Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2018	Feb. 19, 2019	Jun. 29, 2018
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, 2018
Document Fiscal Year Focus	2018
Emerging Growth	false
Entity Small Business	false
Entity Shell Company	false
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		125,595,994
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 2,531,552,680

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets:
Land	$ 507,422	$ 490,625
Buildings and improvements, less accumulated depreciation of $772,093 and $683,770 as of December 31, 2018 and December 31, 2017, respectively	2,305,096	2,243,519
Intangible lease assets, less accumulated amortization of $87,391 and $99,145 as of December 31, 2018 and December 31, 2017, respectively	77,676	77,805
Construction in progress	15,848	11,344
Real estate assets held for sale, net	110,552	561,449
Total real estate assets	3,016,594	3,384,742
Investment in and amounts due from unconsolidated joint venture	0	10
Cash and cash equivalents	4,571	7,382
Tenant receivables, net of allowance for doubtful accounts of $504 and $539 as of December 31, 2018 and December 31, 2017, respectively	10,800	12,139
Straight-line rent receivables	162,589	144,469
Restricted cash and escrows	1,463	1,373
Prepaid expenses and other assets	25,356	20,778
Goodwill	98,918	98,918
Interest rate swaps	1,199	688
Deferred lease costs, less accumulated amortization of $183,611 and $180,120 as of December 31, 2018 and December 31, 2017, respectively	250,148	245,175
Other assets held for sale, net	20,791	84,293
Total assets	3,592,429	3,999,967
Liabilities:
Unsecured debt, net of discount and unamortized debt issuance costs of $9,879 and $7,689 as of December 31, 2018 and December 31, 2017, respectively	1,495,121	1,535,311
Secured debt, net of premiums and unamortized debt issuance costs of $645 and $946 as of December 31, 2018 and December 31, 2017, respectively	190,351	191,616
Accounts payable, accrued expenses, and accrued capital expenditures	102,519	114,853
Dividends payable	26,972	101,800
Deferred income	28,779	29,582
Intangible lease liabilities, less accumulated amortization of $59,144 and $55,847 as of December 31, 2018 and December 31, 2017, respectively	35,708	38,458
Interest rate swaps	839	1,478
Other liabilities held for sale, net	0	380
Total liabilities	1,880,289	2,013,478
Commitments and Contingencies (Note 8)	0	0
Stockholders' Equity:
Shares-in-trust, 150,000,000 shares authorized, none outstanding as of December 31, 2018 or December 31, 2017	0	0
Preferred stock, no par value, 100,000,000 shares authorized, none outstanding as of December 31, 2018 or December 31, 2017	0	0
Common stock, $.01 par value; 750,000,000 shares authorized, 126,218,554 shares issued and outstanding as of December 31, 2018; and 142,358,940 shares issued and outstanding at December 31, 2017	1,262	1,424
Additional paid-in capital	3,683,186	3,677,360
Cumulative distributions in excess of earnings	(1,982,542)	(1,702,281)
Other comprehensive income	8,462	8,164
Piedmont stockholders’ equity	1,710,368	1,984,667
Noncontrolling interest	1,772	1,822
Total stockholders’ equity	1,712,140	1,986,489
Total liabilities and stockholders’ equity	$ 3,592,429	$ 3,999,967

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets:
Intangible lease assets, accumulated amortization	$ 87,391	$ 99,145
Tenant receivables, allowance for doubtful accounts	504	539
Deferred lease costs, accumulated amortization	183,611	180,120
Liabilities:
Intangible lease liabilities, accumulated amortization	$ 59,144	$ 55,847
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	126,218,554	142,358,940
Common stock, shares outstanding	126,218,554	142,358,940
Unsecured Debt
Liabilities:
Discount (premium) and unamortized debt issuance costs	$ 9,879	$ 7,689
Secured Debt
Liabilities:
Discount (premium) and unamortized debt issuance costs	(645)	(946)
Building and building improvements
Assets:
Buildings and improvements, accumulated depreciation	$ 772,093	$ 683,770

CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues:
Rental income									$ 411,667	$ 455,125	$ 439,918
Tenant reimbursements									92,743	98,139	94,901
Total revenues	$ 137,185	$ 129,708	$ 129,174	$ 129,900	$ 139,444	$ 137,587	$ 148,679	$ 148,463	525,967	574,173	555,715
Expenses:
Property operating costs									209,338	222,441	220,796
Depreciation									107,956	119,288	127,733
Amortization									63,295	75,367	75,119
Impairment loss on real estate assets									0	46,461	33,901
General and administrative									29,713	29,319	27,382
Operating Expenses									410,302	492,876	484,931
Real estate operating income									115,665	81,297	70,784
Other income (expense):
Interest expense									(61,023)	(68,124)	(64,860)
Other income/(expense)									1,638	657	(13)
Net recoveries from casualty events									0	0	34
Equity in income of unconsolidated joint ventures									0	3,845	362
Loss on extinguishment of debt									(1,680)	0	0
Gain on sale of real estate assets, net	30,505	0	(23)	45,209	(77)	109,512	6,492	(53)	75,691	115,874	93,410
Nonoperating Income (Expense)									14,626	52,252	28,933
Net income	45,409	16,114	10,940	57,828	(31,388)	126,129	23,707	15,101	130,291	133,549	99,717
Net loss applicable to noncontrolling interest									5	15	15
Net income applicable to Piedmont	$ 45,410	$ 16,114	$ 10,942	$ 57,830	$ (31,383)	$ 126,133	$ 23,710	$ 15,104	$ 130,296	$ 133,564	$ 99,732
Per share information— basic and diluted:
Net income available to common stockholders (in dollars per share)					$ (0.21)	$ 0.87	$ 0.16	$ 0.10	$ 1.00	$ 0.92	$ 0.69
Weighted-average shares outstanding - basic (in shares)									130,161,202	145,043,503	145,230,382
Weighted-average shares outstanding - diluted (in shares)									130,635,650	145,379,994	145,634,953
Property management fee revenue
Revenues:
Property related revenue									$ 1,450	$ 1,735	$ 1,914
Other property related income
Revenues:
Property related revenue									$ 20,107	$ 19,174	$ 18,982

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income applicable to Piedmont	$ 130,296	$ 133,564	$ 99,732
Other comprehensive income:
Effective portion of gain/(loss) on derivative instruments that are designated and qualify as cash flow hedges (See Note 5)	692	2,479	(4,126)
Plus: Reclassification of net (gain)/loss included in net income (See Note 5)	(300)	3,502	4,548
Gain on investment in available for sale securities	0	79	21
Other comprehensive income	392	6,060	443
Comprehensive income applicable to Piedmont	$ 130,688	$ 139,624	$ 100,175

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

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 (in shares) at Dec. 31, 2015		145,512,000
Beginning balance, value at Dec. 31, 2015	$ 2,123,420	$ 1,455	$ 3,669,977	$ (1,550,698)	$ 1,661	$ 1,025
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock repurchases as part of an announced plan (in shares)		(462,000)
Share repurchases as part of an announced plan	(7,943)	$ (5)		(7,938)
Offering costs	(342)		(342)
Noncontrolling interest in consolidated joint venture	888					888
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 (in shares)		185,000
Shares issued and amortized under the 2007 Omnibus Incentive Plan, net of tax	3,668	$ 2	3,666
Net loss applicable to noncontrolling interest	(15)					(15)
Net income applicable to Piedmont	99,732			99,732
Other comprehensive income	$ 443				443
Ending balance, (in shares) at Dec. 31, 2016	145,235,000	145,235,000
Ending balance, value at Dec. 31, 2016	$ 2,097,703	$ 1,452	3,673,128	(1,580,863)	2,104	1,882
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock repurchases as part of an announced plan (in shares)		(3,133,000)
Share repurchases as part of an announced plan	(61,750)	$ (31)		(61,719)
Offering costs	(182)		(182)
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 (in shares)		257,000
Shares issued and amortized under the 2007 Omnibus Incentive Plan, net of tax	4,650	$ 3	4,647
Net loss applicable to noncontrolling interest	(15)					(15)
Net income applicable to Piedmont	133,564			133,564
Other comprehensive income	$ 6,060				6,060
Ending balance, (in shares) at Dec. 31, 2017	142,358,940	142,359,000
Ending balance, value at Dec. 31, 2017	$ 1,986,489	$ 1,424	3,677,360	(1,702,281)	8,164	1,822
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock repurchases as part of an announced plan (in shares)		(16,495,000)
Share repurchases as part of an announced plan	(301,678)	$ (165)		(301,513)
Offering costs	(85)		(85)
Dividends to common stockholders, dividends to preferred stockholders of subsidiary, and dividends reinvested	$ (109,265)		(82)	(109,138)		(45)
Shares issued and amortized under the 2007 Omnibus Incentive Plan, net of tax (in shares)	355,055	355,000
Shares issued and amortized under the 2007 Omnibus Incentive Plan, net of tax	$ 5,996	$ 3	5,993
Net loss applicable to noncontrolling interest	(5)					(5)
Net income applicable to Piedmont	130,296			130,296
Other comprehensive income	$ 392				392
Ending balance, (in shares) at Dec. 31, 2018	126,218,554	126,219,000
Ending balance, value at Dec. 31, 2018	$ 1,712,140	$ 1,262	$ 3,683,186	$ (1,982,542)	$ 8,462	$ 1,772

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Flows from Operating Activities:
Net income	$ 130,291	$ 133,549	$ 99,717
Operating distributions received from unconsolidated joint ventures	10	11	579
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	107,956	119,288	127,733
Amortization of debt issuance costs net of favorable settlement of interest rate swaps	(250)	1,588	1,702
Other amortization	58,330	73,944	74,373
Impairment loss on real estate assets	0	46,461	33,901
Loss on extinguishment of debt	(1,665)	0	0
Stock compensation expense	9,737	9,196	7,928
Equity in income of unconsolidated joint ventures	0	(3,845)	(362)
Gain on sale of real estate assets	(75,691)	(115,874)	(93,410)
Changes in assets and liabilities:
Increase in tenant and straight-line rent receivables, net	(16,094)	(21,392)	(26,747)
Decrease/(increase) in prepaid expenses and other assets	(3,095)	384	1,437
Increase/(decrease) in accounts payable and accrued expenses	(9,092)	(1,521)	3,555
Increase/(decrease) in deferred income	(898)	1,016	1,441
Net cash provided by operating activities	202,869	242,805	231,847
Cash Flows from Investing Activities:
Acquisition of real estate assets and intangibles	(151,914)	(35,262)	(349,668)
Capitalized expenditures	(72,105)	(79,831)	(110,228)
Net sale proceeds from wholly-owned properties	575,227	375,518	365,918
Net sale proceeds received from unconsolidated joint ventures	0	12,334	0
Investments in unconsolidated joint ventures	0	(1,162)	0
Note receivable issuance	(3,200)	0	0
Note receivable repayment	3,200	0	0
Deferred lease costs paid	(27,430)	(30,985)	(25,896)
Net cash provided by/(used in) investing activities	323,778	240,612	(119,874)
Cash Flows from Financing Activities:
Debt issuance and other costs paid	(1,040)	(132)	(264)
Proceeds from debt	977,062	180,000	695,000
Repayments of debt	(1,020,455)	(476,401)	(706,875)
Costs of issuance of common stock	(85)	(182)	(342)
Value of shares withheld for payment of taxes related to employee stock compensation	(2,219)	(3,403)	(2,344)
Repurchases of common stock as part of announced plan	(298,538)	(60,474)	(7,943)
Dividends paid and discount on dividend reinvestments	(184,093)	(122,274)	(91,616)
Net cash used in financing activities	(529,368)	(482,866)	(114,384)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	(2,721)	551	(2,411)
Cash, cash equivalents, and restricted cash and escrows, beginning of year	8,755	8,204	10,615
Cash, cash equivalents, and restricted cash and escrows, end of year	$ 6,034	$ 8,755	$ 8,204

Organization	12 Months Ended
Organization	Dec. 31, 2018
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 which we control. 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, 2018, Piedmont owned 54 in-service office properties and one redevelopment asset, comprising approximately 487,000 square feet (unaudited). As of December 31 2018, Piedmont's 54 in-service office properties comprise approximately 16.2 million square feet (unaudited) of primarily Class A commercial office space and were approximately 93.3% leased. As of December 31, 2018, 92% of Piedmont's Annualized Lease Revenue (unaudited) was generated from select sub-markets located within eight major office markets: 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.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Basis of Presentation and Principles of Consolidation

The consolidated financial statements of Piedmont 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. In accordance with the guidance in Accounting Standards Codification ("ASC") 810, Consolidations, Piedmont is exempt from providing further disclosures related to its VIEs. The other joint venture, Piedmont-CNL Towers Orlando, LLC, which owns CNL Center I and II, in Orlando, Florida is an 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.

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 $1.4 million, $0.2 million, and $4.6 million of interest was capitalized for the years ended December 31, 2018, 2017, and 2016, 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, management assesses whether the respective carrying values 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, 2018 and 2017, respectively, are as follows (in thousands):



	December 31, 2018		December 31, 2017
Intangible Lease Assets:
Above-Market In-Place Lease Assets	$	7,620	$	11,935
In-Place Lease Valuation	$	157,447	$	165,015
Intangible Lease Origination Costs (included as component of Deferred Lease Costs)	$	241,516	$	250,539
Intangible Lease Liabilities (Below-Market In-Place Leases)	$	94,852	$	95,620

For the years ended December 31, 2018, 2017, and 2016, respectively, Piedmont recognized amortization of intangible lease costs as follows (in thousands):



	2018		2017		2016
Amortization of Intangible Lease Origination Costs and In-Place Lease Valuation included in amortization expense	$	48,940	$	58,467	$	58,150
Amortization of Above-Market and Below-Market In-Place Lease intangibles as a net increase to rental revenues	$	7,615	$	6,575	$	5,066

Net intangible assets and liabilities as of December 31, 2018 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
For the year ending December 31:
2019	$	938	$	20,876	$	29,503	$	8,273
2020	197		14,540		22,570		6,654
2021	141		12,449		19,818		6,443
2022	121		10,948		17,550		5,878
2023	97		7,370		11,774		4,367
Thereafter	64		9,935		18,952		4,093
	$	1,558	$	76,118	$	120,167	$	35,708

Weighted-Average Amortization Period (in years)	3		5		6		6


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

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, 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.

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. The majority of Piedmont’s cash and cash equivalents are held at major commercial banks and at times may exceed the Federal Deposit Insurance Corporation limit of $250,000. 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 $91,000, $350,000, and $216,000 of provisions for bad debts during the years ended December 31, 2018, 2017, and 2016, 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;


•	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.

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. If Piedmont concludes, after assessing the totality of events and circumstances during the qualitative analysis, that it is more likely than not that the goodwill balance 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, 2018.

Interest Rate Derivatives

Piedmont periodically enters into interest rate derivative agreements to hedge its exposure to changing interest rates. As of December 31, 2018 and 2017, 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, 2018, 2017, and 2016, Piedmont capitalized approximately $0.3 million, $0.3 million, and $0.4 million, respectively, of such internal leasing 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 $43.6 million, $50.8 million, and $50.1 million of deferred lease costs for the years ended December 31, 2018, 2017, and 2016, respectively, are included in amortization expense; and


•	Approximately $2.6 million, $4.8 million, and $3.9 million, of deferred lease costs related to lease incentives granted to tenants for the years ended December 31, 2018, 2017, and 2016, 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, 2018, 2017, and 2016, 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, 2018, 2017, and 2016, 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, 2018, 2017, and 2016 of approximately $2.4 million, $2.8 million, and $2.9 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. During the year ended December 31, 2018, the board of directors of Piedmont re-authorized the stock repurchase program under which Piedmont may repurchase its own 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, 2018, Piedmont had approximately $86.6 million in remaining capacity under the program which may be used for share repurchases through February 2020.

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

Piedmont's revenues consist of the following:

Rental income - consists of revenue from leases with Piedmont's tenants. 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. Rental income is recognized beginning on the lease commencement date, defined as when the tenant takes possession of or controls the finished space, which is typically when the improvements being recorded as our asset are substantially complete.

In most lease arrangements, Piedmont finances improvements to leased space and is deemed the owner of the tenant improvements. These tenant improvements are recorded as capital assets by Piedmont and depreciated, typically over the lease term. Payments made by the tenants for tenant improvements owned by Piedmont are treated as deferred revenues, amortized into rental income over the lease term. In some instances, Piedmont may cede control of the leased space to the tenant to be responsible for improvements for the space. In such arrangements, payments made by Piedmont to its tenant are treated as lease incentives, amortized as a reduction to rental income over the lease term.

Lease termination revenues are recognized ratably as rental revenue and the corresponding deferred lease costs are amortized to expense over the revised remaining lease term after giving effect to the termination notice.

Tenant reimbursements - consists of separately billed revenue derived from reimbursements for services prescribed by leases with Piedmont's tenants separate from, but in conjunction with, the revenue generated from leasing office space. 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 - consists of revenue earned by Piedmont related to operating and managing office properties owned by other third-parties. Such income is within the scope of Accounting Standards Codification Topic 606, Revenue from Contracts with Customers ("ASC 606") (see Accounting Pronouncements Adopted During the Year Ended December 31, 2018 below for further details). Because property management services represent a performance obligation that are satisfied over the length of the contract, not at any specific point in time, and have the same measure of transfer (time elapsed), property management fee revenue is recognized over time. Any variable consideration transferred as part of these management agreements is recognized

in the quarter that the underlying cash receipts are collected, consistent with the allocation objective of allocating the transaction price in an amount that depicts the amount of consideration to which Piedmont expects to be entitled in exchange for transferring the promised service to the customer.

Other property related income - consists of all other property related income from Piedmont's customers (tenants) that is not derived from a contract meeting the definition of a lease and is therefore also within the scope of ASC 606. Examples of such income include parking revenue and income from licenses with unrelated third-parties to place antennae and/or fiber optic cables in or on Piedmont's buildings. These services also represent a performance obligation that is satisfied over the length of the contract, not at any specific point in time, and has the same measure of transfer (time elapsed); therefore, revenue related to these licenses is also recognized over time.

Gains on the sale of real estate assets, like all non-lease related revenue, are subject to a five-step model requiring that Piedmont identify the contract with the customer, identify the performance obligations in the contract, determine the transaction price, allocate the transaction price to the performance obligations in the contract, and recognize revenue upon satisfaction of the performance obligations. In circumstances where Piedmont contracts to sell a property with material post-sale involvement, such involvement must be accounted for as a separate performance obligation in the contract and a portion of the sales price allocated to each performance obligation. When the post-sale involvement performance obligation is satisfied, the portion of the sales price allocated to it will be recognized as gain on sale of real estate assets. Property dispositions with no continuing involvement will continue to be recognized upon closing of the sale.

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. Forfeitures are recorded when they occur. Awards classified as liability awards are remeasured at each reporting period 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

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, with changes in fair value recognized in net income. As of December 31, 2018, Piedmont held approximately $0.4 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, and accrued capital expenditures in the accompanying consolidated balance sheets.

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, its taxable income 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 $97,000, $(13,000), and $(415,000) in income tax recoveries/(expense) for the years ended December 31, 2018, 2017, and 2016, 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 presented in the accompanying consolidated statements of income have been reclassified to conform to the current period financial statement presentation. These amounts included: (i) the reclassification of approximately $19.2 million and $19.0 million for the years ended December 31, 2017 and 2016, respectively, of parking, antennae license and fiber income that was previously included in rental income into other property related income, as well as certain other miscellaneous revenue into tenant reimbursements and/or property management fee revenue in conjunction with the adoption of ASC 606, as further described below; and (ii) the reclassification of $1.8 million and $1.9 million for the years ended December 31, 2017 and 2016, respectively, of expense related to certain regional employees who are primarily engaged in the operation and management of properties that was previously included in general and administrative expense to property operating costs. Further, reclassifications also relate to properties classified as held for sale as of March 31, 2018, June 30, 2018, September 30, 2018, and December 31, 2018 have been reclassified as held for sale as of December 31, 2017 for comparative purposes (see Note 12).

Accounting Pronouncements Adopted during the Year Ended December 31, 2018

Revenue Recognition

On January 1, 2018, Piedmont adopted ASC 606 which changed 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.

Piedmont's revenues which are included in the scope of ASC 606 include its property management fee revenue, the majority of its parking revenue, as well as certain license agreements which allow third-parties to place their antennas or fiber-optic cabling on or inside Piedmont's buildings. Lease contracts are specifically excluded from ASC 606 and, Piedmont intends to utilize a leasing practical expedient (see further discussion below) to group certain non-lease components related to operating expense reimbursements with other leasing components, provided they meet certain criteria. Because the timing and pattern of transfer of Piedmont's non-lease related revenue already followed the prescribed method of ASC 606, Piedmont was able to effectively adopt ASC 606 on a full retrospective basis, with no impact to the historical timing of recognition of the related revenue; however, such non-lease revenues are now being presented as "Other property related income" in the accompanying consolidated statements of income. Further, for comparative purposes, Piedmont reclassified approximately $19.2 million and $19.0 million for the years ended December 31, 2017 and 2016, respectively, of parking, antennae license, and fiber income that was previously included in rental income into other property related income, as well as certain other miscellaneous revenue into tenant reimbursements and/or property management fee revenue. Piedmont did not elect to adopt any practical expedients provided by ASC 606.

