	)	$	10,529
Income/(loss) from discontinued operations	$	—		$	(1	)	$	1		$	—
Gain/(loss) on sale of real estate assets	$	(20	)	$	73,835		$	(57	)	$	19,652
Net income/(loss) applicable to Piedmont	$	10,372		$	72,278		$	(13,107	)	$	30,189
Basic and diluted earnings/(loss) per share	$	0.07		$	0.50		$	(0.09	)	$	0.21
Dividends declared per share	$	0.21		$	0.21		$	0.21		$	0.21

Guarantor and Non-Guarantor Financial Information (Tables)

12 Months Ended

Dec. 31, 2017

Guarantor and Non-Guarantor Financial Information [Abstract]

Condensed Balance Sheet



Condensed Consolidated Balance Sheets
As of December 31, 2017
(in thousands)	Issuer		Guarantor			Non-Guarantor Subsidiaries		Eliminations			Consolidated
Assets:
Real estate assets, at cost:
Land	$	36,094	$	—		$	508,700	$	—		$	544,794
Buildings and improvements, less accumulated depreciation	180,886		—			2,237,437		(300		)	2,418,023
Intangible lease assets, less accumulated amortization	181		—			77,624		—			77,805
Construction in progress	85		—			11,625		—			11,710
Real estate assets held for sale, net	32,815		—			299,595		—			332,410
Total real estate assets	250,061		—			3,134,981		(300		)	3,384,742
Cash and cash equivalents	3,890		150			3,342		—			7,382
Tenant and straight-line receivables, net, and amounts due from unconsolidated joint ventures	16,891		—			158,418		—			175,309
Advances to affiliates	6,297,632		1,674,276			—		(7,971,908		)	—
Investment in subsidiary	—		3,437,299			172		(3,437,471		)	—
Notes receivable	88,810		—			144,500		(233,310		)	—
Prepaid expenses, restricted cash, escrows, interest rate swap, and other assets	5,094		2			20,222		(740		)	24,578
Goodwill	98,918		—			—		—			98,918
Deferred lease costs, net	16,611		—			245,296		—			261,907
Other assets held for sale, net	2,266		—			44,865		—			47,131
Total assets	$	6,780,173	$	5,111,727		$	3,751,796	$	(11,643,729	)	$	3,999,967
Liabilities:
Debt, net	$	1,535,239	$	—		$	424,998	$	(233,310	)	$	1,726,927
Accounts payable, accrued expenses, dividends payable, and accrued capital expenditures	20,279		104,028			93,086		(740		)	216,653
Advances from affiliates	941,494		5,277,957			1,850,712		(8,070,163		)	—
Deferred income	3,631		—			25,951		—			29,582
Intangible lease liabilities, net	—		—			38,458		—			38,458
Interest rate swaps	1,478		—			—		—			1,478
Other liabilities held for sale, net	—		—			380		—			380
Total liabilities	2,502,121		5,381,985			2,433,585		(8,304,213		)	2,013,478
Stockholders’ Equity:
Common stock	—		1,424			—		—			1,424
Additional paid-in capital	3,433,299		3,680,232			1,300		(3,437,471		)	3,677,360
Retained/(cumulative distributions in excess of) earnings	836,589		(3,951,914		)	1,315,089		97,955			(1,702,281		)
Other comprehensive loss	8,164		—			—		—			8,164
Piedmont stockholders’ equity	4,278,052		(270,258		)	1,316,389		(3,339,516		)	1,984,667
Noncontrolling interest	—		—			1,822		—			1,822
Total stockholders’ equity	4,278,052		(270,258		)	1,318,211		(3,339,516		)	1,986,489
Total liabilities and stockholders’ equity	$	6,780,173	$	5,111,727		$	3,751,796	$	(11,643,729	)	$	3,999,967



Condensed Consolidated Balance Sheets
As of December 31, 2016
(in thousands)	Issuer		Guarantor			Non-Guarantor Subsidiaries		Eliminations			Consolidated
Assets:
Real estate assets, at cost:
Land	$	38,298	$	—		$	504,342	$	—		$	542,640
Buildings and improvements, less accumulated depreciation	202,084		—			2,240,394		(300		)	2,442,178
Intangible lease assets, less accumulated amortization	725		—			98,970		—			99,695
Construction in progress	145		—			34,315		—			34,460
Real estate assets held for sale, net	33,945		—			578,774		—			612,719
Total real estate assets	275,197		—			3,456,795		(300		)	3,731,692
Investments in and amounts due from unconsolidated joint ventures	7,360		—			—		—			7,360
Cash and cash equivalents	3,674		150			3,168		—			6,992
Tenant and straight-line rent receivables, net	18,517		—			144,839		—			163,356
Advances to affiliates	6,464,135		1,315,616			—		(7,779,751		)	—
Investment in subsidiary	—		3,630,564			181		(3,630,745		)	—
Notes receivable	88,910		—			95,790		(184,700		)	—
Prepaid expenses, restricted cash, escrows, and other assets	6,173		—			20,217		(1,897		)	24,493
Goodwill	98,918		—			—		—			98,918
Deferred lease costs, net	14,776		—			261,949		—			276,725
Other assets held for sale, net	3,432		—			55,200		—			58,632
Total assets	$	6,981,092	$	4,946,330		$	4,038,139	$	(11,597,393	)	$	4,368,168
Liabilities:
Debt, net	$	1,701,933	$	—		$	503,242	$	(184,700	)	$	2,020,475
Accounts payable, accrued expenses, and accrued capital expenditures	17,365		31,230			118,712		(1,897		)	165,410
Advances from affiliates	708,340		5,071,521			2,098,146		(7,878,007		)	—
Deferred income	5,206		—			23,200		—			28,406
Intangible lease liabilities, net	—		—			47,537		—			47,537
Interest rate swaps	8,169		—			—		—			8,169
Other liabilities held for sale, net	—		—			468		—			468
Total liabilities	2,441,013		5,102,751			2,791,305		(8,064,604		)	2,270,465
Stockholders’ Equity:
Common stock	—		1,452			—		—			1,452
Additional paid-in capital	3,626,564		3,676,000			1,309		(3,630,745		)	3,673,128
Retained/(cumulative distributions in excess of) earnings	911,411		(3,833,873		)	1,243,643		97,956			(1,580,863		)
Other comprehensive loss	2,104		—			—		—			2,104
Piedmont stockholders’ equity	4,540,079		(156,421		)	1,244,952		(3,532,789		)	2,095,821
Noncontrolling interest	—		—			1,882		—			1,882
Total stockholders’ equity	4,540,079		(156,421		)	1,246,834		(3,532,789		)	2,097,703
Total liabilities and stockholders’ equity	$	6,981,092	$	4,946,330		$	4,038,139	$	(11,597,393	)	$	4,368,168

Condensed Income Statement



Condensed Consolidated Statements of Income
For the year ended December 31, 2017
(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Revenues:
Rental income	$	42,593		$	—		$	434,975		$	(1,791	)	$	475,777
Tenant reimbursements	11,660			—			85,525			(474		)	96,711
Property management fee revenue	—			—			18,155			(16,470		)	1,685
	54,253			—			538,655			(18,735		)	574,173
Expenses:
Property operating costs	22,805			—			216,560			(18,735		)	220,630
Depreciation	12,995			—			106,293			—			119,288
Amortization	3,049			—			72,318			—			75,367
Impairment loss on real estate assets	87			—			46,374			—			46,461
General and administrative	6,443			347			24,340			—			31,130
	45,379			347			465,885			(18,735		)	492,876
Real estate operating income/(loss)	8,874			(347		)	72,770			—			81,297
Other income (expense):
Interest expense	(56,769		)	—			(26,715		)	15,360			(68,124		)
Other income/(expense)	9,168			—			6,849			(15,360		)	657
Equity in income of unconsolidated joint ventures	3,845			—			—			—			3,845
	(43,756		)	—			(19,866		)	—			(63,622		)
Income/(loss) from continuing operations	(34,882		)	(347		)	52,904			—			17,675
Gain on sale of real estate assets	6,431			—			109,443			—			115,874
Net income/(loss)	(28,451		)	(347		)	162,347			—			133,549
Plus: Net loss applicable to noncontrolling interest	—			—			15			—			15
Net income/(loss) applicable to Piedmont	$	(28,451	)	$	(347	)	$	162,362		$	—		$	133,564



Condensed Consolidated Statements of Income
For the year ended December 31, 2016
(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Revenues:
Rental income	$	55,007		$	—		$	407,514		$	(2,631	)	$	459,890
Tenant reimbursements	14,081			—			80,378			(498		)	93,961
Property management fee revenue	—			—			16,897			(15,033		)	1,864
	69,088			—			504,789			(18,162		)	555,715
Expenses:
Property operating costs	31,967			—			205,344			(18,377		)	218,934
Depreciation	16,657			—			111,076			—			127,733
Amortization	3,715			—			71,404			—			75,119
Impairment loss on real estate assets	8,259			—			25,642			—			33,901
General and administrative	28,314			311			36,065			(35,446		)	29,244
	88,912			311			449,531			(53,823		)	484,931
Real estate operating income/(loss)	(19,824		)	(311		)	55,258			35,661			70,784
Other income (expense):
Interest expense	(49,108		)	—			(27,636		)	11,884			(64,860		)
Other income/(expense)	9,560			282			2,029			(11,884		)	(13		)
Net recoveries from casualty events	—			—			34			—			34
Equity in income of unconsolidated joint ventures	362			—			—			—			362
	(39,186		)	282			(25,573		)	—			(64,477		)
Income/(loss) from continuing operations	(59,010		)	(29		)	29,685			35,661			6,307
Gain on sale of real estate assets	31,275			—			62,135			—			93,410
Net income/(loss)	(27,735		)	(29		)	91,820			35,661			99,717
Plus: Net loss applicable to noncontrolling interest	—			—			15			—			15
Net income/(loss) applicable to Piedmont	$	(27,735	)	$	(29	)	$	91,835		$	35,661		$	99,732



