Piedmont Office Realty Trust (PDM) 10-Q 31 Oct 13 2013 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2013	Oct. 30, 2013
Document and Entity Information [Abstract]	'	'
Entity Registrant Name	'Piedmont Office Realty Trust, Inc.	'
Entity Central Index Key	'0001042776	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Document Type	'10-Q	'
Document Period End Date	30-Sep-13	'
Document Fiscal Year Focus	'2013	'
Document Fiscal Period Focus	'Q3	'
Amendment Flag	'false	'
Entity Common Stock, Shares Outstanding	'	161,112,966

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Assets:	'	'
Land	$675,281	$627,351
Buildings and improvements, less accumulated depreciation of $955,480 and $877,644 as of September 30, 2013 and December 31, 2012, respectively	3,049,905	2,891,323
Intangible lease assets, less accumulated amortization of $70,744 and $67,940 as of September 30, 2013 and December 31, 2012, respectively	66,870	54,744
Construction in progress	61,162	20,373
Real estate assets held for sale, net	19,734	18,941
Total real estate assets	3,872,952	3,612,732
Investments in unconsolidated joint ventures	18,668	37,226
Cash and cash equivalents	15,972	12,957
Tenant receivables, net of allowance for doubtful accounts of $306 and $346 as of September 30, 2013 and December 31, 2012, respectively	31,006	25,038
Straight-line rent receivables	135,487	121,506
Due from unconsolidated joint ventures	0	463
Restricted cash and escrows	385	334
Prepaid expenses and other assets	17,610	13,022
Goodwill	180,097	180,097
Interest rate swaps	19,192	1,075
Deferred financing costs, less accumulated amortization of $12,365 and $10,479 as of September 30, 2013 and December 31, 2012, respectively	7,990	6,454
Deferred lease costs, less accumulated amortization of $129,998 and $112,496 as of September 30, 2013 and December 31, 2012, respectively	275,234	243,178
Other assets held for sale, net	1,960	793
Total assets	4,576,553	4,254,875
Liabilities:	'	'
Unsecured debt	835,650	429,000
Secured debt	987,525	987,525
Accounts payable, accrued expenses, and accrued capital expenditures	159,675	127,263
Deferred income	26,575	21,552
Intangible lease liabilities, less accumulated amortization of $43,322 and $40,931 as of September 30, 2013 and December 31, 2012, respectively	41,435	40,805
Interest rate swaps	5,010	8,235
Total liabilities	2,055,870	1,614,380
Commitments and Contingencies	0	0
Stockholders’ Equity:	'	'
Shares-in-trust, 150,000,000 shares authorized; none outstanding as of September 30, 2013 or December 31, 2012	0	0
Preferred stock, no par value, 100,000,000 shares authorized; none outstanding as of September 30, 2013 or December 31, 2012	0	0
Common stock, $.01 par value, 750,000,000 shares authorized; 161,270,766 and 167,556,001 shares issued and outstanding as of September 30, 2013 and December 31, 2012, respectively	1,613	1,676
Additional paid-in capital	3,668,424	3,667,051
Cumulative distributions in excess of earnings	-1,165,794	-1,022,681
Other comprehensive income/(loss)	14,827	-7,160
Piedmont stockholders’ equity	2,519,070	2,638,886
Noncontrolling interest	1,613	1,609
Total stockholders’ equity	2,520,683	2,640,495
Total liabilities and stockholders’ equity	$4,576,553	$4,254,875

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, except Share data, unless otherwise specified
Assets:	'	'
Intangible lease assets, accumulated amortization	$70,744	$67,940
Tenant receivables, allowance for doubtful accounts	306	346
Deferred financing costs, accumulated amortization	12,365	10,479
Deferred lease costs, accumulated amortization	129,998	112,496
Liabilities:	'	'
Intangible lease liabilities, accumulated amortization	43,322	40,931
Stockholders’ Equity:	'	'
Shares-in-trust, shares authorized	150,000,000	150,000,000
Shares-in-trust, shares outstanding	0	0
Preferred stock, par value (in dollars per share)	$0	$0
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$0.01	$0.01
Common stock, shares authorized	750,000,000	750,000,000
Common stock, shares issued	161,270,766	167,556,001
Common stock, shares outstanding	161,270,766	167,556,001
Building and Building Improvements [Member]	'	'
Assets:	'	'
Buildings and improvements, accumulated depreciation	$955,480	$877,644

Consolidated_Statements_of_Inc

Consolidated Statements of Income (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenues:	'	'	'	'
Rental income	$116,810	$104,948	$333,855	$312,007
Tenant reimbursements	27,418	27,132	77,168	80,290
Property management fee revenue	890	520	2,034	1,720
Total revenues	145,118	132,600	413,057	394,017
Expenses:	'	'	'	'
Property operating costs	58,767	50,483	164,420	154,568
Depreciation	30,785	27,921	90,688	81,721
Amortization	13,878	15,165	34,244	39,095
General and administrative	5,841	5,508	16,678	15,629
Operating Expenses	109,271	99,077	306,030	291,013
Real estate operating income	35,847	33,523	107,027	103,004
Other income (expense):	'	'	'	'
Interest expense	-19,331	-16,247	-53,932	-48,727
Interest and other income/(expense)	-611	383	-1,960	765
Litigation settlement recovery/(expense)	0	-7,500	1,250	-7,500
Net recoveries of casualty loss	3,919	0	6,061	0
Equity in income of unconsolidated joint ventures	46	323	604	739
Loss on consolidation	-898	0	-898	0
Nonoperating Income (Expense)	-16,875	-23,041	-48,875	-54,723
Income from continuing operations	18,972	10,482	58,152	48,281
Discontinued operations:	'	'	'	'
Operating income	128	607	1,109	2,914
Impairment loss	0	0	-6,402	0
Gain/(loss) on sale of real estate assets	0	-254	16,258	27,583
Income from discontinued operations	128	353	10,965	30,497
Net income	19,100	10,835	69,117	78,778
Less: Net income attributable to noncontrolling interest	-4	-4	-12	-12
Net income attributable to Piedmont	$19,096	$10,831	$69,105	$78,766
Per share information – basic and diluted:	'	'	'	'
Income from continuing operations (in dollars per share)	$0.12	$0.06	$0.35	$0.28
Income/(loss) from discontinued operations (in dollars per share)	$0	$0	$0.06	$0.18
Net income available to common stockholders (in dollars per share)	$0.12	$0.06	$0.41	$0.46
Weighted-average common shares outstanding – basic	164,683,173	168,805,589	166,597,577	171,162,281
Weighted-average common shares outstanding – diluted	164,796,275	168,929,039	166,734,464	171,295,098

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Net income attributable to Piedmont	$19,096	$10,831	$69,105	$78,766
Other comprehensive income/(loss):	'	'	'	'
Effective portion of gain/(loss) on derivative instruments that are designated and qualify as cash flow hedges (See Note 5)	-2,201	-2,756	19,659	-8,628
Plus: Reclassification of previously recorded loss included in net income (See Note 5)	783	762	2,328	2,249
Other comprehensive income/(loss)	-1,418	-1,994	21,987	-6,379
Comprehensive income attributable to Piedmont	$17,678	$8,837	$91,092	$72,387

Consolidated_Statements_of_Sto

Consolidated Statements of Stockholders' Equity (USD $)	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Cumulative Distributions in Excess of Earnings [Member]	Other Comprehensive Loss [Member]	Non-controlling Interest [Member]
In Thousands, except Share data, unless otherwise specified
Balance at Dec. 31, 2011	$2,773,428	$1,726	$3,663,662	($891,032)	($2,537)	$1,609
Balance (in shares) at Dec. 31, 2011	'	172,630,000	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'
Shares repurchases as part of an announced plan	-88,737	-52	'	-88,685	'	'
Shares repurchases as part of an announced plan (in shares)	'	-5,255,000	'	'	'	'
Offering costs associated with the issuance of common stock	567	'	567	'	'	'
Dividends to common stockholders ($0.80 (YTD 2012) and $0.60 (YTD 2013) per share), distributions to noncontrolling interest, and dividends reinvested	-136,378	'	-195	-136,168	'	-15
Shares issued and amortized under the 2007 Omnibus Incentive Plan, net of tax	3,019	2	3,017	'	'	'
Shares issued and amortized under the 2007 Omnibus Incentive Plan, net of tax (in shares)	'	181,000	'	'	'	'
Net income attributable to noncontrolling interest	15	'	'	'	'	15
Net income attributable to Piedmont	93,204	'	'	93,204	'	'
Other comprehensive income (loss)	-4,623	'	'	'	-4,623	'
Balance at Dec. 31, 2012	2,640,495	1,676	3,667,051	-1,022,681	-7,160	1,609
Balance (in shares) at Dec. 31, 2012	167,556,001	167,556,000	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'
Shares repurchases as part of an announced plan	-112,351	-64	'	-112,287	'	'
Shares repurchases as part of an announced plan (in shares)	'	-6,433,000	'	'	'	'
Offering costs associated with the issuance of common stock	-91	'	-91	'	'	'
Dividends to common stockholders ($0.80 (YTD 2012) and $0.60 (YTD 2013) per share), distributions to noncontrolling interest, and dividends reinvested	-100,102	'	-163	-99,931	'	-8
Shares issued and amortized under the 2007 Omnibus Incentive Plan, net of tax (in shares)	'	148,000	'	'	'	'
Shares issued and amortized under the 2007 Omnibus Incentive Plan, net of tax	1,628	1	1,627	'	'	'
Net income attributable to noncontrolling interest	12	'	'	'	'	12
Net income attributable to Piedmont	69,105	'	'	69,105	'	'
Other comprehensive income (loss)	21,987	'	'	'	21,987	'
Balance at Sep. 30, 2013	$2,520,683	$1,613	$3,668,424	($1,165,794)	$14,827	$1,613
Balance (in shares) at Sep. 30, 2013	161,270,766	161,271,000	'	'	'	'

Consolidated_Statements_of_Sto1

Consolidated Statements of Stockholders' Equity (Parenthetical) (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Statement of Stockholders' Equity [Abstract]	'	'
Dividends to common stockholders (in dollars per share)	$0.60	$0.80

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Cash Flows from Operating Activities:	'	'
Net income	$69,117	$78,778
Operating distributions received from unconsolidated joint ventures	1,475	1,805
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation	91,376	84,100
Amortization of deferred financing costs	1,931	2,056
Settlement of forward starting interest rate swaps	672	0
Other amortization	34,384	38,895
Impairment loss on real estate assets	6,402	0
Stock compensation expense	1,489	1,492
Equity in income of unconsolidated joint ventures	-604	-740
Gain on sale of real estate assets, net	-16,258	-27,583
Loss on consolidation	-898	0
Changes in assets and liabilities:	'	'
Increase in tenant receivables, net	-24,257	-15,358
Increase in restricted cash and escrows	-51	-13,813
Increase in prepaid expenses and other assets	-4,539	-3,335
Increase/(decrease) in accounts payable and accrued expenses	1,291	-483
Increase/(decrease) in deferred income	5,022	-3,211
Net cash provided by operating activities	168,348	142,603
Cash Flows from Investing Activities:	'	'
Acquisition of real estate assets and related intangibles	-250,127	-2,500
Capitalized expenditures, net of accruals	-112,486	-71,936
Acquisition of unconsolidated joint ventures, net of cash assumed	-14,242	0
Net sales proceeds from wholly-owned properties	49,326	74,845
Investments in unconsolidated joint ventures	-793	0
Deferred lease costs paid	-28,349	-39,319
Net cash used in investing activities	-356,671	-38,910
Cash Flows from Financing Activities:	'	'
Deferred financing costs paid	-3,447	-2,991
Proceeds from debt	832,603	365,000
Repayments of debt	-426,000	-401,500
Costs of issuance of common stock	-91	-229
Repurchases of common stock as part of announced plan	-111,625	-80,130
Dividends paid and discount on dividend reinvestments	-100,102	-102,770
Net cash provided by/(used in) financing activities	191,338	-222,620
Net increase/(decrease) in cash and cash equivalents	3,015	-118,927
Cash and cash equivalents, beginning of period	12,957	139,690
Cash and cash equivalents, end of period	15,972	20,763
Supplemental Disclosures of Significant Noncash Investing and Financing Activities:	'	'
Change in accrued share repurchases as part of an announced plan	726	0
Accrued capital expenditures and deferred lease costs	38,837	11,177
Accrued deferred financing costs	$0	$110