Gain/(loss) on Sale of Real Estate Assets

On January 1, 2018, Piedmont adopted 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") concurrently with ASC 606 mentioned above. Piedmont elected to apply the amendments of ASU 2017-05 on a full retrospective basis; however, there were no adjustments to previously recorded gains/(losses) on sale of real estate as a result of the transition.

Equity Investments Held in Non-qualified Deferred Compensation Plan

On January 1, 2018, Piedmont adopted Accounting Standards Update No. 2016-01, Financial Instruments - Overall (Subtopic

825-10), Recognition and Measurement of Financial Assets and Financial Liabilities ("ASU 2016-01"), as well as Accounting Standards Update No. 2018-03 Technical Corrections and Improvements to Financial Instruments-Overall (Subtopic 825-10) ("ASU 2018-03"). These amendments 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. Investments in trading securities held in a "rabbi trust" by Piedmont are the only securities affected by ASU 2016-01 and ASU 2018-03. As such, Piedmont has made a cumulative-effect adjustment to its consolidated balance sheet and consolidated statements of stockholders' equity of approximately $0.1 million from other comprehensive income ("OCI") to cumulative distributions in excess of earnings, and has recorded changes in fair value in net income for the year ended December 31, 2018 related to these investment securities.

Interest Rate Derivatives

On January 1, 2018, Piedmont early adopted Accounting Standards Update No. 2017-12, Derivatives and Hedging: Targeted Improvements to Accounting for Hedging Activities ("ASU 2017-12"). Piedmont adopted ASU 2017-12 using the modified retrospective transition method; however, no adjustment was necessary to account for the cumulative effect of the change on the opening balance of each affected component of equity in the consolidated balance sheet as of the date of adoption because there was no cumulative ineffectiveness that had been recorded on Piedmont's existing interest rate swaps as of December 31, 2017, and all trades were highly effective. The amended presentation and disclosure guidance which is required to be presented prospectively is provided in Note 5.

Other Recent Accounting Pronouncements

The FASB has issued Accounting Standards Update No. 2016-02, Leases (Topic 842) ("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.

Additionally, the FASB has subsequently issued a number of clarifying and technical corrections to ASU 2016-02 through several Accounting Standards Updates ("ASU") as follows:



ASU	Title	Summary	Anticipated Impact on Piedmont's Consolidated Financial Statements Based on Management’s Assessment to Date
ASU 2018-01	Leases (Topic 842) Land Easement Practical Expedient for Transition to Topic 842	Clarifies that a land easement is required to be evaluated to determine whether it should be accounted for as a lease upon adoption of ASU 2016-02; also provides an optional practical transition expedient allowing entities not currently assessing land easements under existing leasing guidance prior to adoption of ASU 2016-02 to not apply the new guidance to land easements existing at the date of initial adoption of ASU 2016-02.	No material impact.

ASU 2018-10	Codification Improvements to Topic 842, Leases	Clarifications and technical corrections to ASU 2016-02.	No material impact.

ASU 2018-11	Leases (Topic 842) Targeted Improvements	Allows certain non-lease operating expense reimbursements which are included in the underlying stated lease rate to be accounted for as part of the lease provided certain criteria are met under an optional practical expedient.	All of Piedmont’s operating expense reimbursements qualify to be accounted for as a part of the underlying lease.

ASU 2018-20	Leases (Topic 842) Narrow-Scope Improvements for Lessors	Allows lessors to exclude sales taxes collected from lessees from revenue; also stipulates certain requirements related to variable consideration; and also requires the lessor to allocate, rather than recognize, certain variable payments to lease and non-lease components when changes to the facts and circumstances of the basis of the payments occurs.	No material impact.

In addition to the practical expedients mentioned above, as part of ASU 2018-01 and ASU 2018-11, Piedmont intends to adopt the other following practical expedients and transition amendments collectively allowed by the FASB relative to the new guidance for lease accounting:


•	a package of practical expedients, applied together, which do not require the reassessment of (1) any expired or existing contracts to determine if they contain a lease; (2) lease classification for any expired or existing leases, and (3) initial direct costs for any existing leases;


•	the presentation of comparative periods in the year of adoption under ASC 840 (the former leasing guidance), which effectively allows for an initial adoption of ASC 842 (the new leasing guidance) on January 1, 2019.

Other than recording an immaterial right-to-use asset and offsetting lease liability under lessee accounting on its balance sheet of approximately $0.3 million, and no longer capitalizing internal direct payroll costs associated with negotiating and executing leases (only accounting for approximately $0.3 million for the year ended December 31, 2018), the adoption of ASU 2016-02 on January 1, 2019 did not have any material impact on Piedmont's consolidated financial statements.

The FASB has issued Accounting Standards Update No. 2018-07, Stock Compensation (Topic 718), Improvements to Nonemployee Share-Based Payment Accounting ("ASU 2018-07"). The provisions of ASU 2018-07 align accounting for stock based compensation for non-employees for goods and services with existing accounting for similar compensation for employees. The amendments supersede previous guidance on accounting for share-based payments to non-employees codified in the FASB's Accounting Standards Codification ("ASC") 505-50. ASU 2018-07 is effective in the first quarter of 2019, with early adoption permitted at any time provided that the entity has already adopted the provisions of ASC 606. The adoption of ASU 2018-07 did not have any material impact on Piedmont's consolidated financial statements.

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. Additionally, the FASB issued Accounting Standards Update No. 2018-19 Codification Improvements to Topic 326, Financial Instruments - Credit Losses which is effective concurrently, with ASU 2016-13, and excludes receivable arising from operating leases from the scope of ASU 2016-13. 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; however, substantially all of Piedmont's receivables are operating lease receivables and as such, Piedmont does not anticipate any material impact to its consolidated financial statements as a result of adoption.

Acquisitions

12 Months Ended

Dec. 31, 2018

Business Combinations [Abstract]

Acquisitions

During the year ended December 31, 2018, Piedmont acquired three separately identifiable assets using proceeds available as a result of dispositions, (see Note 12) proceeds from the $500 Million Unsecured 2018 Line of Credit, and cash on hand, as noted below:



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)
501 West Church Street	Orlando, Florida	February 23, 2018	100	%	182,461	100	%	$	28.0
9320 Excelsior Boulevard	Minneapolis, Minnesota	October 25, 2018	100	%	267,724	100	%	$	48.7
25 Burlington Mall Road	Boston, Massachusetts	December 12, 2018	100	%	287,776	89	%	$	74.0

Debt

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Debt

During the year ended December 31, 2018, Piedmont fully repaid the balances of the $300 Million Unsecured 2013 Term Loan and the $170 Million Unsecured 2015 Term Loan.

Additionally, during the year ended December 31, 2018, Piedmont replaced its $500 Million Unsecured 2015 Line of Credit with a new $500 Million Unsecured Line of Credit (the "$500 Million Unsecured 2018 Line of Credit"). The term of the new $500 Million Unsecured 2018 Line of Credit is four years with a maturity date of September 30, 2022, and Piedmont may extend the term for up to one additional year (through two available six-month extensions) provided Piedmont is not then in default and all representations and warranties are true and correct in all material respects and upon payment of applicable extension fees. Under certain terms of the agreement, Piedmont may increase the new facility by up to an additional $500 million, to an aggregate size of $1.0 billion, provided that no existing bank has any obligation to participate in such increase. Piedmont paid customary arrangement and upfront fees to the lenders in connection with the closing of the new facility.

The $500 Million Unsecured 2018 Line of Credit has the option to bear interest at varying levels (determined with reference to the greater of the credit rating for Piedmont or Piedmont OP) based on the London Interbank Offered Rate (“LIBOR”) or the Base Rate, defined as the greater of the prime rate, the federal funds rate plus 0.5%, or LIBOR for a one-month period plus 0.9%. LIBOR loans are available with interest periods selected by Piedmont of one, two (if available), three, or six months, or to the extent available from all lenders in each case, one year or periods of less than one month. The stated interest rate spread over LIBOR can vary from 0.775% to 1.45% based upon the greater of the then current credit rating of Piedmont.

Further, during the year ended December 31, 2018, Piedmont amended and restated its $300 Million Unsecured 2011 Term Loan (the "Amended and Restated $300 Million Unsecured 2011 Term Loan") to extend its maturity date 22 months, from January 15, 2020 to November 30, 2021. The amendment also decreases the stated interest rate spread over LIBOR from a range of 0.9% to 1.90% to a range of 0.85% to 1.65%. The specific spread in effect from time to time is based upon the greater of the credit rating for Piedmont or Piedmont OP; however, as of December 31, 2018, the spread over LIBOR is 1.0%. All other material terms of the facility remain unchanged.

Finally, during the year ended December 31, 2018, Piedmont entered into a $250 million unsecured term loan facility (the “$250 Million Unsecured 2018 Term Loan”) with a consortium of lenders. The term of the $250 Million Unsecured 2018 Term Loan is seven years with a maturity date of March 31, 2025; however, Piedmont may prepay the $250 Million Unsecured 2018 Term Loan, in whole or in part, at any time after March 29, 2020 without premium or penalty. The $250 Million Unsecured 2018 Term Loan has the option to bear interest at varying levels based on either (i) LIBOR for an interest period selected by Piedmont of one, two, three, or six months, or to the extent available from all lenders in each case, one year or periods of less than one month, or (ii) Base Rate, defined as the greater of the prime rate, the federal funds rate plus 0.5%, or LIBOR for a one-month period plus 1%; plus a stated interest rate spread based on the higher credit rating level issued for either Piedmont or Piedmont OP. The stated interest rate spread over LIBOR can vary from 1.45% to 2.40% based upon the then current credit rating of Piedmont or Piedmont OP, whichever is higher. In conjunction with this new facility, Piedmont also entered into three interest rate swap agreements for a total notional amount of $150 million which effectively fixed $150 million of the $250 Million Unsecured 2018 Term Loan at an interest rate of approximately 4.11%.

The $500 Million Unsecured 2018 Line of Credit, the Amended and Restated $300 Million Unsecured 2011 Term Loan, and the $250 Million Unsecured 2018 Term Loan all have certain financial covenants that require, among other things, the maintenance of an unencumbered interest coverage ratio of at least 1.75, an unencumbered leverage ratio of at least 1.60, a fixed charge coverage ratio of at least 1.50, a leverage ratio of no more than 0.60, and a secured debt ratio of no more than 0.40.

As of December 31, 2018, Piedmont believes it was in compliance with all financial covenants associated with its debt instruments. See Note 6 for a description of Piedmont’s estimated fair value of debt as of December 31, 2018.

The following table summarizes the terms of Piedmont’s indebtedness outstanding as of December 31, 2018 and 2017, including net discounts/premiums and unamortized debt issuance costs (in thousands):



Facility ⁽¹⁾	Stated Rate		Effective Rate ⁽²⁾				Maturity			Amount Outstanding as of
										2018		2017
Secured (Fixed)
$35 Million Fixed-Rate Loan ⁽³⁾	5.55	%	3.75	%			9/1/2021			$	29,706	$	30,670
$160 Million Fixed-Rate Loan ⁽⁴⁾	3.48	%	3.58	%			7/5/2022			160,000		160,000
Net premium and unamortized debt issuance costs										645		946
Subtotal/Weighted Average ⁽⁵⁾	3.80	%								190,351		191,616
Unsecured (Variable and Fixed)
$170 Million Unsecured 2015 Term Loan	LIBOR + 1.125%		2.54	%			5/15/2018			—		170,000
$300 Million Unsecured 2013 Term Loan	LIBOR + 1.20%		2.78	%	⁽⁷⁾		1/31/2019			—		300,000
$500 Million Unsecured 2015 Line of Credit ⁽⁶⁾	LIBOR + 1.00%		3.17	%			6/18/2019			—		23,000
$500 Million Unsecured 2018 Line of Credit ⁽⁶⁾	LIBOR + 0.90%		3.35	%			9/30/2022	⁽⁸	⁾	205,000		—
Amended and Restated $300 Million Unsecured 2011 Term Loan	LIBOR + 1.00%		3.20	%	⁽⁷⁾		11/30/2021			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
$250 Million Unsecured 2018 Term Loan	LIBOR + 1.60%		4.12	%	⁽⁹	⁾	3/31/2025			250,000		—
Discounts and unamortized debt issuance costs										(9,879)		(7,689)
Subtotal/Weighted Average ⁽⁵⁾	3.75	%								1,495,121		1,535,311
Total/Weighted Average ⁽⁵⁾	3.76	%								$	1,685,472	$	1,726,927


⁽¹⁾	Other than the $35 Million Fixed-Rate Loan, all of Piedmont’s outstanding debt as of December 31, 2018 and 2017 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 as of December 31, 2018.


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


⁽⁷⁾	The facility has a stated variable rate; however, Piedmont has entered into interest rate swap agreements which effectively fix, exclusive of changes in Piedmont's credit rating, the rate to that shown as the effective rate through the maturity date of the interest rate swap agreements (see Note 5 for more detail).


⁽⁸⁾	Piedmont may extend the term for up to one additional year (through two available six month extensions to a final extended maturity date of September 29, 2023) provided Piedmont is not then in default and upon payment of extension fees.

⁽⁹⁾

The facility has a stated variable rate; however, Piedmont has entered into interest rate swap agreements which effectively fix, exclusive of changes to Piedmont's credit rating, $150 million of the principal balance to 4.11% through March 29, 2020, and $100 million of the principal balance to 4.21% from March 30, 2020 through the maturity date of the loan. For the remaining variable portion of the loan, Piedmont may periodically select from multiple interest rate options, including the prime rate and various-length LIBOR locks on all or a portion of the principal. All LIBOR selections are subject to an additional spread over the selected rate based on Piedmont’s current credit rating. The rate presented is the weighted-average rate for the effectively fixed and variable portions of the debt outstanding as of December 31, 2018.

A summary of Piedmont's consolidated principal outstanding for aggregate debt maturities of its indebtedness as of December 31, 2018, is provided below (in thousands):



2019	$	932
2020	1,072
2021	327,702
2022	365,000		⁽¹⁾
2023	350,000
Thereafter	650,000
Total	$	1,694,706


⁽¹⁾	Includes the balance outstanding as of December 31, 2018 on the $500 Million Unsecured 2018 Line of Credit of $205 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 September 29, 2023) provided Piedmont is not then in default and upon payment of extension fees.

Piedmont’s weighted-average interest rate as of December 31, 2018 and 2017, for the aforementioned borrowings was approximately 3.76% and 3.48%, respectively. Piedmont made interest payments on all indebtedness, including interest rate swap cash settlements, of approximately $63.1 million, $67.6 million, and $69.0 million during the years ended December 31, 2018, 2017, and 2016, respectively.

Derivative Instruments

12 Months Ended

Dec. 31, 2018

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 exchange of the underlying notional amount.

In January 2018, Piedmont repaid the $300 Million Unsecured 2013 Term Loan in advance of its maturity without penalty (see Note 4 above). In connection with this early debt prepayment, six interest rate swap agreements which were identified as cash flow hedges were also terminated, resulting in a receipt of approximately $0.8 million from Piedmont's counterparties for the settlement of the swaps. These proceeds were recorded in accumulated other comprehensive income/(loss) ("OCI") and will be amortized as an offset to interest expense in the consolidated statement of income over the original term of the terminated interest rate swaps through January 2019. In connection with this termination Piedmont also recognized a non-cash loss of approximately $1.3 million due to it becoming probable that the hedged forecasted transactions would not occur, offset by a mark-to-market gain on these cash flow hedges of approximately $0.1 million for the year ended December 31, 2018.

As of December 31, 2018, Piedmont was party to 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 Amended and Restated $300 Million Unsecured 2011 Term Loan through January 2020, and $150 million of the $250 Million Unsecured 2018 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 75 months.

A detail of Piedmont’s interest rate derivatives outstanding as of December 31, 2018 is as follows:

Interest Rate Derivatives:

Number of Swap Agreements

Associated Debt Instrument

Notional Amount

(in millions)

Effective Date

Maturity Date

Interest rate swaps

Amended and Restated $300 Million Unsecured 2011 Term Loan

300

11/22/2016

1/15/2020

Interest rate swaps

$250 Million Unsecured 2018 Term Loan

100

3/29/2018

3/31/2025

Interest rate swaps

$250 Million Unsecured 2018 Term Loan

3/29/2018

3/29/2020

Total

450

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, 2018 and 2017, respectively, is as follows (in thousands):



Interest rate swaps classified as:	December 31, 2018			December 31, 2017
Gross derivative assets	$	1,199		$	688
Gross derivative liabilities	(839		)	(1,478		)
Net derivative asset/(liability)	$	360		$	(790	)

The gain/(loss) on Piedmont's interest rate derivatives, including previously settled forward swaps, that was recorded in OCI and the accompanying consolidated statements of income as a component of interest expense for the years ended December 31, 2018, 2017, and 2016, respectively, was as follows (in thousands):



Interest Rate Swaps in Cash Flow Hedging Relationships	2018			2017			2016
Amount of gain/(loss) recognized in OCI	$	692		$	2,479		$	(4,126	)
Amount of previously recorded gain/(loss) reclassified from OCI into Interest Expense	$	1,558		$	(3,502	)	$	(4,548	)
Amount of loss recognized on derivative reclassified from OCI into Loss on Extinguishment of Debt	$	(1,258	)	$	—		$	—

Total amount of Interest Expense presented in the consolidated statements of income	$	(61,023	)	$	(68,124	)	$	(64,860	)
Total amount of Loss on Extinguishment of Debt presented in the consolidated statements of income ⁽¹⁾	$	(1,680	)	$	—		$	—


⁽¹⁾	Includes the write-off of approximately $0.4 million of discounts and unamortized debt issuance costs associated with the repayment of debt. (see Note 4).

Piedmont estimates that approximately $3.1 million will be reclassified from OCI as a reduction to interest expense over the next twelve months. Piedmont did not recognize any hedge ineffectiveness on its cash flow hedges during the three years ended December 31, 2018.

See Note 6 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 a 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 could be required to settle its liability obligations under the agreements at their termination value of the estimated fair values plus accrued interest, or approximately $0.3 million as of December 31, 2018. 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 of Financial Instruments

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value Measurements of Financial Instruments

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, 2018 and 2017, respectively (in thousands):



	December 31, 2018					December 31, 2017
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⁾	$	4,571	$	4,571	Level 1	$	7,382	$	7,382	Level 1
Tenant receivables, net ⁽¹⁾	$	10,800	$	10,800	Level 1	$	12,139	$	12,139	Level 1
Restricted cash and escrows ⁽¹⁾	$	1,463	$	1,463	Level 1	$	1,373	$	1,373	Level 1
Interest rate swaps	$	1,199	$	1,199	Level 2	$	688	$	688	Level 2
Liabilities:
Accounts payable and accrued expenses ⁽¹⁾	$	47,328	$	47,328	Level 1	$	126,429	$	126,429	Level 1
Interest rate swaps	$	839	$	839	Level 2	$	1,478	$	1,478	Level 2
Debt, net	$	1,685,472	$	1,698,213	Level 2	$	1,726,927	$	1,759,905	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, 2018 and 2017; 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 as further discussed in Note 5, 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, 2018 and 2017. 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, 2018 and 2017, 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, 2018

Real Estate [Abstract]

Impairment Loss on Real Estate Assets

Piedmont recorded the following impairment losses on real estate assets for the years ended December 31, 2018, 2017, and 2016 (in thousands):



	2018		2017		2016
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


⁽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 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. 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⁾	The impairment loss was calculated as the difference between the carrying value of the asset and the anticipated 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
Commitments and Contingencies	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	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, 2018, commitments related to Piedmont's existing lease portfolio to fund potential non-incremental capital expenditures over the next five years for tenant improvements totaled approximately $45.6 million , 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, 2018, commitments for incremental capital expenditures for tenant improvements associated with executed leases totaled approximately $32.6 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 $0.5 million, $0.3 million and $1.1 million during the years ended December 31, 2018, 2017, and 2016, respectively. 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, 2018

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 of office REITs' TSR. The peer group is predetermined by the Board of Directors, advised by an outside compensation consultant. Any shares earned are awarded at the end of the multi-year performance period and vest upon award. The fair values of performance-based awards are estimated using a Monte Carlo valuation method.

A rollforward of Piedmont's equity based award activity for the year ended December 31, 2018 is as follows:



	Shares		Weighted-Average Grant Date Fair Value
Unvested and Potential Stock Awards as of December 31, 2017	868,437		$	21.69
Deferred Stock Awards Granted	354,236		$	17.84
Increase in Estimated Potential Future Performance Share Awards, net of forfeitures	506,793		$	25.20
Performance Stock Awards Vested	(161,005	)	$	18.47
Deferred Stock Awards Vested	(332,019	)	$	19.21
Deferred Stock Awards Forfeited	(8,959	)	$	19.77
Unvested and Potential Stock Awards as of December 31, 2018	1,227,483		$	23.14

The following table provides additional information regarding stock award activity during the years ended December 31, 2018, 2017, and 2016 (in thousands except for per share data):



	2018		2017		2016
Weighted-Average Grant Date Fair Value of Deferred Stock Granted During the Period (per share)	$	17.84	$	21.38	$	19.96
Total Grant Date Fair Value of Deferred Stock Vested During the Period	$	6,378	$	5,899	$	4,806
Share-based Liability Awards Paid During the Period ⁽¹⁾	$	2,947	$	2,877	$	1,127


⁽¹⁾	Amounts reflect the issuance of performance share awards related to the 2015-17, 2014-16, and 2013-15 Performance Share Plans during the years ended December 31, 2018, 2017, and 2016 respectively.

