Supplemental Cash Flow Elements [Abstract] Accrued capital expenditures and deferred lease costs Increase Decrease In Accrued Capital Expenditures And Deferred Lease Costs Net change in the balance of accrued lease acquisition costs and accrued capital expenditures during the period. These accrued costs consist of items such as leasing commissions, lease incentives, procurement fees, tenant improvements, and/or general building improvements. Accrued dividends and discount on dividend reinvestments Dividends Payable Escrowed cash from prior year applied to acquisitions in the current year Escrow Deposit Disbursements Related to Property Acquisition Change in accrued share repurchases as part of an announced plan Increase (Decrease) in Accrued Share Repurchases Increase (Decrease) in Accrued Share Repurchases Real Estate [Abstract] Schedule of Impaired Long-Lived Assets Held and Used [Table] Schedule of Impaired Long-Lived Assets Held and Used [Table] Disposal Group Classification [Axis] Disposal Group Classification [Axis] Disposal Group Classification [Domain] Disposal Group Classification [Domain] Disposal Group, Held-for-sale, Not Discontinued Operations [Member] Disposal Group, Held-for-sale, Not Discontinued Operations [Member] Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] Disposal Group Name [Axis] Disposal Group Name [Axis] Disposal Groups, Including Discontinued Operations, Name [Domain] Disposal Group Name [Domain] Eastpoint I & II [Member] EASTPOINT I and II [Member] EASTPOINT I and II [Member] 2 Gatehall Drive [Member] GATEHALL DRIVE 2 [Member] GATEHALL DRIVE 2 [Member] 150 West Jefferson [Member] WEST JEFFERSON 150 [Member] WEST JEFFERSON 150 [Member] 9221 Corporate Boulevard [Member] CORPORATE BOULEVARD 9221 [Member] CORPORATE BOULEVARD 9221 [Member] 9200 and 9211 Corporate Boulevard [Member] CORPORATE BOULEVARD 9200 and 9211 [Member] CORPORATE BOULEVARD 9200 and 9211 [Member] Impaired Long-Lived Assets Held and Used [Line Items] Impaired Long-Lived Assets Held and Used [Line Items] Impairment loss on real estate assets Asset Impairment Charges Loss on impairment Impairment of Real Estate Number of assets sold Number of Real Estate Properties Sold Number of Real Estate Properties Sold Impairment loss Impairment of Long-Lived Assets to be Disposed of Guarantor and Non-Guarantor Financial Information [Abstract] Guarantor and Non-Guarantor Financial Information [Abstract] Guarantor and Non-Guarantor Financial Information Condensed Financial Statements [Text Block] Business Combinations [Abstract] Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] CNL Center I and CNL Center II [Member] CNL Center I and CNL Center II [Member] CNL Center I and CNL Center II [Member] One Wayside Road [Member] One Wayside Road [Member] One Wayside Road [Member] Galleria 200 Building [Member] Galleria 200 Building [Member] Galleria 200 Building [Member] 750 W. John Carpenter Freeway [Member] 750 West John Carpenter Freeway [Member] 750 West John Carpenter Freeway [Member] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Line of Credit [Member] Line of Credit [Member] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Unsecured Debt [Member] Unsecured Debt [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] $500 Million Unsecured 2015 Line of Credit [Member] Unsecured 500 Million 2015 Line of Credit [Member] Unsecured 500 Million 2015 Line of Credit [Member] Name of Property [Axis] Name of Property [Axis] Name of Property [Domain] Name of Property [Domain] 500 TownPark Building [Member] 500 TownPark Building [Member] 500 TownPark Building [Member] Enclave Place [Member] ENCLAVE PLACE [Member] ENCLAVE PLACE [Member] Business Acquisition [Line Items] Business Acquisition [Line Items] Number of properties acquired Business Acquisition, Number of Buildings Business Acquisition, Number of Buildings Percentage ownership of properties acquired Business Acquisition, Percentage of Voting Interests Acquired Proceeds from Unsecured Line of Credit Line of Credit Facility, Maximum Borrowing Capacity Rentable Square Feet (Unaudited) Area of Real Estate Property Percentage Leased as of Acquisition (Unaudited) Real Estate Property, Percent of Property Under Lease Percentage of Leased Real Estate Properties Number of stories of office building Real Estate Property, Number of Stories of Building Real Estate Property, Number of Stories of Building Net Contractual Purchase Price (in millions) Business Combination, Consideration Transferred Number of acres of adjacent developable land Area of Land Construction in progress Construction in Progress, Gross Condensed Financial Statements [Table] Condensed Financial Statements [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Issuer [Member] Subsidiary Issuer [Member] Guarantor [Member] Guarantor [Member] The registrant that guarantees the debt issued by another entity it controls, either directly or indirectly. The usual condition for control is ownership of a majority (over 50%) of the outstanding voting stock. The power to control may also exist with a lesser percentage of ownership, for example, by contract, lease, agreement with other stockholders or by court decree. Non-Guarantor Subsidiaries [Member] Non-Guarantor Subsidiaries [Member] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Eliminations [Member] Consolidation, Eliminations [Member] Condensed Financial Statements, Captions [Line Items] Condensed Financial Statements, Captions [Line Items] Assets: Assets [Abstract] Land Land Buildings and improvements, less accumulated depreciation Investment Building and Building Improvements, Net Investment Building and Building Improvements, Net Intangible lease assets, less accumulated amortization Finite-Lived Intangible Assets, Net Real estate assets held for sale, net Real Estate Held-for-sale Total real estate assets Real Estate Investment Property, Net Investments in and amounts due from unconsolidated joint ventures Unconsolidated Equity Method Investments and Due from Joint Ventures Unconsolidated Equity Method Investments and Due from Joint Ventures Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Tenant and straight-line receivables, net Tenant Receivables Including Straight Line Rental Revenue Receivables Tenant Receivables Including Straight Line Rental Revenue Receivables Advances to affiliates Due from Affiliates Investment in subsidiary Investment In Subsidiary Amount of Investment in an affiliate by means of direct or indirect ownership Notes receivable Financing Receivable, Net Prepaid expenses, restricted cash, escrows, and other assets Prepaid Expense and Restricted Cash and Cash Equivalents and Other Assets Prepaid Expense and Restricted Cash and Cash Equivalents and Other Assets Goodwill Goodwill Deferred lease costs, net Deferred Costs, Leasing, Net Other assets held for sale, net Disposal Group, Including Discontinued Operation, Other Assets Total assets Assets Liabilities: Liabilities [Abstract] Debt, net Long-term Debt Accounts payable, accrued expenses, dividends payable, and accrued capital expenditures Accounts Payable and Accrued Liabilities Advances from affiliates Due to Affiliate Deferred income Deferred Revenue Intangible lease liabilities, net Off-market Lease, Unfavorable Interest rate swaps Interest Rate Cash Flow Hedge Liability at Fair Value Total liabilities Liabilities Stockholders’ Equity: Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Common stock Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital, Common Stock Retained/(cumulative distributions in excess of) earnings Accumulated Distributions in Excess of Net Income Other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Piedmont stockholders’ equity Stockholders' Equity Attributable to Parent Noncontrolling interest Stockholders' Equity Attributable to Noncontrolling Interest Total stockholders’ equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Total liabilities and stockholders’ equity Liabilities and Equity Condensed Balance Sheet Condensed Balance Sheet [Table Text Block] Condensed Income Statement Condensed Income Statement [Table Text Block] Condensed Cash Flow Statement Condensed Cash Flow Statement [Table Text Block] Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Stock Based Compensation Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Subsequent Events [Abstract] Subsequent Event [Table] Subsequent Event [Table] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event [Member] Subsequent Event [Member] Sale of Two Independence Square [Member] TWO INDEPENDENCE SQUARE [Member] TWO INDEPENDENCE SQUARE [Member] Subsequent Event [Line Items] Subsequent Event [Line Items] Dividends declared (in dollars per share) Common Stock, Dividends, Per Share, Declared Number of square feet of office building Percentage leased Amount of sales price Disposal Group, Including Discontinued Operation, Consideration Sales price per square foot Disposal Group, Including Discontinued Operation, Consideration per Square Foot Disposal Group, Including Discontinued Operation, Consideration per Square Foot Statement of Cash Flows [Abstract] Cash Flows from Operating Activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Operating distributions received from unconsolidated joint ventures Proceeds from Equity Method Investment, Dividends or Distributions Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation Depreciation, Including Discontinued Operation Depreciation, Including Discontinued Operation Amortization of debt issuance costs Amortization of Debt Issuance Costs and Discounts Gain/(loss) on settlement of forward starting interest rate swaps Deferred Gain/(Loss) on Settlement of Interest Rate Derivative Gain/(Loss) on settlement of interest rate derivative which is recorded as component of accumulated other comprehensive income and recognized as offset/increase to interest expense over the life