Organization

Organization	9 Months Ended
	Sep. 30, 2013
Organization [Abstract]	'
Organization	'
	Organization
	Piedmont Office Realty Trust, Inc. (“Piedmont”) (NYSE: PDM) is a Maryland corporation that operates in a manner so as to qualify as a real estate investment trust (“REIT”) for federal income tax purposes and engages in the acquisition and ownership of commercial real estate properties throughout the United States, including properties that are under construction, are newly constructed, or have operating histories. Piedmont was incorporated in 1997 and commenced operations in June of 1998. Piedmont conducts business primarily through Piedmont Operating Partnership, L.P. (“Piedmont OP”), a Delaware limited partnership, as well as performing the management of its buildings through two wholly-owned subsidiaries, Piedmont Government Services, LLC and Piedmont Office Management, LLC. Piedmont owns 99.9% of, and is the sole general partner of, Piedmont OP and as such, possesses full legal control and authority over the operations of Piedmont OP. The remaining 0.1% ownership interest of Piedmont OP is held indirectly by Piedmont through its wholly-owned subsidiary, Piedmont Office Holdings, Inc ("POH"), the sole limited partner of Piedmont OP. Piedmont OP owns properties directly, through wholly-owned subsidiaries, and through both consolidated and unconsolidated joint ventures. References to Piedmont herein shall include Piedmont and all of its subsidiaries, including Piedmont OP and its subsidiaries and joint ventures.
	As of September 30, 2013, Piedmont owned interests in 77 consolidated office properties, plus two buildings owned through an unconsolidated joint venture. Our 77 consolidated office properties are located in 18 metropolitan areas across the United States. These office properties comprise approximately 21.1 million square feet of primarily Class A commercial office space, and were approximately 86.7% leased as of September 30, 2013.

Summary_of_Significant_Account

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.

Acquisitions

Acquisitions	9 Months Ended
	Sep. 30, 2013
Business Combinations [Abstract]	'
Acquisitions	'
	Acquisitions
	During the nine months ended September 30, 2013, Piedmont acquired the following properties:
	Property		Metropolitan Statistical Area	Date of Acquisition	Rentable Square Feet	Percentage Leased as of Acquisition			Contractual Purchase Price (in millions)
	Arlington Gateway		Washington, D.C.	March 4, 2013	333,948	99		%	$	175.6
	5 & 15 Wayside Road		Boston, MA	March 22, 2013	271,434	95		%	$	69.3
	2020 W. 89th Street	(1)	Kansas City, KS	August 12, 2013	68,376	89		%	$	4.3	(2)
	5301 Maryland Way	(1)	Nashville, TN	August 12, 2013	201,237	100		%	$	18.5	(2)
	4685 Investment Drive	(1)	Detroit, MI	August 12, 2013	77,045	100		%	$	10	(2)
	Land Parcel		Metropolitan Statistical Area	Date of Acquisition	Acreage	Purchase Price (in millions)
	Royal Lane		Dallas, TX	August 1, 2013	10.59	$	2.6
	(1) On August 12, 2013, Piedmont purchased all of the remaining interests in three office properties previously held through two unconsolidated joint ventures for approximately $14.7 million in cash.
	(2) Purchase price represents the estimated fair value of the respective property which was derived by reference to a credible, unrelated third-party offer and verified using discounted cash flow analysis. Under the terms of the respective joint venture agreements, Piedmont exercised its dissenter's right to buy out each of its co-venturers' interests based upon the terms of the third-party offer. The $0.9 million difference between the fair value of the properties acquired and the sum of Piedmont's previously recorded book value in investment in unconsolidated joint ventures plus cash consideration paid for the interests was recorded as a loss on consolidation in Piedmont's consolidated statement of operations for the three months ended September 30, 2013.

Debt

Debt	9 Months Ended
	Sep. 30, 2013
Line of Credit and Notes Payable [Abstract]	'
Debt	'
	Debt
	On May 9, 2013, Piedmont, through its 100% owned operating partnership, Piedmont OP, issued $350 million in aggregate principal amount of 3.40% Senior Notes which mature on June 1, 2023 (the “Senior Notes”). The Senior Notes were originally offered in a private offering and subsequently exchanged for notes registered under the Securities Act of 1933, as amended. The Senior Notes are fully and unconditionally guaranteed on a senior unsecured basis by Piedmont.
	Upon issuance of the Senior Notes, Piedmont OP received proceeds of approximately $348.6 million, reflecting a discount of approximately $1.4 million which is being amortized as interest expense under the effective interest method over the ten-year term of the Senior Notes. In addition, in conjunction with the issuance, Piedmont settled two forward starting rate swaps, consisting of notional amounts of $220 million and $30 million, respectively. The settlement of the swaps resulted in a gain of approximately $0.7 million that is being amortized as an offset to interest expense over the ten-year term of the Senior Notes. See Note 5 for further detail.
	During the nine months ended September 30, 2013, Piedmont incurred additional working capital borrowings of $484.0 million and, utilizing the proceeds of the Senior Notes issuance described above as well as other cash on hand, made repayments totaling $426.0 million on its $500 Million Unsecured Line of Credit. Piedmont also made interest payments on all debt facilities, including interest rate swap cash settlements, of approximately $15.5 million and $15.7 million for the three months ended September 30, 2013 and 2012, respectively, and $47.3 million and $47.1 million for the nine months ended September 30, 2013 and 2012, respectively. For the nine months ended September 30, 2013 Piedmont had no capitalized interest.
	See Note 7 for a description of Piedmont’s estimated fair value of debt as of September 30, 2013.
	The following table summarizes the terms of Piedmont’s indebtedness outstanding as of September 30, 2013 and December 31, 2012 (in thousands):
	Facility		Collateral	Rate(1)			Maturity	Amount Outstanding as of
								September 30,		December 31,
								2013		2012
	Secured (Fixed)
	$200.0 Million Mortgage Note		Aon Center	4.87	%		5/1/14	$	200,000	$	200,000
	$25.0 Million Mortgage Note		Aon Center	5.7	%		5/1/14	25,000		25,000
	$350.0 Million Secured Pooled Facility		Nine Property Collateralized	4.84	%		6/7/14	350,000		350,000
			Pool (2)
	$105.0 Million Fixed-Rate Loan		US Bancorp Center	5.29	%		5/11/15	105,000		105,000
	$125.0 Million Fixed-Rate Loan		Four Property Collateralized	5.5	%		4/1/16	125,000		125,000
			Pool (3)
	$42.5 Million Fixed-Rate Loan		Las Colinas Corporate	5.7	%		10/11/16	42,525		42,525
			Center I & II
	$140.0 Million WDC Mortgage Notes		1201 & 1225 Eye Street	5.76	%		11/1/17	140,000		140,000
	Subtotal/Weighted Average (4)			5.17	%			987,525		987,525
	Unsecured (Variable and Fixed)
	$300 Million Unsecured Term Loan			LIBOR +  1.45%		(5)	11/22/16	300,000		300,000
	$500 Million Unsecured Line of Credit			1.36	%	(6)	8/19/16	187,000		129,000
	$350 Million Senior Notes			3.4	%	(7)	6/1/23	348,650		—
	Subtotal/Weighted Average (4)			2.71	%			835,650		429,000
	Total/ Weighted Average (4)			4.04	%			$	1,823,175	$	1,416,525
	(1)	All of Piedmont’s outstanding debt as of September 30, 2013 and December 31, 2012 is interest-only debt.
	(2)	Nine property collateralized pool includes: 1200 Crown Colony Drive, Braker Pointe III, 2 Gatehall Drive, One and Two Independence Square, 2120 West End Avenue, 400 Bridgewater Crossing, 200 Bridgewater Crossing, and Fairway Center II.
	(3)	Four property collateralized pool includes 1430 Enclave Parkway, Windy Point I and II, and 1055 East Colorado Boulevard.
	(4)	Weighted average is based on contractual balance of outstanding debt and interest rates in the table as of September 30, 2013, except for the $350 Million Senior Notes, which were issued at a discount (see footnote 7 below).
	(5)	The $300 Million Unsecured Term Loan has a stated variable rate; however, Piedmont entered into interest rate swap agreements which effectively fix, exclusive of changes to Piedmont's credit rating, the rate on this facility to 2.69%.
	(6)	Piedmont may select from multiple interest rate options with each draw, including the prime rate and various-length LIBOR locks. All LIBOR selections are subject to an additional spread (1.175% as of September 30, 2013) over the selected rate based on Piedmont’s current credit rating. The outstanding balance as of September 30, 2013 consisted of 30-day LIBOR draws ranging from 0.18% to 0.19% (subject to the additional spread mentioned above).
	(7)	The $350 Million Senior Notes have a fixed coupon rate of 3.40%, however, as a result of the issuance of the notes at a discount, Piedmont recognizes an effective interest rate on this debt issuance of 3.45%.