A detail of Piedmont’s outstanding employee deferred stock awards as of December 31, 2018 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, 2018
January 3, 2014	Deferred Stock Award	72,969	$	16.45	Of the shares granted, 20% vested or will vest on January 3, 2015, 2016, 2017, 2018, and 2019, respectively.	16,416
May 24, 2016	Deferred Stock Award	208,003	$	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.	60,487
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.	139,127	⁽²⁾
May 18, 2017	Deferred Stock Award	219,863	$	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.	123,343
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.	251,123	⁽²⁾
May 17, 2018	Deferred Stock Award-Board of Directors	31,388	$	17.84	Of the shares granted, 100% will vest by May 17, 2019.	31,388
May 17, 2018	Deferred Stock Award	302,706	$	17.84	Of the shares granted, 25% vested on the date of grant, and 25% vested or will vest on May 17, 2019, 2020, and 2021, respectively.	239,567
May 17, 2018	Fiscal Year 2018-2020 Performance Share Program	—	$	23.52	Shares awarded, if any, will vest immediately upon determination of award in 2021.	366,032	⁽²⁾
Total						1,227,483


⁽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, 2018.


⁽²⁾	Estimated based on Piedmont's cumulative TSR for the respective performance period through December 31, 2018. Share estimates are subject to change in future periods based upon Piedmont's relative performance compared to its peer group of office REITs' total stockholder return.

During the years ended December 31, 2018, 2017, and 2016, Piedmont recognized approximately $9.7 million, $9.5 million and $8.0 million of compensation expense related to stock awards, of which approximately $8.6 million, $7.7 million and $6.5 million, related to the amortization of nonvested shares, respectively. During the year ended December 31, 2018, a total of 355,055 shares were issued to employees. As of December 31, 2018, approximately $3.9 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, 2018

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. For each of the years ended December 31, 2018, 2017, and 2016, Piedmont excluded approximately 0.1 million of such anti-dilutive 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, 2018, 2017, and 2016, respectively (in thousands):



	2018	2017	2016
Weighted-average common shares—basic	130,161	145,044	145,230
Plus: Incremental weighted-average shares from time-vested deferred and performance stock awards	475	336	405
Weighted-average common shares—diluted	130,636	145,380	145,635

Common stock issued and outstanding as of period end	126,219	142,359	145,235

Property Dispositions and Assets Held for Sale

12 Months Ended

Dec. 31, 2018

Discontinued Operations and Disposal Groups [Abstract]

Property Dispositions and Assets Held for Sale

Property Dispositions

None of Piedmont's property dispositions during the three years ended December 31, 2018 met the criteria to be reported as discontinued operations. The operational results and gain/(loss) on sale of real estate assets are presented as continuing operations in the accompanying 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 of Real Estate Assets				Net Sales Proceeds
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	⁽¹⁾
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	⁽³⁾
2017 Disposition Portfolio⁽⁴⁾	Various⁽⁴⁾	January 4, 2018	$	45,275			$	419,644	⁽⁵⁾
800 North Brand Boulevard	Glendale, California	November 29, 2018	$	30,416			$	155,583


⁽¹⁾	Piedmont accepted a secured promissory note from the buyer for $33.0 million of the sales proceeds which was subsequently repaid in full. 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.


⁽²⁾	As discussed in Note 7 above, Piedmont recognized an impairment loss prior to, or in conjunction with, the sale of the property. Therefore, 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⁾	Property was owned as part of an unconsolidated joint venture. As such, the gain on sale is presented as equity in income/(loss) of unconsolidated joint ventures in the accompanying consolidated statement of income. Amounts shown above reflect Piedmont's approximate 72% ownership.

⁽⁴⁾

The 2017 Disposition Portfolio is comprised of the following properties: Desert Canyon 300 in Phoenix, Arizona; Windy Point I & II in Schaumburg, Illinois; 2300 Cabot Drive in Lisle, Illinois; 1075 West Entrance Drive in Auburn Hills, Michigan; Auburn Hills Corporate Center in Auburn Hills, Michigan; 5301 Maryland Way in Brentwood, Tennessee; Suwanee Gateway One in Suwanee, Georgia; 5601 Hiatus Road in Tamarac, Florida; Piedmont Pointe I & II in Bethesda, Maryland; 1200 Crown Colony Drive in Quincy, Massachusetts; and 2120 West End Avenue in Nashville, Tennessee.


⁽⁵⁾	Piedmont accepted a secured promissory note from the buyer for $3.2 million which was subsequently repaid in full.

Assets Held for Sale

During the fourth quarter of 2018, Piedmont entered into a binding, non-refundable contract with an unrelated third party buyer to sell the One Independence Square building. The sale is expected to close during first quarter 2019. As a result, One Independence Square met the criteria for held for sale classification as of December 31, 2018. Therefore, the appropriate real estate related amounts are reclassified for both December 31, 2018 and 2017 in the accompanying consolidated balance sheets. The amounts classified as held for sale as of December 31, 2017 also include the 2017 Disposition Portfolio, as well as the 800 North Brand Boulevard building, which were sold during the year ended December 31, 2018.

Details of amounts held for sale as of December 31, 2018 and 2017 are presented below (in thousands):



	December 31, 2018		December 31, 2017
Real estate assets held for sale, net:
Land	$	30,562	$	128,668
Building and improvements, less accumulated depreciation of $48,453 and $270,552 as of December 31, 2018, and 2017, respectively	77,936		430,136
Construction in progress	2,054		2,645
Total real estate assets held for sale, net	$	110,552	$	561,449

Other assets held for sale, net:
Straight-line rent receivables	$	10,756	$	44,666
Prepaid expenses and other assets	430		2,067
Deferred lease costs, less accumulated amortization of $2,446 and $20,169 as of December 31, 2018 and 2017, respectively	9,605		37,560
Total other assets held for sale, net	$	20,791	$	84,293

Other liabilities held for sale, net:
Intangible lease liabilities, less accumulated amortization of $0 and $935 as of December 31, 2018 and 2017, respectively	$	—	$	380

Supplemental Disclosures for the Statement of Consolidated Cash Flows

12 Months Ended

Dec. 31, 2018

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, 2018, 2017, and 2016 (in thousands) are outlined below:



	2018			2017		2016
Accrued capital expenditures and deferred lease costs	$	10,854		$	11,276	$	14,427
Change in accrued dividends and discount on dividend reinvestments	$	(74,828	)	$	71,267	$	30,532
Change in accrued share repurchases as part of an announced plan	$	3,140		$	1,276	$	—
Investment in consolidated joint venture	$	—		$	63,026	$	—

The following table provides a reconciliation of cash, cash equivalents, and restricted cash and escrows as reported, or previously reported, within the consolidated balance sheets to the consolidated statements of cash flows as of years ended ended December 31, 2018, 2017, and 2016 (in thousands).



	2018		2017		2016
Cash and cash equivalents, beginning of period	$	7,382	$	6,992	$	5,441
Restricted cash and escrows, beginning of period	1,373		1,212		5,174
Total cash, cash equivalents, and restricted cash and escrows shown in the consolidated statement of cash flows, beginning of period	$	8,755	$	8,204	$	10,615

Cash and cash equivalents, end of period	$	4,571	$	7,382	$	6,992
Restricted cash and escrows, end of period	1,463		1,373		1,212
Total cash, cash equivalents, and restricted cash and escrows shown in the consolidated statement of cash flows, end of period	$	6,034	$	8,755	$	8,204

Amounts in restricted cash and escrows typically represent escrow accounts for the payment of real estate taxes which are required under certain of Piedmont's debt agreements; earnest money deposited by a buyer to secure the purchase of one of our properties; or security or utility deposits held for tenants as a condition of their lease agreement.

Income Taxes

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Income Taxes

Piedmont’s income tax basis net income for the years ended December 31, 2018, 2017, and 2016, is calculated as follows (in thousands):



	2018			2017			2016
GAAP basis financial statement net income	$	130,296		$	133,564		$	99,732
Increase/(decrease) in net income resulting from:
Depreciation and amortization expense recognized for financial reporting purposes in excess of amounts recognized for income tax purposes	54,420			62,916			69,214
Rental income accrued for income tax purposes less than amounts for financial reporting purposes	(9,681		)	(25,432		)	(18,964		)
Net amortization of above/below-market lease intangibles for income tax purposes in excess of amounts for financial reporting purposes	(7,453		)	(6,041		)	(4,895		)
Gain on disposal of property for financial reporting purposes less than/(in excess of) amounts for income tax purposes	(36,241		)	10,068			(118,713		)
Taxable income or loss of Piedmont Washington Properties, Inc., in excess of/(less than) amount for financial reporting purposes	(2,089		)	176			(1,042		)
Other expenses, including impairment loss on real estate assets, for financial reporting purposes in excess of/ (less than) amounts for income tax purposes	(37,394		)	49,859			42,019
Taxable income for POH in excess of/(less than) amount for financial reporting purposes	(64		)	(28		)	648
Income tax basis net income, prior to dividends paid deduction	$	91,794		$	225,082		$	67,999

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:



	2018		2017		2016
Ordinary income	100.00	%	53.61	%	81.77	%
Return of capital	—	%	—	%	18.23	%
Capital gains	—	%	46.39	%	—	%
	100	%	100	%	100	%

As of December 31, 2018 and 2017, the tax basis carrying value of Piedmont’s total assets was approximately $3.6 billion and $4.2 billion, respectively.

Approximately $2.4 million and $3.8 million of accrued interest and penalties related to uncertain tax positions was included in accounts payable, accrued expenses, and accrued capital expenditures in the accompanying consolidated balance sheets as of December 31, 2018 and 2017, respectively. Piedmont recognized approximately $1.4 million and $0.1 million of recoveries of previously recorded estimated accrued interest and penalties during the year ended December 31, 2018 and 2017, respectively, and no additional expense or recoveries for the year ended December 31, 2016, related to such positions. The tax years 2015 to 2017 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 took effect for taxable years that began on or after January 1, 2018 (subject to certain exceptions), made many significant changes to the U.S. federal income tax laws that profoundly impact the taxation of individuals and corporations (including both regular C corporations and corporations that have elected to be taxed as REITs). There are numerous interpretive issues related to H.R. 1 and the IRS continues to issue clarifying guidance; however, Piedmont has completed its initial taxable income estimates for the year ended December 31, 2018 and none of the revisions resulting from

H.R. 1 were significant enough to warrant a change to Piedmont's current distribution policy. However, Piedmont did record an approximate $0.2 million reduction to its tax liability related to its taxable REIT subsidiary as a result of the rate reduction included in H.R. 1 during the year ended December 31, 2018.

Quarterly Results (unaudited)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Quarterly Results (unaudited)

A summary of the unaudited quarterly financial information for the years ended December 31, 2018 and 2017, is presented below (in thousands, except per-share data):



	2018
	First		Second			Third		Fourth
Revenues	$	129,900	$	129,174		$	129,708	$	137,185
Gain/(loss) on sale of real estate assets	$	45,209	$	(23	)	$	—	$	30,505
Net income	$	57,828	$	10,940		$	16,114	$	45,409
Net income applicable to Piedmont	$	57,830	$	10,942		$	16,114	$	45,410
Basic earnings per share	$	0.43	$	0.09		$	0.13	$	0.35
Diluted earnings per share	$	0.42	$	0.09		$	0.13	$	0.35
Dividends declared per share	$	0.21	$	0.21		$	0.21	$	0.21



	2017
	First			Second		Third		Fourth
Revenues	$	148,463		$	148,679	$	137,587	$	139,444
Gain/(loss) on sale of real estate assets	$	(53	)	$	6,492	$	109,512	$	(77	)
Net income/(loss)	$	15,101		$	23,707	$	126,129	$	(31,388	)
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.

Guarantor and Non-Guarantor Financial Information

12 Months Ended

Dec. 31, 2018

Guarantor and Non-Guarantor Financial Information [Abstract]

Guarantor and Non-Guarantor Financial Information

The following condensed consolidating financial information for Piedmont (the "Parent", "Guarantor", and/or "Consolidated"), Piedmont OP (the "Issuer"), and the other directly and indirectly owned subsidiaries of Piedmont as the Guarantor (the "Non-Guarantors") 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, 2018
(in thousands)	Piedmont (Parent) (Guarantor)		Piedmont OP (the Issuer)		Non-Guarantor Subsidiaries		Eliminations			Consolidated
Assets:
Real estate assets, at cost:
Land	$	—	$	36,094	$	471,328	$	—		$	507,422
Buildings and improvements, less accumulated depreciation	—		176,927		2,128,469		(300		)	2,305,096
Intangible lease assets, less accumulated amortization	—		—		77,676		—			77,676
Construction in progress	—		5,708		10,140		—			15,848
Real estate assets held for sale, net	—		—		110,552		—			110,552
Total real estate assets	—		218,729		2,798,165		(300		)	3,016,594
Cash and cash equivalents	150		—		4,939		(518		)	4,571
Tenant and straight-line receivables, net	—		16,143		157,246		—			173,389
Investment in subsidiaries	1,744,122		2,704,337		166		(4,448,625		)	—
Notes receivable	—		810		144,500		(145,310		)	—
Prepaid expenses, restricted cash, escrows, interest rate swaps, and other assets	42		5,682		22,318		(24		)	28,018
Goodwill	—		98,918		—		—			98,918
Deferred lease costs, net	—		15,158		234,990		—			250,148
Other assets held for sale, net	—		—		20,791		—			20,791
Total assets	$	1,744,314	$	3,059,777	$	3,383,115	$	(4,594,777	)	$	3,592,429
Liabilities:
Debt, net	$	—	$	1,495,904	$	335,717	$	(145,310	)	$	1,686,311
Accounts payable, accrued expenses, dividends payable, interest rate swaps and accrued capital expenditures	32,174		14,543		83,316		(542		)	129,491
Deferred income	—		2,274		26,505		—			28,779
Intangible lease liabilities, net	—		—		35,708		—			35,708
Total liabilities	32,174		1,512,721		481,246		(145,852		)	1,880,289
Equity:
Total stockholders’ equity	1,712,140		1,547,056		2,901,869		(4,448,925		)	1,712,140
Total liabilities and stockholders’ equity	$	1,744,314	$	3,059,777	$	3,383,115	$	(4,594,777	)	$	3,592,429



Condensed Consolidated Balance Sheets
As of December 31, 2017
(in thousands)	Piedmont (Parent) (Guarantor)			Piedmont OP (the Issuer)		Non-Guarantors		Eliminations			Piedmont (Consolidated)
Assets:
Real estate assets, at cost:
Land	$	—		$	36,094	$	454,531	$	—		$	490,625
Buildings and improvements, less accumulated depreciation	—			180,886		2,062,933		(300		)	2,243,519
Intangible lease assets, less accumulated amortization	—			181		77,624		—			77,805
Construction in progress	—			85		11,259		—			11,344
Real estate assets held for sale, net	—			32,815		528,634		—			561,449
Total real estate assets	—			250,061		3,134,981		(300		)	3,384,742
Cash and cash equivalents	150			3,890		3,342		—			7,382
Tenant and straight-line rent receivables, net, and amounts from unconsolidated joint ventures	—			16,891		139,727		—			156,618
Advances to affiliates	1,674,276			6,297,632		—		(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 swaps and other assets	2			5,094		18,483		(740		)	22,839
Goodwill	—			98,918		—		—			98,918
Deferred lease costs, net	—			16,611		228,564		—			245,175
Other assets held for sale, net	—			2,266		82,027		—			84,293
Total assets	$	5,111,727		$	6,780,173	$	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	104,028			20,279		93,086		(740		)	216,653
Advances from affiliates	5,277,957			941,494		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
Liabilities held for sale, net	—			—		380		—			380
Total liabilities	5,381,985			2,502,121		2,433,585		(8,304,213		)	2,013,478
Equity:
Total stockholders’ equity	(270,258		)	4,278,052		1,318,211		(3,339,516		)	1,986,489
Total liabilities and stockholders’ equity	$	5,111,727		$	6,780,173	$	3,751,796	$	(11,643,729	)	$	3,999,967



Condensed Consolidated Statements of Income
For the year ended December 31, 2018
(in thousands)	Piedmont (Parent) (Guarantor)			Piedmont OP (the Issuer)			Non-Guarantors			Eliminations			Consolidated
Revenues:
Rental income	$	—		$	35,221		$	378,473		$	(2,027	)	$	411,667
Tenant reimbursements	—			9,489			83,700			(446		)	92,743
Property management fee revenue	—			—			17,118			(15,668		)	1,450
Other property related income	—			130			19,977			—			20,107
	—			44,840			499,268			(18,141		)	525,967
Expenses:
Property operating costs	—			19,583			207,896			(18,141		)	209,338
Depreciation	—			11,514			96,442			—			107,956
Amortization	—			1,990			61,305			—			63,295
Impairment loss on real estate assets	—			—			—			—			—
General and administrative	289			6,576			22,848			—			29,713
	289			39,663			388,491			(18,141		)	410,302
	(289		)	5,177			110,777			—			115,665
Other income (expense):
Interest expense	—			(54,095		)	(14,558		)	7,630			(61,023		)
Other income/(expense)	—			144			9,124			(7,630		)	1,638
Loss on extinguishment of debt	—			(1,680		)	—			—			(1,680		)
Gain on sale of real estate assets	—			1,417			74,274			—			75,691
	—			(54,214		)	68,840			—			14,626
Income/(loss) before consolidated subsidiaries	(289		)	(49,037		)	179,617			—			130,291
Income from subsidiaries	130,585			178,648			—			(309,233		)	—
Net income	130,296			129,611			179,617			(309,233		)	130,291
Net loss applicable to noncontrolling interest	—			—			5			—			5
Net income applicable to Piedmont	$	130,296		$	129,611		$	179,622		$	(309,233	)	$	130,296



Condensed Consolidated Statements of Income
For the year ended December 31, 2017
(in thousands)	Piedmont (Parent) (Guarantor)			Piedmont OP (the Issuer)			Non-Guarantors			Eliminations			Consolidated
Revenues:
Rental income	$	—		$	42,407		$	414,509		$	(1,791	)	$	455,125
Tenant reimbursements	—			11,702			86,911			(474		)	98,139
Property management fee revenue	—			—			18,205			(16,470		)	1,735
Other property related income	—			144			19,030			—			19,174
	—			54,253			538,655			(18,735		)	574,173
Expenses:
Property operating costs	—			22,805			218,371			(18,735		)	222,441
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	347			6,443			22,529			—			29,319
	347			45,379			465,885			(18,735		)	492,876
	(347		)	8,874			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
Gain on sale of real estate assets, net	—			6,431			109,443			—			115,874
	—			(37,325		)	89,577			—			52,252
Net income/(loss)	(347		)	(28,451		)	162,347			—			133,549
Net loss applicable to noncontrolling interest	—			—			15			—			15
Net income/(loss) applicable to Piedmont	$	(347	)	$	(28,451	)	$	162,362		$	—		$	133,564



Condensed Consolidated Statements of Income
For the year ended December 31, 2016
(in thousands)	Piedmont (Parent) (Guarantor)			Piedmont OP (the Issuer)			Non-Guarantors			Eliminations			Consolidated
Revenues:
Rental income	$	—		$	53,527		$	389,022		$	(2,631	)	$	439,918
Tenant reimbursements	—			14,295			81,104			(498		)	94,901
Property management fee revenue	—			—			16,947			(15,033		)	1,914
Other property related income	—			1,266			17,716			—			18,982
	—			69,088			504,789			(18,162		)	555,715
Expenses:
Property operating costs	—			33,829			205,344			(18,377		)	220,796
Depreciation	—			16,657			111,076			—			127,733
Amortization	—			3,715			71,404			—			75,119
Impairment loss	—			8,259			25,642			—			33,901
General and administrative	311			26,452			36,065			(35,446		)	27,382
	311			88,912			449,531			(53,823		)	484,931
	(311		)	(19,824		)	55,258			35,661			70,784
Other income (expense):
Interest expense	—			(49,108		)	(27,636		)	11,884			(64,860		)
Other income/(expense)	282			9,560			2,029			(11,884		)	(13		)
Net recoveries from casualty events	—			—			34			—			34
Equity in income of unconsolidated joint ventures	—			362			—			—			362
Gain on sale of real estate assets, net	—			31,275			62,135			—			93,410
	282			(7,911		)	36,562			—			28,933
Net income/(loss)	(29		)	(27,735		)	91,820			35,661			99,717
Net loss applicable to noncontrolling interest	—			—			15			—			15
Net income/(loss) applicable to Piedmont	$	(29	)	$	(27,735	)	$	91,835		$	35,661		$	99,732



Consolidating Statements of Comprehensive Income
For the Year Ended December 31, 2018
(in thousands)	Piedmont (Parent) (Guarantor)			Piedmont OP (the Issuer)			Non-Guarantors		Eliminations			Piedmont (Consolidated)
Net income	$	130,296		$	129,611		$	179,622	$	(309,233	)	$	130,296
Effective portion of gain/(loss) on derivative instruments that are designated and qualify as cash flow hedges	692			692			—		(692		)	692
Plus: Reclassification of net (gain)/loss included in net income	(300		)	(300		)	—		300			(300		)
Other comprehensive income	392			392			—		(392		)	392

