Summary of Significant Accounting Policies	9 Months Ended
Sep. 30, 2013
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The consolidated financial statements of Piedmont have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (the “SEC”), including the instructions to Form 10-Q and Article 10 of Regulation S-X, and do not include all of the information and footnotes required by U.S. generally accepted accounting principles (“GAAP”) for complete financial statements. In the opinion of management, the statements for the unaudited interim periods presented include all adjustments, which are of a normal and recurring nature, necessary for a fair presentation of the results for such periods. Results for these interim periods are not necessarily indicative of a full year’s results and certain prior period amounts have been reclassified to conform to the current period financial statement presentation. The reclassifications relate to the required presentation of income from discontinued operations for properties sold during the nine months ended September 30, 2013 and during the year ended December 31, 2012 (see Note 9), as well as reclassifying other rental income as rental income to be consistent with current period presentation, as further described in "Revenue Recognition" below. None of these reclassifications affect net income attributable to Piedmont as presented in previous periods. Piedmont’s consolidated financial statements include the accounts of Piedmont, Piedmont’s wholly-owned subsidiaries, any variable interest entity of which Piedmont or any of its wholly-owned subsidiaries is considered the primary beneficiary, or any entity in which Piedmont or any of its wholly-owned subsidiaries owns a controlling interest. For further information, refer to the financial statements and footnotes included in Piedmont’s Annual Report on Form 10-K for the year ended December 31, 2012, as well as the Current Report on Form 8-K containing Exhibit 99.1 filed on June 4, 2013, for the purpose of recasting certain sections of Piedmont's Annual Report on Form 10-K for the year ended December 31, 2012 for dispositions subsequent to December 31, 2012. 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. Deferred Lease Costs Deferred lease costs are comprised of costs and incentives incurred to acquire operating leases, including intangible lease origination costs and direct payroll costs incurred related to negotiating and executing specific leases, and are capitalized and amortized on a straight-line basis over the terms of the related underlying leases. The amortization of deferred lease costs and intangibles is recorded as amortization expense in the accompanying consolidated statements of income. Upon receipt of a lease termination notice, Piedmont adjusts any unamortized deferred lease costs to their net realizable value 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. Revenue Recognition All leases of real estate assets held by Piedmont are classified as operating leases, and the related base rental income is recognized on a straight-line basis over the terms of the respective leases. Tenant reimbursements are recognized as revenue in the period that the related operating cost is incurred. Rents and tenant reimbursements collected in advance are recorded as deferred income in the accompanying consolidated balance sheets. Lease termination revenues are recognized ratably as rental revenue over the revised remaining lease term after giving effect to the termination notice. Contingent rental income recognition is deferred until the specific lease-related targets are achieved. Gains on the sale of real estate assets are recognized upon completing the sale and, among other things, determining the sale price and transferring all of the risks and rewards of ownership without significant continuing involvement with the purchaser. Recognition of all or a portion of the gain would be deferred until both of these conditions are met. Losses are recognized through impairment charges when identified. Income Taxes Piedmont has elected to be taxed as a REIT under the Internal Revenue Code of 1986, as amended (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. Piedmont is subject to certain taxes related to the operations of properties in certain locations, as well as operations conducted by its taxable REIT subsidiary, POH, which have been provided for in the financial statements.

Summary of Significant Accounting Policies

Basis of Presentation

The consolidated financial statements of Piedmont have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (the “SEC”), including the instructions to Form 10-Q and Article 10 of Regulation S-X, and do not include all of the information and footnotes required by U.S. generally accepted accounting principles (“GAAP”) for complete financial statements. In the opinion of management, the statements for the unaudited interim periods presented include all adjustments, which are of a normal and recurring nature, necessary for a fair presentation of the results for such periods. Results for these interim periods are not necessarily indicative of a full year’s results and certain prior period amounts have been reclassified to conform to the current period financial statement presentation. The reclassifications relate to the required presentation of income from discontinued operations for properties sold during the nine months ended September 30, 2013 and during the year ended December 31, 2012 (see Note 9), as well as reclassifying other rental income as rental income to be consistent with current period presentation, as further described in "Revenue Recognition" below. None of these reclassifications affect net income attributable to Piedmont as presented in previous periods.

Piedmont’s consolidated financial statements include the accounts of Piedmont, Piedmont’s wholly-owned subsidiaries, any variable interest entity of which Piedmont or any of its wholly-owned subsidiaries is considered the primary beneficiary, or any entity in which Piedmont or any of its wholly-owned subsidiaries owns a controlling interest. For further information, refer to the financial statements and footnotes included in Piedmont’s Annual Report on Form 10-K for the year ended December 31, 2012, as well as the Current Report on Form 8-K containing Exhibit 99.1 filed on June 4, 2013, for the purpose of recasting certain sections of Piedmont's Annual Report on Form 10-K for the year ended December 31, 2012 for dispositions subsequent to December 31, 2012.

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.

Deferred Lease Costs

Deferred lease costs are comprised of costs and incentives incurred to acquire operating leases, including intangible lease origination costs and direct payroll costs incurred related to negotiating and executing specific leases, and are capitalized and amortized on a straight-line basis over the terms of the related underlying leases. The amortization of deferred lease costs and intangibles is recorded as amortization expense in the accompanying consolidated statements of income. Upon receipt of a lease termination notice, Piedmont adjusts any unamortized deferred lease costs to their net realizable value 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.

Revenue Recognition

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

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

Income Taxes

Piedmont has elected to be taxed as a REIT under the Internal Revenue Code of 1986, as amended (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. Piedmont is subject to certain taxes related to the operations of properties in certain locations, as well as operations conducted by its taxable REIT subsidiary, POH, which have been provided for in the financial statements.