Derivative_Instruments

Derivative Instruments	9 Months Ended
	Sep. 30, 2013
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Derivative Instruments	'
	Derivative Instruments
	Risk Management Objective of Using Derivatives
	In addition to operational risks which arise in the normal course of business, Piedmont is exposed to economic risks such as interest rate, liquidity, and credit risk. In certain situations, Piedmont has entered into derivative financial instruments such as interest rate swap agreements and other similar agreements to manage interest rate risk exposure arising from current or future variable rate debt transactions. Interest rate swap agreements involve the receipt or payment of future known and uncertain cash amounts, the value of which are determined by interest rates. Piedmont’s objective in using interest rate derivatives is to add stability to interest expense and to manage its exposure to interest rate movements.
	Cash Flow Hedges of Interest Rate Risk
	Interest rate swaps designated as cash flow hedges involve the receipt of variable-rate amounts from a counterparty in exchange for Piedmont making fixed-rate payments over the life of the agreements without changing the underlying notional amount. During the nine months ended September 30, 2013, Piedmont used four interest rate swap agreements with a total notional value of $300 million to hedge the variable cash flows associated with its $300 Million Unsecured Term Loan.
	Additionally, over the course of the twelve months ended September 30, 2013, Piedmont entered into six forward starting interest rate swap agreements with a total notional value of $530 million to hedge the risk of changes in the interest-related cash flows associated with various potential issuances of long-term debt. In conjunction with the issuance of the Senior Notes (see Note 4), Piedmont settled two of the forward starting swap agreements with a total notional value of $250 million for a gain of approximately $0.7 million. The gain was recorded as accumulated other comprehensive income and is being amortized as an offset to interest expense over the ten-year term of the Senior Notes. Piedmont continues to hold the remaining $280 million of forward starting interest rate swaps to hedge its exposure to the variability in future cash flows for additional potential future debt issuances over a maximum period of 126 months.
	A detail of Piedmont’s interest rate derivatives outstanding as of September 30, 2013 is as follows:
	Interest Rate Derivative	Notional Amount			Effective Date		Maturity Date
		(in millions)
	Interest rate swap	$	125		11/22/11		11/22/16
	Interest rate swap	75			11/22/11		11/22/16
	Interest rate swap	50			11/22/11		11/22/16
	Interest rate swap	50			11/22/11		11/22/16
	Forward starting interest rate swap	70			3/3/14		3/3/24
	Forward starting interest rate swap	70			3/3/14		3/3/24
	Forward starting interest rate swap	70			3/3/14		3/3/24
	Forward starting interest rate swap	70			3/3/14		3/3/24
	Total	$	580
	Piedmont has elected to present its interest rate derivatives on its consolidated balance sheets on a gross basis as interest rate swap asset and interest rate swap liabilities. A detail of Piedmont’s interest rate derivatives on a gross and net basis as of September 30, 2013 and December 31, 2012, respectively, is as follows (in thousands):
	Interest rate swaps classified as:	September 30,			December 31,
		2013			2012
	Gross derivative assets	$	19,192		$	1,075
	Gross derivative liabilities	(5,010		)	(8,235		)
	Net derivative asset/(liability)	$	14,182		$	(7,160	)
	All of Piedmont's interest rate derivative agreements outstanding for the periods presented were designated as cash flow hedges of interest rate risk. As such, the effective portion of changes in the fair value of these derivatives designated as, and that qualify as, cash flow hedges is recorded in other comprehensive income ("OCI") and is reclassified into earnings as interest expense in the period that the hedged forecasted transaction affects earnings. The effective portion of Piedmont's interest rate derivatives that was recorded in the accompanying consolidated statements of income for the three and nine months ended September 30, 2013 and 2012, respectively, is as follows:
		Three Months Ended						Nine Months Ended
	Derivative in	September 30,			September 30,			September 30,		September 30,
	Cash Flow Hedging	2013			2012			2013		2012
	Relationships (Interest Rate Swaps) (in thousands)
	Amount of gain/(loss) recognized in OCI on derivative	$	(2,201	)	$	(2,756	)	$	19,659	$	(8,628	)
	Amount of previously recorded loss reclassified from accumulated OCI into interest expense	$	783		$	762		$	2,328	$	2,249
	Piedmont estimates that approximately $5.9 million will be reclassified from accumulated other comprehensive loss to interest expense over the next twelve months. No gain or loss was recognized related to hedge ineffectiveness or to amounts excluded from effectiveness testing on Piedmont’s cash flow hedges during the three and nine months ended September 30, 2013 or 2012.
	Additionally, see Note 7 for fair value disclosures of Piedmont's derivative instruments.
	Credit-risk-related Contingent Features
	Piedmont has agreements with its derivative counterparties that contain a provision whereby if Piedmont defaults on any of its indebtedness, including default where repayment of the indebtedness has not been accelerated by the lender, then Piedmont could also be declared in default on its derivative obligations. If Piedmont were to breach any of the contractual provisions of the derivative contracts, it would be required to settle its obligations under the agreements at their termination value of the fair values plus accrued interest, or approximately $5.1 million. Additionally, Piedmont has rights of set-off under certain of its derivative agreements related to potential termination fees and amounts payable under the agreements, if a termination were to occur.

Variable_Interest_Entities

Variable Interest Entities	9 Months Ended
	Sep. 30, 2013
Variable Interest Entities [Abstract]	'
Variable Interest Entities	'
	Variable Interest Entities
	Variable interest holders who have the power to direct the activities of the VIE that most significantly impact the entity’s economic performance and have the obligation to absorb the majority of losses of the entity or the right to receive significant benefits of the entity are considered to be the primary beneficiary and must consolidate the VIE.
	A summary of Piedmont’s interests in and consolidation treatment of its VIEs as of September 30, 2013 is as follows (net carrying amount in millions):
	Entity	Piedmont’s	Related	Consolidated/	Net Carrying			Net Carrying			Primary Beneficiary
		%	Building	Unconsolidated	Amount as of			Amount as of			Considerations
		Ownership			30-Sep-13			December 31,
		of Entity						2012
	1201 Eye Street NW Associates, LLC	49.50%	1201 Eye Street	Consolidated	$	(4.5	)	$	(5.7	)	In accordance with the partnership’s governing documents, Piedmont is entitled to 100% of the cash flow of the entity and has sole discretion in directing the management and leasing activities of the building.
	1225 Eye Street NW Associates, LLC	49.50%	1225 Eye Street	Consolidated	$	(0.4	)	$	(0.1	)	In accordance with the partnership’s governing documents, Piedmont is entitled to 100% of the cash flow of the entity and has sole discretion in directing the management and leasing activities of the building.
	Piedmont 500 W. Monroe Fee, LLC	100%	500 W. Monroe	Consolidated	$	228		$	194		The Omnibus Agreement with the previous owner includes equity participation rights for the previous owner, if certain financial returns are achieved; however, Piedmont has sole decision making authority and is entitled to the economic benefits of the property until such returns are met.
	Suwanee Gateway One, LLC	100%	Suwanee Gateway One	Consolidated	$	7.4		$	7.6		The fee agreement includes equity participation rights for the incentive manager, if certain returns on investment are achieved; however, Piedmont has sole decision making authority and is entitled to the economic benefits of the property until such returns are met.
	Medici Atlanta, LLC	100%	The Medici	Consolidated	$	14.5		$	13.7		The fee agreement includes equity participation rights for the incentive manager, if certain returns on investment are achieved; however, Piedmont has sole decision making authority and is entitled to the economic benefits of the property until such returns are met.
	400 TownPark, LLC	100%	400 TownPark	Consolidated	$	22.1		$	23.5		The fee agreement includes equity participation rights for the incentive manager, if certain returns on investment are achieved; however, Piedmont has sole decision making authority and is entitled to the economic benefits of the property until such returns are met.
	Each of the VIEs described above has the sole purpose of holding office buildings and their resulting operations, and are classified in the accompanying consolidated balance sheets in the same manner as Piedmont’s wholly-owned properties.

Fair_Value_Measurement_of_Fina

Fair Value Measurement of Financial Instruments	9 Months Ended
	Sep. 30, 2013
Fair Value Measurement of Financial Instruments [Abstract]	'
Fair Value Measurement of Financial Instruments	'
	Fair Value Measurement of Financial Instruments
	Piedmont considers its cash, accounts receivable, restricted cash and escrows, accounts payable and accrued expenses, interest rate swap agreements, and debt to meet the definition of financial instruments. The following table sets forth the carrying and estimated fair value for each of Piedmont’s financial instruments, as well as its level within the GAAP fair value hierarchy, as of September 30, 2013 and December 31, 2012, respectively (in thousands):
		September 30, 2013					December 31, 2012
	Financial Instrument	Carrying Value		Estimated Fair Value		Level Within Fair Value Hierarchy	Carrying Value		Estimated Fair Value		Level Within Fair Value Hierarchy
	Assets:
	Cash and cash equivalents(1)	$	15,972	$	15,972	Level 1	$	12,957	$	12,957	Level 1
	Tenant receivables, net(1)	$	31,006	$	31,006	Level 1	$	25,038	$	25,038	Level 1
	Restricted cash and escrows(1)	$	385	$	385	Level 1	$	334	$	334	Level 1
	Interest rate swap asset	$	19,192	$	19,192	Level 2	$	1,075	$	1,075	Level 2
	Liabilities:
	Accounts payable and accrued expenses(1)	$	22,229	$	22,229	Level 1	$	23,113	$	23,113	Level 1
	Interest rate swap liability	$	5,010	$	5,010	Level 2	$	8,235	$	8,235	Level 2
	Debt	$	1,823,175	$	1,836,413	Level 2	$	1,416,525	$	1,470,002	Level 2
	(1)	For the periods presented, the carrying value of these financial instruments approximates estimated fair value due to their short-term maturity.
	Piedmont's debt was carried at book value as of September 30, 2013 and December 31, 2012; however, Piedmont's estimate of its fair value is disclosed in the table above. Piedmont uses widely accepted valuation techniques including discounted cash flow analysis based on the contractual terms of the debt facilities, including the period to maturity of each instrument, and uses observable market-based inputs for similar debt facilities which have transacted recently in the market. Therefore, the fair values determined are considered to be based on significant other observable inputs (Level 2). Scaling adjustments are made to these inputs to make them applicable to the remaining life of Piedmont's outstanding debt. Piedmont has not changed its valuation technique for estimating the fair value of its debt.
	Piedmont’s interest rate swap and forward starting interest rate swap agreements presented above, and further discussed in Note 5, are classified as “Interest rate swap” assets and liabilities in the accompanying consolidated balance sheets and were carried at fair value as of September 30, 2013 and December 31, 2012. The valuation of these derivative instruments was determined using widely accepted valuation techniques including discounted cash flow analysis based on the contractual terms of the derivatives, including the period to maturity of each instrument, and uses observable market-based inputs, including interest rate curves and implied volatilities. Therefore, the fair values determined are considered to be based on significant other observable inputs (Level 2). In addition, Piedmont considered both its own and the respective counterparties’ risk of nonperformance in determining the fair value of its derivative financial instruments by estimating the current and potential future exposure under the derivative financial instruments that both Piedmont and the counterparties were at risk for as of the valuation date. The credit risk of Piedmont and its counterparties was factored into the calculation of the estimated fair value of the interest rate swaps; however, as of September 30, 2013 and December 31, 2012, this credit valuation adjustment did not comprise a material portion of the estimated fair value. Therefore, Piedmont believes that any unobservable inputs used to determine the fair values of its derivative financial instruments are not significant to the fair value measurements in their entirety, and does not consider any of its derivative financial instruments to be Level 3 assets or liabilities.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2013
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	Commitments and Contingencies
	Commitments Under Existing Agreements
	Certain lease agreements include provisions that, at the option of the tenant, may obligate Piedmont to provide funding for capital improvements. Under its existing lease agreements, Piedmont may be required to fund significant tenant improvements, leasing commissions, and building improvements. In addition, certain agreements contain provisions that require Piedmont to issue corporate or property guarantees to provide funding for capital improvements or other financial obligations. Further, Piedmont classifies such tenant and building improvements into two classes: (i) improvements which incrementally enhance the building's asset value by expanding its revenue generating capacity (“incremental capital expenditures”) and (ii) improvements which maintain the building's existing asset value and its revenue generating capacity (“non-incremental capital expenditures”). As of September 30, 2013, Piedmont anticipates funding potential non-incremental capital expenditures for tenant improvements of approximately $93.7 million related to its existing lease portfolio over the respective lease terms, the majority of which Piedmont estimates may be required to be funded over the next several years. For most of Piedmont’s leases, the timing of the actual funding of these tenant improvements is largely dependent upon tenant requests for reimbursement. In some cases, these obligations may expire with the leases without further recourse to Piedmont.
	Additionally, as of September 30, 2013, commitments for incremental capital expenditures for tenant improvements associated with new leases, primarily at value-add properties, totaled approximately $23.6 million.
	Contingencies Related to Tenant Audits/Disputes
	Certain lease agreements include provisions that grant tenants the right to engage independent auditors to audit their annual operating expense reconciliations. Such audits may result in the re-interpretation of language in the lease agreements which could result in the refund of previously recognized tenant reimbursement revenues, resulting in financial loss to Piedmont. Piedmont recorded additional expense related to such tenant audits/disputes of approximately $0.5 million and $0.2 million during the three months ended September 30, 2013 and September 30, 2012, respectively, and approximately $0.6 million and $0.2 million for the nine months ended September 30, 2013 and September 30, 2012, respectively.
	Letters of Credit
	As of September 30, 2013, Piedmont was subject to the following letters of credit, which reduce the total outstanding capacity under its $500 Million Unsecured Line of Credit:
	Amount		Expiration of Letter of Credit (1)
	$	7,696,548	Jul-14
	$	9,033,164	Jul-14
	$	382,556	Jul-14
	(1)	These letter of credit agreements automatically renew for consecutive, one-year periods each anniversary, subject to the satisfaction of the credit obligation and certain other limitations.