Comprehensive income	$	130,688		$	130,003		$	179,622	$	(309,625	)	$	130,688



Condensed Consolidated Statements of Cash Flows
For the year ended December 31, 2018
(in thousands)	Piedmont (Parent) (Guarantor)			Piedmont OP (the Issuer)			Non-Guarantors			Eliminations			Consolidated
Net Cash Provided By/(Used In) Operating Activities	$	135,755		$	141,293		$	235,562		$	(309,741	)	$	202,869

Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	—			(14,479		)	(209,540		)	—			(224,019		)
Intercompany note receivable	—			88,000			—			(88,000		)	—
Net sales proceeds from wholly-owned properties	—			36,572			538,655			—			575,227
Note receivable issuance	—			—			(3,200		)	—			(3,200		)
Note receivable payment	—			—			3,200			—			3,200
Deferred lease costs paid	—			(3,090		)	(24,340		)	—			(27,430		)
Distributions from subsidiaries	349,135			5,405			—			(354,540		)	—
Net cash provided by/(used in) investing activities	349,135			112,408			304,775			(442,540		)	323,778
Cash Flows from Financing Activities:
Debt issuance costs paid	—			(1,040		)	—			—			(1,040		)
Proceeds from debt	—			977,062			—			—			977,062
Repayments of debt	—			(1,019,000		)	(1,455		)	—			(1,020,455		)
Intercompany note payable	—			—			(88,000		)	88,000			—
Costs of issuance of common stock	(85		)	—			—			—			(85		)
Value of shares withheld to pay tax obligations related to employee stock compensation	(2,219		)	—			—			—			(2,219		)
Repurchases of common stock as part of announced plan	(298,538		)	—			—			—			(298,538		)
Distributions	(184,048		)	(214,596		)	(449,212		)	663,763			(184,093		)
Net cash provided by/(used in) financing activities	(484,890		)	(257,574		)	(538,667		)	751,763			(529,368		)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	—			(3,873		)	1,670			(518		)	(2,721		)
Cash, cash equivalents, and restricted cash and escrows, beginning of year	150			3,907			4,698			—			8,755
Cash, cash equivalents, and restricted cash and escrows, end of year	$	150		$	34		$	6,368		$	(518	)	$	6,034



Condensed Consolidated Statements of Cash Flows
For the year ended December 31, 2017
(in thousands)	Piedmont (Parent) (Guarantor)			Piedmont OP (the Issuer)			Non-Guarantors			Eliminations			Consolidated
Net Cash Provided By/(Used In) Operating Activities	$	5,497		$	(18,989	)	$	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		)
Value of 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	180,791			160,019			(340,810		)	—			—
Dividends paid and discount on dividend reinvestments	(122,229		)	—			(45		)	—			(122,274		)
Net cash provided by/(used in) financing activities	(5,497		)	(9,402		)	(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	150			3,693			4,361			—			8,204
Cash, cash equivalents, and restricted cash and escrows, end of year	$	150		$	3,907		$	4,698		$	—		$	8,755



Condensed Consolidated Statements of Cash Flows
For the year ended December 31, 2016
(in thousands)	Piedmont (Parent) (Guarantor)			Piedmont OP (the Issuer)			Non-Guarantors			Eliminations			Consolidated
Net Cash Provided/(Used In) by Operating Activities	$	5,214		$	(26,263	)	$	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			—
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		)
Value of 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	97,016			(312,218		)	250,862			(35,660		)	—
Dividends paid and discount on dividend reinvestments	(91,601		)	—			(15		)	—			(91,616		)
Net cash provided by/(used in) financing activities	(5,214		)	(165,082		)	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	150			2,196			8,269			—			10,615
Cash, cash equivalents, and restricted cash and escrows, end of year	$	150		$	3,693		$	4,361		$	—		$	8,204

Schedule III - Real Estate and Accumulated Depreciation

12 Months Ended

Dec. 31, 2018

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Abstract]

Schedule III - Real Estate and Accumulated Depreciation

December 31, 2018

(dollars in thousands)



					Initial Cost					Gross Amount at Which Carried at December 31, 2018
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	20,788	1994	12/21/2000	0	-	40
CRESCENT RIDGE II	Minnetonka, MN	100	%	None	7,700	45,154	52,854	8,536		8,021	53,369	61,390	25,620	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	13,188	2001	5/3/2002	0	-	40
6031 CONNECTION DRIVE	Irving, TX	100	%	None	3,157	43,656	46,813	4,691		3,157	48,347	51,504	20,356	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	22,029	2000	8/15/2002	0	-	40
6011 CONNECTION DRIVE	Irving, TX	100	%	None	3,157	29,034	32,191	10,666		3,157	39,700	42,857	12,425	1999	8/15/2002	0	-	40
ONE INDEPENDENCE SQUARE	Washington, DC	100	%	None	29,765	104,814	134,579	24,426		30,562	128,443	159,005	48,453	1991	11/22/2002	0	-	40
US BANCORP CENTER	Minneapolis, MN	100	%	None	11,138	175,629	186,767	23,472		11,138	199,101	210,239	78,042	2000	5/1/2003	0	-	40
GLENRIDGE HIGHLANDS TWO	Atlanta, GA	100	%	None	6,662	69,031	75,693	(16,208	)	6,662	52,823	59,485	24,203	2000	8/1/2003	0	-	40
200 BRIDGEWATER CROSSING	Bridgewater, NJ	100	%	None	8,182	84,160	92,342	(13,916	)	8,328	70,098	78,426	28,421	2002	8/14/2003	0	-	40
400 VIRGINIA AVE	Washington, DC	100	%	None	22,146	49,740	71,886	134		22,146	49,874	72,020	19,117	1985	11/19/2003	0	-	40
4250 NORTH FAIRFAX DRIVE	Arlington, VA	100	%	None	13,636	70,918	84,554	13,636		13,636	84,554	98,190	29,283	1998	11/19/2003	0	-	40
1225 EYE STREET	Washington, DC	98.1	%	None	21,959	47,602	69,561	8,270		21,959	55,872	77,831	21,464	1986	11/19/2003	0	-	40
1201 EYE STREET	Washington, DC	98.6	%	None	31,985	63,139	95,124	8,672		31,985	71,811	103,796	24,231	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	86,647	1987	12/18/2003	0	-	40
60 BROAD STREET	New York, NY	100	%	None	32,522	168,986	201,508	14,807		60,708	155,607	216,315	62,891	1962	12/31/2003	0	-	40
1414 MASSACHUSETTS AVENUE	Cambridge, MA	100	%	None	4,210	35,821	40,031	(8,031	)	4,365	27,635	32,000	10,421	1873	1/8/2004	0	-	40
ONE BRATTLE SQUARE	Cambridge, MA	100	%	None	6,974	64,940	71,914	(23,725	)	7,113	41,076	48,189	15,703	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	8,173	2005	3/16/2004	0	-	40
3100 CLARENDON BOULEVARD	Arlington, VA	100	%	None	11,700	69,705	81,405	46,315		11,791	115,929	127,720	29,690	1987	12/9/2004	0	-	40



					Initial Cost					Gross Amount at Which Carried at December 31, 2018
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)
400 BRIDGEWATER CROSSING	Bridgewater, NJ	100	%	None	10,400	71,052	81,452	(14,215	)	10,400	56,837	67,237	18,090	2002	2/17/2006	0	-	40
LAS COLINAS CORPORATE CENTER I	Irving, TX	100	%	None	3,912	18,830	22,742	(3,701	)	2,543	16,498	19,041	6,281	1998	8/31/2006	0	-	40
LAS COLINAS CORPORATE CENTER II	Irving, TX	100	%	None	4,496	29,881	34,377	(3,846	)	2,543	27,988	30,531	9,774	1998	8/31/2006	0	-	40
TWO PIERCE PLACE	Itasca, IL	100	%	None	4,370	70,632	75,002	8,783		8,156	75,629	83,785	20,322	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	5,749	1997	10/1/2010	0	-	40
TWO MERIDIAN CROSSINGS	Richfield, MN	100	%	None	2,661	25,742	28,403	673		2,661	26,415	29,076	6,167	1998	10/1/2010	0	-	40
500 WEST MONROE STREET	Chicago, IL	100	%	None	36,990	185,113	222,103	52,437		36,990	237,550	274,540	54,023	1991	3/31/2011	0	-	40
THE DUPREE	Atlanta, GA	100	%	None	4,080	14,310	18,390	894		4,080	15,204	19,284	5,235	1997	4/29/2011	0	-	40
THE MEDICI	Atlanta, GA	100	%	None	1,780	11,510	13,290	5,473		1,780	16,983	18,763	4,690	2008	6/7/2011	0	-	40
225 PRESIDENTIAL WAY	Boston, MA	100	%	None	3,626	36,916	40,542	217		3,612	37,147	40,759	11,241	2001	9/13/2011	0	-	40
235 PRESIDENTIAL WAY	Boston, MA	100	%	None	4,154	44,048	48,202	240		4,138	44,304	48,442	13,360	2000	9/13/2011	0	-	40
400 TOWNPARK	Lake Mary, FL	100	%	None	2,570	20,555	23,125	4,725		2,570	25,280	27,850	5,811	2008	11/10/2011	0	-	40
ARLINGTON GATEWAY	Arlington, VA	100	%	None	36,930	129,070	166,000	(1,777	)	36,930	127,293	164,223	19,521	2005	3/4/2013	0	-	40
5 & 15 WAYSIDE ROAD	Burlington, MA	100	%	None	7,190	55,445	62,635	6,653		7,190	62,098	69,288	10,185	1999 / 2001	3/22/2013	0	-	40
6565 MACARTHUR BOULEVARD	Irving, TX	100	%	None	4,820	37,767	42,587	(464	)	4,820	37,303	42,123	5,690	1998	12/5/2013	0	-	40
ONE LINCOLN PARK	Dallas, TX	100	%	None	6,640	44,810	51,450	1,428		6,640	46,238	52,878	8,151	1999	12/20/2013	0	-	40
161 CORPORATE CENTER	Irving, TX	100	%	None	2,020	10,680	12,700	(16	)	2,020	10,664	12,684	2,698	1998	12/30/2013	0	-	40
5 WALL STREET	Burlington, MA	100	%	29,706	9,560	50,276	59,836	365		9,560	50,641	60,201	9,378	2008	6/27/2014	0	-	40
1155 PERIMETER CENTER WEST	Atlanta, GA	100	%	None	5,870	66,849	72,719	32		5,870	66,881	72,751	12,969	2000	8/28/2014	0	-	40



					Initial Cost									Gross Amount at Which Carried at December 31, 2018
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		4,108			2,147		26,033		28,180		1,644		2017	N/A	0	-	40
PARK PLACE ON TURTLE CREEK	Dallas, TX	100	%	None	4,470		38,048		42,518		2,836			4,470		40,884		45,354		6,079		1986	1/16/2015	0	-	40
80 CENTRAL STREET	Boxborough, MA	100	%	None	1,980		8,930		10,910		245			1,980		9,175		11,155		1,451		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		5,188		2015	N/A	0	-	40
SUNTRUST CENTER	Orlando, FL	100	%	None	11,660		139,015		150,675		923			11,660		139,938		151,598		16,979		1988	11/4/2015	0	-	40
GALLERIA 300	Atlanta, GA	100	%	None	4,000		73,554		77,554		1,880			4,000		75,434		79,434		9,400		1987	11/4/2015	0	-	40
GLENRIDGE HIGHLANDS ONE	Atlanta, GA	100	%	None	5,960		50,013		55,973		157			5,960		50,170		56,130		6,321		1998	11/24/2015	0	-	40
CNL CENTER I	Orlando, FL	99	%	None	6,470		77,858		84,328		(28		)	6,470		77,830		84,300		8,382		1999	8/1/2016	0	-	40
CNL CENTER II	Orlando, FL	99	%	None	4,550		55,609		60,159		455			4,550		56,064		60,614		5,458		2006	8/1/2016	0	-	40
ONE WAYSIDE ROAD	Boston, MA	100	%	None	6,240		57,124		63,364		(4,471		)	6,240		52,653		58,893		3,289		1997 / 2008	8/10/2016	0	-	40
GALLERIA 200	Atlanta, GA	100	%	None	6,470		55,825		62,295		549			6,470		56,374		62,844		5,179		1984	10/7/2016	0	-	40
750 WEST JOHN CARPENTER FREEWAY	Irving, TX	100	%	None	7,860		36,303		44,163		1,931			7,860		38,234		46,094		4,196		1999	11/30/2016	0	-	40
NORMAN POINTE I	Bloomington, MN	100	%	None	4,358		22,322		26,680		251			4,360		22,571		26,931		1,034		2000	12/28/2017	0	-	40
501 WEST CHURCH STREET	Orlando, FL	100	%	None	2,805		28,119		30,924		—			2,805		28,119		30,924		1,035		2003	2/23/2018	0	-	40
9320 EXCELSIOR BOULEVARD	Hopkins, MN	100	%	None	3,760		35,289		39,049		—			3,760		35,289		39,049		408		2010	10/25/2018	0	-	40
25 BURLINGTON MALL ROAD	Burlington, MA	100	%	None	10,230		54,787		65,017		—			10,230		54,787		65,017		555		1987	12/12/2018	0	-	40
PIEDMONT POWER, LLC (e)	Bridgewater, NJ	100	%	None	—		79		79		2,740			—		2,819		2,819		818		N/A	12/20/2011	0	-	40
UNDEVELOPED LAND PARCELS (f)	Various	100	%	None	18,061		—		18,061		(860		)	15,914		1,287		17,201		41		N/A	Various			N/A
Total—All Properties					$	504,209	$	3,161,864	$	3,666,073	$	258,458		$	537,984	$	3,386,547	$	3,924,531	$	907,937


^(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 $3.6 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)	Represents solar panels at the 400 Bridgewater Crossing building.


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

Piedmont Office Realty Trust, Inc.

Schedule III - Real Estate and Accumulated Depreciation

December 31, 2018

(dollars in thousands)



	2018			2017				2016
Real Estate:
Balance at the beginning of the year	$	4,438,209		$	4,800,025			$	4,725,096
Additions to/improvements of real estate	206,442			85,368				422,908
Assets disposed	(675,692		)	(353,911		)	⁽¹⁾	(296,319		)
Assets impaired	—			(46,461		)	⁽²⁾	(30,898		)	⁽³⁾
Write-offs of intangible assets ⁽⁴⁾	(33,067		)	(37,188		)		(11,896		)
Write-offs of fully depreciated/amortized assets	(11,361		)	(9,624		)		(8,866		)
Balance at the end of the year	$	3,924,531		$	4,438,209			$	4,800,025
Accumulated Depreciation and Amortization:
Balance at the beginning of the year	$	1,053,467		$	1,058,704			$	1,019,663
Depreciation and amortization expense	128,456			145,837				155,274
Assets disposed	(229,558		)	(104,262		)	⁽¹⁾	(95,471		)
Write-offs of intangible assets ⁽⁴⁾	(33,067		)	(37,188		)		(11,896		)
Write-offs of fully depreciated/amortized assets	(11,361		)	(9,624		)		(8,866		)
Balance at the end of the year	$	907,937		$	1,053,467			$	1,058,704


⁽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 7).


⁽³⁾	Does not include impairment loss recognized on other assets as a result of the allocation of goodwill (see Note 7).

⁽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, 2018

Accounting Policies [Abstract]

Basis of Presentation

Basis of Presentation and Principles of Consolidation

Principles of Consolidation

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;


•	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

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 $43.6 million, $50.8 million, and $50.1 million of deferred lease costs for the years ended December 31, 2018, 2017, and 2016, respectively, are included in amortization expense; and


•	Approximately $2.6 million, $4.8 million, and $3.9 million, of deferred lease costs related to lease incentives granted to tenants for the years ended December 31, 2018, 2017, and 2016, respectively, was included as an offset to rental income.

Debt

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.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.Debt

Deferred Income and Revenue Recognition

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.

Piedmont's revenues consist of the following:

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

Shares-in-trust

Preferred Stock

Common Stock

Dividends

Noncontrolling Interest

Stock-based Compensation and Nonqualified Deferred Compensation Plan

Stock-based Compensation

Non-qualified Deferred Compensation Plan

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, 2018

Revenue Recognition

Gain/(loss) on Sale of Real Estate Assets

Equity Investments Held in Non-qualified Deferred Compensation Plan

On January 1, 2018, Piedmont adopted Accounting Standards Update No. 2016-01, Financial Instruments - Overall (Subtopic

Interest Rate Derivatives

Other Recent Accounting Pronouncements

Additionally, the FASB has subsequently issued a number of clarifying and technical corrections to ASU 2016-02 through several Accounting Standards Updates ("ASU") as follows:



ASU	Title	Summary	Anticipated Impact on Piedmont's Consolidated Financial Statements Based on Management’s Assessment to Date
ASU 2018-01	Leases (Topic 842) Land Easement Practical Expedient for Transition to Topic 842	Clarifies that a land easement is required to be evaluated to determine whether it should be accounted for as a lease upon adoption of ASU 2016-02; also provides an optional practical transition expedient allowing entities not currently assessing land easements under existing leasing guidance prior to adoption of ASU 2016-02 to not apply the new guidance to land easements existing at the date of initial adoption of ASU 2016-02.	No material impact.

ASU 2018-10	Codification Improvements to Topic 842, Leases	Clarifications and technical corrections to ASU 2016-02.	No material impact.

ASU 2018-11	Leases (Topic 842) Targeted Improvements	Allows certain non-lease operating expense reimbursements which are included in the underlying stated lease rate to be accounted for as part of the lease provided certain criteria are met under an optional practical expedient.	All of Piedmont’s operating expense reimbursements qualify to be accounted for as a part of the underlying lease.

ASU 2018-20	Leases (Topic 842) Narrow-Scope Improvements for Lessors	Allows lessors to exclude sales taxes collected from lessees from revenue; also stipulates certain requirements related to variable consideration; and also requires the lessor to allocate, rather than recognize, certain variable payments to lease and non-lease components when changes to the facts and circumstances of the basis of the payments occurs.	No material impact.


•	a package of practical expedients, applied together, which do not require the reassessment of (1) any expired or existing contracts to determine if they contain a lease; (2) lease classification for any expired or existing leases, and (3) initial direct costs for any existing leases;


•	the presentation of comparative periods in the year of adoption under ASC 840 (the former leasing guidance), which effectively allows for an initial adoption of ASC 842 (the new leasing guidance) on January 1, 2019.

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2018

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, 2018		December 31, 2017
Intangible Lease Assets:
Above-Market In-Place Lease Assets	$	7,620	$	11,935
In-Place Lease Valuation	$	157,447	$	165,015
Intangible Lease Origination Costs (included as component of Deferred Lease Costs)	$	241,516	$	250,539
Intangible Lease Liabilities (Below-Market In-Place Leases)	$	94,852	$	95,620

Amortization Of Intangible Lease Costs

For the years ended December 31, 2018, 2017, and 2016, respectively, Piedmont recognized amortization of intangible lease costs as follows (in thousands):



	2018		2017		2016
Amortization of Intangible Lease Origination Costs and In-Place Lease Valuation included in amortization expense	$	48,940	$	58,467	$	58,150
Amortization of Above-Market and Below-Market In-Place Lease intangibles as a net increase to rental revenues	$	7,615	$	6,575	$	5,066

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense

Net intangible assets and liabilities as of December 31, 2018 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
For the year ending December 31:
2019	$	938	$	20,876	$	29,503	$	8,273
2020	197		14,540		22,570		6,654
2021	141		12,449		19,818		6,443
2022	121		10,948		17,550		5,878
2023	97		7,370		11,774		4,367
Thereafter	64		9,935		18,952		4,093
	$	1,558	$	76,118	$	120,167	$	35,708

Weighted-Average Amortization Period (in years)	3		5		6		6


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

Debt (Tables)

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Schedule of Debt



Facility ⁽¹⁾	Stated Rate		Effective Rate ⁽²⁾				Maturity			Amount Outstanding as of
										2018		2017
Secured (Fixed)
$35 Million Fixed-Rate Loan ⁽³⁾	5.55	%	3.75	%			9/1/2021			$	29,706	$	30,670
$160 Million Fixed-Rate Loan ⁽⁴⁾	3.48	%	3.58	%			7/5/2022			160,000		160,000
Net premium and unamortized debt issuance costs										645		946
Subtotal/Weighted Average ⁽⁵⁾	3.80	%								190,351		191,616
Unsecured (Variable and Fixed)
$170 Million Unsecured 2015 Term Loan	LIBOR + 1.125%		2.54	%			5/15/2018			—		170,000
$300 Million Unsecured 2013 Term Loan	LIBOR + 1.20%		2.78	%	⁽⁷⁾		1/31/2019			—		300,000
$500 Million Unsecured 2015 Line of Credit ⁽⁶⁾	LIBOR + 1.00%		3.17	%			6/18/2019			—		23,000
$500 Million Unsecured 2018 Line of Credit ⁽⁶⁾	LIBOR + 0.90%		3.35	%			9/30/2022	⁽⁸	⁾	205,000		—
Amended and Restated $300 Million Unsecured 2011 Term Loan	LIBOR + 1.00%		3.20	%	⁽⁷⁾		11/30/2021			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
$250 Million Unsecured 2018 Term Loan	LIBOR + 1.60%		4.12	%	⁽⁹	⁾	3/31/2025			250,000		—
Discounts and unamortized debt issuance costs										(9,879)		(7,689)
Subtotal/Weighted Average ⁽⁵⁾	3.75	%								1,495,121		1,535,311
Total/Weighted Average ⁽⁵⁾	3.76	%								$	1,685,472	$	1,726,927


⁽¹⁾	Other than the $35 Million Fixed-Rate Loan, all of Piedmont’s outstanding debt as of December 31, 2018 and 2017 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 as of December 31, 2018.