Condensed Consolidated Statements of Income
For the year ended December 31, 2015
(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Revenues:
Rental income	$	67,317		$	—		$	404,460		$	(2,905	)	$	468,872
Tenant reimbursements	13,340			—			100,955			(414		)	113,881
Property management fee revenue	—			—			17,801			(15,785		)	2,016
	80,657			—			523,216			(19,104		)	584,769
Expenses:
Property operating costs	36,380			—			225,428			(19,786		)	242,022
Depreciation	20,891			—			113,612			—			134,503
Amortization	4,598			—			56,288			—			60,886
Impairment loss	6,195			—			37,106			—			43,301
General and administrative	29,645			341			35,923			(35,563		)	30,346
	97,709			341			468,357			(55,349		)	511,058
Real estate operating income/(loss)	(17,052		)	(341		)	54,859			36,245			73,711
Other income (expense):
Interest expense	(51,704		)	—			(33,540		)	11,246			(73,998		)
Other income/(expense)	12,600			—			211			(11,246		)	1,565
Net recoveries/(loss) from casualty events	23			—			(301		)	—			(278		)
Equity in loss of unconsolidated joint ventures	553			—			—			—			553
	(38,528		)	—			(33,630		)	—			(72,158		)
Income/(loss) from continuing operations	(55,580		)	(341		)	21,229			36,245			1,553
Discontinued operations:
Operating income	15			—			69			—			84
Loss on sale of real estate assets	(1		)	—			—			—			(1		)
Income from discontinued operations	14			—			69			—			83
Gain on sale of real estate assets	45,225			—			84,458			—			129,683
Net income/(loss)	(10,341		)	(341		)	105,756			36,245			131,319
Plus: Net income applicable to noncontrolling interest	—			—			(15		)	—			(15		)
Net income/(loss) applicable to Piedmont	$	(10,341	)	$	(341	)	$	105,741		$	36,245		$	131,304

Condensed Cash Flow Statement



Condensed Consolidated Statements of Cash Flows
For the year ended December 31, 2017
(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Net Cash Provided By/(Used In) Operating Activities	$	(18,989	)	$	5,497		$	256,297		$	—		$	242,805

Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	(1,614		)	—			(113,479		)	—			(115,093		)
Intercompany note receivable	100			—			(48,710		)	48,610			—
Net sales proceeds from wholly-owned properties	23,028			—			352,490			—			375,518
Net sales proceeds received from unconsolidated joint ventures	12,334			—			—			—			12,334
Investments in unconsolidated joint ventures	(1,162		)	—			—			—			(1,162		)
Deferred lease costs paid	(4,081		)	—			(26,904		)	—			(30,985		)
Net cash provided by/(used in) investing activities	28,605			—			163,397			48,610			240,612
Cash Flows from Financing Activities:
Debt issuance costs paid	(132		)	—			—			—			(132		)
Proceeds from debt	180,000			—			—			—			180,000
Repayments of debt	(335,000		)	—			(141,401		)	—			(476,401		)
Intercompany note payable	(14,289		)	—			62,899			(48,610		)	—
Costs of issuance of common stock	—			(182		)	—			—			(182		)
Shares withheld to pay tax obligations related to employee stock compensation	—			(3,403		)	—			—			(3,403		)
Repurchases of common stock as part of announced plan	—			(60,474		)	—			—			(60,474		)
(Distributions to)/repayments from affiliates	160,019			180,791			(340,810		)	—			—
Dividends paid and discount on dividend reinvestments	—			(122,229		)	(45		)	—			(122,274		)
Net cash provided by/(used in) financing activities	(9,402		)	(5,497		)	(419,357		)	(48,610		)	(482,866		)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	214			—			337			—			551
Cash, cash equivalents, and restricted cash and escrows, beginning of year	3,693			150			4,361			—			8,204
Cash, cash equivalents, and restricted cash and escrows, end of year	$	3,907		$	150		$	4,698		$	—		$	8,755



Condensed Consolidated Statements of Cash Flows
For the year ended December 31, 2016
(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Net Cash Provided By/(Used In) Operating Activities	$	(26,263	)	$	5,214		$	217,236		$	35,660		$	231,847

Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	(5,060		)	—			(454,836		)	—			(459,896		)
Intercompany note receivable	440			—			(71,900		)	71,460			—
Redemption of noncontrolling interest in unconsolidated variable interest entity	—			—			—			—			—
Net sales proceeds from wholly-owned properties	200,220			—			165,698			—			365,918
Deferred lease costs paid	(2,758		)	—			(23,138		)	—			(25,896		)
Net cash provided by/(used in) investing activities	192,842			—			(384,176		)	71,460			(119,874		)
Cash Flows from Financing Activities:
Debt issuance costs paid	(264		)	—			—			—			(264		)
Proceeds from debt	695,000			—			—			—			695,000
Repayments of debt	(538,000		)	—			(168,875		)	—			(706,875		)
Intercompany note payable	(9,600		)	—			81,060			(71,460		)	—
Costs of issuance of common stock	—			(342		)	—			—			(342		)
Shares withheld to pay tax obligations related to employee stock compensation	—			(2,344		)	—			—			(2,344		)
Repurchases of common stock as part of announced plan	—			(7,943		)	—			—			(7,943		)
(Distributions to)/repayments from affiliates	(312,218		)	97,016			250,862			(35,660		)	—
Dividends paid and discount on dividend reinvestments	—			(91,601		)	(15		)	—			(91,616		)
Net cash provided by/(used in) financing activities	(165,082		)	(5,214		)	163,032			(107,120		)	(114,384		)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	1,497			—			(3,908		)	—			(2,411		)
Cash, cash equivalents, and restricted cash and escrows, beginning of year	2,196			150			8,269			—			10,615
Cash, cash equivalents, and restricted cash and escrows, end of year	$	3,693		$	150		$	4,361		$	—		$	8,204



Condensed Consolidated Statements of Cash Flows
For the year ended December 31, 2015
(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Net Cash Provided/(Used In) by Operating Activities	$	(27,077	)	$	4,699		$	209,821		$	36,245		$	223,688

Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	(12,303		)	—			(494,291		)	—			(506,594		)
Intercompany note receivable	72,000			—			—			(72,000		)	—
Redemption of noncontrolling interest in unconsolidated variable interest entity	—			—			(4,000		)	—			(4,000		)
Net sales proceeds from wholly-owned properties	151,557			—			696,612			—			848,169
Deferred lease costs paid	(3,792		)	—			(33,891		)	—			(37,683		)
Net cash provided by/(used in) investing activities	207,462			—			164,430			(72,000		)	299,892
Cash Flows from Financing Activities:
Debt issuance costs paid	(575		)	—			(506		)	—			(1,081		)
Proceeds from debt	1,142,577			—			159,281			—			1,301,858
Repayments of debt	(1,438,000		)	—			(106,301		)	—			(1,544,301		)
Intercompany note payable	—			—			(72,000		)	72,000			—
Net costs of issuance of common stock	—			(326		)	—			—			(326		)
Shares withheld to pay tax obligations related to employee stock compensation	—			(1,710		)	—			—			(1,710		)
Repurchases of common stock as part of announced plan	—			(158,860		)	—			—			(158,860		)
(Distributions to)/repayments from affiliates	104,495			281,073			(349,323		)	(36,245		)	—
Dividends paid and discount on dividend reinvestments	—			(126,516		)	(15		)	—			(126,531		)
Net cash provided by/(used in) financing activities	(191,503		)	(6,339		)	(368,864		)	35,755			(530,951		)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	(11,118		)	(1,640		)	5,387			—			(7,371		)
Cash, cash equivalents, and restricted cash and escrows, beginning of year	13,314			1,790			2,882			—			17,986
Cash, cash equivalents, and restricted cash and escrows, end of year	$	2,196		$	150		$	8,269		$	—		$	10,615

Organization (Details) ft² in Millions	12 Months Ended
Organization (Details) ft² in Millions	Dec. 31, 2017 ft² segment property subsidiary market
Real Estate Properties [Line Items]
Number of wholly owned subsidiaries \| subsidiary	2
Percentage ownership by sole general partner	99.90%
Percentage ownership by sole limited partner	0.10%
Rentable square feet \| ft²	19
Percentage of annualized lease revenue	88.00%
Number of operating segments \| segment	1
US
Real Estate Properties [Line Items]
Number of office markets \| market	8
In-Service Office Properties
Real Estate Properties [Line Items]
Number of real estate properties \| property	67
Percentage of Class A commercial office space	89.70%

Summary of Significant Accounting Policies (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) property vote $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($)	May 31, 2017 USD ($)
Significant Accounting Policies [Line Items]
Interest capitalized	$ 200	$ 4,600	$ 3,800
Intangible Lease Liabilities (Below-Market In-Place Leases)	95,620	97,230
Amortization of Intangible Lease Origination Costs and In-Place Lease Valuation included in amortization expense	58,467	58,150	42,278
Amortization of Above-Market and Below-Market In-Place Lease intangibles as a net increase to rental revenues	6,575	5,066	4,571
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
Total	77,805	99,695
Below Market Lease, Net, Amortization Income, Fiscal Maturity [Abstract]
2018	8,449
2019	7,263
2020	5,669
2021	5,468
2022	4,847
Thereafter	7,142
Total	$ 38,838
Weighted-Average Amortization Period (in years)	6 years
Significant Accounting Policies [Abstract]
Amortization of deferred common area maintenance recognized	$ 1,400	1,400	2,500
Capitalized internal leasing costs	300	400	1,000
Amortization of deferred lease costs	50,800	50,100	42,500
Amortization of lease incentive	4,800	3,900	4,700
Amortization of fair value adjustments	500	500	500
Amortization of debt discount	200	200	200
Amortization of deferred financing costs and fair market value adjustments on notes payable	$ 2,800	$ 2,900	2,800
Shares-in-trust, shares authorized \| shares	150,000,000	150,000,000
Preferred stock, shares authorized \| shares	100,000,000	100,000,000
Common stock, shares authorized \| shares	750,000,000	750,000,000
Common stock, par value (in dollars per share) \| $ / shares	$ 0.01	$ 0.01
Number of votes for each share of common stock \| vote	1
Stock repurchase program, authorized amount				$ 250,000
Stock repurchase program, remaining authorized repurchase amount	$ 188,200
Dividend reinvestment plan, shareholders discount	2.00%
Net recoveries/(loss)	$ 0	$ 34	(278)
Business interruption insurance recoveries			300
Income tax expense	13	415	85
Hurricane Sandy
Significant Accounting Policies [Abstract]
Net recoveries/(loss)	0	34	(300)
Deferred Compensation, Excluding Share-based Payments and Retirement Benefits \| Trading Securities
Significant Accounting Policies [Abstract]
Assets held as trading securities	800
Above-Market In-place Lease Assets
Significant Accounting Policies [Line Items]
Intangible lease assets	11,935	25,425
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
2018	1,600
2019	910
2020	157
2021	104
2022	84
Thereafter	142
Total	$ 2,997
Weighted-Average Amortization Period (in years)	3 years
In-Place Lease Valuation
Significant Accounting Policies [Line Items]
Intangible lease assets	$ 165,015	183,422
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
2018	18,497
2019	14,181
2020	10,179
2021	9,013
2022	7,869
Thereafter	15,069
Total	$ 74,808
Weighted-Average Amortization Period (in years)	6 years
Intangible Lease Origination Costs
Significant Accounting Policies [Line Items]
Intangible lease assets	$ 250,539	261,075
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
2018	28,023
2019	23,102
2020	17,739
2021	15,685
2022	13,752
Thereafter	27,800
Total	$ 126,101
Weighted-Average Amortization Period (in years)	7 years
Reclassification Adjustment
Significant Accounting Policies [Abstract]
Provision for doubtful accounts	$ 350	216	$ 22
Building
Significant Accounting Policies [Line Items]
Useful life	40 years
Building improvements \| Minimum
Significant Accounting Policies [Line Items]
Useful life	5 years
Building improvements \| Maximum
Significant Accounting Policies [Line Items]
Useful life	25 years
Land improvements \| Minimum
Significant Accounting Policies [Line Items]
Useful life	20 years
Land improvements \| Maximum
Significant Accounting Policies [Line Items]
Useful life	25 years
Furniture, fixtures, and equipment \| Minimum
Significant Accounting Policies [Line Items]
Useful life	3 years
Furniture, fixtures, and equipment \| Maximum
Significant Accounting Policies [Line Items]
Useful life	5 years
1201 Eye Street NW Associates LLC and 1225 Eye Street, NW Associates LLC
Significant Accounting Policies [Line Items]
Number of real estate properties \| property	2
Disposal Group, Held-for-sale, Not Discontinued Operations
Below Market Lease, Net, Amortization Income, Fiscal Maturity [Abstract]
Future amortization of below-market-in-place lease intangibles	$ 380	$ 468