Discontinued_Operations

Discontinued Operations	9 Months Ended
	Sep. 30, 2013
Discontinued Operations and Disposal Groups [Abstract]	'
Discontinued Operations	'
	Discontinued Operations
	Piedmont has classified the results of operations related to the following properties as discontinued operations (in thousands):
	Building(s) Sold		Location		Date of Sale		Gain/(Loss) on Sale				Net Sales Proceeds
	Portland Portfolio(1)		Beaverton, Oregon		March 19, 2012		$	17,823			$	43,832
	26200 Enterprise Way		Lake Forest, California		May 31, 2012		$	10,013			$	24,412
	110 & 112 Hidden Lake Circle Buildings		Duncan, South Carolina		September 21, 2012		$	(259	)		$	25,595
	1111 Durham Avenue		South Plainfield, New Jersey		March 28, 2013		$	(9	)		$	3,752
	1200 Enclave Parkway		Houston, Texas		May 1, 2013		$	16,267			$	45,574
	350 Spectrum Loop(2)		Colorado Springs, Colorado		Held for Sale(2)		N/A				N/A
	(1)	The Portland Portfolio consisted of four office properties known as the Deschutes building, the Rhein building, the Rogue building, and the Willamette building, as well as 18.19 acres of adjoining, undeveloped land.
	(2)	On September 30, 2013, Piedmont entered into a binding agreement to sell the 350 Spectrum Loop building with an expected close in November 2013, and in accordance with GAAP, Piedmont reclassified the building from real estate assets held-for-use to real estate assets held-for-sale on its consolidated balance sheet as of September 30, 2013. As such, Piedmont reclassified the operational results of the property as income from discontinued operations for prior periods to conform with current period presentation.
	Sale of 1111 Durham Avenue building
	In accordance with GAAP during the quarter ended March 31, 2013, Piedmont re-classified the 1111 Durham Avenue building from real estate assets held-for-use (at cost) to real estate assets held for sale (at estimated fair value) and recorded an impairment charge of $6.4 million, which represents the difference in carrying value of the asset at the time the asset met the held for sale criteria. The fair value measurement used in the evaluation of this non-financial asset is considered to be a Level 1 valuation within the fair value hierarchy as defined by GAAP, as there are direct observations and transactions involving the asset. After assessing the age of the building (constructed in 1975) and leasing prospects, Piedmont determined that the sales price should appropriately represent the land value of the asset. As a result, Piedmont disposed of the 1111 Durham Avenue building for a gross sale price of approximately $4.0 million, exclusive of closing costs. The transaction closed on March 28, 2013.
	Assets Held for Sale
	The details comprising assets held for sale, consisting solely of the 350 Spectrum Loop building, are presented below (in thousands):
			September 30, 2013				December 31, 2012
	Real estate assets held for sale, net:
	Land		$	2,185			$	2,186
	Building and improvements, less accumulated depreciation of $6,737 and $6,313 as of September 30, 2013 and December 31, 2012, respectively		16,332				16,755
	Construction in progress		1,217				—
	Total real estate assets held for sale, net		$	19,734			$	18,941
	Other assets held for sale:
	Straight-line rent		$	1,018			$	793
	Deferred lease costs, less accumulated amortization of $78 and $0 as of September 30, 2013 and December 31, 2012, respectively		942				—
	Total other assets held for sale, net		$	1,960			$	793
	Income from Discontinued Operations
	The details comprising income from discontinued operations are presented below (in thousands):
		Three Months Ended								Nine Months Ended
		September 30, 2013				September 30, 2012				September 30, 2013			September 30, 2012
	Revenues:
	Rental income	$	516			$	2,388			$	2,693		$	8,403
	Tenant reimbursements	91				410				650			1,298
		607				2,798				3,343			9,701
	Expenses:
	Property operating costs	316				1,262				1,448			3,834
	Depreciation	141				732				687			2,379
	Amortization	21				159				138			527
	General and administrative	—				38				2			47
		478				2,191				2,275			6,787
	Other income (expense):
	Interest and other income/(expense)	(1		)		—				24			—
	Net recoveries of casualty loss	—				—				17			—
		(1		)		—				41			—
	Operating income, excluding gain/(loss) on sale	128				607				1,109			2,914
	Impairment loss	—				—				(6,402		)	—
	Gain/(loss) on sale of real estate assets	—				(254		)		16,258			27,583
	Income from discontinued operations	$	128			$	353			$	10,965		$	30,497

Stock_Based_Compensation

Stock Based Compensation	9 Months Ended
	Sep. 30, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Stock Based Compensation	'
	Stock Based Compensation
	Deferred Stock Awards
	Piedmont has granted deferred stock awards in the form of restricted stock to its employees. The awards are determined by the Compensation Committee of the board of directors of Piedmont on an annual basis and typically vest over a three-year period beginning on the grant date. In addition, Piedmont has adopted a multi-year performance share program for certain of its employees. Restricted shares are earned based on the relative performance of Piedmont's total stockholder return as compared with a predetermined peer group's total stockholder return over a three-year period. Shares are not awarded until after the end of the third year in the performance period and vest immediately upon award.
	A rollforward of Piedmont's deferred stock award activity for the nine months ended September 30, 2013 is as follows:
		Shares		Weighted-Average Grant Date Fair Value
	Unvested Deferred Stock Awards as of December 31, 2012	318,893		$	18.41
	Deferred Stock Awards Granted During Nine Months Ended September 30, 2013	161,257		$	19.47
	Deferred Stock Awards Vested During Nine Months Ended September 30, 2013	(204,295	)	$	18.93
	Deferred Stock Awards Forfeited During Nine Months Ended September 30, 2013	(2,862	)	$	18.55
	Unvested Deferred Stock Awards as of September 30, 2013	272,993		$	18.64
	The following table provides additional information regarding stock award activity during the three and nine months ended September 30, 2013 and 2012, respectively (in thousands except for per share data):
		Three Months Ended							Nine Months Ended
		September 30,			September 30,				September 30,			September 30,
		2013			2012				2013			2012
	Weighted-Average Grant Date Fair Value of Shares Granted During the Period	$	—		$	17.1			$	19.47		$	17.48
	Total Grant Date Fair Value of Shares Vested During the Period	$	28		$	28			$	3,867		$	5,241
	Share-based Liability Awards Paid During the Period(1)	$	—		$	—			$	103		$	798
	(1)	Amounts reflect the issuance of performance share awards during the period.
	A detail of Piedmont’s outstanding employee deferred stock awards as of September 30, 2013 is as follows:
	Date of grant		Type of Award	Net Shares			Grant				Vesting Schedule	Unvested Shares as of
				Granted (1)			Date Fair					30-Sep-13
							Value
	5-Apr-11		Annual Deferred Stock Award	116,116			$	19.4			Of the shares granted, 25% vested on the date of grant, and 25% vested or will vest on April 5, 2012, 2013, and 2014, respectively.	37,196
	5-Apr-11		Fiscal Year 2011-2013 Performance Share Program	—			$	18.27			Shares awarded, if any, will vest immediately upon determination of award in 2014.	—		(2)
	4-Apr-12		Annual Deferred Stock Award	191,786			$	17.53			Of the shares granted, 25% vested on the date of grant, and 25% will vest on April 4, 2013, 2014, and 2015, respectively.	116,289
	4-Apr-12		Fiscal Year 2012-2014 Performance Share Program	—			$	17.42			Shares awarded, if any, will vest immediately upon determination of award in 2015.	—		(2)
	April 2, 2013		Annual Deferred Stock Award	146,679			$	19.47			Of the shares granted, 25% vested on the date of grant, and 25% will vest on April 2, 2014, 2015, and 2016, respectively.	119,508
	April 2, 2013		Fiscal Year 2013-2015 Performance Share Program	—			$	18.91			Shares awarded, if any, will vest immediately upon determination of award in 2016.	—		(2)
	Total											272,993
	(1)	Amounts reflect the total grant, net of shares surrendered upon vesting to satisfy required minimum tax withholding obligations through September 30, 2013.
	(2)	Estimated based on Piedmont's cumulative total stockholder return ("TSR") for the respective performance period through September 30, 2013. As of September 30, 2013, Piedmont's TSR for each of these respective plans was below threshold. Such estimates are subject to change in future periods based on both Piedmont's and its peers' stock performance and dividends paid.
	During the three months ended September 30, 2013 and 2012, respectively, Piedmont recognized approximately $0.7 million and $0.9 million of compensation expense related to stock awards, all of which related to the amortization of nonvested shares. During the nine months ended September 30, 2013 and 2012, respectively, Piedmont recognized approximately $3.0 million and $3.1 million of compensation expense related to stock awards, of which approximately $1.8 million and $1.8 million relates to the amortization of nonvested shares, respectively. During the nine months ended September 30, 2013, a total of 147,515 shares were issued to employees, directors, and officers. As of September 30, 2013, approximately $2.5 million of unrecognized compensation cost related to nonvested, annual deferred stock awards remained, which Piedmont will record in its consolidated statements of income over a weighted-average vesting period of approximately one year.

Earnings_Per_Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Abstract]	'
Earnings Per Share	'
	Earnings Per Share
	There are no adjustments to “Net income attributable to Piedmont” or “Income from continuing operations” for the diluted earnings per share computations.
	Net income per share-basic is calculated as net income available to common stockholders divided by the weighted average number of common shares outstanding during the period. Net income per share-diluted is calculated as net income available to common stockholders divided by the diluted weighted average number of common shares outstanding during the period, including nonvested restricted stock. Diluted weighted average number of common shares is calculated to reflect the potential dilution under the treasury stock method that would occur as if the remaining unvested restricted stock awards has vested and resulted in additional common shares outstanding.
	The following table reconciles the denominator for the basic and diluted earnings per share computations shown on the consolidated statements of income for the three and nine months ended September 30, 2013 and 2012, respectively (in thousands):
		Three Months Ended		Nine Months Ended
		September 30, 2013	September 30, 2012	September 30, 2013	September 30, 2012
	Weighted-average common shares – basic	164,683	168,806	166,598	171,162
	Plus incremental weighted-average shares from time-vested conversions:
	Restricted stock awards	113	123	136	133
	Weighted-average common shares – diluted	164,796	168,929	166,734	171,295