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


⁽⁷⁾	The facility has a stated variable rate; however, Piedmont has entered into interest rate swap agreements which effectively fix, exclusive of changes in Piedmont's credit rating, the rate to that shown as the effective rate through the maturity date of the interest rate swap agreements (see Note 5 for more detail).


⁽⁸⁾	Piedmont may extend the term for up to one additional year (through two available six month extensions to a final extended maturity date of September 29, 2023) provided Piedmont is not then in default and upon payment of extension fees.

⁽⁹⁾

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, 2018, is provided below (in thousands):



2019	$	932
2020	1,072
2021	327,702
2022	365,000		⁽¹⁾
2023	350,000
Thereafter	650,000
Total	$	1,694,706

⁽¹⁾

Includes the balance outstanding as of December 31, 2018 on the $500 Million Unsecured 2018 Line of Credit of $205 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 September 29, 2023) provided Piedmont is not then in default and upon payment of extension fees.

Derivative Instruments (Tables)

12 Months Ended

Dec. 31, 2018

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, 2018 is as follows:

Interest Rate Derivatives:

Number of Swap Agreements

Associated Debt Instrument

Notional Amount

(in millions)

Effective Date

Maturity Date

Interest rate swaps

Amended and Restated $300 Million Unsecured 2011 Term Loan

300

11/22/2016

1/15/2020

Interest rate swaps

$250 Million Unsecured 2018 Term Loan

100

3/29/2018

3/31/2025

Interest rate swaps

$250 Million Unsecured 2018 Term Loan

3/29/2018

3/29/2020

Total

450

Schedule of Interest Rate Derivatives

A detail of Piedmont’s interest rate derivatives on a gross and net basis as of December 31, 2018 and 2017, respectively, is as follows (in thousands):



Interest rate swaps classified as:	December 31, 2018			December 31, 2017
Gross derivative assets	$	1,199		$	688
Gross derivative liabilities	(839		)	(1,478		)
Net derivative asset/(liability)	$	360		$	(790	)

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



Interest Rate Swaps in Cash Flow Hedging Relationships	2018			2017			2016
Amount of gain/(loss) recognized in OCI	$	692		$	2,479		$	(4,126	)
Amount of previously recorded gain/(loss) reclassified from OCI into Interest Expense	$	1,558		$	(3,502	)	$	(4,548	)
Amount of loss recognized on derivative reclassified from OCI into Loss on Extinguishment of Debt	$	(1,258	)	$	—		$	—

Total amount of Interest Expense presented in the consolidated statements of income	$	(61,023	)	$	(68,124	)	$	(64,860	)
Total amount of Loss on Extinguishment of Debt presented in the consolidated statements of income ⁽¹⁾	$	(1,680	)	$	—		$	—


⁽¹⁾	Includes the write-off of approximately $0.4 million of discounts and unamortized debt issuance costs associated with the repayment of debt. (see Note 4).

Fair Value Measurements of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2018

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, 2018 and 2017, respectively (in thousands):



	December 31, 2018					December 31, 2017
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⁾	$	4,571	$	4,571	Level 1	$	7,382	$	7,382	Level 1
Tenant receivables, net ⁽¹⁾	$	10,800	$	10,800	Level 1	$	12,139	$	12,139	Level 1
Restricted cash and escrows ⁽¹⁾	$	1,463	$	1,463	Level 1	$	1,373	$	1,373	Level 1
Interest rate swaps	$	1,199	$	1,199	Level 2	$	688	$	688	Level 2
Liabilities:
Accounts payable and accrued expenses ⁽¹⁾	$	47,328	$	47,328	Level 1	$	126,429	$	126,429	Level 1
Interest rate swaps	$	839	$	839	Level 2	$	1,478	$	1,478	Level 2
Debt, net	$	1,685,472	$	1,698,213	Level 2	$	1,726,927	$	1,759,905	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, 2018

Real Estate [Abstract]

Impairment Loss on Real Estate Assets

Piedmont recorded the following impairment losses on real estate assets for the years ended December 31, 2018, 2017, and 2016 (in thousands):



	2018		2017		2016
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


⁽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⁾	The impairment loss was calculated as the difference between the carrying value of the asset and the anticipated contracted sales price, less estimated selling costs.

⁽⁵⁾

Stock Based Compensation (Tables)

12 Months Ended

Dec. 31, 2018

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, 2018 is as follows:



	Shares		Weighted-Average Grant Date Fair Value
Unvested and Potential Stock Awards as of December 31, 2017	868,437		$	21.69
Deferred Stock Awards Granted	354,236		$	17.84
Increase in Estimated Potential Future Performance Share Awards, net of forfeitures	506,793		$	25.20
Performance Stock Awards Vested	(161,005	)	$	18.47
Deferred Stock Awards Vested	(332,019	)	$	19.21
Deferred Stock Awards Forfeited	(8,959	)	$	19.77
Unvested and Potential Stock Awards as of December 31, 2018	1,227,483		$	23.14

The following table provides additional information regarding stock award activity during the years ended December 31, 2018, 2017, and 2016 (in thousands except for per share data):



	2018		2017		2016
Weighted-Average Grant Date Fair Value of Deferred Stock Granted During the Period (per share)	$	17.84	$	21.38	$	19.96
Total Grant Date Fair Value of Deferred Stock Vested During the Period	$	6,378	$	5,899	$	4,806
Share-based Liability Awards Paid During the Period ⁽¹⁾	$	2,947	$	2,877	$	1,127

⁽¹⁾

Amounts reflect the issuance of performance share awards related to the 2015-17, 2014-16, and 2013-15 Performance Share Plans during the years ended December 31, 2018, 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, 2018 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, 2018
January 3, 2014	Deferred Stock Award	72,969	$	16.45	Of the shares granted, 20% vested or will vest on January 3, 2015, 2016, 2017, 2018, and 2019, respectively.	16,416
May 24, 2016	Deferred Stock Award	208,003	$	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.	60,487
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.	139,127	⁽²⁾
May 18, 2017	Deferred Stock Award	219,863	$	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.	123,343
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.	251,123	⁽²⁾
May 17, 2018	Deferred Stock Award-Board of Directors	31,388	$	17.84	Of the shares granted, 100% will vest by May 17, 2019.	31,388
May 17, 2018	Deferred Stock Award	302,706	$	17.84	Of the shares granted, 25% vested on the date of grant, and 25% vested or will vest on May 17, 2019, 2020, and 2021, respectively.	239,567
May 17, 2018	Fiscal Year 2018-2020 Performance Share Program	—	$	23.52	Shares awarded, if any, will vest immediately upon determination of award in 2021.	366,032	⁽²⁾
Total						1,227,483


⁽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, 2018.


⁽²⁾	Estimated based on Piedmont's cumulative TSR for the respective performance period through December 31, 2018. Share estimates are subject to change in future periods based upon Piedmont's relative performance compared to its peer group of office REITs' total stockholder return.

Property Dispositions and Assets Held for Sale (Tables)

12 Months Ended

Dec. 31, 2018

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 of Real Estate Assets				Net Sales Proceeds
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	⁽¹⁾
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	⁽³⁾
2017 Disposition Portfolio⁽⁴⁾	Various⁽⁴⁾	January 4, 2018	$	45,275			$	419,644	⁽⁵⁾
800 North Brand Boulevard	Glendale, California	November 29, 2018	$	30,416			$	155,583


⁽¹⁾	Piedmont accepted a secured promissory note from the buyer for $33.0 million of the sales proceeds which was subsequently repaid in full. 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.


⁽²⁾	As discussed in Note 7 above, Piedmont recognized an impairment loss prior to, or in conjunction with, the sale of the property. Therefore, 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⁾	Property was owned as part of an unconsolidated joint venture. As such, the gain on sale is presented as equity in income/(loss) of unconsolidated joint ventures in the accompanying consolidated statement of income. Amounts shown above reflect Piedmont's approximate 72% ownership.

⁽⁴⁾


⁽⁵⁾	Piedmont accepted a secured promissory note from the buyer for $3.2 million which was subsequently repaid in full.

Assets Held For Sale and Discontinude Operations

Details of amounts held for sale as of December 31, 2018 and 2017 are presented below (in thousands):



	December 31, 2018		December 31, 2017
Real estate assets held for sale, net:
Land	$	30,562	$	128,668
Building and improvements, less accumulated depreciation of $48,453 and $270,552 as of December 31, 2018, and 2017, respectively	77,936		430,136
Construction in progress	2,054		2,645
Total real estate assets held for sale, net	$	110,552	$	561,449

Other assets held for sale, net:
Straight-line rent receivables	$	10,756	$	44,666
Prepaid expenses and other assets	430		2,067
Deferred lease costs, less accumulated amortization of $2,446 and $20,169 as of December 31, 2018 and 2017, respectively	9,605		37,560
Total other assets held for sale, net	$	20,791	$	84,293

Other liabilities held for sale, net:
Intangible lease liabilities, less accumulated amortization of $0 and $935 as of December 31, 2018 and 2017, respectively	$	—	$	380

- 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.

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+ Details

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

12 Months Ended

Dec. 31, 2018

Supplemental Cash Flow Elements [Abstract]

Schedule of Cash Flow, Supplemental Disclosures

Certain noncash investing and financing activities for the years ended December 31, 2018, 2017, and 2016 (in thousands) are outlined below:



	2018			2017		2016
Accrued capital expenditures and deferred lease costs	$	10,854		$	11,276	$	14,427
Change in accrued dividends and discount on dividend reinvestments	$	(74,828	)	$	71,267	$	30,532
Change in accrued share repurchases as part of an announced plan	$	3,140		$	1,276	$	—
Investment in consolidated joint venture	$	—		$	63,026	$	—



	2018		2017		2016
Cash and cash equivalents, beginning of period	$	7,382	$	6,992	$	5,441
Restricted cash and escrows, beginning of period	1,373		1,212		5,174
Total cash, cash equivalents, and restricted cash and escrows shown in the consolidated statement of cash flows, beginning of period	$	8,755	$	8,204	$	10,615

Cash and cash equivalents, end of period	$	4,571	$	7,382	$	6,992
Restricted cash and escrows, end of period	1,463		1,373		1,212
Total cash, cash equivalents, and restricted cash and escrows shown in the consolidated statement of cash flows, end of period	$	6,034	$	8,755	$	8,204

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Schedule of Tax Basis Income

Piedmont’s income tax basis net income for the years ended December 31, 2018, 2017, and 2016, is calculated as follows (in thousands):



	2018			2017			2016
GAAP basis financial statement net income	$	130,296		$	133,564		$	99,732
Increase/(decrease) in net income resulting from:
Depreciation and amortization expense recognized for financial reporting purposes in excess of amounts recognized for income tax purposes	54,420			62,916			69,214
Rental income accrued for income tax purposes less than amounts for financial reporting purposes	(9,681		)	(25,432		)	(18,964		)
Net amortization of above/below-market lease intangibles for income tax purposes in excess of amounts for financial reporting purposes	(7,453		)	(6,041		)	(4,895		)
Gain on disposal of property for financial reporting purposes less than/(in excess of) amounts for income tax purposes	(36,241		)	10,068			(118,713		)
Taxable income or loss of Piedmont Washington Properties, Inc., in excess of/(less than) amount for financial reporting purposes	(2,089		)	176			(1,042		)
Other expenses, including impairment loss on real estate assets, for financial reporting purposes in excess of/ (less than) amounts for income tax purposes	(37,394		)	49,859			42,019
Taxable income for POH in excess of/(less than) amount for financial reporting purposes	(64		)	(28		)	648
Income tax basis net income, prior to dividends paid deduction	$	91,794		$	225,082		$	67,999

Schedule of Characterization Of Dividends To Common Stockholders



	2018		2017		2016
Ordinary income	100.00	%	53.61	%	81.77	%
Return of capital	—	%	—	%	18.23	%
Capital gains	—	%	46.39	%	—	%
	100	%	100	%	100	%

Quarterly Results (unaudited) (Tables)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Schedule of Quarterly Financial Information

A summary of the unaudited quarterly financial information for the years ended December 31, 2018 and 2017, is presented below (in thousands, except per-share data):



	2018
	First		Second			Third		Fourth
Revenues	$	129,900	$	129,174		$	129,708	$	137,185
Gain/(loss) on sale of real estate assets	$	45,209	$	(23	)	$	—	$	30,505
Net income	$	57,828	$	10,940		$	16,114	$	45,409
Net income applicable to Piedmont	$	57,830	$	10,942		$	16,114	$	45,410
Basic earnings per share	$	0.43	$	0.09		$	0.13	$	0.35
Diluted earnings per share	$	0.42	$	0.09		$	0.13	$	0.35
Dividends declared per share	$	0.21	$	0.21		$	0.21	$	0.21



	2017
	First			Second		Third		Fourth
Revenues	$	148,463		$	148,679	$	137,587	$	139,444
Gain/(loss) on sale of real estate assets	$	(53	)	$	6,492	$	109,512	$	(77	)
Net income/(loss)	$	15,101		$	23,707	$	126,129	$	(31,388	)
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.

Guarantor and Non-Guarantor Financial Information (Tables)

12 Months Ended

Dec. 31, 2018

Guarantor and Non-Guarantor Financial Information [Abstract]

Condensed Balance Sheet



Condensed Consolidated Balance Sheets
As of December 31, 2018
(in thousands)	Piedmont (Parent) (Guarantor)		Piedmont OP (the Issuer)		Non-Guarantor Subsidiaries		Eliminations			Consolidated
Assets:
Real estate assets, at cost:
Land	$	—	$	36,094	$	471,328	$	—		$	507,422
Buildings and improvements, less accumulated depreciation	—		176,927		2,128,469		(300		)	2,305,096
Intangible lease assets, less accumulated amortization	—		—		77,676		—			77,676
Construction in progress	—		5,708		10,140		—			15,848
Real estate assets held for sale, net	—		—		110,552		—			110,552
Total real estate assets	—		218,729		2,798,165		(300		)	3,016,594
Cash and cash equivalents	150		—		4,939		(518		)	4,571
Tenant and straight-line receivables, net	—		16,143		157,246		—			173,389
Investment in subsidiaries	1,744,122		2,704,337		166		(4,448,625		)	—
Notes receivable	—		810		144,500		(145,310		)	—
Prepaid expenses, restricted cash, escrows, interest rate swaps, and other assets	42		5,682		22,318		(24		)	28,018
Goodwill	—		98,918		—		—			98,918
Deferred lease costs, net	—		15,158		234,990		—			250,148
Other assets held for sale, net	—		—		20,791		—			20,791
Total assets	$	1,744,314	$	3,059,777	$	3,383,115	$	(4,594,777	)	$	3,592,429
Liabilities:
Debt, net	$	—	$	1,495,904	$	335,717	$	(145,310	)	$	1,686,311
Accounts payable, accrued expenses, dividends payable, interest rate swaps and accrued capital expenditures	32,174		14,543		83,316		(542		)	129,491
Deferred income	—		2,274		26,505		—			28,779
Intangible lease liabilities, net	—		—		35,708		—			35,708
Total liabilities	32,174		1,512,721		481,246		(145,852		)	1,880,289
Equity:
Total stockholders’ equity	1,712,140		1,547,056		2,901,869		(4,448,925		)	1,712,140
Total liabilities and stockholders’ equity	$	1,744,314	$	3,059,777	$	3,383,115	$	(4,594,777	)	$	3,592,429



Condensed Consolidated Balance Sheets
As of December 31, 2017
(in thousands)	Piedmont (Parent) (Guarantor)			Piedmont OP (the Issuer)		Non-Guarantors		Eliminations			Piedmont (Consolidated)
Assets:
Real estate assets, at cost:
Land	$	—		$	36,094	$	454,531	$	—		$	490,625
Buildings and improvements, less accumulated depreciation	—			180,886		2,062,933		(300		)	2,243,519
Intangible lease assets, less accumulated amortization	—			181		77,624		—			77,805
Construction in progress	—			85		11,259		—			11,344
Real estate assets held for sale, net	—			32,815		528,634		—			561,449
Total real estate assets	—			250,061		3,134,981		(300		)	3,384,742
Cash and cash equivalents	150			3,890		3,342		—			7,382
Tenant and straight-line rent receivables, net, and amounts from unconsolidated joint ventures	—			16,891		139,727		—			156,618
Advances to affiliates	1,674,276			6,297,632		—		(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 swaps and other assets	2			5,094		18,483		(740		)	22,839
Goodwill	—			98,918		—		—			98,918
Deferred lease costs, net	—			16,611		228,564		—			245,175
Other assets held for sale, net	—			2,266		82,027		—			84,293
Total assets	$	5,111,727		$	6,780,173	$	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	104,028			20,279		93,086		(740		)	216,653
Advances from affiliates	5,277,957			941,494		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
Liabilities held for sale, net	—			—		380		—			380
Total liabilities	5,381,985			2,502,121		2,433,585		(8,304,213		)	2,013,478
Equity:
Total stockholders’ equity	(270,258		)	4,278,052		1,318,211		(3,339,516		)	1,986,489
Total liabilities and stockholders’ equity	$	5,111,727		$	6,780,173	$	3,751,796	$	(11,643,729	)	$	3,999,967

Condensed Income Statement



Condensed Consolidated Statements of Income
For the year ended December 31, 2018
(in thousands)	Piedmont (Parent) (Guarantor)			Piedmont OP (the Issuer)			Non-Guarantors			Eliminations			Consolidated
Revenues:
Rental income	$	—		$	35,221		$	378,473		$	(2,027	)	$	411,667
Tenant reimbursements	—			9,489			83,700			(446		)	92,743
Property management fee revenue	—			—			17,118			(15,668		)	1,450
Other property related income	—			130			19,977			—			20,107
	—			44,840			499,268			(18,141		)	525,967
Expenses:
Property operating costs	—			19,583			207,896			(18,141		)	209,338
Depreciation	—			11,514			96,442			—			107,956
Amortization	—			1,990			61,305			—			63,295
Impairment loss on real estate assets	—			—			—			—			—
General and administrative	289			6,576			22,848			—			29,713
	289			39,663			388,491			(18,141		)	410,302
	(289		)	5,177			110,777			—			115,665
Other income (expense):
Interest expense	—			(54,095		)	(14,558		)	7,630			(61,023		)
Other income/(expense)	—			144			9,124			(7,630		)	1,638
Loss on extinguishment of debt	—			(1,680		)	—			—			(1,680		)
Gain on sale of real estate assets	—			1,417			74,274			—			75,691
	—			(54,214		)	68,840			—			14,626
Income/(loss) before consolidated subsidiaries	(289		)	(49,037		)	179,617			—			130,291
Income from subsidiaries	130,585			178,648			—			(309,233		)	—
Net income	130,296			129,611			179,617			(309,233		)	130,291
Net loss applicable to noncontrolling interest	—			—			5			—			5
Net income applicable to Piedmont	$	130,296		$	129,611		$	179,622		$	(309,233	)	$	130,296



Condensed Consolidated Statements of Income
For the year ended December 31, 2017
(in thousands)	Piedmont (Parent) (Guarantor)			Piedmont OP (the Issuer)			Non-Guarantors			Eliminations			Consolidated
Revenues:
Rental income	$	—		$	42,407		$	414,509		$	(1,791	)	$	455,125
Tenant reimbursements	—			11,702			86,911			(474		)	98,139
Property management fee revenue	—			—			18,205			(16,470		)	1,735
Other property related income	—			144			19,030			—			19,174
	—			54,253			538,655			(18,735		)	574,173
Expenses:
Property operating costs	—			22,805			218,371			(18,735		)	222,441
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	347			6,443			22,529			—			29,319
	347			45,379			465,885			(18,735		)	492,876
	(347		)	8,874			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
Gain on sale of real estate assets, net	—			6,431			109,443			—			115,874
	—			(37,325		)	89,577			—			52,252
Net income/(loss)	(347		)	(28,451		)	162,347			—			133,549
Net loss applicable to noncontrolling interest	—			—			15			—			15
Net income/(loss) applicable to Piedmont	$	(347	)	$	(28,451	)	$	162,362		$	—		$	133,564



Condensed Consolidated Statements of Income
For the year ended December 31, 2016
(in thousands)	Piedmont (Parent) (Guarantor)			Piedmont OP (the Issuer)			Non-Guarantors			Eliminations			Consolidated
Revenues:
Rental income	$	—		$	53,527		$	389,022		$	(2,631	)	$	439,918
Tenant reimbursements	—			14,295			81,104			(498		)	94,901
Property management fee revenue	—			—			16,947			(15,033		)	1,914
Other property related income	—			1,266			17,716			—			18,982
	—			69,088			504,789			(18,162		)	555,715
Expenses:
Property operating costs	—			33,829			205,344			(18,377		)	220,796
Depreciation	—			16,657			111,076			—			127,733
Amortization	—			3,715			71,404			—			75,119
Impairment loss	—			8,259			25,642			—			33,901
General and administrative	311			26,452			36,065			(35,446		)	27,382
	311			88,912			449,531			(53,823		)	484,931
	(311		)	(19,824		)	55,258			35,661			70,784
Other income (expense):
Interest expense	—			(49,108		)	(27,636		)	11,884			(64,860		)
Other income/(expense)	282			9,560			2,029			(11,884		)	(13		)
Net recoveries from casualty events	—			—			34			—			34
Equity in income of unconsolidated joint ventures	—			362			—			—			362
Gain on sale of real estate assets, net	—			31,275			62,135			—			93,410
	282			(7,911		)	36,562			—			28,933
Net income/(loss)	(29		)	(27,735		)	91,820			35,661			99,717
Net loss applicable to noncontrolling interest	—			—			15			—			15
Net income/(loss) applicable to Piedmont	$	(29	)	$	(27,735	)	$	91,835		$	35,661		$	99,732