Acquisitions (Details) $ in Millions	12 Months Ended
Acquisitions (Details) $ in Millions	Dec. 31, 2017 USD ($) ft² building
Business Acquisition [Line Items]
Number of properties acquired \| building	1
Rentable Square Feet (Unaudited)	19,000,000
Norman Pointe I
Business Acquisition [Line Items]
Ownership Percentage Acquired	100.00%
Rentable Square Feet (Unaudited)	213,851
Percentage Leased as of Acquisition (Unaudited)	71.00%
Net Contractual Purchase Price (in millions) \| $	$ 35.2

Unconsolidated Joint Venture (Details) - USD ($)	Jul. 27, 2017	Dec. 31, 2017	Dec. 31, 2016
Fund XIII and REIT Joint Venture
Investment [Line Items]
Piedmont's investment in unconsolidated joint venture		$ 0	$ 7,400,000
Piedmont’s ownership percentage		72.00%
8560 Upland Drive \| Disposal Group, Disposed of by Sale, Not Discontinued Operations
Investment [Line Items]
Piedmont’s ownership percentage		72.00%
Piedmont's approximate share of purchase price	$ 12,700,000

Debt (Details)		12 Months Ended
Debt (Details)	Jan. 04, 2018 USD ($)	Dec. 31, 2017 USD ($) period	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Debt Instrument [Line Items]
Weighted average interest rate		3.48%	3.43%
Amount of indebtedness outstanding		$ 1,726,927,000	$ 2,020,475,000
Interest paid		$ 67,600,000	69,000,000	$ 76,400,000
Secured (Fixed)
Debt Instrument [Line Items]
Weighted average interest rate		3.81%
Amount of indebtedness outstanding		$ 191,616,000	332,744,000
Net premium, discounts, and unamortized debt issuance costs		$ 946,000	1,161,000
Unsecured (Variable and Fixed)
Debt Instrument [Line Items]
Weighted average interest rate		3.43%
Amount of indebtedness outstanding		$ 1,535,311,000	1,687,731,000
Net premium, discounts, and unamortized debt issuance costs		(7,689,000)	(10,269,000)
$140 Million WDC Fixed-Rate Loans \| Secured (Fixed)
Debt Instrument [Line Items]
Repayments of debt		$ 140,000,000
Interest rate percentage		5.76%
Effective rate percentage		5.76%
Amount of indebtedness outstanding		$ 0	140,000,000
Face amount of facility		$ 140,000,000
$35 Million Fixed-Rate Loan \| Secured (Fixed)
Debt Instrument [Line Items]
Interest rate percentage		5.55%
Effective rate percentage		3.75%
Amount of indebtedness outstanding		$ 30,670,000	31,583,000
Face amount of facility		$ 35,000,000	35,000,000
$160.0 Million Fixed Rate Loan \| Secured (Fixed)
Debt Instrument [Line Items]
Interest rate percentage		3.48%
Effective rate percentage		3.58%
Amount of indebtedness outstanding		$ 160,000,000	160,000,000
Face amount of facility		$ 160,000,000
$170 Million Unsecured 2015 Term Loan \| Unsecured (Variable and Fixed)
Debt Instrument [Line Items]
Effective rate percentage		2.54%
Amount of indebtedness outstanding		$ 170,000,000	170,000,000
Face amount of facility		$ 170,000,000
$170 Million Unsecured 2015 Term Loan \| Unsecured (Variable and Fixed) \| LIBOR
Debt Instrument [Line Items]
Basis Spread on Variable Rate		1.125%
$300 Million Unsecured 2013 Term Loan \| Unsecured (Variable and Fixed)
Debt Instrument [Line Items]
Amount of indebtedness outstanding		$ 300,000,000	300,000,000
Face amount of facility		$ 300,000,000
$300 Million Unsecured 2013 Term Loan \| Unsecured (Variable and Fixed) \| Interest rate swap liability
Debt Instrument [Line Items]
Effective rate percentage		2.78%
$300 Million Unsecured 2013 Term Loan \| Unsecured (Variable and Fixed) \| LIBOR
Debt Instrument [Line Items]
Basis Spread on Variable Rate		1.20%
$500 Million Unsecured 2015 Line of Credit \| Unsecured (Variable and Fixed) \| Line of Credit
Debt Instrument [Line Items]
Amount of line of credit		$ 500,000,000
Net borrowings incurred		$ 155,000,000
Effective rate percentage		2.57%
Amount of indebtedness outstanding		$ 23,000,000	178,000,000
Face amount of facility		$ 500,000,000
Additional extension period		1 year
Number of extension periods \| period		2
Extension period		6 months
$500 Million Unsecured 2015 Line of Credit \| Unsecured (Variable and Fixed) \| Line of Credit \| LIBOR
Debt Instrument [Line Items]
Basis Spread on Variable Rate		1.00%
$300 Million Unsecured 2011 Term Loan \| Unsecured (Variable and Fixed)
Debt Instrument [Line Items]
Amount of indebtedness outstanding		$ 300,000,000	300,000,000
Face amount of facility		$ 300,000,000
$300 Million Unsecured 2011 Term Loan \| Unsecured (Variable and Fixed) \| Interest rate swap liability
Debt Instrument [Line Items]
Effective rate percentage		3.35%
$300 Million Unsecured 2011 Term Loan \| Unsecured (Variable and Fixed) \| LIBOR
Debt Instrument [Line Items]
Basis Spread on Variable Rate		1.15%
$350 Million Unsecured Senior Notes \| Unsecured (Variable and Fixed)
Debt Instrument [Line Items]
Interest rate percentage		3.40%
Effective rate percentage		3.43%
Amount of indebtedness outstanding		$ 350,000,000	350,000,000
Face amount of facility		$ 350,000,000
$400 Million Unsecured Senior Notes \| Unsecured (Variable and Fixed)
Debt Instrument [Line Items]
Interest rate percentage		4.45%
Effective rate percentage		4.10%
Amount of indebtedness outstanding		$ 400,000,000	$ 400,000,000
Face amount of facility		$ 400,000,000
Subsequent Event \| $170 Million Unsecured 2015 Term Loan \| Unsecured (Variable and Fixed)
Debt Instrument [Line Items]
Repayments of debt	$ 170,000,000
Subsequent Event \| $300 Million Unsecured 2013 Term Loan \| Unsecured (Variable and Fixed)
Debt Instrument [Line Items]
Repayments of debt	300,000,000
Subsequent Event \| $500 Million Unsecured 2015 Line of Credit \| Unsecured (Variable and Fixed) \| Line of Credit
Debt Instrument [Line Items]
Amount of line of credit	$ 500,000,000

Debt (Maturities of Long-term Debt) (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Debt Disclosure [Abstract]
2018	$ 170,882
2019	324,014
2020	301,072
2021	27,702
2022	160,000
Thereafter	750,000
Total	$ 1,733,670

Variable Interest Entities and Equity Participation Rights (Details) - USD ($) $ in Millions			12 Months Ended
	Dec. 31, 2017	Jul. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
1201 Eye Street N.W. Associates, LLC
Variable Interest Entity [Line Items]
Percent of cash flow entitled to the entity	100.00%		100.00%
Piedmont’s % Ownership of Entity			98.60%
Net Carrying Amount	$ 81.1		$ 81.1	$ (6.7)
1225 Eye Street N.W. Associates, LLC
Variable Interest Entity [Line Items]
Percent of cash flow entitled to the entity	100.00%		100.00%
Piedmont’s % Ownership of Entity			98.10%
Net Carrying Amount	$ 65.2		$ 65.2	9.9
Piedmont 500 W. Monroe Fee, LLC
Variable Interest Entity [Line Items]
Percent of cash flow entitled to the entity	100.00%		100.00%
Piedmont’s % Ownership of Entity			100.00%
Net Carrying Amount	$ 263.2		$ 263.2	$ 262.4
1201 Eye Street NW Associates LLC and 1225 Eye Street, NW Associates LLC
Variable Interest Entity [Line Items]
Repayment of secured debt			$ 140.0
1225 Equity LLC \| 1225 Eye Street N.W. Associates, LLC
Variable Interest Entity [Line Items]
Piedmont’s % Ownership of Entity	98.10%	49.50%