Guarantor_and_NonGuarantor_Fin

Guarantor and Non-Guarantor Financial Information	9 Months Ended
	Sep. 30, 2013
Guarantor and Non-Guarantor Financial Information [Abstract]	'
Guarantor and Non-Guarantor Financial Information	'
	Guarantor and Non-Guarantor Financial Information
	The following condensed consolidating financial information for Piedmont Operating Partnership, LP (the "Issuer"), Piedmont Office Realty Trust, Inc. (the "Guarantor"), and the other directly and indirectly owned subsidiaries of the Guarantor (the "Non-Guarantor Subsidiaries") is provided pursuant to the requirements of Rule 3-10 of Regulation S-X regarding financial statements of guarantors and issuers of guaranteed registered securities. The principal elimination entries relate to investments in subsidiaries and intercompany balances and transactions, including transactions with the Non-Guarantor Subsidiaries. Additionally, certain reclassifications have been made to the statements presented below to reflect investments in subsidiaries, which had previously been presented on a net basis, on a gross basis. As all investments in subsidiaries are eliminated in consolidation, none of these reclassifications affect the total financial position or net income attributable to Piedmont as presented in previous periods.
	Condensed Consolidated Balance Sheets
	As of September 30, 2013
	(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
	Assets:
	Real estate assets, at cost:
	Land	$	88,054		$	—		$	587,227		$	—		$	675,281
	Buildings and improvements, less accumulated depreciation	492,098			—			2,558,107			(300		)	3,049,905
	Intangible lease assets, less accumulated amortization	2,547			—			64,323			—			66,870
	Construction in progress	2,546			—			58,616			—			61,162
	Real estate assets held for sale, net	19,734			—			—			—			19,734
	Total real estate assets	604,979			—			3,268,273			(300		)	3,872,952
	Investments in and amounts due from unconsolidated joint ventures	18,668			—			—			—			18,668
	Cash and cash equivalents	12,096			146			3,730			—			15,972
	Tenant and straight-line rent receivables, net	35,914			—			130,579			—			166,493
	Advances to affiliates	5,110,420			1,293,461			(1,086,177		)	(5,317,704		)	—
	Investment in subsidiary	—			4,035,964			199			(4,036,163		)	—
	Notes receivable	160,000			2,000			23,890			(185,890		)	—
	Prepaid expenses, restricted cash, escrows, and other assets	5,671			47			13,218			(941		)	17,995
	Goodwill	180,097			—			—			—			180,097
	Interest rate swaps	19,192			—			—			—			19,192
	Deferred financing costs, net	6,703			—			1,287			—			7,990
	Deferred lease costs, net	36,293			—			238,941			—			275,234
	Other assets held for sale, net	1,960			—			—			—			1,960
	Total assets	$	6,191,993		$	5,331,618		$	2,593,940		$	(9,540,998	)	$	4,576,553
	Liabilities:
	Secured and unsecured debt	$	859,540		$	—		$	1,149,525		$	(185,890	)	$	1,823,175
	Accounts payable, accrued expenses, and accrued capital expenditures	20,937			1,360			138,319			(941		)	159,675
	Advances from affiliates	306,636			4,807,113			244,499			(5,358,248		)	—
	Deferred income	8,533			—			18,042			—			26,575
	Intangible lease liabilities, net	6			—			41,429			—			41,435
	Interest rate swaps	5,010			—			—			—			5,010
	Total liabilities	1,200,662			4,808,473			1,591,814			(5,545,079		)	2,055,870
	Stockholders’ Equity:
	Common stock	—			1,613			—			—			1,613
	Additional paid-in capital	4,035,964			3,668,424			199			(4,036,163		)	3,668,424
	Retained/(cumulative distributions in excess of) earnings	940,540			(3,146,892		)	1,000,314			40,244			(1,165,794		)
	Other comprehensive loss	14,827			—			—			—			14,827
	Piedmont stockholders’ equity	4,991,331			523,145			1,000,513			(3,995,919		)	2,519,070
	Noncontrolling interest	—			—			1,613			—			1,613
	Total stockholders’ equity	4,991,331			523,145			1,002,126			(3,995,919		)	2,520,683
	Total liabilities and stockholders’ equity	$	6,191,993		$	5,331,618		$	2,593,940		$	(9,540,998	)	$	4,576,553
	Condensed Consolidated Balance Sheets
	As of December 31, 2012
	(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
	Assets:
	Real estate assets, at cost:
	Land	$	91,782		$	—		$	535,569		$	—		$	627,351
	Buildings and improvements, less accumulated depreciation	511,793			—			2,379,530			—			2,891,323
	Intangible lease assets, less accumulated amortization	3,265			—			51,479			—			54,744
	Construction in progress	1,056			—			19,317			—			20,373
	Real estate assets held for sale, net	18,941			—			—			—			18,941
	Total real estate assets	626,837			—			2,985,895			—			3,612,732
	Investments in and amounts due from unconsolidated joint ventures	37,689			—			—			—			37,689
	Cash and cash equivalents	62,371			238			(49,652		)	—			12,957
	Tenant receivables, net	33,495			—			113,049			—			146,544
	Advances to affiliates	4,623,173			1,300,158			(908,506		)	(5,014,825		)	—
	Investment in subsidiary	—			4,068,844			200			(4,069,044		)	—
	Notes receivable	160,000			2,500			23,890			(186,390		)	—
	Prepaid expenses, restricted cash, escrows, and other assets	4,218			15			10,071			(948		)	13,356
	Goodwill	180,097			—			—			—			180,097
	Interest rate swaps	1,075			—			—			—			1,075
Deferred financing costs, net	4,292			—			2,162			—			6,454
Deferred lease costs, net	31,357			—			211,821			—			243,178
Other assets held for sale, net	793			—			—			—			793
Total assets	$	5,765,397		$	5,371,755		$	2,388,930		$	(9,271,207	)	$	4,254,875
Liabilities:
Secured and unsecured debt	$	452,890		$	—		$	1,150,025		$	(186,390	)	$	1,416,525
Accounts payable, accrued expenses, and accrued capital expenditures	20,443			645			107,123			(948		)	127,263
Advances from affiliates	274,159			4,636,936			135,940			(5,047,035		)	—
Deferred income	5,991			—			15,561			—			21,552
Intangible lease liabilities, net	24			—			40,781						40,805
Interest rate swaps	8,235			—			—			—			8,235
Total liabilities	761,742			4,637,581			1,449,430			(5,234,373		)	1,614,380
Stockholders’ Equity:
Common stock	—			1,676			—			—			1,676
Additional paid-in capital	4,068,844			3,667,051			200			(4,069,044		)	3,667,051
Retained/(cumulative distributions in excess of) earnings	941,971			(2,934,553		)	937,691			32,210			(1,022,681		)
Other comprehensive loss	(7,160		)	—			—			—			(7,160		)
Piedmont stockholders’ equity	5,003,655			734,174			937,891			(4,036,834		)	2,638,886
Noncontrolling interest	—			—			1,609			—			1,609
Total stockholders’ equity	5,003,655			734,174			939,500			(4,036,834		)	2,640,495
Total liabilities and stockholders’ equity	$	5,765,397		$	5,371,755		$	2,388,930		$	(9,271,207	)	$	4,254,875
Condensed Consolidated Statements of Income
For the three months ended September 30, 2013
(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Revenues:
Rental income	$	20,700		$	—		$	97,492		$	(1,382	)	$	116,810
Tenant reimbursements	4,035			—			23,452			(69		)	27,418
Property management fee revenue	—			—			4,003			(3,113		)	890
	24,735			—			124,947			(4,564		)	145,118
Expenses:
Property operating costs	10,939			—			52,597			(4,769		)	58,767
Depreciation	6,068			—			24,717			—			30,785
Amortization	1,353			—			12,525			—			13,878
General and administrative	5,624			64			6,469			(6,316		)	5,841
	23,984			64			96,308			(11,085		)	109,271
Real estate operating income/(loss)	751			(64		)	28,639			6,521			35,847
Other income (expense):
Interest expense	(6,444		)	—			(16,028		)	3,141			(19,331		)
Interest and other income/(expense)	2,262			42			226			(3,141		)	(611		)
Net casualty (loss)/recoveries	(85		)	—			4,004			—			3,919
Equity in income of unconsolidated joint ventures	46			—			—			—			46
Loss on consolidation	(898		)	—			—			—			(898		)
	(5,119		)	42			(11,798		)	—			(16,875		)
Income/(loss) from continuing operations	(4,368		)	(22		)	16,841			6,521			18,972
Discontinued operations:
Operating income/(loss)	131			—			(3		)	—			128
Income/(loss) from discontinued operations	131			—			(3		)	—			128
Net income/(loss)	(4,237		)	(22		)	16,838			6,521			19,100
Less: Net income attributable to noncontrolling interest	—			—			(4		)	—			(4		)
Net income/(loss) attributable to Piedmont	$	(4,237	)	$	(22	)	$	16,834		$	6,521		$	19,096
Condensed Consolidated Statements of Income
For the three months ended September 30, 2012
(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Revenues:
Rental income	$	18,889		$	—		$	87,448		$	(1,389	)	$	104,948
Tenant reimbursements	4,655			—			22,547			(70		)	27,132
Property management fee revenue	—			—			3,634			(3,114		)	520
	23,544			—			113,629			(4,573		)	132,600
Expenses:
Property operating costs	11,279			—			44,006			(4,802		)	50,483
Depreciation	6,200			—			21,721			—			27,921
Amortization	1,378			—			13,787			—			15,165
General and administrative	4,895			84			6,503			(5,974		)	5,508
	23,752			84			86,017			(10,776		)	99,077
Real estate operating income/(loss)	(208		)	(84		)	27,612			6,203			33,523
Other income (expense):
Interest expense	(3,360		)	—			(16,041		)	3,154			(16,247		)
Interest and other income/(expense)	3,245			—			292			(3,154		)	383
Litigation settlement expense	(7,500		)	—			—			—			(7,500		)
Equity in income of unconsolidated joint ventures	323			—			—			—			323
	(7,292		)	—			(15,749		)	—			(23,041		)
Income/(loss) from continuing operations	(7,500		)	(84		)	11,863			6,203			10,482
Discontinued operations:
Operating income	509			—			98			—			607
Loss on sale of real estate assets	(254		)	—			—			—			(254		)
Income from discontinued operations	255			—			98			—			353
Net income/(loss)	(7,245		)	(84		)	11,961			6,203			10,835
Less: Net income attributable to noncontrolling interest	—			—			(4		)	—			(4		)
Net income/(loss) attributable to Piedmont	$	(7,245	)	$	(84	)	$	11,957		$	6,203		$	10,831
Condensed Consolidated Statements of Income
For the nine months ended September 30, 2013
(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Revenues:
Rental income	$	57,754		$	—		$	279,931		$	(3,830	)	$	333,855
Tenant reimbursements	12,018			—			65,357			(207		)	77,168
Property management fee revenue	—			—			11,392			(9,358		)	2,034
	69,772			—			356,680			(13,395		)	413,057
Expenses:
Property operating costs	31,107			—			147,014			(13,701		)	164,420
Depreciation	18,074			—			72,614			—			90,688
Amortization	3,926			—			30,318			—			34,244
General and administrative	16,024			249			18,896			(18,491		)	16,678
	69,131			249			268,842			(32,192		)	306,030
Real estate operating income/(loss)	641			(249		)	87,838			18,797			107,027
Other income (expense):
Interest expense	(15,478		)	—			(47,879		)	9,425			(53,932		)
Interest and other income/(expense)	7,834			128			(497		)	(9,425		)	(1,960		)
Litigation settlement recovery	1,250			—			—			—			1,250
Net casualty (loss)/recoveries	(239		)	—			6,300			—			6,061
Equity in income of unconsolidated joint ventures	604			—			—			—			604
Loss on consolidation	(898		)	—			—			—			(898		)
	(6,927		)	128			(42,076		)	—			(48,875		)
Income/(loss) from continuing operations	(6,286		)	(121		)	45,762			18,797			58,152
Discontinued operations:
Operating income, excluding impairment loss	503			—			606						1,109
Impairment loss	(6,402		)	—			—			—			(6,402		)
Gain/(loss) on sale of real estate assets	(9		)	—			16,267			—			16,258
Income/(loss) from discontinued operations	(5,908		)	—			16,873			—			10,965
Net income/(loss)	(12,194		)	(121		)	62,635			18,797			69,117
Less: Net income attributable to noncontrolling interest	—			—			(12		)	—			(12		)
Net income/(loss) attributable to Piedmont	$	(12,194	)	$	(121	)	$	62,623		$	18,797		$	69,105
Condensed Consolidated Statements of Income
For the nine months ended September 30, 2012
(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Revenues:
Rental income	$	55,272		$	—		$	260,287		$	(3,552	)	$	312,007
Tenant reimbursements	12,774			—			67,727			(211		)	80,290
Property management fee revenue	—			—			10,705			(8,985		)	1,720
	68,046			—			338,719			(12,748		)	394,017
Expenses:
Property operating costs	31,416			—			136,444			(13,292		)	154,568
Depreciation	17,439			—			64,282			—			81,721
Amortization	3,981			—			35,114			—			39,095
General and administrative	14,930			224			18,057			(17,582		)	15,629
	67,766			224			253,897			(30,874		)	291,013
Real estate operating income/(loss)	280			(224		)	84,822			18,126			103,004
Other income (expense):
Interest expense	(9,120		)	—			(48,965		)	9,358			(48,727		)
Interest and other income/(expense)	9,268			—			855			(9,358		)	765
Litigation settlement expense	(7,500		)	—			—			—			(7,500		)
Equity in income of unconsolidated joint ventures	739			—			—			—			739
	(6,613		)	—			(48,110		)	—			(54,723		)
Income/(loss) from continuing operations	(6,333		)	(224		)	36,712			18,126			48,281
Discontinued operations:
Operating income	2,795			—			119			—			2,914
Gain on sale of real estate assets	27,582			—			1			—			27,583
Income from discontinued operations	30,377			—			120			—			30,497
Net income/(loss)	24,044			(224		)	36,832			18,126			78,778
Less: Net income attributable to noncontrolling interest	—			—			(12		)	—			(12		)
Net income/(loss) attributable to Piedmont	$	24,044		$	(224	)	$	36,820		$	18,126		$	78,766
Condensed Consolidated Statements of Cash Flows
For the nine months ended September 30, 2013
(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Net Cash Provided by Operating Activities	$	18,325		$	1,363		$	129,863		$	18,797		$	168,348
Cash Flows from Investing Activities:
Investment in real estate assets and real estate related intangibles, net of accruals	(5,858		)	—			(357,055		)	300			(362,613		)
Intercompany note receivable	—			500			—			(500		)	—
Assets assumed upon acquisition of joint ventures	18,045			—			(32,287		)	—			(14,242		)
Net sales proceeds from wholly-owned properties	3,752			—			45,574			—			49,326
Investments in unconsolidated joint ventures	(793		)	—			—			—			(793		)
Deferred lease costs paid	(10,015		)	—			(18,334		)	—			(28,349		)
Net cash (used in)/provided by investing activities	5,131			500			(362,102		)	(200		)	(356,671		)
Cash Flows from Financing Activities:
Deferred financing costs paid	(3,447		)	—			—			—			(3,447		)
Proceeds from debt	832,603			—			—			—			832,603
Repayments of debt	(426,000		)	—			—			—			(426,000		)
Intercompany note payable	—			—			(500		)	500			—
Costs of issuance of common stock	—			(91		)	—			—			(91		)
Repurchases of common stock as part of announced plan	—			(111,625		)	—			—			(111,625		)
Distributions to/repayments from affiliates	(476,887		)	209,855			286,129			(19,097		)	—
Dividends paid and discount on dividend reinvestments	—			(100,094		)	(8		)	—			(100,102		)
Net cash provided by/(used in) financing activities	(73,731		)	(1,955		)	285,621			(18,597		)	191,338
Net increase/(decrease) in cash and cash equivalents	(50,275		)	(92		)	53,382			—			3,015
Cash and cash equivalents, beginning of period	62,371			238			(49,652		)	—			12,957
Cash and cash equivalents, end of period	$	12,096		$	146		$	3,730		$	—		$	15,972
Condensed Consolidated Statements of Cash Flows
For the nine months ended September 30, 2012
(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Net Cash Provided by Operating Activities	$	748		$	1,527		$	122,202		$	18,126		$	142,603
Cash Flows from Investing Activities:
Investment in real estate assets and real estate related intangibles, net of accruals	(16,558		)	—			(57,878		)	—			(74,436		)
Intercompany note receivable	(3,100		)	—			—			3,100			—
Net sales proceeds from wholly-owned properties	74,845			—			—			—			74,845
Deferred lease costs paid	(2,837		)	—			(36,482		)	—			(39,319		)
Net cash provided by/(used in) investing activities	52,350			—			(94,360		)	3,100			(38,910		)
Cash Flows from Financing Activities:
Deferred financing costs paid	(2,991		)	—			—			—			(2,991		)
Proceeds from debt	365,000			—			—			—			365,000
Repayments of debt	(216,500		)	—			(185,000		)	—			(401,500		)
Intercompany note payable	—			—			3,100			(3,100		)	—
Costs of issuance of common stock	—			(229		)	—			—			(229		)
Repurchases of common stock as part of announced plan	—			(80,130		)	—			—			(80,130		)
Distributions to/repayments from affiliates	(305,743		)	181,605			142,264			(18,126		)	—
Dividends paid and discount on dividend reinvestments	—			(102,762		)	(8		)	—			(102,770		)
Net cash used in financing activities	(160,234		)	(1,516		)	(39,644		)	(21,226		)	(222,620		)
Net (decrease)/increase in cash and cash equivalents	(107,136		)	11			(11,802		)	—			(118,927		)
Cash and cash equivalents, beginning of period	166,920			139			(27,369		)	—			139,690
Cash and cash equivalents, end of period	$	59,784		$	150		$	(39,171	)	$	—		$	20,763