Consolidating Statements of Comprehensive Income



Consolidating Statements of Comprehensive Income
For the Year Ended December 31, 2018
(in thousands)	Piedmont (Parent) (Guarantor)			Piedmont OP (the Issuer)			Non-Guarantors		Eliminations			Piedmont (Consolidated)
Net income	$	130,296		$	129,611		$	179,622	$	(309,233	)	$	130,296
Effective portion of gain/(loss) on derivative instruments that are designated and qualify as cash flow hedges	692			692			—		(692		)	692
Plus: Reclassification of net (gain)/loss included in net income	(300		)	(300		)	—		300			(300		)
Other comprehensive income	392			392			—		(392		)	392

Comprehensive income	$	130,688		$	130,003		$	179,622	$	(309,625	)	$	130,688

Condensed Cash Flow Statement



Condensed Consolidated Statements of Cash Flows
For the year ended December 31, 2018
(in thousands)	Piedmont (Parent) (Guarantor)			Piedmont OP (the Issuer)			Non-Guarantors			Eliminations			Consolidated
Net Cash Provided By/(Used In) Operating Activities	$	135,755		$	141,293		$	235,562		$	(309,741	)	$	202,869

Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	—			(14,479		)	(209,540		)	—			(224,019		)
Intercompany note receivable	—			88,000			—			(88,000		)	—
Net sales proceeds from wholly-owned properties	—			36,572			538,655			—			575,227
Note receivable issuance	—			—			(3,200		)	—			(3,200		)
Note receivable payment	—			—			3,200			—			3,200
Deferred lease costs paid	—			(3,090		)	(24,340		)	—			(27,430		)
Distributions from subsidiaries	349,135			5,405			—			(354,540		)	—
Net cash provided by/(used in) investing activities	349,135			112,408			304,775			(442,540		)	323,778
Cash Flows from Financing Activities:
Debt issuance costs paid	—			(1,040		)	—			—			(1,040		)
Proceeds from debt	—			977,062			—			—			977,062
Repayments of debt	—			(1,019,000		)	(1,455		)	—			(1,020,455		)
Intercompany note payable	—			—			(88,000		)	88,000			—
Costs of issuance of common stock	(85		)	—			—			—			(85		)
Value of shares withheld to pay tax obligations related to employee stock compensation	(2,219		)	—			—			—			(2,219		)
Repurchases of common stock as part of announced plan	(298,538		)	—			—			—			(298,538		)
Distributions	(184,048		)	(214,596		)	(449,212		)	663,763			(184,093		)
Net cash provided by/(used in) financing activities	(484,890		)	(257,574		)	(538,667		)	751,763			(529,368		)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	—			(3,873		)	1,670			(518		)	(2,721		)
Cash, cash equivalents, and restricted cash and escrows, beginning of year	150			3,907			4,698			—			8,755
Cash, cash equivalents, and restricted cash and escrows, end of year	$	150		$	34		$	6,368		$	(518	)	$	6,034



Condensed Consolidated Statements of Cash Flows
For the year ended December 31, 2017
(in thousands)	Piedmont (Parent) (Guarantor)			Piedmont OP (the Issuer)			Non-Guarantors			Eliminations			Consolidated
Net Cash Provided By/(Used In) Operating Activities	$	5,497		$	(18,989	)	$	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		)
Value of 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	180,791			160,019			(340,810		)	—			—
Dividends paid and discount on dividend reinvestments	(122,229		)	—			(45		)	—			(122,274		)
Net cash provided by/(used in) financing activities	(5,497		)	(9,402		)	(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	150			3,693			4,361			—			8,204
Cash, cash equivalents, and restricted cash and escrows, end of year	$	150		$	3,907		$	4,698		$	—		$	8,755



Condensed Consolidated Statements of Cash Flows
For the year ended December 31, 2016
(in thousands)	Piedmont (Parent) (Guarantor)			Piedmont OP (the Issuer)			Non-Guarantors			Eliminations			Consolidated
Net Cash Provided/(Used In) by Operating Activities	$	5,214		$	(26,263	)	$	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			—
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		)
Value of 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	97,016			(312,218		)	250,862			(35,660		)	—
Dividends paid and discount on dividend reinvestments	(91,601		)	—			(15		)	—			(91,616		)
Net cash provided by/(used in) financing activities	(5,214		)	(165,082		)	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	150			2,196			8,269			—			10,615
Cash, cash equivalents, and restricted cash and escrows, end of year	$	150		$	3,693		$	4,361		$	—		$	8,204

Organization (Details) ft² in Thousands	12 Months Ended
Organization (Details) ft² in Thousands	Dec. 31, 2018 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%
Number of real estate properties \| property	4
Rentable square feet \| ft²	16,200
Percentage of annualized lease revenue	92.00%
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	54
Percentage of Class A commercial office space	93.30%
Redevelopment Asset
Real Estate Properties [Line Items]
Rentable square feet \| ft²	487

Summary of Significant Accounting Policies (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) property vote Joint_Venture $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($)	Jan. 01, 2019 USD ($)
Significant Accounting Policies [Line Items]
Number of real estate properties \| property	4
Number of joint ventures \| Joint_Venture	3
Interest capitalized	$ 1,400	$ 200	$ 4,600
Intangible Lease Liabilities (Below-Market In-Place Leases)	94,852	95,620
Amortization of Intangible Lease Origination Costs and In-Place Lease Valuation included in amortization expense	48,940	58,467	58,150
Amortization of Above-Market and Below-Market In-Place Lease intangibles as a net increase to rental revenues	7,615	6,575	5,066
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
Total	77,676	77,805
Below Market Lease, Net, Amortization Income, Fiscal Maturity [Abstract]
2019	8,273
2020	6,654
2021	6,443
2022	5,878
2023	4,367
Thereafter	4,093
Total	$ 35,708
Weighted-Average Amortization Period (in years)	6 years
Significant Accounting Policies [Abstract]
Provision for doubtful accounts	$ 91	350	216
Capitalized internal leasing costs	300	300	400
Amortization of deferred lease costs	43,600	50,800	50,100
Amortization of lease incentive	2,600	4,800	3,900
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	$ 2,400	$ 2,800	2,900
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, remaining authorized repurchase amount	$ 86,600
Dividend reinvestment plan, shareholders discount	2.00%
Income tax benefit (expense)	$ 97	$ (13)	(415)
Rental income	411,667	455,125	439,918
General and administrative	29,713	29,319	27,382
Property operating costs	209,338	222,441	220,796
Deferred Compensation, Excluding Share-based Payments and Retirement Benefits
Significant Accounting Policies [Abstract]
Assets held as trading securities	400
Above-Market In-place Lease Assets
Significant Accounting Policies [Line Items]
Intangible lease assets	7,620	11,935
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
2019	938
2020	197
2021	141
2022	121
2023	97
Thereafter	64
Total	$ 1,558
Weighted-Average Amortization Period (in years)	3 years
In-Place Lease Valuation
Significant Accounting Policies [Line Items]
Intangible lease assets	$ 157,447	165,015
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
2019	20,876
2020	14,540
2021	12,449
2022	10,948
2023	7,370
Thereafter	9,935
Total	$ 76,118
Weighted-Average Amortization Period (in years)	5 years
Intangible Lease Origination Costs
Significant Accounting Policies [Line Items]
Intangible lease assets	$ 241,516	250,539
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
2019	29,503
2020	22,570
2021	19,818
2022	17,550
2023	11,774
Thereafter	18,952
Total	$ 120,167
Weighted-Average Amortization Period (in years)	6 years
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
Accounting Standards Update 2016-01
Significant Accounting Policies [Abstract]
Cumulative effect of accounting change	$ (100)
Difference between Revenue Guidance in Effect before and after Topic 606 \| Accounting Standards Update 2014-09
Significant Accounting Policies [Abstract]
Rental income		(19,200)	(19,000)
Property related revenue		19,200	19,000
General and administrative		(1,800)	(1,900)
Restatement Adjustment
Significant Accounting Policies [Abstract]
Property operating costs		$ 1,800	$ 1,900
Subsequent Event \| Accounting Standards Update 2016-02
Significant Accounting Policies [Abstract]
Lease liability				$ 300

Acquisitions (Details)	Dec. 12, 2018 USD ($) ft²	Oct. 25, 2018 USD ($) ft²	Feb. 23, 2018 USD ($) ft²	Dec. 31, 2018 USD ($) ft² building
Business Acquisition [Line Items]
Number of properties acquired \| building				3
Rentable square feet \| ft²				16,200,000
501 West Church Street
Business Acquisition [Line Items]
Ownership Percentage Acquired			100.00%
Rentable square feet \| ft²			182,461
Percentage Leased as of Acquisition (Unaudited)			100.00%
Net Contractual Purchase Price (in millions) \| $			$ 28,000,000.0
9320 Excelsior Boulevard
Business Acquisition [Line Items]
Ownership Percentage Acquired		100.00%
Rentable square feet \| ft²		267,724
Percentage Leased as of Acquisition (Unaudited)		100.00%
Net Contractual Purchase Price (in millions) \| $		$ 48,700,000
25 Burlington Mall Road
Business Acquisition [Line Items]
Ownership Percentage Acquired	100.00%
Rentable square feet \| ft²	287,776
Percentage Leased as of Acquisition (Unaudited)	89.00%
Net Contractual Purchase Price (in millions) \| $	$ 74,000,000.0
Unsecured Debt \| Line of Credit \| Unsecured 500 Million 2018 Line Of Credit
Business Acquisition [Line Items]
Amount of line of credit \| $				$ 500,000,000

Debt (Narrative) (Details)	1 Months Ended	12 Months Ended
Debt (Narrative) (Details)	Jan. 31, 2018 USD ($)	Dec. 31, 2018 USD ($) contract period	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Debt Instrument [Line Items]
Weighted average interest rate		3.76%	3.48%
Interest paid		$ 63,100,000	$ 67,600,000	$ 69,000,000.0
Unsecured (Variable and Fixed)
Debt Instrument [Line Items]
Derivative, notional amount		$ 450,000,000
Weighted average interest rate		3.75%
$300 Million Unsecured 2013 Term Loan \| Unsecured (Variable and Fixed)
Debt Instrument [Line Items]
Repayments of debt	$ 300,000,000	$ 300,000,000
Face amount of facility		$ 300,000,000
$300 Million Unsecured 2013 Term Loan \| Unsecured (Variable and Fixed) \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable interest rate		1.20%
$170 Million Unsecured 2015 Term Loan \| Unsecured (Variable and Fixed)
Debt Instrument [Line Items]
Repayments of debt		$ 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 interest rate		1.125%
$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
Face amount of facility		$ 500,000,000
$500 Million Unsecured 2015 Line of Credit \| Unsecured (Variable and Fixed) \| Line of Credit \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable interest rate		1.00%
Unsecured 500 Million 2018 Line Of Credit \| Unsecured (Variable and Fixed)
Debt Instrument [Line Items]
Face amount of facility		$ 500,000,000
Unsecured 500 Million 2018 Line Of Credit \| Unsecured (Variable and Fixed) \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable interest rate		0.90%
Unsecured 500 Million 2018 Line Of Credit \| Unsecured (Variable and Fixed) \| Line of Credit
Debt Instrument [Line Items]
Amount of line of credit		$ 500,000,000
Debt instrument term		4 years
Number of extension periods \| period		2
Maturity extension period		6 months
Optional increase to maximum borrowing capacity		$ 500,000,000
Maximum borrowing capacity, after optional increase		$ 1,000,000,000.0
Additional extension period		1 year
Unsecured 500 Million 2018 Line Of Credit \| Unsecured (Variable and Fixed) \| Line of Credit \| Federal Funds Effective Swap Rate
Debt Instrument [Line Items]
Basis spread on variable interest rate		0.50%
Unsecured 500 Million 2018 Line Of Credit \| Unsecured (Variable and Fixed) \| Line of Credit \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable interest rate		0.90%
Amended and Restated $300 Million Unsecured 2011 Term Loan \| Unsecured (Variable and Fixed)
Debt Instrument [Line Items]
Face amount of facility		$ 300,000,000
Additional extension period		22 months
Amended and Restated $300 Million Unsecured 2011 Term Loan \| Unsecured (Variable and Fixed) \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable interest rate		1.00%
Amended and Restated $300 Million Unsecured 2011 Term Loan \| Unsecured (Variable and Fixed) \| Line of Credit \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable interest rate		1.00%
$250 Million Unsecured 2018 Term Loan \| Interest rate swaps
Debt Instrument [Line Items]
Number of swap agreements \| contract		3
Derivative, notional amount		$ 150,000,000
$250 Million Unsecured 2018 Term Loan \| Federal Funds Effective Swap Rate
Debt Instrument [Line Items]
Basis spread on variable interest rate		0.50%
$250 Million Unsecured 2018 Term Loan \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable interest rate		1.00%
$250 Million Unsecured 2018 Term Loan \| Unsecured (Variable and Fixed)
Debt Instrument [Line Items]
Debt instrument term		7 years
Face amount of facility		$ 250,000,000
Derivative, notional amount		$ 150,000,000
$250 Million Unsecured 2018 Term Loan \| Unsecured (Variable and Fixed) \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable interest rate		1.60%
Unsecured, 2018 $500 Million Line Of Credit, 2011 $300 Million Term Loan And 2018 $250 Million Term Loan \| Unsecured (Variable and Fixed)
Debt Instrument [Line Items]
Unencumbered interest coverage ratio		1.75
Unencumbered leverage ratio		1.60
Fixed charge coverage ratio		1.50
Maximum leverage ratio		0.60
Maximum secured debt ratio		0.40
Minimum \| Unsecured 500 Million 2018 Line Of Credit \| Unsecured (Variable and Fixed) \| Line of Credit
Debt Instrument [Line Items]
Basis spread on variable interest rate		0.775%
Minimum \| Amended and Restated $300 Million Unsecured 2011 Term Loan \| Unsecured (Variable and Fixed) \| Line of Credit
Debt Instrument [Line Items]
Basis spread on variable interest rate		0.85%	0.90%
Minimum \| $250 Million Unsecured 2018 Term Loan \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable interest rate		1.45%
Maximum \| Unsecured 500 Million 2018 Line Of Credit \| Unsecured (Variable and Fixed) \| Line of Credit
Debt Instrument [Line Items]
Basis spread on variable interest rate		1.45%
Maximum \| Amended and Restated $300 Million Unsecured 2011 Term Loan \| Unsecured (Variable and Fixed) \| Line of Credit
Debt Instrument [Line Items]
Basis spread on variable interest rate		1.65%	1.90%
Maximum \| $250 Million Unsecured 2018 Term Loan \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable interest rate		2.40%
Through March 29, 2020 \| $250 Million Unsecured 2018 Term Loan \| Unsecured (Variable and Fixed)
Debt Instrument [Line Items]
Derivative fixed interest rate		4.11%

Debt (Schedule of Debt) (Details)	12 Months Ended
Debt (Schedule of Debt) (Details)	Dec. 31, 2018 USD ($) period	Dec. 31, 2017 USD ($)
Debt Instrument [Line Items]
Subtotal/Weighted Average	3.76%	3.48%
Amount Outstanding	$ 1,685,472,000	$ 1,726,927,000
Secured Debt
Debt Instrument [Line Items]
Subtotal/Weighted Average	3.80%
Amount Outstanding	$ 190,351,000	191,616,000
Premium (discount) and unamortized debt issuance costs	$ 645,000	946,000
Secured Debt \| Secured 35 Million Mortgage Loan
Debt Instrument [Line Items]
Stated Rate	5.55%
Effective Rate	3.75%
Amount Outstanding	$ 29,706,000	30,670,000
Face amount of facility	$ 35,000,000	35,000,000
Secured Debt \| Fixed Rate 160 Million Loan
Debt Instrument [Line Items]
Stated Rate	3.48%
Effective Rate	3.58%
Amount Outstanding	$ 160,000,000	160,000,000
Face amount of facility	$ 160,000,000
Unsecured Debt
Debt Instrument [Line Items]
Subtotal/Weighted Average	3.75%
Amount Outstanding	$ 1,495,121,000	1,535,311,000
Premium (discount) and unamortized debt issuance costs	(9,879,000)	(7,689,000)
Derivative, notional amount	$ 450,000,000
Unsecured Debt \| $170 Million Unsecured 2015 Term Loan
Debt Instrument [Line Items]
Effective Rate	2.54%
Amount Outstanding	$ 0	170,000,000
Face amount of facility	170,000,000
Unsecured Debt \| $300 Million Unsecured 2013 Term Loan
Debt Instrument [Line Items]
Amount Outstanding	0	300,000,000
Face amount of facility	300,000,000
Unsecured Debt \| Unsecured 500 Million 2018 Line Of Credit
Debt Instrument [Line Items]
Face amount of facility	500,000,000
Unsecured Debt \| Amended and Restated $300 Million Unsecured 2011 Term Loan
Debt Instrument [Line Items]
Amount Outstanding	300,000,000	300,000,000
Face amount of facility	$ 300,000,000
Additional extension period	22 months
Unsecured Debt \| Unsecured Senior 350 Million Notes
Debt Instrument [Line Items]
Stated Rate	3.40%
Effective Rate	3.43%
Amount Outstanding	$ 350,000,000	350,000,000
Face amount of facility	$ 350,000,000
Unsecured Debt \| Unsecured Senior 400 Million Notes
Debt Instrument [Line Items]
Stated Rate	4.45%
Effective Rate	4.10%
Amount Outstanding	$ 400,000,000	400,000,000
Face amount of facility	$ 400,000,000
Unsecured Debt \| $250 Million Unsecured 2018 Term Loan
Debt Instrument [Line Items]
Effective Rate	4.12%
Amount Outstanding	$ 250,000,000	0
Face amount of facility	250,000,000
Derivative, notional amount	$ 150,000,000
Line of Credit \| Unsecured Debt \| $500 Million Unsecured 2015 Line of Credit
Debt Instrument [Line Items]
Effective Rate	3.17%
Amount Outstanding	$ 0	23,000,000
Face amount of facility	$ 500,000,000
Line of Credit \| Unsecured Debt \| Unsecured 500 Million 2018 Line Of Credit
Debt Instrument [Line Items]
Effective Rate	3.35%
Amount Outstanding	$ 205,000,000	$ 0
Additional extension period	1 year
Number of extension periods \| period	2
Maturity extension period	6 months
Interest rate swaps \| $250 Million Unsecured 2018 Term Loan
Debt Instrument [Line Items]
Derivative, notional amount	$ 150,000,000
Interest rate swaps \| Seven Year Interest Rate Swap Agreement
Debt Instrument [Line Items]
Derivative, notional amount	$ 100,000,000
Interest rate swaps \| Unsecured Debt \| $300 Million Unsecured 2013 Term Loan
Debt Instrument [Line Items]
Effective Rate	2.78%
Interest rate swaps \| Unsecured Debt \| Amended and Restated $300 Million Unsecured 2011 Term Loan
Debt Instrument [Line Items]
Effective Rate	3.20%
Through March 29, 2020 \| Unsecured Debt \| $250 Million Unsecured 2018 Term Loan
Debt Instrument [Line Items]
Derivative fixed interest rate	4.11%
From March 30, 2020 Through March 31, 2025 \| Unsecured Debt \| $250 Million Unsecured 2018 Term Loan
Debt Instrument [Line Items]
Derivative fixed interest rate	4.21%
LIBOR \| $250 Million Unsecured 2018 Term Loan
Debt Instrument [Line Items]
Basis spread on variable interest rate	1.00%
LIBOR \| Unsecured Debt \| $170 Million Unsecured 2015 Term Loan
Debt Instrument [Line Items]
Basis spread on variable interest rate	1.125%
LIBOR \| Unsecured Debt \| $300 Million Unsecured 2013 Term Loan
Debt Instrument [Line Items]
Basis spread on variable interest rate	1.20%
LIBOR \| Unsecured Debt \| Unsecured 500 Million 2018 Line Of Credit
Debt Instrument [Line Items]
Basis spread on variable interest rate	0.90%
LIBOR \| Unsecured Debt \| Amended and Restated $300 Million Unsecured 2011 Term Loan
Debt Instrument [Line Items]
Basis spread on variable interest rate	1.00%
LIBOR \| Unsecured Debt \| $250 Million Unsecured 2018 Term Loan
Debt Instrument [Line Items]
Basis spread on variable interest rate	1.60%
LIBOR \| Line of Credit \| Unsecured Debt \| $500 Million Unsecured 2015 Line of Credit
Debt Instrument [Line Items]
Basis spread on variable interest rate	1.00%
LIBOR \| Line of Credit \| Unsecured Debt \| Unsecured 500 Million 2018 Line Of Credit
Debt Instrument [Line Items]
Basis spread on variable interest rate	0.90%
LIBOR \| Line of Credit \| Unsecured Debt \| Amended and Restated $300 Million Unsecured 2011 Term Loan
Debt Instrument [Line Items]
Basis spread on variable interest rate	1.00%