Derivative Instruments (Details)		12 Months Ended
Derivative Instruments (Details)	Jan. 04, 2018 USD ($)	Dec. 31, 2017 USD ($) contract	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Derivative [Line Items]
Maximum length of time of cash flow hedge		24 months
Interest Rate Cash Flow Hedge Derivative at Fair Value, Net [Abstract]
Gross derivative assets		$ 688,000	$ 0
Interest rate swaps		(1,478,000)	(8,169,000)
Net derivative liability		(790,000)	(8,169,000)
Amount that will be reclassified from accumulated other comprehensive income over the next twelve months		(700,000)
Net gain/ (loss) related to hedge ineffectiveness and terminations of cash flow hedges		0	0	$ 37,000
Unsecured Debt
Derivative [Line Items]
Total notional amount of forward starting interest rate agreements		600,000,000
Interest Rate Contract \| Interest Expense
Interest Rate Cash Flow Hedge Derivative at Fair Value, Net [Abstract]
Amount of gain/(loss) recognized in OCI on derivatives		2,479,000	(4,126,000)	(12,509,000)
Amount of previously recorded loss reclassified from accumulated OCI into interest expense		3,502,000	$ 4,548,000	$ 5,875,000
Credit Risk Contract
Interest Rate Cash Flow Hedge Derivative at Fair Value, Net [Abstract]
Assets needed for immediate settlement, aggregate fair value		900,000
$300 Million Unsecured 2011 Term Loan \| Unsecured Debt
Derivative [Line Items]
Face amount of facility		$ 300,000,000
$300 Million Unsecured 2011 Term Loan \| Interest Rate Swap 7 through 9 \| Unsecured Debt
Derivative [Line Items]
Number of Swap Agreements \| contract		3
Total notional amount of forward starting interest rate agreements		$ 300,000,000
$300 Million Unsecured 2013 Term Loan \| Unsecured Debt
Derivative [Line Items]
Face amount of facility		$ 300,000,000
$300 Million Unsecured 2013 Term Loan \| Interest Rate Swap 1 through 4 \| Unsecured Debt
Derivative [Line Items]
Number of Swap Agreements \| contract		4
Total notional amount of forward starting interest rate agreements		$ 200,000,000
$300 Million Unsecured 2013 Term Loan \| Interest Rate Swap 5 through 6 \| Unsecured Debt
Derivative [Line Items]
Number of Swap Agreements \| contract		2
Total notional amount of forward starting interest rate agreements		$ 100,000,000
$160.0 Million Fixed Rate Loan \| Secured Debt
Derivative [Line Items]
Face amount of facility		$ 160,000,000
Subsequent Event \| $300 Million Unsecured 2013 Term Loan \| Unsecured Debt
Derivative [Line Items]
Repayments of debt	$ 300,000,000
Proceeds from termination of interest rate swap agreement	800,000
Subsequent Event \| $300 Million Unsecured 2013 Term Loan \| Interest rate swap \| Unsecured Debt
Derivative [Line Items]
Net loss on interest rate cash flow hedge termination	$ 1,100,000

Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swap asset	$ 688	$ 0
Interest rate swap liability	1,478	8,169
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	7,382	6,992
Tenant receivables, net and Notes receivable	12,139	26,494
Restricted cash and escrows	1,373	1,212
Accounts payable and accrued expenses	126,429	44,733
Debt, net	1,726,927	2,020,475
Carrying Value \| Interest rate swap liability
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swap asset	688	0
Interest rate swap liability	1,478	8,169
Estimated Fair Value \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	7,382	6,992
Tenant receivables, net and Notes receivable	12,139	26,494
Restricted cash and escrows	1,373	1,212
Accounts payable and accrued expenses	126,429	44,733
Estimated Fair Value \| Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, net	1,759,905	2,027,436
Estimated Fair Value \| Level 2 \| Interest rate swap liability
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swap asset	688	0
Interest rate swap liability	$ 1,478	$ 8,169

Impairment Loss on Real Estate Assets (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jul. 31, 2016 property
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment loss on real estate assets	$ 46,461	$ 33,901	$ 43,301
Impairment of real estate			43,301
Disposal Group, Held-for-sale, Not Discontinued Operations \| Eastpoint I & II
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment loss on real estate assets	0	0	6,195
Disposal Group, Held-for-sale, Not Discontinued Operations \| 2 Gatehall Drive
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment loss on real estate assets	0	0	37,106
Disposal Group, Held-for-sale, Not Discontinued Operations \| 150 West Jefferson
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment loss on real estate assets	0	8,259	0
Disposal Group, Held-for-sale, Not Discontinued Operations \| 9200 and 9211 Corporate Boulevard
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment loss on real estate assets	0	22,950	0
Number of assets sold \| property				2
Impairment of real estate		23,000
Disposal Group, Held-for-sale, Not Discontinued Operations \| Disposal Group of 13 Assets
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment loss on real estate assets	46,461	0	0
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| 9221 Corporate Boulevard
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment loss on real estate assets	$ 0	2,692	$ 0
Impairment of real estate		$ 2,700

Commitments and Contingencies (Details) $ in Thousands	12 Months Ended
Commitments and Contingencies (Details) $ in Thousands	Dec. 31, 2017 USD ($) category	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Loss Contingencies [Line Items]
Number of tenant and building improvement categories \| category	2
Operating Leases, Future Minimum Payments Due [Abstract]
2018	$ 93
2019	93
2020	93
2021	93
2022	93
Thereafter	2,346
Total	2,811
Land
Operating Leases, Future Minimum Payments Due [Abstract]
Ground rent expense	100	$ 100	$ 200
Building
Operating Leases, Future Minimum Payments Due [Abstract]
Net book value of real estate assets subject to operating ground leases	4,800	4,700
Collectibility of Tenant Reimbursements
Loss Contingencies [Line Items]
Additional expense related to such tenant audits/disputes	$ 300	$ 1,100	$ 400
NonIncremental Capital Expenditures
Loss Contingencies [Line Items]
Period for commitments for funding non-incremental capital expenditures	3 years
Non-incremental and incremental capital expenditures for tenant improvements	$ 38,600
NonIncremental Capital Expenditures \| Maximum
Loss Contingencies [Line Items]
Period for commitments for funding non-incremental capital expenditures	5 years
Incremental Capital Expenditures
Loss Contingencies [Line Items]
Non-incremental and incremental capital expenditures for tenant improvements	$ 14,100

Stock Based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands					12 Months Ended
	May 18, 2017	May 24, 2016	May 01, 2015	Jan. 03, 2014	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	May 18, 2017	May 24, 2016	May 01, 2015	Jan. 03, 2014
Stock Awards
Rollforward of deferred stock award activity
Unvested Deferred Stock Awards as of the beginning of the year (in shares)					944,223
Unvested Deferred Stock Awards as of end of the year (in shares)					868,437	944,223
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Unvested Deferred Stock Awards, Weighted-Average Grant Date Fair Value at beginning of year (in dollars per share)					$ 19.44
Unvested Deferred Stock Awards, Weighted-Average Grant Date Fair Value at end of year (in dollars per share)					21.69	$ 19.44
Grant Date Fair Value (in dollars per share)					$ 19.44	$ 19.44
Unvested Shares (in shares)					944,223	944,223
Deferred Stock Award
Rollforward of deferred stock award activity
Deferred Stock Awards Granted (in shares)					299,251
Deferred Stock Awards Vested (in shares)					(305,107)
Deferred Stock Awards Forfeited (in shares)					(9,010)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Deferred Stock Awards Granted, Weighted-Average Grant Date Fair (in dollars per share)					$ 21.38	$ 19.96	$ 17.59
Deferred Stock Awards Vested, Weighted-Average Grant Date Fair Value (in dollars per share)					19.34
Deferred Stock Awards Forfeited, Weighted Average Grant Date Fair Value (in dollars per share)					$ 19.93
Total Grant Date Fair Value of Deferred Stock Vested During the Period					$ 5,899	$ 4,806	$ 4,239
Performance Shares
Rollforward of deferred stock award activity
Increase in Estimated Potential Future Performance Share Awards, net of forfeitures (in shares)					57,526
Deferred Stock Awards Vested (in shares)					(118,446)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Increase in Estimated Potential Future Performance Share Awards, Weighted Average Grant Date Fair Value (in dollars per share)					$ 24.68
Deferred Stock Awards Vested, Weighted-Average Grant Date Fair Value (in dollars per share)					$ 22.00
Share-based Liability Awards Paid During the Period					$ 2,877	$ 1,127	$ 0
Deferred Stock Award, Granted January 3, 2014 \| Deferred Stock Award
Rollforward of deferred stock award activity
Unvested Deferred Stock Awards as of end of the year (in shares)					32,829
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Unvested Deferred Stock Awards, Weighted-Average Grant Date Fair Value at end of year (in dollars per share)				$ 16.45
Net Shares Granted (in shares)											79,119
Grant Date Fair Value (in dollars per share)				$ 16.45							$ 16.45
Unvested Shares (in shares)					32,829
Deferred Stock Award, Granted January 3, 2014 \| Share-based Compensation Award, Tranche One \| Deferred Stock Award
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Vesting percentage				20.00%
Deferred Stock Award, Granted January 3, 2014 \| Share-based Compensation Award, Tranche Two \| Deferred Stock Award
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Vesting percentage				20.00%
Deferred Stock Award, Granted January 3, 2014 \| Share-based Compensation Award, Tranche Three \| Deferred Stock Award
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Vesting percentage				20.00%
Deferred Stock Award, Granted January 3, 2014 \| Share-based Compensation Award, Tranche Four \| Deferred Stock Award
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Vesting percentage				20.00%
Deferred Stock Award, Granted January 3, 2014 \| Share-based Compensation Award, Tranche Five \| Deferred Stock Award
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Vesting percentage				20.00%
Deferred Stock Award, Granted May 1, 2015 \| Deferred Stock Award
Rollforward of deferred stock award activity
Unvested Deferred Stock Awards as of end of the year (in shares)					66,922
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Unvested Deferred Stock Awards, Weighted-Average Grant Date Fair Value at end of year (in dollars per share)			$ 17.59
Net Shares Granted (in shares)										216,811
Grant Date Fair Value (in dollars per share)			$ 17.59							$ 17.59
Unvested Shares (in shares)					66,922
Deferred Stock Award, Granted May 1, 2015 \| Share-based Compensation Award, Tranche One \| Deferred Stock Award
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Vesting percentage			25.00%
Deferred Stock Award, Granted May 1, 2015 \| Share-based Compensation Award, Tranche Two \| Deferred Stock Award
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Vesting percentage			25.00%
Deferred Stock Award, Granted May 1, 2015 \| Share-based Compensation Award, Tranche Three \| Deferred Stock Award
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Vesting percentage			25.00%
Deferred Stock Award, Granted May 1, 2015 \| Share-based Compensation Award, Tranche Four \| Deferred Stock Award
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Vesting percentage			25.00%
Performance Share Program Award, Granted May 1, 2015 \| Performance Shares
Rollforward of deferred stock award activity
Unvested Deferred Stock Awards as of end of the year (in shares)					161,005
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Unvested Deferred Stock Awards, Weighted-Average Grant Date Fair Value at end of year (in dollars per share)			$ 18.42
Net Shares Granted (in shares)										0
Grant Date Fair Value (in dollars per share)			$ 18.42							$ 18.42
Unvested Shares (in shares)					161,005
Deferred Stock Award, Granted May 24, 2016 \| Deferred Stock Award
Rollforward of deferred stock award activity
Unvested Deferred Stock Awards as of end of the year (in shares)					132,195
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Unvested Deferred Stock Awards, Weighted-Average Grant Date Fair Value at end of year (in dollars per share)		$ 19.91
Net Shares Granted (in shares)									232,960
Grant Date Fair Value (in dollars per share)		$ 19.91							$ 19.91
Unvested Shares (in shares)					132,195
Deferred Stock Award, Granted May 24, 2016 \| Share-based Compensation Award, Tranche One \| Deferred Stock Award
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Vesting percentage		25.00%
Deferred Stock Award, Granted May 24, 2016 \| Share-based Compensation Award, Tranche Two \| Deferred Stock Award
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Vesting percentage		25.00%
Deferred Stock Award, Granted May 24, 2016 \| Share-based Compensation Award, Tranche Three \| Deferred Stock Award
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Vesting percentage		25.00%
Deferred Stock Award, Granted May 24, 2016 \| Share-based Compensation Award, Tranche Four \| Deferred Stock Award
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Vesting percentage		25.00%
Performance Share Program Award, Granted May 24, 2016 \| Performance Shares
Rollforward of deferred stock award activity
Unvested Deferred Stock Awards as of end of the year (in shares)					122,154
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Unvested Deferred Stock Awards, Weighted-Average Grant Date Fair Value at end of year (in dollars per share)		$ 23.02
Net Shares Granted (in shares)									0
Grant Date Fair Value (in dollars per share)		$ 23.02							$ 23.02
Unvested Shares (in shares)					122,154
Deferred Stock Award, Granted May 18, 2017 Deferred Stock Award Independent Directors \| Share-based Compensation Award, Tranche One \| Deferred Stock Award \| Independent directors
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Vesting percentage	100.00%
Deferred Stock Award, Granted May 18, 2017 \| Deferred Stock Award
Rollforward of deferred stock award activity
Unvested Deferred Stock Awards as of end of the year (in shares)					199,810
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Unvested Deferred Stock Awards, Weighted-Average Grant Date Fair Value at end of year (in dollars per share)	$ 21.38
Net Shares Granted (in shares)								246,671
Grant Date Fair Value (in dollars per share)	21.38							$ 21.38
Unvested Shares (in shares)					199,810
Deferred Stock Award, Granted May 18, 2017 \| Deferred Stock Award \| Independent directors
Rollforward of deferred stock award activity
Unvested Deferred Stock Awards as of end of the year (in shares)					26,187
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Unvested Deferred Stock Awards, Weighted-Average Grant Date Fair Value at end of year (in dollars per share)	21.38
Net Shares Granted (in shares)								26,187
Grant Date Fair Value (in dollars per share)	$ 21.38							$ 21.38
Unvested Shares (in shares)					26,187
Deferred Stock Award, Granted May 18, 2017 \| Share-based Compensation Award, Tranche One \| Deferred Stock Award
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Vesting percentage	25.00%
Deferred Stock Award, Granted May 18, 2017 \| Share-based Compensation Award, Tranche Two \| Deferred Stock Award
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Vesting percentage	25.00%
Deferred Stock Award, Granted May 18, 2017 \| Share-based Compensation Award, Tranche Three \| Deferred Stock Award
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Vesting percentage	25.00%
Deferred Stock Award, Granted May 18, 2017 \| Share-based Compensation Award, Tranche Four \| Deferred Stock Award
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Vesting percentage	25.00%
Performance Share Program Award, Granted May 18, 2017 \| Performance Shares
Rollforward of deferred stock award activity
Unvested Deferred Stock Awards as of end of the year (in shares)					127,335
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Unvested Deferred Stock Awards, Weighted-Average Grant Date Fair Value at end of year (in dollars per share)	$ 30.45
Net Shares Granted (in shares)								0
Grant Date Fair Value (in dollars per share)	$ 30.45							$ 30.45
Unvested Shares (in shares)					127,335