Other_Subsequent_Events

Other Subsequent Events	9 Months Ended
	Sep. 30, 2013
Subsequent Events [Abstract]	'
Other Subsequent Events	'
	Other Subsequent Events
	Fourth Quarter Dividend Declaration
	On October 30, 2013, the board of directors of Piedmont declared dividends for the fourth quarter of 2013 in the amount of $0.20 per common share outstanding to stockholders of record as of the close of business on November 29, 2013. Such dividends are to be paid on December 20, 2013.
	Amendment and Restatement of Stock Repurchase Plan
	Our current stock repurchase plan expires in November of 2013. On October 30, 2013, our board of directors amended and restated the plan to authorize $150 million in stock repurchases over the next two years. Piedmont may repurchase the shares from time to time, in accordance with applicable securities laws, in the open market or in privately negotiated transactions. Repurchases will depend upon market conditions and other factors, and repurchases may be commenced or suspended from time to time in Piedmont's discretion, without prior notice.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2013
Accounting Policies [Abstract]	'
Deferred Lease Costs	'
	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	'
	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	'
	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.

Acquisitions_Tables

Acquisitions (Tables)	9 Months Ended
	Sep. 30, 2013
Business Combinations [Abstract]	'
Schedule of acquired properties	'
	During the nine months ended September 30, 2013, Piedmont acquired the following properties:
	Property		Metropolitan Statistical Area	Date of Acquisition	Rentable Square Feet	Percentage Leased as of Acquisition			Contractual Purchase Price (in millions)
	Arlington Gateway		Washington, D.C.	March 4, 2013	333,948	99		%	$	175.6
	5 & 15 Wayside Road		Boston, MA	March 22, 2013	271,434	95		%	$	69.3
	2020 W. 89th Street	(1)	Kansas City, KS	August 12, 2013	68,376	89		%	$	4.3	(2)
	5301 Maryland Way	(1)	Nashville, TN	August 12, 2013	201,237	100		%	$	18.5	(2)
	4685 Investment Drive	(1)	Detroit, MI	August 12, 2013	77,045	100		%	$	10	(2)
	Land Parcel		Metropolitan Statistical Area	Date of Acquisition	Acreage	Purchase Price (in millions)
	Royal Lane		Dallas, TX	August 1, 2013	10.59	$	2.6
	(1) On August 12, 2013, Piedmont purchased all of the remaining interests in three office properties previously held through two unconsolidated joint ventures for approximately $14.7 million in cash.
	(2) Purchase price represents the estimated fair value of the respective property which was derived by reference to a credible, unrelated third-party offer and verified using discounted cash flow analysis. Under the terms of the respective joint venture agreements, Piedmont exercised its dissenter's right to buy out each of its co-venturers' interests based upon the terms of the third-party offer. The $0.9 million difference between the fair value of the properties acquired and the sum of Piedmont's previously recorded book value in investment in unconsolidated joint ventures plus cash consideration paid for the interests was recorded as a loss on consolidation in Piedmont's consolidated statement of operations for the three months ended September 30, 2013.

Debt_Tables

Debt (Tables)	9 Months Ended
	Sep. 30, 2013
Line of Credit and Notes Payable [Abstract]	'
Schedule of Debt	'
	The following table summarizes the terms of Piedmont’s indebtedness outstanding as of September 30, 2013 and December 31, 2012 (in thousands):
	Facility		Collateral	Rate(1)			Maturity	Amount Outstanding as of
								September 30,		December 31,
								2013		2012
	Secured (Fixed)
	$200.0 Million Mortgage Note		Aon Center	4.87	%		5/1/14	$	200,000	$	200,000
	$25.0 Million Mortgage Note		Aon Center	5.7	%		5/1/14	25,000		25,000
	$350.0 Million Secured Pooled Facility		Nine Property Collateralized	4.84	%		6/7/14	350,000		350,000
			Pool (2)
	$105.0 Million Fixed-Rate Loan		US Bancorp Center	5.29	%		5/11/15	105,000		105,000
	$125.0 Million Fixed-Rate Loan		Four Property Collateralized	5.5	%		4/1/16	125,000		125,000
			Pool (3)
	$42.5 Million Fixed-Rate Loan		Las Colinas Corporate	5.7	%		10/11/16	42,525		42,525
			Center I & II
	$140.0 Million WDC Mortgage Notes		1201 & 1225 Eye Street	5.76	%		11/1/17	140,000		140,000
	Subtotal/Weighted Average (4)			5.17	%			987,525		987,525
	Unsecured (Variable and Fixed)
	$300 Million Unsecured Term Loan			LIBOR +  1.45%		(5)	11/22/16	300,000		300,000
	$500 Million Unsecured Line of Credit			1.36	%	(6)	8/19/16	187,000		129,000
	$350 Million Senior Notes			3.4	%	(7)	6/1/23	348,650		—
	Subtotal/Weighted Average (4)			2.71	%			835,650		429,000
	Total/ Weighted Average (4)			4.04	%			$	1,823,175	$	1,416,525
	(1)	All of Piedmont’s outstanding debt as of September 30, 2013 and December 31, 2012 is interest-only debt.
	(2)	Nine property collateralized pool includes: 1200 Crown Colony Drive, Braker Pointe III, 2 Gatehall Drive, One and Two Independence Square, 2120 West End Avenue, 400 Bridgewater Crossing, 200 Bridgewater Crossing, and Fairway Center II.
	(3)	Four property collateralized pool includes 1430 Enclave Parkway, Windy Point I and II, and 1055 East Colorado Boulevard.
	(4)	Weighted average is based on contractual balance of outstanding debt and interest rates in the table as of September 30, 2013, except for the $350 Million Senior Notes, which were issued at a discount (see footnote 7 below).
	(5)	The $300 Million Unsecured Term Loan has a stated variable rate; however, Piedmont entered into interest rate swap agreements which effectively fix, exclusive of changes to Piedmont's credit rating, the rate on this facility to 2.69%.
	(6)	Piedmont may select from multiple interest rate options with each draw, including the prime rate and various-length LIBOR locks. All LIBOR selections are subject to an additional spread (1.175% as of September 30, 2013) over the selected rate based on Piedmont’s current credit rating. The outstanding balance as of September 30, 2013 consisted of 30-day LIBOR draws ranging from 0.18% to 0.19% (subject to the additional spread mentioned above).
	(7)	The $350 Million Senior Notes have a fixed coupon rate of 3.40%, however, as a result of the issuance of the notes at a discount, Piedmont recognizes an effective interest rate on this debt issuance of 3.45%.