of the respective underlying debt facility. Other amortization Amortization of Intangible Assets Stock compensation expense Share-based Compensation Equity in loss/(income) of unconsolidated joint ventures Income (Loss) from Equity Method Investments, Actual Cash Impact Income (Loss) from Equity Method Investments, Actual Cash Impact Gain on sale of real estate assets, net Gain (Loss) on Sale of Properties Retirement of shares returned from escrow Retirement of Shares Returned from Escrow, Operating Activity Retirement of Shares Returned from Escrow, Operating Activity Changes in assets and liabilities: Increase (Decrease) in Operating Assets [Abstract] Increase in tenant and straight-line rent receivables, net Increase (Decrease) in Accounts Receivable Decrease/(increase) in restricted cash and escrows Increase (Decrease) in Restricted Cash for Operating Activities Decrease/(increase) in prepaid expenses and other assets Increase (Decrease) in Prepaid Expense and Other Assets Increase/(decrease) in accounts payable and accrued expenses Increase (Decrease) in Accounts Payable and Accrued Liabilities Increase/(decrease) in deferred income Increase (Decrease) in Deferred Revenue Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Cash Flows from Investing Activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Acquisition of real estate assets, net of related debt assumed, and intangibles Payments to Acquire Real Estate Net cash held in escrow for acquisitions Increase (Decrease) in Restricted Cash Capitalized expenditures, net of accruals Payments for Tenant Improvements, Capital Improvements, and to Develop Real Estate Assets Payments for Tenant Improvements, Capital Improvements, and to Develop Real Estate Assets Redemption of noncontrolling interest in unconsolidated variable interest entity Payments for Repurchase of Redeemable Noncontrolling Interest Net sale proceeds from wholly-owned properties Proceeds from Divestiture of Businesses, Net of Cash Divested Net sale proceeds received from unconsolidated joint ventures Proceeds from Sale of Equity Method Investments Investments in unconsolidated joint ventures Payments to Acquire Equity Method Investments Deferred lease costs paid Increase (Decrease) in Lease Acquisition Costs Net cash provided by/(used in) investing activities Net Cash Provided by (Used in) Investing Activities Cash Flows from Financing Activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Debt issuance costs paid Payments of Debt Issuance Costs Proceeds from debt Proceeds from Notes Payable Repayments of debt Repayments of Notes Payable Discount paid due to loan modification Payments of Debt Discount Due to Loan Modification Costs paid to lender for modification of loan facility accounted for as discount on debt in the period of payment. Costs of issuance of common stock Payments of Stock Issuance Costs Shares withheld to pay tax obligations related to employee stock compensation Payments Related to Tax Withholding for Share-based Compensation Repurchases of common stock as part of announced plan Payments for Repurchase of Common Stock Dividends paid and discount on dividend reinvestments Payments of Dividends Common Stock, Distributions To Noncontrolling Interest and Discount on Dividend Reinvestment Sum of a) The cash outflow from the distribution of an entity's earnings in the form of dividends to common stockholders, and b) Distributions to noncontrolling interest, and c)Discount on dividend reinvestments. Net cash provided by/(used in) financing activities Net Cash Provided by (Used in) Financing Activities Net increase/(decrease) in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents, beginning of year Cash and cash equivalents, end of year Subsequent events Subsequent Events [Text Block] Earnings Per Share [Abstract] Earnings Per Share Earnings Per Share [Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Variable Interest Entities and Equity Participation Rights Variable Interest Entity Disclosure [Text Block] Organization Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Statement of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] Statement, Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Stock [Member] Common Stock [Member] Additional Paid-In Capital [Member] Additional Paid-in Capital [Member] Cumulative Distributions in Excess of Earnings [Member] Retained Earnings [Member] Other Comprehensive Income/ (Loss) [Member] AOCI Attributable to Parent [Member] Non-controlling Interest [Member] Noncontrolling Interest [Member] Statement [Line Items] Statement [Line Items] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Balance, value Balance (in shares) Common Stock, Shares, Outstanding Share repurchases as part of an announced plan Stock Repurchased and Retired During Period, Value Stock repurchases as part of an announced plan (in shares) Stock Repurchased and Retired During Period, Shares Retirement of shares returned from escrow Retirement of Shares Returned from Escrow Retirement of Shares Returned from Escrow Retirement of shares returned from escrow (in shares) Retirement of Shares Returned From Escrow, Shares Retirement of Shares Returned From Escrow, Shares Offering costs Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs Redemption of noncontrolling interest in consolidated variable interest entity Redemption of Noncontrolling Interest in Consolidated Variable Interest Entity Redemption of noncontrolling interest in consolidated variable interest entity Reallocation of noncontrolling interest of subsidiary Noncontrolling Interest, Reallocation of Noncontrolling Interest of Subsidiary Reallocation of noncontrolling interest of subsidiary Noncontrolling interest in consolidated joint venture Noncontrolling Interest, Increase from Business Combination Dividends to common stockholders, dividends to preferred stockholders of subsidiary, and dividends reinvested Dividends, Minority Interest (Decrease) From Distributions to Noncontrolling Interest Holders and Stock Issued During Period Value Dividend Reinvestment Plan Sum of a) Equity impact of aggregate cash, stock, and paid-in-kind dividends declared for all securities (common shares, preferred shares, etc.) during the period, b) Decrease in noncontrolling interest balance from payment of dividends or other distributions by the non-wholly owned subsidiary or partially owned entity, included in the consolidation of the parent entity, to the noncontrolling interest holders, and c) Value of stock issued during the period from a dividend reinvestment plan (DRP). A dividend reinvestment plan allows the holder of the stock to reinvest dividends paid to them by the entity on new issues of stock or stock purchased and reissued by the entity. Shares issued and amortized under the 2007 Omnibus Incentive Plan, net of tax Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures Shares issued under the 2007 Omnibus Incentive Plan, net of tax (in shares) Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures Net income (loss) applicable to noncontrolling interest Net Income (Loss) Attributable to Noncontrolling Interest Net income applicable to Piedmont Net Income (Loss) Attributable to Parent Other comprehensive income/ (loss) Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Balance, value Balance, (in shares) Acquisitions and Development Projects Business Combination Disclosure [Text Block] Leases [Abstract] Operating Leases Leases of Lessor Disclosure [Text Block] Fair Value Disclosures [Abstract] Fair Value, by Balance Sheet Grouping Fair Value, by Balance Sheet Grouping [Table Text Block] Debt Disclosure [Abstract] 2017 Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months 2018 Long-term Debt, Maturities, Repayments of Principal in Year Two 2019 Long-term Debt, Maturities, Repayments of Principal in Year Three 2020 Long-term Debt, Maturities, Repayments of Principal in Year Four 2021 Long-term Debt, Maturities, Repayments of Principal in Year Five Thereafter Long-term Debt, Maturities, Repayments of Principal after Year Five Total Long-term Debt, Gross Statement of Comprehensive Income [Abstract] Other comprehensive income/(loss): Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Effective portion of loss on derivative instruments that are designated and qualify as cash flow hedges (See Note 7) Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax Reclassification of previously recorded loss included in net income (See Note 7) Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax Gain/(loss) on investment in available for sale securities Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax Other comprehensive income/(loss) Comprehensive income applicable to Piedmont Comprehensive Income (Loss), Net of Tax, Attributable to Parent Derivative Instruments and Hedging Activities Disclosure [Abstract] Schedule of Notional Amounts of Outstanding Derivative Positions Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block] Schedule of Interest Rate Derivatives Schedule of Interest Rate Derivatives [Table Text Block] Schedule of Derivative Instruments, Effect on Other Comprehensive Income (Loss) Schedule of Derivative Instruments, Effect on Other Comprehensive Income (Loss) [Table Text Block] Accounting Policies [Abstract] Significant Accounting Policies [Table] Significant Accounting Policies [Table] Significant Accounting Policies [Table] Variable Interest Entities [Axis] Variable Interest Entities [Axis] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Primary Beneficiary [Member] Variable Interest Entity, Primary Beneficiary [Member] 1201 Eye Street NW Associates LLC and 1225 Eye Street, NW Associates LLC [Member] Eye Street 1201 NW Associates LLC and Eye Street 1225, NW Associates LLC [Member] Eye Street 1201 NW Associates LLC and Eye Street 1225, NW Associates LLC [Member] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Building [Member] Building [Member] Building Improvements [Member] Building Improvements [Member] Land Improvements [Member] Land Improvements [Member] Furniture, fixtures, and equipment [Member] Furniture and Fixtures [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum [Member] Minimum [Member] Maximum [Member] Maximum [Member] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Reclassification Adjustment [Member] Restatement Adjustment [Member] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Above-Market In-Place Lease Assets [Member] Above Market Leases [Member] In-Place Lease Valuation [Member] Leases, Acquired-in-Place [Member] Intangible Lease Origination Costs (included as component of Deferred Lease Costs) [Member] Lease Origination Costs [Member] Lease Origination Costs [Member] Deferred Bonus and Profit Sharing Arrangements, Individual Contracts, Type of Deferred Compensation [Axis] Deferred Bonus and Profit Sharing Arrangements, Individual Contracts, Type of Deferred Compensation [Axis] Deferred Bonus and Profit Sharing Arrangement, Individual Contract, Type of Deferred Compensation [Domain] Deferred Bonus and Profit Sharing Arrangement, Individual Contract, Type of Deferred Compensation [Domain] Deferred Compensation, Excluding Share-based Payments and Retirement Benefits [Member] Deferred Compensation, Excluding Share-based Payments and Retirement Benefits [Member] Investments by Category [Axis] Investments by Category [Axis] Marketable Securities and Investments Held at Cost [Domain] Marketable Securities and Investments Held at Cost [Domain] Trading Securities [Member] Trading Securities [Member] Business Interruption Loss [Axis] Business Interruption Loss [Axis] Business Interruption Loss [Domain] Business Interruption Loss [Domain] Hurricane Sandy [Member] Hurricane Sandy [Member] Hurricane Sandy [Member] New Accounting Pronouncement, Early Adoption [Axis] New Accounting Pronouncement, Early Adoption [Axis] New Accounting Principles, Early Adoption [Domain] New Accounting Principles, Early Adoption [Domain] New Accounting Pronouncement, Early Adoption, Effect [Member] New Accounting Pronouncement, Early Adoption, Effect [Member] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2016-09 [Member] Accounting Standards Update 2016-09 [Member] Accounting Standards Update 2016-09 [Member] Products and Services [Axis] Products and Services [Axis] Products and Services [Domain] Products and Services [Domain] Total Revenues Derived from Long Term Leases to Tenants or Reimbursement of Property Tax and Insurance Expenses [Member] Total Revenues Derived from Long Term Leases to Tenants or Reimbursement of Property Tax and Insurance Expenses [Member] Total Revenues Derived from Long Term Leases to Tenants or Reimbursement of Property Tax and Insurance Expenses [Member] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Sales Revenue, Net [Member] Sales Revenue, Net [Member] Significant Accounting Policies [Line Items] Significant Accounting Policies [Line Items] Significant Accounting Policies [Line Items] Number of real estate properties Number of Real Estate Properties Piedmont’s % Ownership of Entity Ownership Percentage by Parent Ownership Percentage by Parent Percentage interest in joint venture purchased Interest capitalized Interest Costs Capitalized Useful life Property, Plant and Equipment, Useful Life Intangible Lease Assets: Finite-Lived Intangible Assets, Gross Intangible Lease Liabilities (Below-Market In-Place Leases) Below Market Lease, Gross Amortization of Intangible Lease Origination Costs and In-Place Lease Valuation included in amortization expense Amortization Of Intangible Lease Origination Costs And Absorption Period Costs Amortization Of Intangible Lease Origination Costs And Absorption Period Costs Amortization of Above-Market and Below-Market In-Place Lease intangibles as a net increase to rental revenues Amortization of above and below Market Leases Finite-Lived Intangible Assets, Future Amortization Expense [Abstract] Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract] 2017 Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months 2018 Finite-Lived Intangible Assets, Amortization Expense, Year Two 2019 Finite-Lived Intangible Assets, Amortization Expense, Year Three 2020 Finite-Lived Intangible Assets, Amortization Expense, Year Four 2021 Finite-Lived Intangible Assets, Amortization Expense, Year Five Thereafter Finite-Lived Intangible Assets, Amortization Expense, after Year Five Total Weighted-Average Amortization Period (in years) Finite-Lived Intangible Asset, Useful Life Below Market Lease, Net, Amortization Income, Fiscal Maturity [Abstract] Below Market Lease, Net, Amortization Income, Fiscal Year Maturity [Abstract] 2017 Below Market Lease, Amortization Income, Next Twelve Months 2018 Below Market Lease, Amortization Income, Year Two 2019 Below Market Lease, Amortization Income, Year Three 2020 Below Market Lease, Amortization Income, Year Four 2021 Below Market Lease, Amortization Income, Year Five Thereafter Below Market Lease, Amortization Income, after Year Five Total Below Market Lease, Net Weighted-Average Amortization Period (in years) Finite-Lived Intangible Liabilities, Weighted-Average Useful Life Finite-Lived Intangible Liabilities, Weighted-Average Useful Life Significant Accounting Policies [Abstract] Significant Accounting Policies [Abstract] Significant Accounting Policies [Abstract] Number of unconsolidated joint ventures Number Of Unconsolidated Joint Venture Partnerships Number Of Unconsolidated Joint Venture Partnerships Provision for doubtful accounts Provision for Doubtful Accounts Recoveries of bad debts Valuation Allowances and Reserves, Additions for Recoveries Amortization of deferred common area maintenance recognized Amortization Deferred Common Area Maintenance Amortization of deferred common area maintenance costs Capitalized internal leasing costs Capitalized Deferred Costs, Internal Leasing Capitalized Deferred Costs, Internal Leasing Amortization of deferred lease costs Amortization of Deferred Leasing Fees Amortization of lease incentive Amortization of Lease Incentives Amortization of fair value adjustments Amortization for Estimated Fair Value Adjustment for Debt Assumed Amortization for Estimated Fair Value Adjustment for Debt Assumed Amortization of debt discount Amortization of Debt Discount (Premium) Amortization of deferred financing costs and fair market value adjustments on notes payable Amortization of Debt Issuance Costs Shares-in-trust, shares authorized Shares In Trust Authorized Shares In Trust Authorized Preferred stock, shares authorized Preferred Stock, Shares Authorized Common stock, shares authorized Common Stock, Shares Authorized Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Number of votes for each share of common stock Common Stock, Voting Rights, Number of Votes for Each Share Common Stock, Voting Rights, Number of Votes for Each Share Stock repurchase program, authorized amount Stock Repurchase Program, Authorized Amount Stock repurchase program, remaining authorized repurchase amount Stock Repurchase Program, Remaining Authorized Repurchase Amount Dividend reinvestment plan, shareholders discount Dividend Reinvestment Plan, Shareholders Discount Dividend Reinvestment Plan, Shareholders Discount Assets held as trading securities Assets Held-in-trust Number of class action lawsuits settled Number of Lawsuits as Defendant Number of Lawsuits as Defendant Recoveries related to settled class action lawsuits Insurance Recoveries Net recoveries/(loss) Insured Event, Gain (Loss) Business interruption insurance recoveries Gain on Business Interruption Insurance Recovery Income tax expense Income Tax Expense (Benefit) Reclassification from cash outflows from operating activities to cash outflows from financing activities Percentage of total revenues Concentration Risk, Percentage Net Cash Provided By/(Used In) Operating Activities Cash Flows from Investing Activities: Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals Payments to Acquire and Develop Real Estate Intercompany note receivable Payments for (Proceeds from) Intercompany Notes Receivable, Investing Activities Payments for (Proceeds from) Intercompany Notes Receivable, Investing Activities Discount due to loan modification Intercompany note payable Payments for (Proceeds from) Intercompany Notes Payable Payments for (Proceeds from) Intercompany Notes Payable (Distributions to)/repayments from affiliates Payments for (Proceeds from) Intercompany Distributions Payments for (Proceeds from) Intercompany Distributions Schedule of Nonvested Share Activity Schedule of Nonvested Share Activity [Table Text Block] Schedule of Outstanding Employee Deferred Stock Awards Disclosure of Share-based Compensation Arrangements by Share-based Payment Award [Table Text Block] Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] 1201 Eye Street N.W. Associates, LLC [Member] Eye Street 1201 NW Associates LLC [Member] Eye Street 1201 NW Associates LLC [Member] 1225 Eye Street N.W. Associates, LLC [Member] Eye Street 1225 NW Associates LLC [Member] Eye Street 1225 NW Associates LLC [Member] Piedmont 500 W. Monroe Fee LLC [Member] Piedmont 500 W. Monroe Fee LLC [Member] Piedmont 500 W. Monroe Fee LLC [Member] Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Piedmont’s % Ownership of Entity Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage Net Carrying Amount Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net Percent of cash flow entitled to entity Variable Interest Entity Cash Flow Percent Entitled To Entity Variable Interest Entity Cash Flow Percent Entitled To Entity Fair Value Measurements Fair Value Disclosures [Text Block] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Discontinued Operations and Disposal Groups [Abstract] Schedule of Disposal Groups, Including Discontinued