Stock Based Compensation (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense and directors' fees related to stock awards	$ 9.5	$ 8.0	$ 8.9
Compensation expense, non-vested awards	$ 7.7	$ 6.5	$ 7.0
Number of shares issued to employees, directors and officers	256,628
Nonvested awards, total compensation cost not yet recognized	$ 3.8
Weighted Average
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested awards, total compensation cost not yet recognized, period for recognition	1 year
Stock Awards \| Independent directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	1 year

Earnings Per Share (Details) - shares	12 Months Ended
Earnings Per Share (Details) - shares	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Weighted-average shares outstanding - basic (in shares)	145,043,503	145,230,382	150,537,757
Deferred and performance stock awards (in shares)	336,000	405,000	342,000
Weighted-average shares outstanding - diluted (in shares)	145,379,994	145,634,953	150,880,116
Common stock, shares outstanding (in shares)	142,358,940	145,235,313	145,511,644

Operating Leases (Details) $ in Thousands	12 Months Ended
Operating Leases (Details) $ in Thousands	Dec. 31, 2017 USD ($) market
Revenues from External Customers and Long-Lived Assets [Line Items]
Percentage of annualized lease revenue	88.00%
Operating Leases, Future Minimum Payments Receivable [Abstract]
2018	$ 417,643
2019	401,120
2020	377,556
2021	344,991
2022	316,053
Thereafter	1,348,156
Total	$ 3,205,519
Customer Concentration Risk \| Federal Governmental Agencies
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	1.90%
US
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of office markets \| market	8
Disposal Group, Held-for-sale, Not Discontinued Operations
Operating Leases, Future Minimum Payments Receivable [Abstract]
2018	$ 377,447
2019	361,280
2020	338,269
2021	307,008
2022	287,175
Thereafter	1,298,890
Total	$ 2,970,069

Property Dispositions, Assets Held for Sale and Discontinued Operations (Property Dispositions) (Details) - USD ($) $ in Thousands																					12 Months Ended
	Jul. 27, 2017	Jul. 05, 2017	Jun. 16, 2017	Dec. 29, 2016	Dec. 22, 2016	Sep. 28, 2016	Jul. 29, 2016	Jul. 27, 2016	May 02, 2016	Apr. 28, 2016	Apr. 21, 2016	Dec. 21, 2015	Oct. 29, 2015	Sep. 01, 2015	Aug. 10, 2015	Jul. 28, 2015	May 01, 2015	Apr. 29, 2015	Apr. 28, 2015	Jan. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net Sales Proceeds																					$ 375,518	$ 365,918	$ 848,169
Net Sales Proceeds, equity method investment																					12,334	0	$ 0
Notes receivable																					$ 0	$ 0
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| 3900 Dallas Parkway
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(Loss) on Sale																				$ 8,940
Net Sales Proceeds																				$ 25,803
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| 5601 Headquarters Drive
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(Loss) on Sale																			$ 6,390
Net Sales Proceeds																			$ 33,326
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| River Corporate Center
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(Loss) on Sale																		$ 4,144
Net Sales Proceeds																		$ 24,223
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Copper Ridge Center
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(Loss) on Sale																	$ 11,358
Net Sales Proceeds																	50,372
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Copper Ridge Center \| Notes Receivable \| Secured Promissory Note
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Notes receivable																	$ 45,400
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Eastpoint I & II
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(Loss) on Sale																$ (177)
Net Sales Proceeds																$ 17,342
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| 3750 Brookside Parkway
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(Loss) on Sale															$ 761
Net Sales Proceeds															$ 13,624
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Chandler Forum
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(Loss) on Sale														$ 13,805
Net Sales Proceeds														$ 32,267
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Aon Center
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(Loss) on Sale													$ 84,218
Net Sales Proceeds													$ 646,243
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| 2 Gatehall Drive
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(Loss) on Sale												$ 162
Net Sales Proceeds												$ 50,369
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| 1055 East Colorado Boulevard
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(Loss) on Sale											$ 29,462
Net Sales Proceeds											$ 60,076
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Fairway Center II
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(Loss) on Sale										$ 14,406
Net Sales Proceeds										$ 33,062
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| 1901 Main Street
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(Loss) on Sale									$ 29,964
Net Sales Proceeds									63,149
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| 1901 Main Street \| Notes Receivable \| Secured Promissory Note
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Notes receivable									$ 33,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| 9221 Corporate Boulevard
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(Loss) on Sale								$ (192)
Net Sales Proceeds								$ 12,035
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| 150 West Jefferson
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(Loss) on Sale							$ (664)
Net Sales Proceeds							$ 77,844
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| 9200 and 9211 Corporate Boulevard
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(Loss) on Sale						$ (41)
Net Sales Proceeds						$ 12,519
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| 11695 Johns Creek Parkway
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(Loss) on Sale					$ 1,978
Net Sales Proceeds					$ 13,827
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Braker Pointe III
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(Loss) on Sale				$ 18,579
Net Sales Proceeds				$ 48,006
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Sarasota Commerce Center II
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(Loss) on Sale			$ 6,493
Net Sales Proceeds			$ 23,090
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Two Independence Square
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(Loss) on Sale		$ 109,381
Net Sales Proceeds		$ 352,428
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| 8560 Upland Drive
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(Loss) on Sale, equity method investment	$ 3,683
Net Sales Proceeds, equity method investment	$ 12,334
Piedmont’s ownership percentage																					72.00%

Property Dispositions, Assets Held for Sale, and Discontinued Operations (Assets Held-for-Sale) (Details) $ in Thousands	3 Months Ended
	Dec. 31, 2017 USD ($) agreement asset	Dec. 31, 2016 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of binding contracts to sell assets \| agreement	2
Number of assets being sold \| asset	14
Total other assets held for sale, net	$ 47,131	$ 58,632
Disposal Group, Held-for-sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total real estate assets held for sale, net	332,410	612,719
Straight-line rent receivables	25,975	28,986
Prepaid expenses and other assets	328	374
Deferred lease costs, less accumulated amortization of $16,549 and $18,937 as of December 31, 2017 and 2016, respectively	20,828	29,272
Accumulated amortization on deferred lease costs	16,549	18,937
Total other assets held for sale, net	47,131	58,632
Intangible lease liabilities, less accumulated amortization of $935 and $848 as of December 31, 2017 and 2016, respectively	380	468
Accumulated amortization on Intangible lease liabilities	935	848
Disposal Group, Held-for-sale, Not Discontinued Operations \| Land
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Real estate assets held for sale, net:	74,498	127,209
Disposal Group, Held-for-sale, Not Discontinued Operations \| Building and building improvements
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Real estate assets held for sale, net:	255,634	485,145
Accumulated depreciation (building improvements)	169,116	244,269
Disposal Group, Held-for-sale, Not Discontinued Operations \| Construction in progress
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Real estate assets held for sale, net:	$ 2,278	$ 365

Property Dispositions, Assets Held for Sale, and Discontinued Operations (Discontinued Operations) (Details) - USD ($) $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Expenses:
Operating income, excluding loss on sale of real estate assets					$ 0	$ 0	$ 84
Loss on sale of real estate assets					0	0	(1)
Income from discontinued operations	$ 0	$ 1	$ (1)	$ 0	0	0	83
Discontinued operations
Revenues:
Rental income					0	0	19
Tenant reimbursements					0	0	64
Revenue					0	0	83
Expenses:
Property operating costs					0	0	1
Expenses					0	0	1
Operating income, excluding loss on sale of real estate assets					0	0	84
Loss on sale of real estate assets					0	0	(1)
Income from discontinued operations					$ 0	$ 0	$ 83