Derivative_Instruments_Tables

Derivative Instruments (Tables)	9 Months Ended
	Sep. 30, 2013
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Schedule of Notional Amounts of Outstanding Derivative Positions	'
	A detail of Piedmont’s interest rate derivatives outstanding as of September 30, 2013 is as follows:
	Interest Rate Derivative	Notional Amount			Effective Date		Maturity Date
		(in millions)
	Interest rate swap	$	125		11/22/11		11/22/16
	Interest rate swap	75			11/22/11		11/22/16
	Interest rate swap	50			11/22/11		11/22/16
	Interest rate swap	50			11/22/11		11/22/16
	Forward starting interest rate swap	70			3/3/14		3/3/24
	Forward starting interest rate swap	70			3/3/14		3/3/24
	Forward starting interest rate swap	70			3/3/14		3/3/24
	Forward starting interest rate swap	70			3/3/14		3/3/24
	Total	$	580
Schedule of Interest Rate Derivatives	'
	A detail of Piedmont’s interest rate derivatives on a gross and net basis as of September 30, 2013 and December 31, 2012, respectively, is as follows (in thousands):
	Interest rate swaps classified as:	September 30,			December 31,
		2013			2012
	Gross derivative assets	$	19,192		$	1,075
	Gross derivative liabilities	(5,010		)	(8,235		)
	Net derivative asset/(liability)	$	14,182		$	(7,160	)
Schedule of Derivative Instruments, Effect on Other Comprehensive Income (Loss)	'
	All of Piedmont's interest rate derivative agreements outstanding for the periods presented were designated as cash flow hedges of interest rate risk. As such, the effective portion of changes in the fair value of these derivatives designated as, and that qualify as, cash flow hedges is recorded in other comprehensive income ("OCI") and is reclassified into earnings as interest expense in the period that the hedged forecasted transaction affects earnings. The effective portion of Piedmont's interest rate derivatives that was recorded in the accompanying consolidated statements of income for the three and nine months ended September 30, 2013 and 2012, respectively, is as follows:
		Three Months Ended						Nine Months Ended
	Derivative in	September 30,			September 30,			September 30,		September 30,
	Cash Flow Hedging	2013			2012			2013		2012
	Relationships (Interest Rate Swaps) (in thousands)
	Amount of gain/(loss) recognized in OCI on derivative	$	(2,201	)	$	(2,756	)	$	19,659	$	(8,628	)
	Amount of previously recorded loss reclassified from accumulated OCI into interest expense	$	783		$	762		$	2,328	$	2,249

Variable_Interest_Entities_Tab

Variable Interest Entities (Tables)	9 Months Ended
	Sep. 30, 2013
Variable Interest Entities [Abstract]	'
Schedule of Variable Interest Entities	'
	A summary of Piedmont’s interests in and consolidation treatment of its VIEs as of September 30, 2013 is as follows (net carrying amount in millions):
	Entity	Piedmont’s	Related	Consolidated/	Net Carrying			Net Carrying			Primary Beneficiary
		%	Building	Unconsolidated	Amount as of			Amount as of			Considerations
		Ownership			30-Sep-13			December 31,
		of Entity						2012
	1201 Eye Street NW Associates, LLC	49.50%	1201 Eye Street	Consolidated	$	(4.5	)	$	(5.7	)	In accordance with the partnership’s governing documents, Piedmont is entitled to 100% of the cash flow of the entity and has sole discretion in directing the management and leasing activities of the building.
	1225 Eye Street NW Associates, LLC	49.50%	1225 Eye Street	Consolidated	$	(0.4	)	$	(0.1	)	In accordance with the partnership’s governing documents, Piedmont is entitled to 100% of the cash flow of the entity and has sole discretion in directing the management and leasing activities of the building.
	Piedmont 500 W. Monroe Fee, LLC	100%	500 W. Monroe	Consolidated	$	228		$	194		The Omnibus Agreement with the previous owner includes equity participation rights for the previous owner, if certain financial returns are achieved; however, Piedmont has sole decision making authority and is entitled to the economic benefits of the property until such returns are met.
	Suwanee Gateway One, LLC	100%	Suwanee Gateway One	Consolidated	$	7.4		$	7.6		The fee agreement includes equity participation rights for the incentive manager, if certain returns on investment are achieved; however, Piedmont has sole decision making authority and is entitled to the economic benefits of the property until such returns are met.
	Medici Atlanta, LLC	100%	The Medici	Consolidated	$	14.5		$	13.7		The fee agreement includes equity participation rights for the incentive manager, if certain returns on investment are achieved; however, Piedmont has sole decision making authority and is entitled to the economic benefits of the property until such returns are met.
	400 TownPark, LLC	100%	400 TownPark	Consolidated	$	22.1		$	23.5		The fee agreement includes equity participation rights for the incentive manager, if certain returns on investment are achieved; however, Piedmont has sole decision making authority and is entitled to the economic benefits of the property until such returns are met.

Fair_Value_Measurement_of_Fina1

Fair Value Measurement of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2013
Fair Value Measurement of Financial Instruments [Abstract]	'
Fair Value, by Balance Sheet Grouping	'
	The following table sets forth the carrying and estimated fair value for each of Piedmont’s financial instruments, as well as its level within the GAAP fair value hierarchy, as of September 30, 2013 and December 31, 2012, respectively (in thousands):
		September 30, 2013					December 31, 2012
	Financial Instrument	Carrying Value		Estimated Fair Value		Level Within Fair Value Hierarchy	Carrying Value		Estimated Fair Value		Level Within Fair Value Hierarchy
	Assets:
	Cash and cash equivalents(1)	$	15,972	$	15,972	Level 1	$	12,957	$	12,957	Level 1
	Tenant receivables, net(1)	$	31,006	$	31,006	Level 1	$	25,038	$	25,038	Level 1
	Restricted cash and escrows(1)	$	385	$	385	Level 1	$	334	$	334	Level 1
	Interest rate swap asset	$	19,192	$	19,192	Level 2	$	1,075	$	1,075	Level 2
	Liabilities:
	Accounts payable and accrued expenses(1)	$	22,229	$	22,229	Level 1	$	23,113	$	23,113	Level 1
	Interest rate swap liability	$	5,010	$	5,010	Level 2	$	8,235	$	8,235	Level 2
	Debt	$	1,823,175	$	1,836,413	Level 2	$	1,416,525	$	1,470,002	Level 2
	(1)	For the periods presented, the carrying value of these financial instruments approximates estimated fair value due to their short-term maturity.

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2013
Commitments and Contingencies Disclosure [Abstract]	'
Schedule of Letters of Credit	'
	As of September 30, 2013, Piedmont was subject to the following letters of credit, which reduce the total outstanding capacity under its $500 Million Unsecured Line of Credit:
	Amount		Expiration of Letter of Credit (1)
	$	7,696,548	Jul-14
	$	9,033,164	Jul-14
	$	382,556	Jul-14
	(1)	These letter of credit agreements automatically renew for consecutive, one-year periods each anniversary, subject to the satisfaction of the credit obligation and certain other limitations.

Discontinued_Operations_Tables

Discontinued Operations (Tables)	9 Months Ended
	Sep. 30, 2013
Discontinued Operations and Disposal Groups [Abstract]	'
Schedule of Disposal Groups, Including Discontinued Operations, Results Of Operations	'
	Piedmont has classified the results of operations related to the following properties as discontinued operations (in thousands):
	Building(s) Sold		Location		Date of Sale		Gain/(Loss) on Sale				Net Sales Proceeds
	Portland Portfolio(1)		Beaverton, Oregon		March 19, 2012		$	17,823			$	43,832
	26200 Enterprise Way		Lake Forest, California		May 31, 2012		$	10,013			$	24,412
	110 & 112 Hidden Lake Circle Buildings		Duncan, South Carolina		September 21, 2012		$	(259	)		$	25,595
	1111 Durham Avenue		South Plainfield, New Jersey		March 28, 2013		$	(9	)		$	3,752
	1200 Enclave Parkway		Houston, Texas		May 1, 2013		$	16,267			$	45,574
	350 Spectrum Loop(2)		Colorado Springs, Colorado		Held for Sale(2)		N/A				N/A
	(1)	The Portland Portfolio consisted of four office properties known as the Deschutes building, the Rhein building, the Rogue building, and the Willamette building, as well as 18.19 acres of adjoining, undeveloped land.
	(2)	On September 30, 2013, Piedmont entered into a binding agreement to sell the 350 Spectrum Loop building with an expected close in November 2013, and in accordance with GAAP, Piedmont reclassified the building from real estate assets held-for-use to real estate assets held-for-sale on its consolidated balance sheet as of September 30, 2013. As such, Piedmont reclassified the operational results of the property as income from discontinued operations for prior periods to conform with current period presentation.
Disclosure of Long Lived Assets Held-for-sale	'
	The details comprising assets held for sale, consisting solely of the 350 Spectrum Loop building, are presented below (in thousands):
			September 30, 2013				December 31, 2012
	Real estate assets held for sale, net:
	Land		$	2,185			$	2,186
	Building and improvements, less accumulated depreciation of $6,737 and $6,313 as of September 30, 2013 and December 31, 2012, respectively		16,332				16,755
	Construction in progress		1,217				—
	Total real estate assets held for sale, net		$	19,734			$	18,941
	Other assets held for sale:
	Straight-line rent		$	1,018			$	793
	Deferred lease costs, less accumulated amortization of $78 and $0 as of September 30, 2013 and December 31, 2012, respectively		942				—
	Total other assets held for sale, net		$	1,960			$	793
Schedule of Disposal Groups, Including Discontinued Operations, Income Statement, Balance Sheet and Additional Disclosures	'
	The details comprising income from discontinued operations are presented below (in thousands):
		Three Months Ended								Nine Months Ended
		September 30, 2013				September 30, 2012				September 30, 2013			September 30, 2012
	Revenues:
	Rental income	$	516			$	2,388			$	2,693		$	8,403
	Tenant reimbursements	91				410				650			1,298
		607				2,798				3,343			9,701
	Expenses:
	Property operating costs	316				1,262				1,448			3,834
	Depreciation	141				732				687			2,379
	Amortization	21				159				138			527
	General and administrative	—				38				2			47
		478				2,191				2,275			6,787
	Other income (expense):
	Interest and other income/(expense)	(1		)		—				24			—
	Net recoveries of casualty loss	—				—				17			—
		(1		)		—				41			—
	Operating income, excluding gain/(loss) on sale	128				607				1,109			2,914
	Impairment loss	—				—				(6,402		)	—
	Gain/(loss) on sale of real estate assets	—				(254		)		16,258			27,583
	Income from discontinued operations	$	128			$	353			$	10,965		$	30,497