Operations, Income Statement, Balance Sheet and Additional Disclosures Disposal Groups, Including Discontinued Operations [Table Text Block] Details of Impairment of Long-Lived Assets Held and Used by Asset Disclosure of Long Lived Assets Held-for-sale [Table Text Block] Schedule of Disposal Groups, Including Discontinued Operations, Results Of Operations Schedule of Disposal Groups, Including Discontinued Operations, Results Of Operations [Table Text Block] Schedule of Disposal Groups, Including Discontinued Operations, Results Of Operations [Table Text Block] Schedule of Revenues from External Customers and Long-Lived Assets [Table] Concentration Risk by Type [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Customer Concentration Risk [Member] Customer Concentration Risk [Member] Major Customers [Axis] Customer [Axis] Name of Major Customer [Domain] Customer [Domain] Federal Governmental Agencies [Member] Federal Governmental Agencies [Member] Federal Governmental Agencies [Member] Revenues from External Customers and Long-Lived Assets [Line Items] Percentage of annualized lease revenue Operating Leases, Income Statement, Percentage of Annualized Lease Revenue Operating Leases, Income Statement, Percentage of Annualized Lease Revenue Concentration risk, percentage Operating Leases, Future Minimum Payments Receivable [Abstract] 2017 Operating Leases, Future Minimum Payments Receivable, Current 2018 Operating Leases, Future Minimum Payments Receivable, in Two Years 2019 Operating Leases, Future Minimum Payments Receivable, in Three Years 2020 Operating Leases, Future Minimum Payments Receivable, in Four Years 2021 Operating Leases, Future Minimum Payments Receivable, in Five Years Thereafter Operating Leases, Future Minimum Payments Receivable, Thereafter Total Operating Leases, Future Minimum Payments Receivable Schedule of Cash Flow, Supplemental Disclosures Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Quarterly Financial Information Disclosure [Abstract] Schedule of Quarterly Financial Information Quarterly Financial Information [Table Text Block] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] Land [Member] Land [Member] Building and building improvements [Member] Building and Building Improvements [Member] Construction in Progress [Member] Construction in Progress [Member] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Real estate assets held for sale, net: Disposal Group, Including Discontinued Operation, Property, Plant and Equipment Accumulated depreciation (building improvements) Disposal Group, Including Discontinued Operation, Accumulated Depreciation, Property Plant and Equipment Disposal Group, Including Discontinued Operation, Accumulated Depreciation, Property Plant and Equipment Total real estate assets held for sale, net Real Estate Held-for-sale, Net Net carrying amount as of the balance sheet date of investments in land, buildings, finite-lived intangibles, and construction in progress classified as held for sale. Straight-line rent receivables Disposal Group, Including Discontinued Operation, Straight-line Rent Disposal Group, Including Discontinued Operation, Straight-line Rent Prepaid expenses and other assets Disposal Group, Including Discontinued Operation, Prepaid and Other Assets Deferred lease costs, less accumulated amortization of $0 and $1,162 as of December 31, 2016 and 2015, respectively Disposal Group, Including Discontinued Operation, Deferred Lease Costs, Net Disposal Group, Including Discontinued Operation, Deferred Lease Costs, Net Accumulated amortization on deferred lease costs Disposal Group, Including Discontinued Operation, Deferred Lease Costs, Accumulated Amortization Disposal Group, Including Discontinued Operation, Deferred Lease Costs, Accumulated Amortization Total other assets held for sale, net Loss Contingencies [Table] Loss Contingencies [Table] Category of Item Purchased [Axis] Category of Item Purchased [Axis] Long-term Purchase Commitment, Category of Item Purchased [Domain] Long-term Purchase Commitment, Category of Item Purchased [Domain] NonIncremental Capital Expenditures [Member] NonIncremental Capital Expenditures [Member] Non-Incremental Capital Expenditures are defined as capital expenditures of a recurring nature related to tenant improvements and leasing commissions that do not incrementally enhance the underlying assets' income generating capacity. We exclude first generation tenant improvements and leasing commissions from this measure, in addition to other capital expenditures that qualify as Incremental Capital Expenditures, as defined above. Incremental Capital Expenditures [Member] Incremental Capital Expenditures [Member] Incremental Capital Expenditures are defined as capital expenditures of a non-recurring nature that incrementally enhance the underlying assets' income generating capacity. Tenant improvements, leasing commissions, building capital and deferred lease incentives ("Leasing Costs") incurred to lease space that was vacant at acquisition, Leasing Costs for spaces vacant for greater than one year, Leasing Costs for spaces at newly acquired properties for which in-place leases expire shortly after acquisition, improvements associated with the expansion of a building and renovations that change the underlying classification of a building are included in this measure. Loss Contingencies by Nature of Contingency [Axis] Loss Contingency Nature [Axis] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Collectibility of Tenant Reimbursements [Member] Collectibility of Tenant Reimbursements [Member] Collectibility of Tenant Reimbursements [Member] Major Property Class [Axis] Major Property Class [Axis] Major Property Class [Domain] Major Property Class [Domain] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Number of tenant and building improvement categories Number of Tenant and Building Improvement Categories Number of Tenant and Building Improvement Categories Period for commitments for funding non-incremental capital expenditures Long-term Purchase Commitment, Period Non-incremental capital expenditures for tenant improvements Commitment to Provide Funding to Tenants for Capital Improvements Commitment to Provide Funding to Tenants for Capital Improvements Additional expense related to such tenant audits/disputes Loss Contingency, Loss in Period Operating Leases, Future Minimum Payments Due [Abstract] Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] 2017 Operating Leases, Future Minimum Payments Due, Next Twelve Months 2018 Operating Leases, Future Minimum Payments, Due in Two Years 2019 Operating Leases, Future Minimum Payments, Due in Three Years 2020 Operating Leases, Future Minimum Payments, Due in Four Years 2021 Operating Leases, Future Minimum Payments, Due in Five Years Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Total Operating Leases, Future Minimum Payments Due Ground rent expense Operating Leases, Rent Expense Net book value of real estate assets subject to operating ground leases Property Subject to or Available for Operating Lease, Net Statement of Financial Position [Abstract] Buildings and improvements, less accumulated depreciation of $944,573 and $889,857 as of December 31, 2016 and December 31, 2015, respectively Intangible lease assets, less accumulated amortization of $109,152 and $93,012 as of December 31, 2016 and December 31, 2015, respectively Investment in and amounts due from unconsolidated joint venture Tenant receivables, net of allowance for doubtful accounts of $197 and $83 as of December 31, 2016 and December 31, 2015, respectively Accounts Receivable, Net Straight-line rent receivables Deferred Rent Receivables, Net Restricted cash and escrows Restricted Cash and Cash Equivalents Prepaid expenses and other assets Prepaid Expense and Other Assets Deferred lease costs, less accumulated amortization of $178,468 and $146,700 as of December 31, 2016 and December 31, 2015, respectively Unsecured debt, net of discount and unamortized debt issuance costs of $10,269 and $12,779 as of December 31, 2016 and December 31, 2015, respectively Unsecured Debt Secured debt, net of premiums and unamortized debt issuance costs of $1,161 and $1,319 as of December 31, 2016 and December 31, 2015, respectively Secured Debt Intangible lease liabilities, less accumulated amortization of $49,225 and $42,315 as of December 31, 2016 and December 31, 2015, respectively Commitments and Contingencies Commitments and Contingencies Stockholders' Equity: Stockholders' Equity Attributable to Parent [Abstract] Shares-in-trust, 150,000,000 shares authorized, none outstanding as of December 31, 2016 or December 31, 2015 Common Stock Held in Trust Preferred stock, no par value, 100,000,000 shares authorized, none outstanding as of December 31, 2016 or December 31, 2015 Preferred Stock, Value, Issued Common stock, $.01 par value; 750,000,000 shares authorized, 145,235,313 shares issued and outstanding as of December 31, 2016; and 145,511,644 shares issued and outstanding at December 31, 2015 Cumulative distributions in excess of earnings Other comprehensive income Derivative Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Income Tax Disclosure [Abstract] Income Taxes Income Tax Disclosure [Text Block] Property Dispositions, Assets Held for Sale, and Discontinued Operations Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Schedule of Business Acquisitions, by Acquisition Schedule of Business Acquisitions, by Acquisition [Table Text Block] Impairment Loss on Real Estate Assets Asset Impairment Charges [Text Block] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Principles of Consolidation Consolidation, Policy [Policy Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] Real Estate Assets Real Estate Assets [Policy Text Block] Describes the accounting policy pertaining to long-lived real estate assets, both tangible and intangible, which are held-for-use; and the methods for depreciating or amortizing such assets. Fair Value of Assets and Liabilities of Acquired Properties Business Combinations Policy [Policy Text Block] Investments in and Amounts Due from Unconsolidated Joint Ventures Investments In Unconsolidated Joint Ventures [Policy Text Block] Disclosure of accounting policy for investment in unconsolidated joint ventures or partnerships that are included in the enterprise's financial statements using the equity method of accounting. Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Tenant Receivables, net and Straight-line Rent Receivables Tenant Receivables Net [Policy Text Block] Disclosure of accounting policy for tenant receivables and straight-line rent receivables, net of allowance for doubtful accounts. Restricted Cash and Escrows Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Prepaid Expenses and Other Assets Prepaid Expenses and Other Assets [Policy Text Block] Disclosure of accounting policy for prepaid and other assets. Goodwill Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block] Interest Rate Derivatives Derivatives, Policy [Policy Text Block] Deferred Lease Costs Deferred Charges, Policy [Policy Text Block] Debt Debt, Policy [Policy Text Block] Deferred Income Revenue Recognition, Deferred Revenue [Policy Text Block] Shares-in-trust, Preferred Stock, Common Stock, Dividends Stockholders' Equity, Policy [Policy Text Block] Noncontrolling Interest Noncontrolling Interest [Policy Text Block] Disclosure of accounting policy for noncontrolling interests. Revenue Recognition Revenue Recognition, Policy [Policy Text Block] Stock-based Compensation and Nonqualified Deferred Compensation Plan Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block] Legal Fees and Related Insurance Recoveries Legal Costs, Policy [Policy Text Block] Casualty Losses and Litigation Settlement Expense and Related Insurance Recoveries Net Casualty Losses Litigation Settlements Losses Gains [Policy Text Block] Disclosure of accounting policy for costs associated with natural disasters and litigation settlements, and related insurance recoveries (if applicable). Discontinued Operations and Disclosures of Disposals of Components of an Entity Discontinued Operations, Policy [Policy Text Block] Net Income Available to Common Stockholders Per Share Earnings Per Share, Policy [Policy Text Block] Income Taxes Income Tax, Policy [Policy Text Block] Reclassifications Comparability of Prior Year Financial Data, Policy [Policy Text Block] Accounting Pronouncements Adopted and Other Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Supplemental Disclosures of Noncash Activities Cash Flow, Supplemental Disclosures [Text Block] Schedule of Tax Basis Income Schedule of Tax Basis Income [Table Text Block] Schedule of reconciliation between GAAP basis financial statement net income and Income Tax basis net income, prior to dividends paid deduction. Schedule of Characterization Of Dividends To Common Stockholders Schedule of Characterization Of Dividends To Common Stockholders [Table Text Block] Schedule of characterization of dividends to common stockholders between ordinary income, capital gains, and return of capital. Income Taxes [Table] Income Taxes [Table] Income Taxes [Table] Piedmont Washington Properties, Inc [Member] Piedmont Washington Properties, Inc [Member] Piedmont Washington Properties, Inc [Member] Piedmont Office Holdings, Inc [Member] Piedmont Office Holdings, Inc [Member] Piedmont Office Holdings, Inc [Member] Income Taxes [Line Items] Income Taxes [Line Items] [Line Items] for Income Taxes [Table] Depreciation and amortization expense recognized for financial reporting purposes in excess of amounts recognized for income tax purposes Effective Income Tax Rate Reconciliation, Nondeductible Expense, Depreciation and Amortization, Amount Rental income accrued for income tax purposes less than amounts for financial reporting purposes Effective Income Tax Rate Reconciliation, Deductions, Rental Income Accrued Effective Income Tax Rate Reconciliation, Deductions, Rental Income Accrued Net amortization of above/below-market lease intangibles for income tax purposes in excess of amounts for financial reporting purposes Effective Income Tax Rate Reconciliation, Nondeductible Expense, Leases, Amount Gain on disposal of property for financial reporting purposes in excess of amounts for income tax purposes Effective Income Tax Rate Reconciliation, Disposition of Asset, Amount Taxable income (loss) in excess of amount for financial reporting purposes Effective Income Tax Rate Reconciliation, Excess Taxable Income (Loss) to Determine Income Tax Basis in Net Income (Loss) Effective Income Tax Rate Reconciliation, Excess Taxable Income (Loss) to Determine Income Tax Basis in Net Income (Loss) Other expenses, including impairment loss on real estate assets, for financial reporting purposes in excess of amounts for income tax purposes Effective Income Tax Rate Reconciliation, Other Reconciling Items, Amount Income tax basis net income, prior to dividends paid deduction Income Tax Basis Net Income Prior To Dividends Paid Deduction Income Tax Basis Net Income Prior To Dividends Paid Deduction Ordinary income, Percent Common Stock Dividends, Ordinary Income, Percent Common Stock Dividends, Ordinary Income, Percent Return of capital, Percent Common Stock Dividends, Return Of Capital, Percent Common Stock Dividends, Return Of Capital, Percent Capital gains, Percent Common Stock Dividends, Capital Gains, Percent Common Stock Dividends, Capital Gains, Percent Common Stock Dividends, Percent Common Stock Dividends, Percent Common Stock Dividends, Percent Tax basis of total assets Tax Basis Of Total Assets Tax Basis Of Total Assets Accrued interest and penalties related to uncertain tax positions Liability for Uncertainty in Income Taxes, Noncurrent Discontinued Operations [Member] Discontinued Operations [Member] Discontinued Operations, Disposed of by Sale [Member] Discontinued Operations, Disposed of by Sale [Member] 11107 and 11109 Sunset Hills Road [Member] Sunset Hills Road, 11107 and 11109 [Member] Sunset Hills Road, 11107 and 11109 [Member] 1441 West Long Lake Road [Member] West Long Lake Road 1441 [Member] West Long Lake Road 1441 [Member] 4685 Investment Drive [Member] INVESTMENT DRIVE 4685 [Member] INVESTMENT DRIVE 4685 [Member] Gain/(Loss) on Sale Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax Net Sales Proceeds Revenues: Revenues [Abstract] Rental income Disposal Group, Including Discontinued Operation, Rental Income Tenant reimbursements Disposal Group, Including Discontinued Operation, Tenant Reimbursement Disposal Group, Including Discontinued Operation, Tenant Reimbursement Property management fee revenue Disposal Group, Including Discontinued Operation, Property Management Fee Revenue Disposal Group, Including Discontinued Operation, Property Management Fee Revenue Revenue Disposal Group, Including Discontinued Operation, Revenue Expenses: Expenses [Abstract] Expenses [Abstract] Property operating costs Disposal Group, Including Discontinued Operation, Property Operating Costs Disposal Group, Including Discontinued Operation, Property Operating Costs Depreciation Disposal Group, Including Discontinued Operation, Depreciation Disposal Group, Including Discontinued Operation, Depreciation Amortization Disposal Group, Including Discontinued Operation, Amortization Disposal Group, Including Discontinued Operation, Amortization Expenses Disposal Group, Including Discontinued Operation, Operating Expense Other income (expense): Other Income and Expenses [Abstract] Other income/(expense) Disposal Group Including Discontinued Operation Interest And Other Income Expense Disposal Group Including Discontinued Operation Interest And Other Income Expense Total Other income (expense) Disposal Group Including Discontinued Other Income Expense Disposal Group Including Discontinued Other Income Expense Operating income, excluding gain/(loss) on sale of real estate assets Disposal Group, Including Discontinued Operation, Operating Income (Loss) Gain/(loss) on sale of real estate assets Income from discontinued operations Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest 2020 W. 89th Street [Member] Building 2020 [Member] Building 2020 [Member] Two Park Center [Member] TWO PARK CENTER [Member] TWO PARK CENTER [Member] 3900 Dallas Parkway [Member] DALLAS PARKWAY 3900 [Member] DALLAS PARKWAY 3900 [Member] 5601 Headquarters Drive [Member] HEADQUARTERS DRIVE 5601 [Member] HEADQUARTERS DRIVE 5601 [Member] River Corporate Center [Member] RIVER CORPORATE CENTER [Member] RIVER CORPORATE CENTER [Member] Copper Ridge Center [Member] COPPER RIDGE CENTER [Member] COPPER RIDGE CENTER [Member] 3750 Brookside Parkway [Member] BROOKSIDE PARKWAY 3750 [Member] BROOKSIDE PARKWAY 3750 [Member] Chandler Forum [Member] CHANDLER FORUM [Member] CHANDLER FORUM [Member] Aon Center [Member] AON CENTER [Member] AON CENTER [Member] 1055 East Colorado [Member] EAST COLORADO BOULEVARD 1055 [Member] EAST COLORADO BOULEVARD 1055 [Member] Fairway Center II [Member] FAIRWAY CENTER II [Member] FAIRWAY CENTER II [Member] 1901 Main Street [Member] MAIN STREET 1901 [Member] MAIN STREET 1901 [Member] 11695 Johns Creek Parkway [Member] JOHNS CREEK PARKWAY 11695 [Member] JOHNS CREEK PARKWAY 11695 [Member] Braker Pointe III [Member] BRAKER POINTE III [Member] BRAKER POINTE III [Member] Receivable Type [Axis] Receivable Type [Axis] Receivable [Domain] Receivable [Domain] Notes Receivable [Member] Notes Receivable [Member] Schedule of Receivables with Imputed Interest, Name of Receivable with Imputed Interest [Axis] Schedule of Receivables with Imputed Interest, Name of Receivable with Imputed Interest [Axis] Name of Receivable with Imputed Interest [Domain] Name of Receivable with Imputed Interest [Domain] Secured Promissory