Supplemental Disclosures for the Statement of Consolidated Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplemental Cash Flow Elements [Abstract]
Accrued capital expenditures and deferred lease costs	$ 11,276	$ 14,427	$ 20,630
Change in accrued dividends and discount on dividend reinvestments	71,267	30,532	0
Change in accrued share repurchases as part of an announced plan	1,276	0	0
Investment in consolidated joint venture	63,026	0	0
Cash and cash equivalents	7,382	6,992	5,441
Restricted cash and escrows:
Real estate tax and escrowed cash	833	757	4,772
Security and utility deposit escrows	540	455	402
Total cash, cash equivalents, and restricted cash and escrows shown in the consolidated statement of cash flows	$ 8,755	$ 8,204	$ 10,615

Income Taxes (Details) - USD ($)	3 Months Ended								12 Months Ended
Income Taxes (Details) - USD ($)	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Line Items]
Net income applicable to Piedmont	$ (31,383,000)	$ 126,133,000	$ 23,710,000	$ 15,104,000	$ 30,189,000	$ (13,107,000)	$ 72,278,000	$ 10,372,000	$ 133,564,000	$ 99,732,000	$ 131,304,000
Depreciation and amortization expense recognized for financial reporting purposes in excess of/(less than) amounts recognized for income tax purposes									62,916,000	69,214,000	(1,717,000)
Rental income accrued for income tax purposes less than amounts for financial reporting purposes									(25,432,000)	(18,964,000)	(12,123,000)
Net amortization of above/below-market lease intangibles for income tax purposes in excess of amounts for financial reporting purposes									(6,041,000)	(4,895,000)	(4,614,000)
Gain on disposal of property for financial reporting purposes less than/(in excess of) amounts for income tax purposes									10,068,000	(118,713,000)	(43,493,000)
Other expenses, including impairment loss on real estate assets, for financial reporting purposes in excess of amounts for income tax purposes									49,859,000	42,019,000	54,425,000
Income tax basis net income, prior to dividends paid deduction									$ 225,082,000	$ 67,999,000	$ 126,273,000
Ordinary income, Percent									53.61%	81.77%	31.75%
Return of capital, Percent									0.00%	18.23%	0.00%
Capital gains, Percent									46.39%	0.00%	68.25%
Common Stock Dividends, Percent									100.00%	100.00%	100.00%
Tax basis of total assets	4,200,000,000				4,300,000,000				$ 4,200,000,000	$ 4,300,000,000
Accrued interest and penalties related to uncertain tax positions	$ 3,800,000				$ 3,800,000				3,800,000	3,800,000
Recovery of tax expense, including potential interest and penalties									100,000	0	$ 0
Piedmont Washington Properties, Inc
Income Taxes [Line Items]
Taxable income (loss) in excess of/(less than) amount for financial reporting purposes									176,000	(1,042,000)	2,491,000
Piedmont Office Holdings, Inc
Income Taxes [Line Items]
Taxable income (loss) in excess of/(less than) amount for financial reporting purposes									$ (28,000)	$ 648,000	$ 0

Quarterly Results (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended								12 Months Ended
	Feb. 07, 2018	Jan. 09, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Subsequent Event [Line Items]
Special dividend (in usd per share)											$ 1.34	$ 0.84	$ 0.84
Revenues			$ 139,444	$ 137,587	$ 148,679	$ 148,463	$ 143,911	$ 138,485	$ 135,307	$ 138,012	$ 574,173	$ 555,715	$ 584,769
Real estate operating income/(loss)			(16,250)	28,756	35,491	33,300	26,633	2,988	14,791	26,372	81,297	70,784	73,711
Income/(loss) from continuing operations			(31,311)	16,617	17,215	15,154	10,529	(13,065)	(1,553)	10,396	17,675	6,307	1,553
Income/(loss) from discontinued operations							0	1	(1)	0	0	0	83
Gain/(loss) on sale of real estate assets			(77)	109,512	6,492	(53)	19,652	(57)	73,835	(20)	115,874	93,410	129,683
Net income/(loss) applicable to Piedmont			$ (31,383)	$ 126,133	$ 23,710	$ 15,104	$ 30,189	$ (13,107)	$ 72,278	$ 10,372	$ 133,564	$ 99,732	$ 131,304
Basic and diluted earnings/(loss) per share			$ (0.21)	$ 0.87	$ 0.16	$ 0.10	$ 0.21	$ (0.09)	$ 0.50	$ 0.07	$ 0.92	$ 0.69	$ 0.87
Dividends declared per share			$ 0.71	$ 0.21	$ 0.21	$ 0.21	$ 0.21	$ 0.21	$ 0.21	$ 0.21
Subsequent Event
Subsequent Event [Line Items]
Special dividend (in usd per share)		$ 0.50
Dividends declared per share	$ 0.21

Guarantor and Non-Guarantor Financial Information- Condensed Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets:
Land	$ 544,794	$ 542,640
Buildings and improvements, less accumulated depreciation	2,418,023	2,442,178
Intangible lease assets, less accumulated amortization	77,805	99,695
Construction in progress	11,710	34,460
Real estate assets held for sale, net	332,410	612,719
Total real estate assets	3,384,742	3,731,692
Investments in and amounts due from unconsolidated joint ventures	10	7,360
Cash and cash equivalents	7,382	6,992	$ 5,441
Tenant and straight-line receivables, net, and amounts due from unconsolidated joint ventures	175,309	163,356
Advances to affiliates	0	0
Investment in subsidiary	0	0
Notes receivable	0	0
Prepaid expenses, restricted cash, escrows, interest rate swap, and other assets	24,578	24,493
Goodwill	98,918	98,918
Deferred lease costs, net	261,907	276,725
Other assets held for sale, net	47,131	58,632
Total assets	3,999,967	4,368,168
Liabilities:
Debt, net	1,726,927	2,020,475
Accounts payable, accrued expenses, dividends payable, and accrued capital expenditures	216,653	165,410
Advances from affiliates	0	0
Deferred income	29,582	28,406
Intangible lease liabilities, net	38,458	47,537
Other liabilities held for sale, net	380	468
Interest rate swaps	1,478	8,169
Total liabilities	2,013,478	2,270,465
Stockholders’ Equity:
Common stock	1,424	1,452
Additional paid-in capital	3,677,360	3,673,128
Retained/(cumulative distributions in excess of) earnings	(1,702,281)	(1,580,863)
Other comprehensive loss	8,164	2,104
Piedmont stockholders’ equity	1,984,667	2,095,821
Noncontrolling interest	1,822	1,882
Total stockholders’ equity	1,986,489	2,097,703	$ 2,123,420	$ 2,280,677
Total liabilities and stockholders’ equity	3,999,967	4,368,168
Eliminations
Assets:
Land	0	0
Buildings and improvements, less accumulated depreciation	(300)	(300)
Intangible lease assets, less accumulated amortization	0	0
Construction in progress	0	0
Real estate assets held for sale, net	0	0
Total real estate assets	(300)	(300)
Investments in and amounts due from unconsolidated joint ventures		0
Cash and cash equivalents	0	0
Tenant and straight-line receivables, net, and amounts due from unconsolidated joint ventures	0	0
Advances to affiliates	(7,971,908)	(7,779,751)
Investment in subsidiary	(3,437,471)	(3,630,745)
Notes receivable	(233,310)	(184,700)
Prepaid expenses, restricted cash, escrows, interest rate swap, and other assets	(740)	(1,897)
Goodwill	0	0
Deferred lease costs, net	0	0
Other assets held for sale, net	0	0
Total assets	(11,643,729)	(11,597,393)
Liabilities:
Debt, net	(233,310)	(184,700)
Accounts payable, accrued expenses, dividends payable, and accrued capital expenditures	(740)	(1,897)
Advances from affiliates	(8,070,163)	(7,878,007)
Deferred income	0	0
Intangible lease liabilities, net	0	0
Other liabilities held for sale, net	0	0
Interest rate swaps	0	0
Total liabilities	(8,304,213)	(8,064,604)
Stockholders’ Equity:
Common stock	0	0
Additional paid-in capital	(3,437,471)	(3,630,745)
Retained/(cumulative distributions in excess of) earnings	97,955	97,956
Other comprehensive loss	0	0
Piedmont stockholders’ equity	(3,339,516)	(3,532,789)
Noncontrolling interest	0	0
Total stockholders’ equity	(3,339,516)	(3,532,789)
Total liabilities and stockholders’ equity	(11,643,729)	(11,597,393)
Issuer
Assets:
Land	36,094	38,298
Buildings and improvements, less accumulated depreciation	180,886	202,084
Intangible lease assets, less accumulated amortization	181	725
Construction in progress	85	145
Real estate assets held for sale, net	32,815	33,945
Total real estate assets	250,061	275,197
Investments in and amounts due from unconsolidated joint ventures		7,360
Cash and cash equivalents	3,890	3,674
Tenant and straight-line receivables, net, and amounts due from unconsolidated joint ventures	16,891	18,517
Advances to affiliates	6,297,632	6,464,135
Investment in subsidiary	0	0
Notes receivable	88,810	88,910
Prepaid expenses, restricted cash, escrows, interest rate swap, and other assets	5,094	6,173
Goodwill	98,918	98,918
Deferred lease costs, net	16,611	14,776
Other assets held for sale, net	2,266	3,432
Total assets	6,780,173	6,981,092
Liabilities:
Debt, net	1,535,239	1,701,933
Accounts payable, accrued expenses, dividends payable, and accrued capital expenditures	20,279	17,365
Advances from affiliates	941,494	708,340
Deferred income	3,631	5,206
Intangible lease liabilities, net	0	0
Other liabilities held for sale, net	0	0
Interest rate swaps	1,478	8,169
Total liabilities	2,502,121	2,441,013
Stockholders’ Equity:
Common stock	0	0
Additional paid-in capital	3,433,299	3,626,564
Retained/(cumulative distributions in excess of) earnings	836,589	911,411
Other comprehensive loss	8,164	2,104
Piedmont stockholders’ equity	4,278,052	4,540,079
Noncontrolling interest	0	0
Total stockholders’ equity	4,278,052	4,540,079
Total liabilities and stockholders’ equity	6,780,173	6,981,092
Guarantor
Assets:
Land	0	0
Buildings and improvements, less accumulated depreciation	0	0
Intangible lease assets, less accumulated amortization	0	0
Construction in progress	0	0
Real estate assets held for sale, net	0	0
Total real estate assets	0	0
Investments in and amounts due from unconsolidated joint ventures		0
Cash and cash equivalents	150	150
Tenant and straight-line receivables, net, and amounts due from unconsolidated joint ventures	0	0
Advances to affiliates	1,674,276	1,315,616
Investment in subsidiary	3,437,299	3,630,564
Notes receivable	0	0
Prepaid expenses, restricted cash, escrows, interest rate swap, and other assets	2	0
Goodwill	0	0
Deferred lease costs, net	0	0
Other assets held for sale, net	0	0
Total assets	5,111,727	4,946,330
Liabilities:
Debt, net	0	0
Accounts payable, accrued expenses, dividends payable, and accrued capital expenditures	104,028	31,230
Advances from affiliates	5,277,957	5,071,521
Deferred income	0	0
Intangible lease liabilities, net	0	0
Other liabilities held for sale, net	0	0
Interest rate swaps	0	0
Total liabilities	5,381,985	5,102,751
Stockholders’ Equity:
Common stock	1,424	1,452
Additional paid-in capital	3,680,232	3,676,000
Retained/(cumulative distributions in excess of) earnings	(3,951,914)	(3,833,873)
Other comprehensive loss	0	0
Piedmont stockholders’ equity	(270,258)	(156,421)
Noncontrolling interest	0	0
Total stockholders’ equity	(270,258)	(156,421)
Total liabilities and stockholders’ equity	5,111,727	4,946,330
Non-Guarantor Subsidiaries
Assets:
Land	508,700	504,342
Buildings and improvements, less accumulated depreciation	2,237,437	2,240,394
Intangible lease assets, less accumulated amortization	77,624	98,970
Construction in progress	11,625	34,315
Real estate assets held for sale, net	299,595	578,774
Total real estate assets	3,134,981	3,456,795
Investments in and amounts due from unconsolidated joint ventures		0
Cash and cash equivalents	3,342	3,168
Tenant and straight-line receivables, net, and amounts due from unconsolidated joint ventures	158,418	144,839
Advances to affiliates	0	0
Investment in subsidiary	172	181
Notes receivable	144,500	95,790
Prepaid expenses, restricted cash, escrows, interest rate swap, and other assets	20,222	20,217
Goodwill	0	0
Deferred lease costs, net	245,296	261,949
Other assets held for sale, net	44,865	55,200
Total assets	3,751,796	4,038,139
Liabilities:
Debt, net	424,998	503,242
Accounts payable, accrued expenses, dividends payable, and accrued capital expenditures	93,086	118,712
Advances from affiliates	1,850,712	2,098,146
Deferred income	25,951	23,200
Intangible lease liabilities, net	38,458	47,537
Other liabilities held for sale, net	380	468
Interest rate swaps	0	0
Total liabilities	2,433,585	2,791,305
Stockholders’ Equity:
Common stock	0	0
Additional paid-in capital	1,300	1,309
Retained/(cumulative distributions in excess of) earnings	1,315,089	1,243,643
Other comprehensive loss	0	0
Piedmont stockholders’ equity	1,316,389	1,244,952
Noncontrolling interest	1,822	1,882
Total stockholders’ equity	1,318,211	1,246,834
Total liabilities and stockholders’ equity	$ 3,751,796	$ 4,038,139