Debt (Maturities of Long-term Debt) (Details)	12 Months Ended
Debt (Maturities of Long-term Debt) (Details)	Dec. 31, 2018 USD ($) period	Dec. 31, 2017 USD ($)
Debt Instrument [Line Items]
2019	$ 932,000
2020	1,072,000
2021	327,702,000
2022	365,000,000
2023	350,000,000
Thereafter	650,000,000
Total	1,694,706,000
Notes payable	1,685,472,000	$ 1,726,927,000
Unsecured Debt
Debt Instrument [Line Items]
Notes payable	1,495,121,000	1,535,311,000
Unsecured 500 Million 2018 Line Of Credit \| Unsecured Debt \| Line of Credit
Debt Instrument [Line Items]
Amount of line of credit	500,000,000
Notes payable	$ 205,000,000	0
Additional extension period	1 year
Number of extension periods \| period	2
Maturity extension period	6 months
$500 Million Unsecured 2015 Line of Credit \| Unsecured Debt \| Line of Credit
Debt Instrument [Line Items]
Amount of line of credit	$ 500,000,000
Notes payable	$ 0	$ 23,000,000

Derivative Instruments (Narrative) (Details)	1 Months Ended	12 Months Ended
Derivative Instruments (Narrative) (Details)	Jan. 31, 2018 USD ($) contract	Dec. 31, 2018 USD ($)
Derivative [Line Items]
Maximum length of time of cash flow hedge		75 months
Gain (loss) to be reclassified		$ 3,100,000
Interest rate swaps
Derivative [Line Items]
Number of terminated derivatives \| contract	6
Gain on cash flow hedging instruments		100,000
Credit Risk Contract
Derivative [Line Items]
Assets needed for immediate settlement, aggregate fair value		300,000
Unsecured Debt \| $300 Million Unsecured 2013 Term Loan
Derivative [Line Items]
Repayments of debt	$ 300,000,000	300,000,000
Proceeds from termination of interest rate swap agreement	800,000
Face amount of facility		300,000,000
Unsecured Debt \| $300 Million Unsecured 2013 Term Loan \| Interest rate swaps
Derivative [Line Items]
Net loss on interest rate cash flow hedge termination	$ 1,300,000
Unsecured Debt \| Amended and Restated $300 Million Unsecured 2011 Term Loan
Derivative [Line Items]
Face amount of facility		300,000,000
Unsecured Debt \| $250 Million Unsecured 2018 Term Loan
Derivative [Line Items]
Face amount of facility		250,000,000
Amount of hedged debt		$ 150,000,000

Derivative Instruments (Schedule of Notional Amounts of Outstanding Derivative Positions) (Details) - Unsecured Debt	Dec. 31, 2018 USD ($) contract
Derivative [Line Items]
Derivative, notional amount	$ 450,000,000
Amended and Restated $300 Million Unsecured 2011 Term Loan \| Interest Rate Swap 1 through 3
Derivative [Line Items]
Number of swap agreements \| contract	3
Derivative, notional amount	$ 300,000,000
$250 Million Unsecured 2018 Term Loan
Derivative [Line Items]
Derivative, notional amount	$ 150,000,000
$250 Million Unsecured 2018 Term Loan \| Interest Rate Swap 4 through 5
Derivative [Line Items]
Number of swap agreements \| contract	2
Derivative, notional amount	$ 100,000,000
$250 Million Unsecured 2018 Term Loan \| Interest Rate Swap 6
Derivative [Line Items]
Number of swap agreements \| contract	1
Derivative, notional amount	$ 50,000,000

Derivative Instruments (Schedule of Interest Rate Derivatives) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross derivative assets	$ 1,199	$ 688
Gross derivative liabilities	(839)	(1,478)
Net derivative asset/(liability)	$ 360	$ (790)

Derivative Instruments (Schedule of Derivative Instruments, Effect on other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Amount of gain/(loss) recognized in OCI	$ 692	$ 2,479	$ (4,126)
Total amount of Interest Expense presented in the consolidated statements of income	(61,023)	(68,124)	(64,860)
Total amount of Loss on Extinguishment of Debt presented in the consolidated statements of income (1)	(1,680)	0	0
Write off of deferred debt issuance cost	400
Interest rate swaps
Derivative [Line Items]
Total amount of Interest Expense presented in the consolidated statements of income	(61,023)	(68,124)	(64,860)
Interest Expense \| Interest rate swaps
Derivative [Line Items]
Amount of gain/(loss) recognized in OCI	692	2,479	(4,126)
Amount of gain/(loss) reclassified from OCI	1,558	(3,502)	(4,548)
Gain (Loss) On Extinguishment Of Debt \| Interest rate swaps
Derivative [Line Items]
Amount of gain/(loss) reclassified from OCI	$ (1,258)	$ 0	$ 0

Fair Value Measurements of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps	$ 1,199	$ 688
Interest rate swaps	839	1,478
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	4,571	7,382
Tenant receivables, net and Notes receivable	10,800	12,139
Restricted cash and escrows	1,463	1,373
Accounts payable and accrued expenses	47,328	126,429
Debt, net	1,685,472	1,726,927
Carrying Value \| Interest rate swaps
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps	1,199	688
Interest rate swaps	839	1,478
Estimated Fair Value \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	4,571	7,382
Tenant receivables, net and Notes receivable	10,800	12,139
Restricted cash and escrows	1,463	1,373
Accounts payable and accrued expenses	47,328	126,429
Estimated Fair Value \| Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, net	1,698,213	1,759,905
Estimated Fair Value \| Level 2 \| Interest rate swaps
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps	1,199	688
Interest rate swaps	$ 839	$ 1,478

Impairment Loss on Real Estate Assets (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Jul. 31, 2016 USD ($) property	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment loss on real estate assets		$ 0	$ 46,461	$ 33,901
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	0	8,259
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	0	22,950
Impairment of real estate	$ 23,000
Number of assets sold \| property	2
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		0	46,461	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	$ 0	2,692
Impairment of real estate				$ 2,700

Commitments and Contingencies (Details) $ in Millions	12 Months Ended
Commitments and Contingencies (Details) $ in Millions	Dec. 31, 2018 USD ($) category	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Loss Contingencies [Line Items]
Number of tenant and building improvement categories \| category	2
Collectibility of Tenant Reimbursements
Loss Contingencies [Line Items]
Additional expense related to such tenant audits/disputes	$ 0.5	$ 0.3	$ 1.1
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	$ 45.6
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	$ 32.6

Stock Based Compensation (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense and directors' fees related to stock awards	$ 9.7	$ 9.5	$ 8.0
Compensation expense, non-vested awards	$ 8.6	$ 7.7	$ 6.5
Number of shares issued to employees, directors and officers (in shares)	355,055
Nonvested awards, total compensation cost not yet recognized	$ 3.9
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

Stock Based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands					12 Months Ended
	May 17, 2018	May 18, 2017	May 24, 2016	Jan. 03, 2014	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	May 17, 2018	May 18, 2017	May 24, 2016	Jan. 03, 2014
Stock Awards
Rollforward of deferred stock award activity
Unvested and Potential Stock Awards as of the beginning of the year (in shares)					868,437
Unvested and Potential Stock Awards as of end of the year (in shares)					1,227,483	868,437
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Unvested and Potential Stock Awards, Weighted-Average Grant Date Fair Value at beginning of year (in dollars per share)					$ 21.69
Unvested and Potential Stock Awards, Weighted-Average Grant Date Fair Value at end of year (in dollars per share)					23.14	$ 21.69
Grant Date Fair Value (in dollars per share)					$ 21.69	$ 21.69
Unvested Shares (in shares)					868,437	868,437
Deferred Stock Award
Rollforward of deferred stock award activity
Deferred Stock Awards Granted (in shares)					354,236
Deferred Stock Awards Vested (in shares)					(332,019)
Deferred Stock Awards Forfeited (in shares)					(8,959)
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)					$ 17.84	$ 21.38	$ 19.96
Deferred Stock Awards Vested, Weighted-Average Grant Date Fair Value (in dollars per share)					19.21
Deferred Stock Awards Forfeited, Weighted Average Grant Date Fair Value (in dollars per share)					$ 19.77
Total Grant Date Fair Value of Deferred Stock Vested During the Period					$ 6,378	$ 5,899	$ 4,806
Performance Shares
Rollforward of deferred stock award activity
Increase in Estimated Potential Future Performance Share Awards, net of forfeitures (in shares)					506,793
Deferred Stock Awards Vested (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]
Increase in Estimated Potential Future Performance Share Awards, Weighted Average Grant Date Fair Value (in dollars per share)					$ 25.20
Deferred Stock Awards Vested, Weighted-Average Grant Date Fair Value (in dollars per share)					$ 18.47
Share-based Liability Awards Paid During the Period					$ 2,947	$ 2,877	$ 1,127
Deferred Stock Award, Granted January 3, 2014 \| Deferred Stock Award
Rollforward of deferred stock award activity
Unvested and Potential Stock Awards as of end of the year (in shares)					16,416
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Unvested and Potential Stock Awards, Weighted-Average Grant Date Fair Value at end of year (in dollars per share)				$ 16.45
Net Shares Granted (in shares)											72,969
Grant Date Fair Value (in dollars per share)				$ 16.45							$ 16.45
Unvested Shares (in shares)					16,416
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 24, 2016 \| Deferred Stock Award
Rollforward of deferred stock award activity
Unvested and Potential Stock Awards as of end of the year (in shares)					60,487
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Unvested and Potential Stock Awards, Weighted-Average Grant Date Fair Value at end of year (in dollars per share)			$ 19.91
Net Shares Granted (in shares)										208,003
Grant Date Fair Value (in dollars per share)			$ 19.91							$ 19.91
Unvested Shares (in shares)					60,487
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 and Potential Stock Awards as of end of the year (in shares)					139,127
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Unvested and Potential 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)					139,127
Deferred Stock Award, Granted May 18, 2017 \| Deferred Stock Award
Rollforward of deferred stock award activity
Unvested and Potential Stock Awards as of end of the year (in shares)					123,343
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Unvested and Potential Stock Awards, Weighted-Average Grant Date Fair Value at end of year (in dollars per share)		$ 21.38
Net Shares Granted (in shares)									219,863
Grant Date Fair Value (in dollars per share)		$ 21.38							$ 21.38
Unvested Shares (in shares)					123,343
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 and Potential Stock Awards as of end of the year (in shares)					251,123
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Unvested and Potential 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)					251,123
Deferred Stock Award, Granted May 17, 2018 Deferred Stock Award Independent Directors \| Deferred Stock Award \| Independent directors
Rollforward of deferred stock award activity
Unvested and Potential Stock Awards as of end of the year (in shares)					31,388
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Unvested and Potential Stock Awards, Weighted-Average Grant Date Fair Value at end of year (in dollars per share)	$ 17.84
Net Shares Granted (in shares)								31,388
Grant Date Fair Value (in dollars per share)	$ 17.84							$ 17.84
Unvested Shares (in shares)					31,388
Deferred Stock Award, Granted May 17, 2018 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 17, 2018 \| Deferred Stock Award
Rollforward of deferred stock award activity
Unvested and Potential Stock Awards as of end of the year (in shares)					239,567
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Unvested and Potential Stock Awards, Weighted-Average Grant Date Fair Value at end of year (in dollars per share)	$ 17.84
Net Shares Granted (in shares)								302,706
Grant Date Fair Value (in dollars per share)	$ 17.84							$ 17.84
Unvested Shares (in shares)					239,567
Deferred Stock Award, Granted May 17, 2018 \| 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 17, 2018 \| 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 17, 2018 \| 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 17, 2018 \| 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 17, 2018 \| Performance Shares
Rollforward of deferred stock award activity
Unvested and Potential Stock Awards as of end of the year (in shares)					366,032
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Unvested and Potential Stock Awards, Weighted-Average Grant Date Fair Value at end of year (in dollars per share)	$ 23.52
Net Shares Granted (in shares)								0
Grant Date Fair Value (in dollars per share)	$ 23.52							$ 23.52
Unvested Shares (in shares)					366,032

Earnings Per Share (Details) - shares	12 Months Ended
Earnings Per Share (Details) - shares	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Antidilutive securities excluded from computation of earnings per share (in shares)	100,000	100,000	100,000
Weighted-average common shares outstanding - basic (in shares)	130,161,202	145,043,503	145,230,382
Plus: Incremental weighted-average shares from time-vested deferred and performance stock awards (in shares)	475,000	336,000	405,000
Weighted-average common shares outstanding - diluted (in shares)	130,635,650	145,379,994	145,634,953
Common stock issued and outstanding as of period end (in shares)	126,218,554	142,358,940	145,235,000

Operating Leases (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Leases [Abstract]
2019	$ 370,495
2020	352,541
2021	337,951
2022	324,960
2023	291,603
Thereafter	1,247,649
Total	$ 2,925,199

Property Dispositions and Assets Held for Sale (Property Dispositions) (Details) - USD ($) $ in Thousands														12 Months Ended
	Nov. 29, 2018	Jan. 04, 2018	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. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net Sales Proceeds, equity method investment														$ 0	$ 12,334	$ 0
Notes receivable														$ 0	$ 0
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 of Real Estate Assets													$ 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 of Real Estate Assets												$ 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 of Real Estate Assets											$ 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 of Real Estate Assets										$ (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 of Real Estate Assets									$ (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 of Real Estate Assets								$ (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 of Real Estate Assets							$ 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 of Real Estate Assets						$ 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 of Real Estate Assets					$ 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 of Real Estate Assets				$ 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%
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| 2017 Disposition Portfolio
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(Loss) on Sale of Real Estate Assets		$ 45,275
Net Sales Proceeds		419,644
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| 800 North Brand Boulevard
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(Loss) on Sale of Real Estate Assets	$ 30,416
Net Sales Proceeds	$ 155,583
Secured Debt \| Secured Promissory Note
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Notes receivable		$ 3,200

Property Dispositions and Assets Held for Sale (Assets Held-for-Sale) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total other assets held for sale, net	$ 20,791	$ 84,293
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	110,552	561,449
Straight-line rent receivables	10,756	44,666
Prepaid expenses and other assets	430	2,067
Deferred lease costs, less accumulated amortization of $2,446 and $20,169 as of December 31, 2018 and 2017, respectively	9,605	37,560
Accumulated amortization on deferred lease costs	2,446	20,169
Total other assets held for sale, net	20,791	84,293
Intangible lease liabilities, less accumulated amortization of $0 and $935 as of December 31, 2018 and 2017, respectively	0	380
Accumulated amortization on Intangible lease liabilities	0	935
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:	30,562	128,668
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:	77,936	430,136
Accumulated depreciation (building improvements)	48,453	270,552
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:	$ 2,054	$ 2,645

Supplemental Disclosures for the Statement of Consolidated Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplemental Cash Flow Elements [Abstract]
Accrued capital expenditures and deferred lease costs	$ 10,854	$ 11,276	$ 14,427
Change in accrued dividends and discount on dividend reinvestments	(74,828)	71,267	30,532
Change in accrued share repurchases as part of an announced plan	3,140	1,276	0
Investment in consolidated joint venture	0	63,026	0
Cash and cash equivalents	4,571	7,382	6,992	$ 5,441
Restricted cash and escrows	1,463	1,373	1,212	5,174
Total cash, cash equivalents, and restricted cash and escrows shown in the consolidated statement of cash flows	$ 6,034	$ 8,755	$ 8,204	$ 10,615

Income Taxes (Details) - USD ($)	3 Months Ended								12 Months Ended
Income Taxes (Details) - USD ($)	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Line Items]
Net income applicable to Piedmont	$ 45,410,000	$ 16,114,000	$ 10,942,000	$ 57,830,000	$ (31,383,000)	$ 126,133,000	$ 23,710,000	$ 15,104,000	$ 130,296,000	$ 133,564,000	$ 99,732,000
Depreciation and amortization expense recognized for financial reporting purposes in excess of amounts recognized for income tax purposes									54,420,000	62,916,000	69,214,000
Rental income accrued for income tax purposes less than amounts for financial reporting purposes									(9,681,000)	(25,432,000)	(18,964,000)
Net amortization of above/below-market lease intangibles for income tax purposes in excess of amounts for financial reporting purposes									(7,453,000)	(6,041,000)	(4,895,000)
Gain on disposal of property for financial reporting purposes less than/(in excess of) amounts for income tax purposes									(36,241,000)	10,068,000	(118,713,000)
Other expenses, including impairment loss on real estate assets, for financial reporting purposes in excess of/ (less than) amounts for income tax purposes									(37,394,000)	49,859,000	42,019,000
Income tax basis net income, prior to dividends paid deduction									$ 91,794,000	$ 225,082,000	$ 67,999,000
Ordinary income, Percent									100.00%	53.61%	81.77%
Return of capital, Percent									0.00%	0.00%	18.23%
Capital gains, Percent									0.00%	46.39%	0.00%
Common Stock Dividends, Percent									100.00%	100.00%	100.00%
Tax basis of total assets	3,600,000,000				4,200,000,000				$ 3,600,000,000	$ 4,200,000,000
Accrued interest and penalties related to uncertain tax positions	$ 2,400,000				$ 3,800,000				2,400,000	3,800,000
Recovery of tax expense, including potential interest and penalties									1,400,000	100,000	$ 0
Reduction to tax liability related to RIET subsidiary									200,000
Piedmont Washington Properties, Inc
Income Taxes [Line Items]
Taxable income (loss) in excess of/(less than) amount for financial reporting purposes									(2,089,000)	176,000	(1,042,000)
Piedmont Office Holdings, Inc
Income Taxes [Line Items]
Taxable income (loss) in excess of/(less than) amount for financial reporting purposes									$ (64,000)	$ (28,000)	$ 648,000

Quarterly Results (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended								12 Months Ended
	Dec. 13, 2017	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Revenues		$ 137,185	$ 129,708	$ 129,174	$ 129,900	$ 139,444	$ 137,587	$ 148,679	$ 148,463	$ 525,967	$ 574,173	$ 555,715
Gain/(loss) on sale of real estate assets		30,505	0	(23)	45,209	(77)	109,512	6,492	(53)	75,691	115,874	93,410
Net income		45,409	16,114	10,940	57,828	(31,388)	126,129	23,707	15,101	130,291	133,549	99,717
Net income/(loss) applicable to Piedmont		$ 45,410	$ 16,114	$ 10,942	$ 57,830	$ (31,383)	$ 126,133	$ 23,710	$ 15,104	$ 130,296	$ 133,564	$ 99,732
Basic earnings per share (in dollars per share)		$ 0.35	$ 0.13	$ 0.09	$ 0.43
Diluted earnings per share (in dollars per share)		0.35	0.13	0.09	0.42
Basic and diluted earnings/(loss) per share (in dollars per share)						$ (0.21)	$ 0.87	$ 0.16	$ 0.10	$ 1.00	$ 0.92	$ 0.69
Dividends declared (in dollars per share)		$ 0.21	$ 0.21	$ 0.21	$ 0.21	$ 0.71	$ 0.21	$ 0.21	$ 0.21
Special dividend (in dollars per share)	$ 0.50									$ 0.84	$ 1.34	$ 0.84