Note [Member] Secured Promissory Note [Member] Secured Promissory Note [Member] Gain/(Loss) on Sale Gains (Losses) on Sales of Investment Real Estate Equity Method Investments and Joint Ventures [Abstract] Unconsolidated Joint Venture Equity Method Investments and Joint Ventures Disclosure [Text Block] Revenues Revenues Real estate operating income Operating Income (Loss) Income/(loss) from continuing operations Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest Income/(loss) from discontinued operations Gain/(loss) on sale of real estate assets Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes Net income/(loss) applicable to Piedmont Basic and diluted earnings/(loss) per share Earnings Per Share, Basic and Diluted Dividends declared per share Schedule of Future Minimum Rental Payments for Operating Leases Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Rental income Operating Leases, Income Statement, Lease Revenue Tenant reimbursements Tenant Reimbursements Property management fee revenue Management Fees Revenue Total revenues Expenses: Operating Expenses [Abstract] Property operating costs Direct Costs of Leased and Rented Property or Equipment Depreciation Depreciation Amortization Amortization of Deferred Charges General and administrative General and Administrative Expense Operating Expenses Operating Expenses Real estate operating income Other income (expense): Nonoperating Income (Expense) [Abstract] Interest expense Interest Expense Other income/(expense) Other Nonoperating Income (Expense) Net recoveries/(loss) from casualty events and litigation settlements Equity in income/(loss) of unconsolidated joint ventures Income (Loss) from Equity Method Investments Nonoperating Income (Expense) Nonoperating Income (Expense) Income from continuing operations Discontinued operations: Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent [Abstract] Operating income Gain on sale of real estate assets Net income Less: Net loss/(income) applicable to noncontrolling interest Net income applicable to Piedmont Derivative [Table] Derivative [Table] $300 Million Unsecured 2011 Term Loan [Member] $300 Million 2011 Unsecured Term Loan Maturing 2020 [Member] $300 Million 2011 Unsecured Term Loan Maturing 2020 [Member] $300 Million Unsecured 2013 Term Loan [Member] Unsecured 300 million 2013 Term Loan Maturing 2019 [Member] Unsecured 300 million 2013 Term Loan Maturing 2019 [Member] $160.0 Million Fixed Rate Loan [Member] Fixed Rate 160 Million Loan [Member] Fixed Rate 160 Million Loan [Member] Derivative Instrument Risk [Axis] Derivative Instrument [Axis] Derivative Contract Type [Domain] Derivative Contract [Domain] Interest Rate Contract [Member] Interest Rate Contract [Member] Interest Rate Swap 1 through 4 [Member] Interest Rate Swap 1 through 4 [Member] Interest Rate Swap 5 through 6 [Member] Interest Rate Swap 5 through 6 [Member] Interest Rate Swap 5 through 6 [Member] Interest Rate Swap 7 through 9 [Member] Interest Rate Swap 7 through 9 [Member] Interest Rate Swap 7 through 9 [Member] Forward Starting Interest Rate Swap [Member] Forward Starting Interest Rate Swap [Member] Forward Starting Interest Rate Swap [Member] Credit Risk Contract [Member] Credit Risk Contract [Member] Secured Debt [Member] Secured Debt [Member] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Interest Expense [Member] Interest Expense [Member] Derivative [Line Items] Derivative [Line Items] Face amount of facility Debt Instrument, Face Amount Total notional amount of forward starting interest rate agreements Derivative, Notional Amount Net loss from settlement of forward starting interest rate swaps Deferred Gain (Loss) on Discontinuation of Interest Rate Cash Flow Hedge including Gain (Loss) Recognized in Earnings on Hedge Ineffectiveness Deferred Gain (Loss) on Discontinuation of Interest Rate Cash Flow Hedge including Gain (Loss) Recognized in Earnings on Hedge Ineffectiveness Net gain/ (loss) related to hedge ineffectiveness and terminations of cash flow hedges Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness Term of loan Debt Instrument, Term Number of forward starting interest rate swaps settled Number of Interest Rate Derivatives Settled Number of Interest Rate Derivatives Settled Settlement value of forward starting interest rate swaps Gain (Loss) on Discontinuation of Interest Rate Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring, Net Maximum length of time of cash flow hedge Maximum Length of Time Hedged in Cash Flow Hedge Number of Swap Agreements Number of Interest Rate Derivatives Held Interest Rate Cash Flow Hedge Derivative at Fair Value, Net [Abstract] Interest Rate Cash Flow Hedge Derivative at Fair Value, Net [Abstract] Gross derivative assets Interest Rate Cash Flow Hedge Asset at Fair Value Net derivative liability Interest Rate Cash Flow Hedge Derivative at Fair Value, Net Amount of gain/(loss) recognized in OCI on derivatives Unrealized Gain (Loss) on Interest Rate Cash Flow Hedges, Pretax, Accumulated Other Comprehensive Income (Loss) Amount of previously recorded loss reclassified from accumulated OCI into interest expense Interest Rate Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net Amount that will be reclassified from accumulated other comprehensive income over the next twelve months Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net Assets needed for immediate settlement, aggregate fair value Assets Needed for Immediate Settlement, Aggregate Fair Value Debt Debt Disclosure [Text Block] Weighted-average common shares—basic Weighted Average Number of Shares Outstanding, Basic Deferred and performance stock awards (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Weighted-average shares outstanding - diluted Weighted Average Number of Shares Outstanding, Diluted Common stock, shares outstanding Schedule of Debt Instruments [Table] Schedule of Debt Instruments [Table] Schedule of Debt Instruments [Table] $125.0 Million Fixed-Rate Loan [Member] Fixed-Rate 125Million Loan [Member] Fixed-Rate 125Million Loan [Member] $42.5 Million Fixed-Rate Loan [Member] Fixed-Rate 42.5Million Loan [Member] Fixed-Rate 42.5Million Loan [Member] $140 Million WDC Fixed-Rate Loans [Member] WDC Mortgage Notes [Member] WDC Mortgage Notes [Member] $35.0 Million Fixed-Rate Loan [Member] Mortgage Loan Maturing September 1, 2021 [Member] Mortgage Loan Maturing September 1, 2021 [Member] $170 Million Unsecured 2015 Term Loan [Member] Unsecured 170 Million 2015 Term Loan [Member] Unsecured 170 Million 2015 Term Loan [Member] $350 Million Unsecured Senior Notes [Member] Unsecured Senior 350 Million Notes [Member] Unsecured Senior 350 Million Notes [Member] $400 Million Unsecured Senior Notes [Member] Unsecured Senior 400 Million Notes [Member] Unsecured Senior 400 Million Notes [Member] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] LIBOR [Member] London Interbank Offered Rate (LIBOR) [Member] Interest Rate Swap [Member] Interest Rate Swap [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Amount of principal paid off Repayments of Debt Amount of line of credit Net borrowings incurred Proceeds from Lines of Credit Interest rate percentage Debt Instrument, Interest Rate, Stated Percentage Weighted average interest rate Debt, Weighted Average Interest Rate Basis spread on variable percentage rate Debt Instrument, Basis Spread on Variable Rate Effective rate percentage Debt Instrument, Interest Rate, Effective Percentage Amount of indebtedness outstanding Notes and Loans Payable Net premium, discounts, and unamortized debt issuance costs Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net Additional extension period Line Of Credit Facility, Maximum Maturity Extension Period Line Of Credit Facility, Maximum Maturity Extension Period Number of extension periods Line Of Credit Facility, Number of Maturity Extension Periods Line Of Credit Facility, Number of Maturity Extension Periods Extension period Line Of Credit Facility, Maturity Extension Period Line Of Credit Facility, Maturity Extension Period Interest payments Interest Paid Summary of Significant Accounting Policies Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block] SEC Schedule III, Real Estate and Accumulated Depreciation Disclosure [Abstract] Schedule III - Real Estate and Accumulated Depreciation SEC Schedule III, Real Estate and Accumulated Depreciation Disclosure [Text Block] Schedule of Variable Interest Entities Schedule of Variable Interest Entities [Table Text Block] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] Fund XIII And REIT Joint Venture [Member] Fund XIII And REIT Joint Venture [Member] Investment [Line Items] Piedmont’s Ownership Percentage Equity Method Investment, Ownership Percentage Net Book Value Equity Method Investments Buildings and improvements, accumulated depreciation Real Estate Investment Property, Accumulated Depreciation Intangible lease assets, accumulated amortization Finite-Lived Intangible Assets, Accumulated Amortization Tenant receivables, allowance for doubtful accounts Allowance for Doubtful Accounts Receivable Deferred lease costs, accumulated amortization Deferred Costs, Leasing, Accumulated Amortization Net of discount, premiums and unamortized debt issuance costs Intangible lease liabilities, accumulated amortization Intangible Lease Liabilities Accumulated Amortization Intangible Lease Liabilities Accumulated Amortization Shares-in-trust, shares outstanding Shares In Trust, Outstanding Shares In Trust, Outstanding Preferred stock, par value (in dollars per share) Preferred Stock, No Par Value Preferred stock, shares outstanding Preferred Stock, Shares Outstanding Common stock, shares issued Common Stock, Shares, Issued Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping, Disclosure Item Amounts [Axis] Measurement Basis [Axis] Fair Value, Disclosure Item Amounts [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement [Member] Portion at Fair Value Measurement [Member] Carrying Value [Member] Reported Value Measurement [Member] Estimated Fair Value [Member] Estimate of Fair Value Measurement [Member] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Cash and cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Tenant receivables, net and Notes receivable Receivables, Fair Value Disclosure Restricted cash and escrows Restricted Cash and Escrows, Fair Value Disclosure This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents the amount of restricted cash and escrows existing as of the balance sheet date. Accounts payable and accrued expenses Accounts Payable, Fair Value Disclosure Interest rate swap liability Debt, net Notes Payable, Fair Value Disclosure Schedule of Equity Method Investments Equity Method Investments [Table Text Block] Quarterly Results (unaudited) Quarterly Financial Information [Text Block] Schedule of Debt Schedule of Debt [Table Text Block] Schedule of Maturities of Long-term Debt Schedule of Maturities of Long-term Debt [Table Text Block] Document and Entity Information [Abstract] Document and Entity Information [Abstract] Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Voluntary Filers Entity Current Reporting Status Entity Current Reporting Status Entity Public Float Entity Public Float Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Award Date [Axis] Award Date [Axis] Award Date [Domain] Award Date [Domain] Deferred Stock Award, Granted January 3, 2014 [Member] Deferred Stock Award, Granted January 3, 2014 [Member] Deferred Stock Award, Granted January 3, 2014 [Member] Deferred Stock Award, Granted May 9, 2014 [Member] Deferred Stock Award, Granted May 9, 2014 [Member] Deferred Stock Award, Granted May 9, 2014 [Member] Performance Share Program Award, Granted May 9, 2014 [Member] Performance Share Program Award, Granted May 9, 2014 [Member] Performance Share Program Award, Granted May 9, 2014 [Member] Deferred Stock Award, Granted May 1, 2015 [Member] Deferred Stock Award, Granted May 1, 2015 [Member] Deferred Stock Award, Granted May 1, 2015 [Member] Performance Share Program Award, Granted May 1, 2015 [Member] Performance Share Program Award, Granted May 1, 2015 [Member] Performance Share Program Award, Granted May 1, 2015 [Member] Deferred Stock Award, Granted May 12, 2016 [Member] Deferred Stock Award, Granted May 12, 2016 [Member] Deferred Stock Award, Granted May 12, 2016 [Member] Deferred Stock Award, Granted May 24, 2016 [Member] Deferred Stock Award, Granted May 24, 2016 [Member] Deferred Stock Award, Granted May 24, 2016 [Member] Performance Share Program Award, Granted May 24, 2016 [Member] Performance Share Program Award, Granted May 24, 2016 [Member] Performance Share Program Award, Granted May 24, 2016 [Member] Vesting [Axis] Vesting [Axis] Vesting [Domain] Vesting [Domain] Share-based Compensation Award, Tranche One [Member] Share-based Compensation Award, Tranche One [Member] Share-based Compensation Award, Tranche Two [Member] Share-based Compensation Award, Tranche Two [Member] Share-based Compensation Award, Tranche Three [Member] Share-based Compensation Award, Tranche Three [Member] Share-based Compensation Award, Tranche Four [Member] Share-based Compensation Award, Tranche Four [Member] Share-based Compensation Award, Tranche Four [Member] Share-based Compensation Award, Tranche Five [Member] Share-based Compensation Award, Tranche Five [Member] Share-based Compensation Award, Tranche Five [Member] Award Type [Axis] Equity Award [Domain] Stock Awards [Member] Stock Awards [Member] Stock Awards [Member] Deferred Stock Award [Member] Deferred Stock Award [Member] Deferred Stock Award [Member] Performance Shares [Member] Performance Shares [Member] Title of Individual [Axis] Title of Individual [Axis] Relationship to Entity [Domain] Relationship to Entity [Domain] Independent directors [Member] Director [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Rollforward of deferred stock award activity Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Unvested Deferred Stock Awards as of the beginning of the year (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Deferred Stock Awards Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Increase in Estimated Potential Future Performance Share Awards, net of forfeitures (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Increase (Decrease) in Estimated Potential Future Awards, Net of Forfeitures Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Increase (Decrease) in Estimated Potential Future Awards, Net of Forfeitures Deferred Stock Awards Vested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Deferred Stock Awards Forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Unvested Deferred Stock Awards as of end of the year (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Unvested Deferred Stock Awards, Weighted-Average Grant Date Fair Value at beginning of year (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Deferred Stock Awards Granted, Weighted-Average Grant Date Fair (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Increase in Estimated Potential Future Performance Share Awards, Weighted Average Grant Date Fair Value (in dollars per share) Share Based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other Than Options, Change in Estimated Potential Future Awards, Weighted Average Grant Date Fair Value Share Based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other Than Options, Change in Estimated Potential Future Awards, Weighted Average Grant Date Fair Value Deferred Stock Awards Vested, Weighted-Average Grant Date Fair Value (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Deferred Stock Awards Forfeited, Weighted Average Grant Date Fair Value (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Unvested Deferred Stock Awards, Weighted-Average Grant Date Fair Value at end of year (in dollars per share) Total Grant Date Fair Value of Deferred Stock Vested During the Period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value Share-based Liability Awards Paid During the Period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Share-based Liabilities Paid Net Shares Granted (in shares) Share Based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other Than Options, Net Shares Granted The number of share grants, net of shares surrendered for taxes, made on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). Grant Date Fair Value (in dollars per share) Vesting percentage Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Unvested Shares (in shares) Income Statement [Abstract] Other income/(expense) Per share information— basic and diluted: Earnings Per Share, Basic and Diluted [Abstract] Income from continuing operations and gain on sale of real estate assets (in dollars per share) Income (Loss) from Continuing Operations, Per Basic and Diluted Share Income from discontinued operations (in dollars per share) Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic and Diluted Share Net income available to common stockholders (in dollars per share) Weighted-average shares outstanding - basic (in shares) Weighted-average shares outstanding - diluted (in shares) Real Estate and Accumulated Depreciation, by Property [Table] SEC Schedule III, Real Estate and Accumulated Depreciation, by Property [Table] Real Estate and Accumulated Depreciation, Description of Property [Axis] Real Estate and Accumulated Depreciation, Name of Property [Domain] 1430 ENCLAVE PARKWAY [Member] ENCLAVE PARKWAY 1430 [Member] ENCLAVE PARKWAY 1430 [Member] CRESCENT RIDGE II [Member] CRESCENT RIDGE II [Member] CRESCENT RIDGE II [Member] 1200 CROWN COLONY DRIVE [Member] CROWN COLONY DRIVE 1200 [Member] CROWN COLONY DRIVE 1200 [Member] 5601 HIATUS ROAD [Member] HIATUS ROAD 5601 [Member] HIATUS ROAD 5601 [Member] WINDY POINT I [Member] WINDY POINT I [Member] WINDY POINT I [Member] WINDY POINT II [Member] WINDY POINT II [Member] WINDY POINT II [Member] SARASOTA COMMERCE CENTER II [Member] SARASOTA COMMERCE CENTER II [Member] SARASOTA COMMERCE CENTER II [Member] 2001 NW 64TH STREET [Member] NW 64th Street 2001 [Member] NW 64th STREET 2001 [Member] 90 CENTRAL STREET [Member] CENTRAL STREET 90 [Member] CENTRAL STREET 90 [Member] DESERT CANYON 300 [Member] DESERT CANYON 300 [Member] DESERT CANYON 300 [Member] 6031 CONNECTION DRIVE [Member] CONNECTION DRIVE 6031 [Member] CONNECTION DRIVE 6031 [Member] 6021 CONNECTION DRIVE [Member] CONNECTION DRIVE 6021 [Member] CONNECTION DRIVE 6021 [Member] 6011 CONNECTION DRIVE [Member] CONNECTION DRIVE 6011 [Member] CONNECTION DRIVE 6011 [Member] TWO INDEPENDENCE SQUARE [Member] ONE INDEPENDENCE SQUARE [Member] ONE INDEPENDENCE SQUARE [Member] ONE INDEPENDENCE SQUARE [Member] 2120 WEST END AVENUE [Member] WEST END AVENUE 2120 [Member] WEST END AVENUE 2120 [Member] 800 NORTH BRAND BOULEVARD [Member] NORTH BRAND BOULEVARD 800 [Member] NORTH BRAND BOULEVARD 800 [Member] US BANCORP CENTER [Member] US BANCORP CENTER [Member] US BANCORP CENTER [Member] AUBURN HILLS CORPORATE CENTER [Member] Auburn Hills Corporate Center Building [Member] Auburn Hills Corporate Center Building [Member] GLENRIDGE HIGHLANDS TWO [Member] GLENRIDGE HIGHLANDS TWO [Member] GLENRIDGE HIGHLANDS TWO [Member] 200 BRIDGEWATER CROSSING [Member] BRIDGEWATER CROSSING 200 [Member] BRIDGEWATER CROSSING 200 [Member] 400 VIRGINIA AVE [Member] VIRGINIA AVE 400 [Member] VIRGINIA AVE 400 [Member] 4250 NORTH FAIRFAX DRIVE [Member] NORTH FAIRFAX DRIVE 4250 [Member] NORTH FAIRFAX DRIVE 4250 [Member] 1225 EYE STREET [Member] EYE STREET 1225 [Member] EYE STREET 1225 [Member] 1201 EYE STREET [Member] EYE STREET 1201 [Member] EYE STREET 1201 [Member] 1901 MARKET STREET [Member] MARKET STREET 1901 [Member] MARKET STREET 1901 [Member] 60 BROAD STREET [Member] BROAD STREET 60 [Member] BROAD STREET 60 [Member] 1414 MASSACHUSETTS