Guarantor and Non-Guarantor Financial Information - Condensed Consolidated Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Rental income									$ 475,777	$ 459,890	$ 468,872
Tenant reimbursements									96,711	93,961	113,881
Property management fee revenue									1,685	1,864	2,016
Total revenues	$ 139,444	$ 137,587	$ 148,679	$ 148,463	$ 143,911	$ 138,485	$ 135,307	$ 138,012	574,173	555,715	584,769
Expenses:
Property operating costs									220,630	218,934	242,022
Depreciation									119,288	127,733	134,503
Amortization									75,367	75,119	60,886
Impairment loss											43,301
Impairment loss on real estate assets									46,461	33,901	43,301
General and administrative									31,130	29,244	30,346
Operating Expenses									492,876	484,931	511,058
Real estate operating income	(16,250)	28,756	35,491	33,300	26,633	2,988	14,791	26,372	81,297	70,784	73,711
Other income (expense):
Interest expense									(68,124)	(64,860)	(73,998)
Other income/(expense)									657	(13)	1,565
Net recoveries/(loss) from casualty events									0	34	(278)
Equity in income of unconsolidated joint ventures									3,845	362	553
Nonoperating Income (Expense)									(63,622)	(64,477)	(72,158)
Income from continuing operations	(31,311)	16,617	17,215	15,154	10,529	(13,065)	(1,553)	10,396	17,675	6,307	1,553
Discontinued operations:
Operating income									0	0	84
Loss on sale of real estate assets									0	0	(1)
Income from discontinued operations					0	1	(1)	0	0	0	83
Gain on sale of real estate assets	(77)	109,512	6,492	(53)	19,652	(57)	73,835	(20)	115,874	93,410	129,683
Net income									133,549	99,717	131,319
Plus: Net loss/(income) applicable to noncontrolling interest									15	15	(15)
Net income applicable to Piedmont	$ (31,383)	$ 126,133	$ 23,710	$ 15,104	$ 30,189	$ (13,107)	$ 72,278	$ 10,372	133,564	99,732	131,304
Eliminations
Revenues:
Rental income									(1,791)	(2,631)	(2,905)
Tenant reimbursements									(474)	(498)	(414)
Property management fee revenue									(16,470)	(15,033)	(15,785)
Total revenues									(18,735)	(18,162)	(19,104)
Expenses:
Property operating costs									(18,735)	(18,377)	(19,786)
Depreciation									0	0	0
Amortization									0	0	0
Impairment loss											0
Impairment loss on real estate assets									0	0
General and administrative									0	(35,446)	(35,563)
Operating Expenses									(18,735)	(53,823)	(55,349)
Real estate operating income									0	35,661	36,245
Other income (expense):
Interest expense									15,360	11,884	11,246
Other income/(expense)									(15,360)	(11,884)	(11,246)
Net recoveries/(loss) from casualty events										0	0
Equity in income of unconsolidated joint ventures									0	0	0
Nonoperating Income (Expense)									0	0	0
Income from continuing operations									0	35,661	36,245
Discontinued operations:
Operating income											0
Loss on sale of real estate assets											0
Income from discontinued operations											0
Gain on sale of real estate assets									0	0	0
Net income									0	35,661	36,245
Plus: Net loss/(income) applicable to noncontrolling interest									0	0	0
Net income applicable to Piedmont									0	35,661	36,245
Guarantor
Revenues:
Rental income									0	0	0
Tenant reimbursements									0	0	0
Property management fee revenue									0	0	0
Total revenues									0	0	0
Expenses:
Property operating costs									0	0	0
Depreciation									0	0	0
Amortization									0	0	0
Impairment loss											0
Impairment loss on real estate assets									0	0
General and administrative									347	311	341
Operating Expenses									347	311	341
Real estate operating income									(347)	(311)	(341)
Other income (expense):
Interest expense									0	0	0
Other income/(expense)									0	282	0
Net recoveries/(loss) from casualty events										0	0
Equity in income of unconsolidated joint ventures									0	0	0
Nonoperating Income (Expense)									0	282	0
Income from continuing operations									(347)	(29)	(341)
Discontinued operations:
Operating income											0
Loss on sale of real estate assets											0
Income from discontinued operations											0
Gain on sale of real estate assets									0	0	0
Net income									(347)	(29)	(341)
Plus: Net loss/(income) applicable to noncontrolling interest									0	0	0
Net income applicable to Piedmont									(347)	(29)	(341)
Issuer
Revenues:
Rental income									42,593	55,007	67,317
Tenant reimbursements									11,660	14,081	13,340
Property management fee revenue									0	0	0
Total revenues									54,253	69,088	80,657
Expenses:
Property operating costs									22,805	31,967	36,380
Depreciation									12,995	16,657	20,891
Amortization									3,049	3,715	4,598
Impairment loss											6,195
Impairment loss on real estate assets									87	8,259
General and administrative									6,443	28,314	29,645
Operating Expenses									45,379	88,912	97,709
Real estate operating income									8,874	(19,824)	(17,052)
Other income (expense):
Interest expense									(56,769)	(49,108)	(51,704)
Other income/(expense)									9,168	9,560	12,600
Net recoveries/(loss) from casualty events										0	23
Equity in income of unconsolidated joint ventures									3,845	362	553
Nonoperating Income (Expense)									(43,756)	(39,186)	(38,528)
Income from continuing operations									(34,882)	(59,010)	(55,580)
Discontinued operations:
Operating income											15
Loss on sale of real estate assets											(1)
Income from discontinued operations											14
Gain on sale of real estate assets									6,431	31,275	45,225
Net income									(28,451)	(27,735)	(10,341)
Plus: Net loss/(income) applicable to noncontrolling interest									0	0	0
Net income applicable to Piedmont									(28,451)	(27,735)	(10,341)
Non-Guarantor Subsidiaries
Revenues:
Rental income									434,975	407,514	404,460
Tenant reimbursements									85,525	80,378	100,955
Property management fee revenue									18,155	16,897	17,801
Total revenues									538,655	504,789	523,216
Expenses:
Property operating costs									216,560	205,344	225,428
Depreciation									106,293	111,076	113,612
Amortization									72,318	71,404	56,288
Impairment loss											37,106
Impairment loss on real estate assets									46,374	25,642
General and administrative									24,340	36,065	35,923
Operating Expenses									465,885	449,531	468,357
Real estate operating income									72,770	55,258	54,859
Other income (expense):
Interest expense									(26,715)	(27,636)	(33,540)
Other income/(expense)									6,849	2,029	211
Net recoveries/(loss) from casualty events										34	(301)
Equity in income of unconsolidated joint ventures									0	0	0
Nonoperating Income (Expense)									(19,866)	(25,573)	(33,630)
Income from continuing operations									52,904	29,685	21,229
Discontinued operations:
Operating income											69
Loss on sale of real estate assets											0
Income from discontinued operations											69
Gain on sale of real estate assets									109,443	62,135	84,458
Net income									162,347	91,820	105,756
Plus: Net loss/(income) applicable to noncontrolling interest									15	15	(15)
Net income applicable to Piedmont									$ 162,362	$ 91,835	$ 105,741