Guarantor and Non-Guarantor Financial Information - Condensed Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Real estate assets, at cost:
Land	$ 507,422	$ 490,625
Buildings and improvements, less accumulated depreciation	2,305,096	2,243,519
Intangible lease assets, less accumulated amortization	77,676	77,805
Construction in progress	15,848	11,344
Real estate assets held for sale, net	110,552	561,449
Total real estate assets	3,016,594	3,384,742
Cash and cash equivalents	4,571	7,382	$ 6,992	$ 5,441
Tenant and straight-line receivables, net	173,389	156,618
Advances to affiliates		0
Investment in subsidiaries	0	0
Notes receivable	0	0
Prepaid expenses, restricted cash, escrows, interest rate swaps, and other assets	28,018	22,839
Goodwill	98,918	98,918
Deferred lease costs, net	250,148	245,175
Other assets held for sale, net	20,791	84,293
Total assets	3,592,429	3,999,967
Liabilities:
Debt, net	1,686,311	1,726,927
Accounts payable, accrued expenses, dividends payable, interest rate swaps and accrued capital expenditures	129,491	216,653
Advances from affiliates		0
Deferred income	28,779	29,582
Intangible lease liabilities, net	35,708	38,458
Interest rate swaps	839	1,478
Liabilities held for sale, net	0	380
Total liabilities	1,880,289	2,013,478
Equity:
Total stockholders’ equity	1,712,140	1,986,489	$ 2,097,703	$ 2,123,420
Total liabilities and stockholders’ equity	3,592,429	3,999,967
Eliminations
Real estate assets, at cost:
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)
Cash and cash equivalents	(518)	0
Tenant and straight-line receivables, net	0	0
Advances to affiliates		(7,971,908)
Investment in subsidiaries	(4,448,625)	(3,437,471)
Notes receivable	(145,310)	(233,310)
Prepaid expenses, restricted cash, escrows, interest rate swaps, and other assets	(24)	(740)
Goodwill	0	0
Deferred lease costs, net	0	0
Other assets held for sale, net	0	0
Total assets	(4,594,777)	(11,643,729)
Liabilities:
Debt, net	(145,310)	(233,310)
Accounts payable, accrued expenses, dividends payable, interest rate swaps and accrued capital expenditures	(542)	(740)
Advances from affiliates		(8,070,163)
Deferred income	0	0
Intangible lease liabilities, net	0	0
Interest rate swaps		0
Liabilities held for sale, net		0
Total liabilities	(145,852)	(8,304,213)
Equity:
Total stockholders’ equity	(4,448,925)	(3,339,516)
Total liabilities and stockholders’ equity	(4,594,777)	(11,643,729)
Piedmont (Parent) (Guarantor) \| Reportable Legal Entities
Real estate assets, at cost:
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
Cash and cash equivalents	150	150
Tenant and straight-line receivables, net	0	0
Advances to affiliates		1,674,276
Investment in subsidiaries	1,744,122	3,437,299
Notes receivable	0	0
Prepaid expenses, restricted cash, escrows, interest rate swaps, and other assets	42	2
Goodwill	0	0
Deferred lease costs, net	0	0
Other assets held for sale, net	0	0
Total assets	1,744,314	5,111,727
Liabilities:
Debt, net	0	0
Accounts payable, accrued expenses, dividends payable, interest rate swaps and accrued capital expenditures	32,174	104,028
Advances from affiliates		5,277,957
Deferred income	0	0
Intangible lease liabilities, net	0	0
Interest rate swaps		0
Liabilities held for sale, net		0
Total liabilities	32,174	5,381,985
Equity:
Total stockholders’ equity	1,712,140	(270,258)
Total liabilities and stockholders’ equity	1,744,314	5,111,727
Piedmont OP (the Issuer) \| Reportable Legal Entities
Real estate assets, at cost:
Land	36,094	36,094
Buildings and improvements, less accumulated depreciation	176,927	180,886
Intangible lease assets, less accumulated amortization	0	181
Construction in progress	5,708	85
Real estate assets held for sale, net	0	32,815
Total real estate assets	218,729	250,061
Cash and cash equivalents	0	3,890
Tenant and straight-line receivables, net	16,143	16,891
Advances to affiliates		6,297,632
Investment in subsidiaries	2,704,337	0
Notes receivable	810	88,810
Prepaid expenses, restricted cash, escrows, interest rate swaps, and other assets	5,682	5,094
Goodwill	98,918	98,918
Deferred lease costs, net	15,158	16,611
Other assets held for sale, net	0	2,266
Total assets	3,059,777	6,780,173
Liabilities:
Debt, net	1,495,904	1,535,239
Accounts payable, accrued expenses, dividends payable, interest rate swaps and accrued capital expenditures	14,543	20,279
Advances from affiliates		941,494
Deferred income	2,274	3,631
Intangible lease liabilities, net	0	0
Interest rate swaps		1,478
Liabilities held for sale, net		0
Total liabilities	1,512,721	2,502,121
Equity:
Total stockholders’ equity	1,547,056	4,278,052
Total liabilities and stockholders’ equity	3,059,777	6,780,173
Non-Guarantor Subsidiaries \| Reportable Legal Entities
Real estate assets, at cost:
Land	471,328	454,531
Buildings and improvements, less accumulated depreciation	2,128,469	2,062,933
Intangible lease assets, less accumulated amortization	77,676	77,624
Construction in progress	10,140	11,259
Real estate assets held for sale, net	110,552	528,634
Total real estate assets	2,798,165	3,134,981
Cash and cash equivalents	4,939	3,342
Tenant and straight-line receivables, net	157,246	139,727
Advances to affiliates		0
Investment in subsidiaries	166	172
Notes receivable	144,500	144,500
Prepaid expenses, restricted cash, escrows, interest rate swaps, and other assets	22,318	18,483
Goodwill	0	0
Deferred lease costs, net	234,990	228,564
Other assets held for sale, net	20,791	82,027
Total assets	3,383,115	3,751,796
Liabilities:
Debt, net	335,717	424,998
Accounts payable, accrued expenses, dividends payable, interest rate swaps and accrued capital expenditures	83,316	93,086
Advances from affiliates		1,850,712
Deferred income	26,505	25,951
Intangible lease liabilities, net	35,708	38,458
Interest rate swaps		0
Liabilities held for sale, net		380
Total liabilities	481,246	2,433,585
Equity:
Total stockholders’ equity	2,901,869	1,318,211
Total liabilities and stockholders’ equity	$ 3,383,115	$ 3,751,796

Guarantor and Non-Guarantor Financial Information - Condensed Consolidated Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues:
Rental income									$ 411,667	$ 455,125	$ 439,918
Tenant reimbursements									92,743	98,139	94,901
Total revenues	$ 137,185	$ 129,708	$ 129,174	$ 129,900	$ 139,444	$ 137,587	$ 148,679	$ 148,463	525,967	574,173	555,715
Expenses:
Property operating costs									209,338	222,441	220,796
Depreciation									107,956	119,288	127,733
Amortization									63,295	75,367	75,119
Impairment loss on real estate assets									0	46,461	33,901
General and administrative									29,713	29,319	27,382
Operating Expenses									410,302	492,876	484,931
Real estate operating income									115,665	81,297	70,784
Other income (expense):
Interest expense									(61,023)	(68,124)	(64,860)
Other income/(expense)									1,638	657	(13)
Net recoveries from casualty events									0	0	34
Equity in income of unconsolidated joint ventures									0	3,845	362
Loss on extinguishment of debt									(1,680)	0	0
Gain on sale of real estate assets, net	30,505	0	(23)	45,209	(77)	109,512	6,492	(53)	75,691	115,874	93,410
Nonoperating Income (Expense)									14,626	52,252	28,933
Net income									130,291	133,549	99,717
Income from subsidiaries									0
Net income	45,409	16,114	10,940	57,828	(31,388)	126,129	23,707	15,101	130,291	133,549	99,717
Net loss applicable to noncontrolling interest									5	15	15
Net income applicable to Piedmont	$ 45,410	$ 16,114	$ 10,942	$ 57,830	$ (31,383)	$ 126,133	$ 23,710	$ 15,104	130,296	133,564	99,732
Eliminations
Revenues:
Rental income									(2,027)	(1,791)	(2,631)
Tenant reimbursements									(446)	(474)	(498)
Total revenues									(18,141)	(18,735)	(18,162)
Expenses:
Property operating costs									(18,141)	(18,735)	(18,377)
Depreciation									0	0	0
Amortization									0	0	0
Impairment loss on real estate assets									0	0	0
General and administrative									0	0	(35,446)
Operating Expenses									(18,141)	(18,735)	(53,823)
Real estate operating income									0	0	35,661
Other income (expense):
Interest expense									7,630	15,360	11,884
Other income/(expense)									(7,630)	(15,360)	(11,884)
Net recoveries from casualty events											0
Equity in income of unconsolidated joint ventures										0	0
Loss on extinguishment of debt									0
Gain on sale of real estate assets, net									0	0	0
Nonoperating Income (Expense)									0	0	0
Net income									0	0	35,661
Income from subsidiaries									(309,233)
Net income									(309,233)
Net loss applicable to noncontrolling interest									0	0	0
Net income applicable to Piedmont									(309,233)	0	35,661
Piedmont (Parent) (Guarantor) \| Reportable Legal Entities
Revenues:
Rental income									0	0	0
Tenant reimbursements									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 on real estate assets									0	0	0
General and administrative									289	347	311
Operating Expenses									289	347	311
Real estate operating income									(289)	(347)	(311)
Other income (expense):
Interest expense									0	0	0
Other income/(expense)									0	0	282
Net recoveries from casualty events											0
Equity in income of unconsolidated joint ventures										0	0
Loss on extinguishment of debt									0
Gain on sale of real estate assets, net									0	0	0
Nonoperating Income (Expense)									0	0	282
Net income									(289)	(347)	(29)
Income from subsidiaries									130,585
Net income									130,296
Net loss applicable to noncontrolling interest									0	0	0
Net income applicable to Piedmont									130,296	(347)	(29)
Piedmont OP (the Issuer) \| Reportable Legal Entities
Revenues:
Rental income									35,221	42,407	53,527
Tenant reimbursements									9,489	11,702	14,295
Total revenues									44,840	54,253	69,088
Expenses:
Property operating costs									19,583	22,805	33,829
Depreciation									11,514	12,995	16,657
Amortization									1,990	3,049	3,715
Impairment loss on real estate assets									0	87	8,259
General and administrative									6,576	6,443	26,452
Operating Expenses									39,663	45,379	88,912
Real estate operating income									5,177	8,874	(19,824)
Other income (expense):
Interest expense									(54,095)	(56,769)	(49,108)
Other income/(expense)									144	9,168	9,560
Net recoveries from casualty events											0
Equity in income of unconsolidated joint ventures										3,845	362
Loss on extinguishment of debt									(1,680)
Gain on sale of real estate assets, net									1,417	6,431	31,275
Nonoperating Income (Expense)									(54,214)	(37,325)	(7,911)
Net income									(49,037)	(28,451)	(27,735)
Income from subsidiaries									178,648
Net income									129,611
Net loss applicable to noncontrolling interest									0	0	0
Net income applicable to Piedmont									129,611	(28,451)	(27,735)
Non-Guarantor Subsidiaries \| Reportable Legal Entities
Revenues:
Rental income									378,473	414,509	389,022
Tenant reimbursements									83,700	86,911	81,104
Total revenues									499,268	538,655	504,789
Expenses:
Property operating costs									207,896	218,371	205,344
Depreciation									96,442	106,293	111,076
Amortization									61,305	72,318	71,404
Impairment loss on real estate assets									0	46,374	25,642
General and administrative									22,848	22,529	36,065
Operating Expenses									388,491	465,885	449,531
Real estate operating income									110,777	72,770	55,258
Other income (expense):
Interest expense									(14,558)	(26,715)	(27,636)
Other income/(expense)									9,124	6,849	2,029
Net recoveries from casualty events											34
Equity in income of unconsolidated joint ventures										0	0
Loss on extinguishment of debt									0
Gain on sale of real estate assets, net									74,274	109,443	62,135
Nonoperating Income (Expense)									68,840	89,577	36,562
Net income									179,617	162,347	91,820
Income from subsidiaries									0
Net income									179,617
Net loss applicable to noncontrolling interest									5	15	15
Net income applicable to Piedmont									179,622	162,362	91,835
Management Service
Revenues:
Property management fee revenue									1,450	1,735	1,914
Management Service \| Eliminations
Revenues:
Property management fee revenue									(15,668)	(16,470)	(15,033)
Management Service \| Piedmont (Parent) (Guarantor) \| Reportable Legal Entities
Revenues:
Property management fee revenue									0	0	0
Management Service \| Piedmont OP (the Issuer) \| Reportable Legal Entities
Revenues:
Property management fee revenue									0	0	0
Management Service \| Non-Guarantor Subsidiaries \| Reportable Legal Entities
Revenues:
Property management fee revenue									17,118	18,205	16,947
Other property related income
Revenues:
Property management fee revenue									20,107	19,174	18,982
Other property related income \| Eliminations
Revenues:
Property management fee revenue									0	0	0
Other property related income \| Piedmont (Parent) (Guarantor) \| Reportable Legal Entities
Revenues:
Property management fee revenue									0	0	0
Other property related income \| Piedmont OP (the Issuer) \| Reportable Legal Entities
Revenues:
Property management fee revenue									130	144	1,266
Other property related income \| Non-Guarantor Subsidiaries \| Reportable Legal Entities
Revenues:
Property management fee revenue									$ 19,977	$ 19,030	$ 17,716

Guarantor and Non-Guarantor Financial Information - Consolidating Statements of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Net income applicable to Piedmont	$ 45,410	$ 16,114	$ 10,942	$ 57,830	$ (31,383)	$ 126,133	$ 23,710	$ 15,104	$ 130,296	$ 133,564	$ 99,732
Effective portion of gain/(loss) on derivative instruments that are designated and qualify as cash flow hedges (See Note 5)									692	2,479	(4,126)
Plus: Reclassification of net (gain)/loss included in net income									(300)	3,502	4,548
Other comprehensive income									392	6,060	443
Comprehensive income applicable to Piedmont									130,688	139,624	100,175
Reportable Legal Entities \| Piedmont (Parent) (Guarantor)
Condensed Financial Statements, Captions [Line Items]
Net income applicable to Piedmont									130,296	(347)	(29)
Effective portion of gain/(loss) on derivative instruments that are designated and qualify as cash flow hedges (See Note 5)									692
Plus: Reclassification of net (gain)/loss included in net income									(300)
Other comprehensive income									392
Comprehensive income applicable to Piedmont									130,688
Reportable Legal Entities \| Piedmont OP (the Issuer)
Condensed Financial Statements, Captions [Line Items]
Net income applicable to Piedmont									129,611	(28,451)	(27,735)
Effective portion of gain/(loss) on derivative instruments that are designated and qualify as cash flow hedges (See Note 5)									692
Plus: Reclassification of net (gain)/loss included in net income									(300)
Other comprehensive income									392
Comprehensive income applicable to Piedmont									130,003
Reportable Legal Entities \| Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income applicable to Piedmont									179,622	162,362	91,835
Effective portion of gain/(loss) on derivative instruments that are designated and qualify as cash flow hedges (See Note 5)									0
Plus: Reclassification of net (gain)/loss included in net income									0
Other comprehensive income									0
Comprehensive income applicable to Piedmont									179,622
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net income applicable to Piedmont									(309,233)	$ 0	$ 35,661
Effective portion of gain/(loss) on derivative instruments that are designated and qualify as cash flow hedges (See Note 5)									(692)
Plus: Reclassification of net (gain)/loss included in net income									300
Other comprehensive income									(392)
Comprehensive income applicable to Piedmont									$ (309,625)

Guarantor and Non-Guarantor Financial Information - Condensed Consolidated Statements of Cash Flows (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided By/(Used In) Operating Activities	$ 202,869,000	$ 242,805,000	$ 231,847,000
Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	(224,019,000)	(115,093,000)	(459,896,000)
Intercompany note receivable	0	0	0
Net sale proceeds from wholly-owned properties	575,227,000	375,518,000	365,918,000
Net sale proceeds received from unconsolidated joint ventures	0	12,334,000	0
Note receivable issuance	(3,200,000)	0	0
Note receivable repayment	3,200,000	0	0
Investments in unconsolidated joint ventures		(1,162,000)
Deferred lease costs paid	(27,430,000)	(30,985,000)	(25,896,000)
Distributions from subsidiaries	0
Net cash provided by/(used in) investing activities	323,778,000	240,612,000	(119,874,000)
Cash Flows from Financing Activities:
Debt issuance costs paid	(1,040,000)	(132,000)	(264,000)
Proceeds from debt	977,062,000	180,000,000	695,000,000
Repayments of debt	(1,020,455,000)	(476,401,000)	(706,875,000)
Intercompany note payable	0	0	0
Costs of issuance of common stock	(85,000)	(182,000)	(342,000)
Value of shares withheld for payment of taxes related to employee stock compensation	(2,219,000)	(3,403,000)	(2,344,000)
Repurchases of common stock as part of announced plan	(298,538,000)	(60,474,000)	(7,943,000)
(Distributions to)/repayments from affiliates		0	0
Distributions	(184,093,000)	(122,274,000)	(91,616,000)
Net cash used in financing activities	(529,368,000)	(482,866,000)	(114,384,000)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	(2,721,000)	551,000	(2,411,000)
Cash, cash equivalents, and restricted cash and escrows, beginning of year	8,755,000	8,204,000	10,615,000
Cash, cash equivalents, and restricted cash and escrows, end of year	6,034,000	8,755,000	8,204,000
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided By/(Used In) Operating Activities	(309,741,000)	0	35,660,000
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	(88,000,000)	48,610,000	71,460,000
Net sale proceeds from wholly-owned properties	0	0	0
Net sale proceeds received from unconsolidated joint ventures		0
Note receivable issuance	0
Note receivable repayment	0
Investments in unconsolidated joint ventures		0
Deferred lease costs paid	0	0	0
Distributions from subsidiaries	(354,540,000)
Net cash provided by/(used in) investing activities	(442,540,000)	48,610,000	71,460,000
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	88,000,000	(48,610,000)	(71,460,000)
Costs of issuance of common stock	0	0	0
Value of shares withheld for payment of taxes 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		0	35,660,000
Distributions	663,763,000	0	0
Net cash used in financing activities	751,763,000	(48,610,000)	(107,120,000)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	(518,000)	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	(518,000)	0	0
Piedmont (Parent) (Guarantor) \| Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided By/(Used In) Operating Activities	135,755,000	5,497,000	5,214,000
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
Net sale proceeds from wholly-owned properties	0	0	0
Net sale proceeds received from unconsolidated joint ventures		0
Note receivable issuance	0
Note receivable repayment	0
Investments in unconsolidated joint ventures		0
Deferred lease costs paid	0	0	0
Distributions from subsidiaries	349,135,000
Net cash provided by/(used in) investing activities	349,135,000	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	(85,000)	(182,000)	(342,000)
Value of shares withheld for payment of taxes related to employee stock compensation	(2,219,000)	(3,403,000)	(2,344,000)
Repurchases of common stock as part of announced plan	(298,538,000)	(60,474,000)	(7,943,000)
(Distributions to)/repayments from affiliates		(180,791,000)	(97,016,000)
Distributions	(184,048,000)	(122,229,000)	(91,601,000)
Net cash used in financing activities	(484,890,000)	(5,497,000)	(5,214,000)
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	150,000	150,000	150,000
Cash, cash equivalents, and restricted cash and escrows, end of year	150,000	150,000	150,000
Piedmont OP (the Issuer) \| Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided By/(Used In) Operating Activities	141,293,000	(18,989,000)	(26,263,000)
Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	(14,479,000)	(1,614,000)	(5,060,000)
Intercompany note receivable	88,000,000	100,000	440,000
Net sale proceeds from wholly-owned properties	36,572,000	23,028,000	200,220,000
Net sale proceeds received from unconsolidated joint ventures		12,334,000
Note receivable issuance	0
Note receivable repayment	0
Investments in unconsolidated joint ventures		(1,162,000)
Deferred lease costs paid	(3,090,000)	(4,081,000)	(2,758,000)
Distributions from subsidiaries	5,405,000
Net cash provided by/(used in) investing activities	112,408,000	28,605,000	192,842,000
Cash Flows from Financing Activities:
Debt issuance costs paid	(1,040,000)	(132,000)	(264,000)
Proceeds from debt	977,062,000	180,000,000	695,000,000
Repayments of debt	(1,019,000,000)	(335,000,000)	(538,000,000)
Intercompany note payable	0	(14,289,000)	(9,600,000)
Costs of issuance of common stock	0	0	0
Value of shares withheld for payment of taxes 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
Distributions	(214,596,000)	0	0
Net cash used in financing activities	(257,574,000)	(9,402,000)	(165,082,000)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	(3,873,000)	214,000	1,497,000
Cash, cash equivalents, and restricted cash and escrows, beginning of year	3,907,000	3,693,000	2,196,000
Cash, cash equivalents, and restricted cash and escrows, end of year	34,000	3,907,000	3,693,000
Non-Guarantor Subsidiaries \| Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided By/(Used In) Operating Activities	235,562,000	256,297,000	217,236,000
Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	(209,540,000)	(113,479,000)	(454,836,000)
Intercompany note receivable	0	(48,710,000)	(71,900,000)
Net sale proceeds from wholly-owned properties	538,655,000	352,490,000	165,698,000
Net sale proceeds received from unconsolidated joint ventures		0
Note receivable issuance	(3,200,000)
Note receivable repayment	3,200,000
Investments in unconsolidated joint ventures		0
Deferred lease costs paid	(24,340,000)	(26,904,000)	(23,138,000)
Distributions from subsidiaries	0
Net cash provided by/(used in) investing activities	304,775,000	163,397,000	(384,176,000)
Cash Flows from Financing Activities:
Debt issuance costs paid	0	0	0
Proceeds from debt	0	0	0
Repayments of debt	(1,455,000)	(141,401,000)	(168,875,000)
Intercompany note payable	(88,000,000)	62,899,000	81,060,000
Costs of issuance of common stock	0	0	0
Value of shares withheld for payment of taxes 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)
Distributions	(449,212,000)	(45,000)	(15,000)
Net cash used in financing activities	(538,667,000)	(419,357,000)	163,032,000
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	1,670,000	337,000	(3,908,000)
Cash, cash equivalents, and restricted cash and escrows, beginning of year	4,698,000	4,361,000	8,269,000
Cash, cash equivalents, and restricted cash and escrows, end of year	$ 6,368,000	$ 4,698,000	$ 4,361,000

Subsequent events	12 Months Ended
Subsequent events	Dec. 31, 2018
Subsequent Events [Abstract]
Subsequent events	Subsequent events Declaration of Dividend for the First Quarter 2019 On February 5, 2019, the board of directors of Piedmont declared dividends for the first quarter 2019 in the amount of $0.21 per share on its common stock to stockholders of record as of the close of business on February 28, 2019. Such dividends are to be paid on March 15, 2019.

Label	Element	Value
Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 94,000
AOCI Attributable to Parent [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (94,000)

Subsequent events (Details) - $ / shares		3 Months Ended
Subsequent events (Details) - $ / shares	Feb. 05, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017
Subsequent Event [Line Items]
Dividends declared (in dollars per share)		$ 0.21	$ 0.21	$ 0.21	$ 0.21	$ 0.71	$ 0.21	$ 0.21	$ 0.21
Subsequent Event
Subsequent Event [Line Items]
Dividends declared (in dollars per share)	$ 0.21