AVENUE [Member] MASSACHUSETTS AVENUE 1414 [Member] MASSACHUSETTS AVENUE 1414 [Member] ONE BRATTLE SQUARE [Member] ONE BRATTLE SQUARE [Member] ONE BRATTLE SQUARE [Member] 600 CORPORATE DRIVE [Member] CORPORATE DRIVE 600 [Member] CORPORATE DRIVE 600 [Member] 1075 WEST ENTRANCE DRIVE [Member] WEST ENTRANCE DRIVE 1075 [Member] WEST ENTRANCE DRIVE 1075 [Member] 3100 CLARENDON BOULEVARD [Member] CLARENDON BOULEVARD 3100 [Member] CLARENDON BOULEVARD 3100 [Member] 400 BRIDGEWATER CROSSING [Member] BRIDGEWATER CROSSING 400 [Member] BRIDGEWATER CROSSING 400 [Member] LAS COLINAS CORPORATE CENTER I [Member] LAS COLINAS CORPORATE CENTER I [Member] LAS COLINAS CORPORATE CENTER I [Member] LAS COLINAS CORPORATE CENTER II [Member] LAS COLINAS CORPORATE CENTER II [Member] LAS COLINAS CORPORATE CENTER II [Member] TWO PIERCE PLACE [Member] TWO PIERCE PLACE [Member] TWO PIERCE PLACE [Member] 2300 CABOT DRIVE [Member] CABOT DRIVE 2300 [Member] CABOT DRIVE 2300 [Member] PIEDMONT POINTE I [Member] PIEDMONT POINTE I [Member] PIEDMONT POINTE I [Member] PIEDMONT POINTE II [Member] PIEDMONT POINTE II [Member] PIEDMONT POINTE II [Member] SUWANEE GATEWAY ONE [Member] SUWANEE GATEWAY ONE [Member] SUWANEE GATEWAY ONE [Member] ONE MERIDIAN CROSSINGS [Member] ONE MERIDIAN CROSSINGS [Member] ONE MERIDIAN CROSSINGS [Member] TWO MERIDIAN CROSSINGS [Member] TWO MERIDIAN CROSSINGS [Member] TWO MERIDIAN CROSSINGS [Member] 500 WEST MONROE STREET [Member] WEST MONROE STREET 500 [Member] WEST MONROE STREET 500 [Member] THE DUPREE [Member] DUPREE [Member] DUPREE [Member] THE MEDICI [Member] MEDICI [Member] MEDICI [Member] 225 PRESIDENTIAL WAY [Member] PRESIDENTIAL WAY 225 [Member] PRESIDENTIAL WAY 225 [Member] 235 PRESIDENTIAL WAY [Member] PRESIDENTIAL WAY 235 [Member] PRESIDENTIAL WAY 235 [Member] 400 TOWNPARK [Member] TOWNPARK 400 [Member] TOWNPARK 400 [Member] ARLINGTON GATEWAY [Member] Arlington Gateway [Member] Arlington Gateway [Member] 5 & 15 WAYSIDE ROAD [Member] Wayside Road, 5 and 15 [Member] Wayside Road, 5 and 15 [Member] 5301 MARYLAND WAY [Member] MARYLAND WAY 5301 [Member] MARYLAND WAY 5301 [Member] 6565 MACARTHUR BLVD [Member] Six Five Six Five MacArthur Blvd [Member] Six Five Six Five MacArthur Blvd [Member] ONE LINCOLN PARK [Member] One Lincoln Park [Member] One Lincoln Park [Member] 161 CORPORATE CENTER [Member] CORPORATE CENTER 161 [Member] CORPORATE CENTER 161 [Member] 5 WALL STREET [Member] The 5 Wall Street Building [Member] The 5 Wall Street Building [Member] 1155 PERIMETER CENTER WEST [Member] Perimeter Center West 1155 [Member] Perimeter Center West 1155 [Member] PARK PLACE ON TURTLE CREEK [Member] Park Place on Turtle Creek [Member] Park Place on Turtle Creek [Member] 80 CENTRAL STREET [Member] Central Street 80 [Member] Central Street 80 [Member] ENCLAVE PLACE [Member] SUNTRUST CENTER [Member] SunTrust Center [Member] SunTrust Center [Member] GALLERIA 300 [Member] Galleria 300 [Member] Galleria 300 [Member] GLENRIDGE HIGHLANDS ONE [Member] GLENRIDGE HIGHLANDS ONE [Member] GLENRIDGE HIGHLANDS ONE [Member] CNL CENTER I [Member] CNL CENTER I [Member] CNL CENTER I [Member] CNL CENTER II [Member] CNL CENTER II [Member] CNL CENTER II [Member] ONE WAYSIDE ROAD [Member] GALLERIA 200 [Member] 750 W. JOHN CARPENTER FREEWAY [Member] PIEDMONT POWER, LLC [Member] PIEDMONT POWER LLC [Member] PIEDMONT POWER, LLC [Member] UNDEVELOPED LAND PARCELS [Member] UNDEVELOPED LAND PARCELS [Member] UNDEVELOPED LAND PARCELS [Member] 8560 UPLAND DRIVE [Member] UPLAND DRIVE 8560 [Member] UPLAND DRIVE 8560 [Member] Real Estate Properties [Axis] Real Estate Property Ownership [Axis] Real Estate Properties [Domain] Real Estate Properties [Domain] Wholly Owned Properties [Member] Wholly Owned Properties [Member] Partially Owned Properties [Member] Partially Owned Properties [Member] 1225 Equity LLC [Member] 1225 Equity LLC [Member] 1225 Equity LLC [Member] 1201 Equity LLC [Member] 1201 Equity LLC [Member] 1201 Equity LLC [Member] Real Estate and Accumulated Depreciation [Line Items] SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items] Ownership Percentage Real Estate and Accumulated Depreciation, Ownership Percentage Real Estate and Accumulated Depreciation, Ownership Percentage Encumbrances SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances Initial Cost, Land SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land Initial Cost, Buildings and Improvements SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements Initial Cost, Total Real Estate and Accumulated Depreciation, Initial Cost Real Estate and Accumulated Depreciation, Initial Cost Costs Capitalized Subsequent to Acquisition SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Improvements Gross Amount at Which Carried, Land SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land Gross Amount at Which Carried, Buildings and Improvements SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements Gross Amount at Which Carried, Total SEC Schedule III, Real Estate, Gross Accumulated Depreciation and Amortization Real Estate, Accumulated Depreciation And Amortization Real Estate, Accumulated Depreciation And Amortization Life on which Depreciation and Amortization is Computed SEC Schedule III, Real Estate and Accumulated Depreciation, Life Used for Depreciation Number of acres of adjacent land purchased Purchase price of adjoining, developable land Payments to Acquire Land Real Estate: SEC Schedule III, Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] Balance at the beginning of the year Additions to/improvements of real estate SEC Schedule III, Real Estate, Improvements Assets disposed SEC Schedule III, Real Estate, Cost of Real Estate Sold Assets impaired Real Estate, Assets Impaired Real Estate, Assets Impaired Write-offs of intangible assets Real Estate, Write-down of Intangible Assets Real Estate, Write-down of Intangible Assets Write-offs of fully depreciated/amortized assets Real Estate, Write-down of Depreciated and Amortized Assets Real Estate, Write-down of Depreciated and Amortized Assets Balance at the end of the year Accumulated Depreciation and Amortization: SEC Schedule III, Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] Balance at the beginning of the year Depreciation and amortization expense Depreciation, Depletion and Amortization Assets disposed SEC Schedule III, Real Estate Accumulated Depreciation, Real Estate Sold Write-offs of intangible assets Real Estate Accumulated Depreciation, Write Offs Of Intangible Assets Real Estate Accumulated Depreciation, Write Offs Of Intangible Assets Write-offs of fully depreciated/amortized assets Real Estate Accumulated Depreciation, Write Offs Of Fully Depreciated And Amortized Assets Real Estate Accumulated Depreciation, Write Offs Of Fully Depreciated And Amortized Assets Balance at the end of the year Award Type [Axis] Equity Award [Domain] Weighted Average [Member] Weighted Average [Member] Vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Compensation expense and directors' fees related to stock awards Allocated Share-based Compensation Expense Compensation expense, non-vested awards Share Based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other Than Options, Amortization Of Nonvested Shares Share Based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other Than Options, Amortization Of Nonvested Shares Number of shares issued to employees, directors and officers Nonvested awards, total compensation cost not yet recognized Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Nonvested awards, total compensation cost not yet recognized, period for recognition Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Schedule of Weighted Average Number of Shares Schedule of Weighted Average Number of Shares [Table Text Block] Schedule of Real Estate Properties [Table] Schedule of Real Estate Properties [Table] Real Estate, Type of Property [Axis] Real Estate, Type of Property [Axis] Real Estate Properties [Domain] Real Estate [Domain] In-Service Office Properties [Member] In Service Office Properties [Member] In Service Office Properties [Member] Redevelopment Asset [Member] Redevelopment Asset [Member] Redevelopment Asset [Member] Development Assets [Member] Development Assets [Member] Development Assets [Member] Unconsolidated Joint Venture [Member] Unconsolidated Joint Venture [Member] Unconsolidated Joint Venture [Member] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] US [Member] UNITED STATES Real Estate Properties [Line Items] Real Estate Properties [Line Items] Number of wholly owned subsidiaries Number Of Wholly Owned Management Subsidiaries Number Of Wholly Owned Management Subsidiaries Percentage ownership by sole general partner Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest Percentage ownership by sole limited partner Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest Number of office properties under development Number of Real Estate Properties Under Development Number of Real Estate Properties Under Development Rentable square feet Net Rentable Area Percentage of Class A commercial office space Real Estate Properties Leased, Percent Real Estate Properties Leased Percent Number of office markets Real Estate Investments, Number of Office Markets Real Estate Investments, Number of Office Markets Number of operating segments Number of Operating Segments Property, Plant and Equipment Property, Plant and Equipment [Table Text Block] Schedule of Finite-Lived Intangible Assets by Major Class Schedule of Finite-Lived Intangible Assets [Table Text Block] Amortization Of Intangible Lease Costs Amortization Of Intangible Lease Costs [Table Text Block] Amortization Of Intangible Lease Costs [Table Text Block] Schedule of Finite-Lived Intangible Assets, Future Amortization Expense Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Dividends to common stockholders per share Common Stock, Dividends, Per Share, Cash Paid