Guarantor and Non-Guarantor Financial Information - Condensed Consolidated Statements of Cash Flows (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided By/(Used In) Operating Activities	$ 242,805,000	$ 231,847,000	$ 223,688,000
Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	(115,093,000)	(459,896,000)	(506,594,000)
Intercompany note receivable	0	0	0
Redemption of noncontrolling interest in unconsolidated variable interest entity	0	0	(4,000,000)
Net sale proceeds from wholly-owned properties	375,518,000	365,918,000	848,169,000
Net sale proceeds received from unconsolidated joint ventures	12,334,000	0	0
Investments in unconsolidated joint ventures	(1,162,000)	0	0
Deferred lease costs paid	(30,985,000)	(25,896,000)	(37,683,000)
Net cash provided by/(used in) investing activities	240,612,000	(119,874,000)	299,892,000
Cash Flows from Financing Activities:
Debt issuance costs paid	(132,000)	(264,000)	(1,081,000)
Proceeds from debt	180,000,000	695,000,000	1,301,858,000
Repayments of debt	(476,401,000)	(706,875,000)	(1,544,301,000)
Intercompany note payable	0	0	0
Costs of issuance of common stock	(182,000)	(342,000)	(326,000)
Shares withheld to pay tax obligations related to employee stock compensation	(3,403,000)	(2,344,000)	(1,710,000)
Repurchases of common stock as part of announced plan	(60,474,000)	(7,943,000)	(158,860,000)
(Distributions to)/repayments from affiliates	0	0	0
Dividends paid and discount on dividend reinvestments	(122,274,000)	(91,616,000)	(126,531,000)
Net cash used in financing activities	(482,866,000)	(114,384,000)	(530,951,000)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	551,000	(2,411,000)	(7,371,000)
Cash, cash equivalents, and restricted cash and escrows, beginning of year	8,204,000	10,615,000	17,986,000
Cash, cash equivalents, and restricted cash and escrows, end of year	8,755,000	8,204,000	10,615,000
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided By/(Used In) Operating Activities	0	35,660,000	36,245,000
Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	0	0	0
Intercompany note receivable	48,610,000	71,460,000	(72,000,000)
Redemption of noncontrolling interest in unconsolidated variable interest entity		0	0
Net sale proceeds from wholly-owned properties	0	0	0
Net sale proceeds received from unconsolidated joint ventures	0
Investments in unconsolidated joint ventures	0
Deferred lease costs paid	0	0	0
Net cash provided by/(used in) investing activities	48,610,000	71,460,000	(72,000,000)
Cash Flows from Financing Activities:
Debt issuance costs paid	0	0	0
Proceeds from debt	0	0	0
Repayments of debt	0	0	0
Intercompany note payable	(48,610,000)	(71,460,000)	72,000,000
Costs of issuance of common stock	0	0	0
Shares withheld to pay tax obligations related to employee stock compensation	0	0
Repurchases of common stock as part of announced plan	0	0	0
(Distributions to)/repayments from affiliates	0	(35,660,000)	(36,245,000)
Dividends paid and discount on dividend reinvestments	0	0	0
Net cash used in financing activities	(48,610,000)	(107,120,000)	35,755,000
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	0	0	0
Cash, cash equivalents, and restricted cash and escrows, beginning of year	0	0	0
Cash, cash equivalents, and restricted cash and escrows, end of year	0	0	0
Guarantor
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided By/(Used In) Operating Activities	5,497,000	5,214,000	4,699,000
Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	0	0	0
Intercompany note receivable	0	0	0
Redemption of noncontrolling interest in unconsolidated variable interest entity		0	0
Net sale proceeds from wholly-owned properties	0	0	0
Net sale proceeds received from unconsolidated joint ventures	0
Investments in unconsolidated joint ventures	0
Deferred lease costs paid	0	0	0
Net cash provided by/(used in) investing activities	0	0	0
Cash Flows from Financing Activities:
Debt issuance costs paid	0	0	0
Proceeds from debt	0	0	0
Repayments of debt	0	0	0
Intercompany note payable	0	0	0
Costs of issuance of common stock	(182,000)	(342,000)	(326,000)
Shares withheld to pay tax obligations related to employee stock compensation	(3,403,000)	(2,344,000)	(1,710,000)
Repurchases of common stock as part of announced plan	(60,474,000)	(7,943,000)	(158,860,000)
(Distributions to)/repayments from affiliates	180,791,000	97,016,000	281,073,000
Dividends paid and discount on dividend reinvestments	(122,229,000)	(91,601,000)	(126,516,000)
Net cash used in financing activities	(5,497,000)	(5,214,000)	(6,339,000)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	0	0	(1,640,000)
Cash, cash equivalents, and restricted cash and escrows, beginning of year	150,000	150,000	1,790,000
Cash, cash equivalents, and restricted cash and escrows, end of year	150,000	150,000	150,000
Issuer
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided By/(Used In) Operating Activities	(18,989,000)	(26,263,000)	(27,077,000)
Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	(1,614,000)	(5,060,000)	(12,303,000)
Intercompany note receivable	100,000	440,000	72,000,000
Redemption of noncontrolling interest in unconsolidated variable interest entity		0	0
Net sale proceeds from wholly-owned properties	23,028,000	200,220,000	151,557,000
Net sale proceeds received from unconsolidated joint ventures	12,334,000
Investments in unconsolidated joint ventures	(1,162,000)
Deferred lease costs paid	(4,081,000)	(2,758,000)	(3,792,000)
Net cash provided by/(used in) investing activities	28,605,000	192,842,000	207,462,000
Cash Flows from Financing Activities:
Debt issuance costs paid	(132,000)	(264,000)	(575,000)
Proceeds from debt	180,000,000	695,000,000	1,142,577,000
Repayments of debt	(335,000,000)	(538,000,000)	(1,438,000,000)
Intercompany note payable	(14,289,000)	(9,600,000)	0
Costs of issuance of common stock	0	0	0
Shares withheld to pay tax obligations related to employee stock compensation	0	0	0
Repurchases of common stock as part of announced plan	0	0	0
(Distributions to)/repayments from affiliates	160,019,000	(312,218,000)	104,495,000
Dividends paid and discount on dividend reinvestments	0	0	0
Net cash used in financing activities	(9,402,000)	(165,082,000)	(191,503,000)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	214,000	1,497,000	(11,118,000)
Cash, cash equivalents, and restricted cash and escrows, beginning of year	3,693,000	2,196,000	13,314,000
Cash, cash equivalents, and restricted cash and escrows, end of year	3,907,000	3,693,000	2,196,000
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided By/(Used In) Operating Activities	256,297,000	217,236,000	209,821,000
Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	(113,479,000)	(454,836,000)	(494,291,000)
Intercompany note receivable	(48,710,000)	(71,900,000)	0
Redemption of noncontrolling interest in unconsolidated variable interest entity		0	(4,000,000)
Net sale proceeds from wholly-owned properties	352,490,000	165,698,000	696,612,000
Net sale proceeds received from unconsolidated joint ventures	0
Investments in unconsolidated joint ventures	0
Deferred lease costs paid	(26,904,000)	(23,138,000)	(33,891,000)
Net cash provided by/(used in) investing activities	163,397,000	(384,176,000)	164,430,000
Cash Flows from Financing Activities:
Debt issuance costs paid	0	0	(506,000)
Proceeds from debt	0	0	159,281,000
Repayments of debt	(141,401,000)	(168,875,000)	(106,301,000)
Intercompany note payable	62,899,000	81,060,000	(72,000,000)
Costs of issuance of common stock	0	0	0
Shares withheld to pay tax obligations related to employee stock compensation	0	0	0
Repurchases of common stock as part of announced plan	0	0	0
(Distributions to)/repayments from affiliates	(340,810,000)	250,862,000	(349,323,000)
Dividends paid and discount on dividend reinvestments	(45,000)	(15,000)	(15,000)
Net cash used in financing activities	(419,357,000)	163,032,000	(368,864,000)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	337,000	(3,908,000)	5,387,000
Cash, cash equivalents, and restricted cash and escrows, beginning of year	4,361,000	8,269,000	2,882,000
Cash, cash equivalents, and restricted cash and escrows, end of year	$ 4,698,000	$ 4,361,000	$ 8,269,000

Subsequent events (Details) $ / shares in Units, ft² in Thousands, shares in Millions				2 Months Ended	3 Months Ended								12 Months Ended
	Feb. 19, 2018 USD ($) ft²	Feb. 07, 2018 $ / shares	Jan. 04, 2018 USD ($)	Feb. 21, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) agreement asset buyer $ / shares	Sep. 30, 2017 $ / shares	Jun. 30, 2017 $ / shares	Mar. 31, 2017 $ / shares	Dec. 31, 2016 $ / shares	Sep. 30, 2016 $ / shares	Jun. 30, 2016 $ / shares	Mar. 31, 2016 $ / shares	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	May 31, 2017 USD ($)
Subsequent Event [Line Items]
Dividends declared (in dollars per share) \| $ / shares					$ 0.71	$ 0.21	$ 0.21	$ 0.21	$ 0.21	$ 0.21	$ 0.21	$ 0.21
Number of binding contracts to sell assets \| agreement					2
Number of buyers \| buyer					2
Number of assets being sold \| asset					14
Payment to acquire real estate													$ 35,262,000	$ 349,668,000	$ 387,923,000
Stock repurchase program, authorized amount																$ 250,000,000
Stock repurchase program, remaining authorized repurchase amount					$ 188,200,000								188,200,000
Subsequent Event
Subsequent Event [Line Items]
Dividends declared (in dollars per share) \| $ / shares		$ 0.21
Stock repurchase program, authorized amount				$ 200,000,000
Common stock repurchased and retired (in shares) \| shares				7.8
Weighted-average price of common stock repurchased and retired (in USD per share) \| $ / shares				$ 18.97
Stock repurchase program, remaining authorized repurchase amount				$ 40,000,000
Subsequent Event \| 2017 Disposition Portfolio \| Disposal Group, Disposed of by Sale, Not Discontinued Operations
Subsequent Event [Line Items]
Piedmont's approximate share of purchase price			$ 425,900,000
Amount subject to contingent proceeds upon certain leasing activity			4,500,000
Unsecured Debt \| $500 Million Unsecured 2015 Line of Credit \| Line of Credit
Subsequent Event [Line Items]
Amount of line of credit					$ 500,000,000								$ 500,000,000
Unsecured Debt \| $500 Million Unsecured 2015 Line of Credit \| Line of Credit \| Subsequent Event
Subsequent Event [Line Items]
Amount of line of credit			500,000,000
Unsecured Debt \| $170 Million Unsecured 2015 Term Loan \| Subsequent Event
Subsequent Event [Line Items]
Repayments of debt			170,000,000
Unsecured Debt \| $300 Million Unsecured 2013 Term Loan \| Subsequent Event
Subsequent Event [Line Items]
Repayments of debt			$ 300,000,000
501 West Church Street \| Subsequent Event
Subsequent Event [Line Items]
Payment to acquire real estate	$ 28,000,000
Real estate acquired, number of square feet \| ft²	182

Unconsolidated Joint Venture	12 Months Ended
Unconsolidated Joint Venture	Dec. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Unconsolidated Joint Venture	Unconsolidated Joint Venture As of December 31, 2017 and 2016, Piedmont's investment in unconsolidated joint venture was $0 and $7.4 million, respectively. Piedmont owned a 72% interest in Fund XIII and REIT Joint Venture which held the 8560 Upland Drive building. During the year ended December 31, 2017, Fund XIII and REIT Joint Venture sold the remaining property located in Denver, Colorado. Piedmont's share of the purchase price was approximately $12.7 million (see Note 14).