Stock_Based_Compensation_Table

Stock Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Schedule of Nonvested Share Activity	'
	A rollforward of Piedmont's deferred stock award activity for the nine months ended September 30, 2013 is as follows:
		Shares		Weighted-Average Grant Date Fair Value
	Unvested Deferred Stock Awards as of December 31, 2012	318,893		$	18.41
	Deferred Stock Awards Granted During Nine Months Ended September 30, 2013	161,257		$	19.47
	Deferred Stock Awards Vested During Nine Months Ended September 30, 2013	(204,295	)	$	18.93
	Deferred Stock Awards Forfeited During Nine Months Ended September 30, 2013	(2,862	)	$	18.55
	Unvested Deferred Stock Awards as of September 30, 2013	272,993		$	18.64
	The following table provides additional information regarding stock award activity during the three and nine months ended September 30, 2013 and 2012, respectively (in thousands except for per share data):
		Three Months Ended							Nine Months Ended
		September 30,			September 30,				September 30,			September 30,
		2013			2012				2013			2012
	Weighted-Average Grant Date Fair Value of Shares Granted During the Period	$	—		$	17.1			$	19.47		$	17.48
	Total Grant Date Fair Value of Shares Vested During the Period	$	28		$	28			$	3,867		$	5,241
	Share-based Liability Awards Paid During the Period(1)	$	—		$	—			$	103		$	798
	(1)	Amounts reflect the issuance of performance share awards during the period.
Schedule of Outstanding Employee Deferred Stock Awards	'
	A detail of Piedmont’s outstanding employee deferred stock awards as of September 30, 2013 is as follows:
	Date of grant		Type of Award	Net Shares			Grant				Vesting Schedule	Unvested Shares as of
				Granted (1)			Date Fair					30-Sep-13
							Value
	5-Apr-11		Annual Deferred Stock Award	116,116			$	19.4			Of the shares granted, 25% vested on the date of grant, and 25% vested or will vest on April 5, 2012, 2013, and 2014, respectively.	37,196
	5-Apr-11		Fiscal Year 2011-2013 Performance Share Program	—			$	18.27			Shares awarded, if any, will vest immediately upon determination of award in 2014.	—		(2)
	4-Apr-12		Annual Deferred Stock Award	191,786			$	17.53			Of the shares granted, 25% vested on the date of grant, and 25% will vest on April 4, 2013, 2014, and 2015, respectively.	116,289
	4-Apr-12		Fiscal Year 2012-2014 Performance Share Program	—			$	17.42			Shares awarded, if any, will vest immediately upon determination of award in 2015.	—		(2)
	April 2, 2013		Annual Deferred Stock Award	146,679			$	19.47			Of the shares granted, 25% vested on the date of grant, and 25% will vest on April 2, 2014, 2015, and 2016, respectively.	119,508
	April 2, 2013		Fiscal Year 2013-2015 Performance Share Program	—			$	18.91			Shares awarded, if any, will vest immediately upon determination of award in 2016.	—		(2)
	Total											272,993
	(1)	Amounts reflect the total grant, net of shares surrendered upon vesting to satisfy required minimum tax withholding obligations through September 30, 2013.
	(2)	Estimated based on Piedmont's cumulative total stockholder return ("TSR") for the respective performance period through September 30, 2013. As of September 30, 2013, Piedmont's TSR for each of these respective plans was below threshold. Such estimates are subject to change in future periods based on both Piedmont's and its peers' stock performance and dividends paid.

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Abstract]	'
Schedule of Weighted Average Number of Shares	'
	The following table reconciles the denominator for the basic and diluted earnings per share computations shown on the consolidated statements of income for the three and nine months ended September 30, 2013 and 2012, respectively (in thousands):
		Three Months Ended		Nine Months Ended
		September 30, 2013	September 30, 2012	September 30, 2013	September 30, 2012
	Weighted-average common shares – basic	164,683	168,806	166,598	171,162
	Plus incremental weighted-average shares from time-vested conversions:
	Restricted stock awards	113	123	136	133
	Weighted-average common shares – diluted	164,796	168,929	166,734	171,295

Guarantor_and_NonGuarantor_Fin1

Guarantor and Non-Guarantor Financial Information (Tables)	9 Months Ended
	Sep. 30, 2013
Guarantor and Non-Guarantor Financial Information [Abstract]	'
Condensed Consolidated Balance Sheets	'
	Condensed Consolidated Balance Sheets
	As of September 30, 2013
	(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
	Assets:
	Real estate assets, at cost:
	Land	$	88,054		$	—		$	587,227		$	—		$	675,281
	Buildings and improvements, less accumulated depreciation	492,098			—			2,558,107			(300		)	3,049,905
	Intangible lease assets, less accumulated amortization	2,547			—			64,323			—			66,870
	Construction in progress	2,546			—			58,616			—			61,162
	Real estate assets held for sale, net	19,734			—			—			—			19,734
	Total real estate assets	604,979			—			3,268,273			(300		)	3,872,952
	Investments in and amounts due from unconsolidated joint ventures	18,668			—			—			—			18,668
	Cash and cash equivalents	12,096			146			3,730			—			15,972
	Tenant and straight-line rent receivables, net	35,914			—			130,579			—			166,493
	Advances to affiliates	5,110,420			1,293,461			(1,086,177		)	(5,317,704		)	—
	Investment in subsidiary	—			4,035,964			199			(4,036,163		)	—
	Notes receivable	160,000			2,000			23,890			(185,890		)	—
	Prepaid expenses, restricted cash, escrows, and other assets	5,671			47			13,218			(941		)	17,995
	Goodwill	180,097			—			—			—			180,097
	Interest rate swaps	19,192			—			—			—			19,192
	Deferred financing costs, net	6,703			—			1,287			—			7,990
	Deferred lease costs, net	36,293			—			238,941			—			275,234
	Other assets held for sale, net	1,960			—			—			—			1,960
	Total assets	$	6,191,993		$	5,331,618		$	2,593,940		$	(9,540,998	)	$	4,576,553
	Liabilities:
	Secured and unsecured debt	$	859,540		$	—		$	1,149,525		$	(185,890	)	$	1,823,175
	Accounts payable, accrued expenses, and accrued capital expenditures	20,937			1,360			138,319			(941		)	159,675
	Advances from affiliates	306,636			4,807,113			244,499			(5,358,248		)	—
	Deferred income	8,533			—			18,042			—			26,575
	Intangible lease liabilities, net	6			—			41,429			—			41,435
	Interest rate swaps	5,010			—			—			—			5,010
	Total liabilities	1,200,662			4,808,473			1,591,814			(5,545,079		)	2,055,870
	Stockholders’ Equity:
	Common stock	—			1,613			—			—			1,613
	Additional paid-in capital	4,035,964			3,668,424			199			(4,036,163		)	3,668,424
	Retained/(cumulative distributions in excess of) earnings	940,540			(3,146,892		)	1,000,314			40,244			(1,165,794		)
	Other comprehensive loss	14,827			—			—			—			14,827
	Piedmont stockholders’ equity	4,991,331			523,145			1,000,513			(3,995,919		)	2,519,070
	Noncontrolling interest	—			—			1,613			—			1,613
	Total stockholders’ equity	4,991,331			523,145			1,002,126			(3,995,919		)	2,520,683
	Total liabilities and stockholders’ equity	$	6,191,993		$	5,331,618		$	2,593,940		$	(9,540,998	)	$	4,576,553
	Condensed Consolidated Balance Sheets
	As of December 31, 2012
	(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
	Assets:
	Real estate assets, at cost:
	Land	$	91,782		$	—		$	535,569		$	—		$	627,351
	Buildings and improvements, less accumulated depreciation	511,793			—			2,379,530			—			2,891,323
	Intangible lease assets, less accumulated amortization	3,265			—			51,479			—			54,744
	Construction in progress	1,056			—			19,317			—			20,373
	Real estate assets held for sale, net	18,941			—			—			—			18,941
	Total real estate assets	626,837			—			2,985,895			—			3,612,732
	Investments in and amounts due from unconsolidated joint ventures	37,689			—			—			—			37,689
	Cash and cash equivalents	62,371			238			(49,652		)	—			12,957
	Tenant receivables, net	33,495			—			113,049			—			146,544
	Advances to affiliates	4,623,173			1,300,158			(908,506		)	(5,014,825		)	—
	Investment in subsidiary	—			4,068,844			200			(4,069,044		)	—
	Notes receivable	160,000			2,500			23,890			(186,390		)	—
	Prepaid expenses, restricted cash, escrows, and other assets	4,218			15			10,071			(948		)	13,356
	Goodwill	180,097			—			—			—			180,097
	Interest rate swaps	1,075			—			—			—			1,075
	Deferred financing costs, net	4,292			—			2,162			—			6,454
	Deferred lease costs, net	31,357			—			211,821			—			243,178
Other assets held for sale, net	793			—			—			—			793
Total assets	$	5,765,397		$	5,371,755		$	2,388,930		$	(9,271,207	)	$	4,254,875
Liabilities:
Secured and unsecured debt	$	452,890		$	—		$	1,150,025		$	(186,390	)	$	1,416,525
Accounts payable, accrued expenses, and accrued capital expenditures	20,443			645			107,123			(948		)	127,263
Advances from affiliates	274,159			4,636,936			135,940			(5,047,035		)	—
Deferred income	5,991			—			15,561			—			21,552
Intangible lease liabilities, net	24			—			40,781						40,805
Interest rate swaps	8,235			—			—			—			8,235
Total liabilities	761,742			4,637,581			1,449,430			(5,234,373		)	1,614,380
Stockholders’ Equity:
Common stock	—			1,676			—			—			1,676
Additional paid-in capital	4,068,844			3,667,051			200			(4,069,044		)	3,667,051
Retained/(cumulative distributions in excess of) earnings	941,971			(2,934,553		)	937,691			32,210			(1,022,681		)
Other comprehensive loss	(7,160		)	—			—			—			(7,160		)
Piedmont stockholders’ equity	5,003,655			734,174			937,891			(4,036,834		)	2,638,886
Noncontrolling interest	—			—			1,609			—			1,609
Total stockholders’ equity	5,003,655			734,174			939,500			(4,036,834		)	2,640,495
Total liabilities and stockholders’ equity	$	5,765,397		$	5,371,755		$	2,388,930		$	(9,271,207	)	$	4,254,875
Condensed Consolidated Statements of Income	'
	Condensed Consolidated Statements of Income
	For the three months ended September 30, 2013
	(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
	Revenues:
	Rental income	$	20,700		$	—		$	97,492		$	(1,382	)	$	116,810
	Tenant reimbursements	4,035			—			23,452			(69		)	27,418
	Property management fee revenue	—			—			4,003			(3,113		)	890
		24,735			—			124,947			(4,564		)	145,118
	Expenses:
	Property operating costs	10,939			—			52,597			(4,769		)	58,767
	Depreciation	6,068			—			24,717			—			30,785
	Amortization	1,353			—			12,525			—			13,878
	General and administrative	5,624			64			6,469			(6,316		)	5,841
		23,984			64			96,308			(11,085		)	109,271
	Real estate operating income/(loss)	751			(64		)	28,639			6,521			35,847
	Other income (expense):
	Interest expense	(6,444		)	—			(16,028		)	3,141			(19,331		)
	Interest and other income/(expense)	2,262			42			226			(3,141		)	(611		)
	Net casualty (loss)/recoveries	(85		)	—			4,004			—			3,919
	Equity in income of unconsolidated joint ventures	46			—			—			—			46
	Loss on consolidation	(898		)	—			—			—			(898		)
		(5,119		)	42			(11,798		)	—			(16,875		)
	Income/(loss) from continuing operations	(4,368		)	(22		)	16,841			6,521			18,972
	Discontinued operations:
	Operating income/(loss)	131			—			(3		)	—			128
	Income/(loss) from discontinued operations	131			—			(3		)	—			128
	Net income/(loss)	(4,237		)	(22		)	16,838			6,521			19,100
	Less: Net income attributable to noncontrolling interest	—			—			(4		)	—			(4		)
	Net income/(loss) attributable to Piedmont	$	(4,237	)	$	(22	)	$	16,834		$	6,521		$	19,096
	Condensed Consolidated Statements of Income
	For the three months ended September 30, 2012
	(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
	Revenues:
	Rental income	$	18,889		$	—		$	87,448		$	(1,389	)	$	104,948
	Tenant reimbursements	4,655			—			22,547			(70		)	27,132
	Property management fee revenue	—			—			3,634			(3,114		)	520
		23,544			—			113,629			(4,573		)	132,600
	Expenses:
	Property operating costs	11,279			—			44,006			(4,802		)	50,483
	Depreciation	6,200			—			21,721			—			27,921
	Amortization	1,378			—			13,787			—			15,165
	General and administrative	4,895			84			6,503			(5,974		)	5,508
		23,752			84			86,017			(10,776		)	99,077
	Real estate operating income/(loss)	(208		)	(84		)	27,612			6,203			33,523
	Other income (expense):
	Interest expense	(3,360		)	—			(16,041		)	3,154			(16,247		)
	Interest and other income/(expense)	3,245			—			292			(3,154		)	383
	Litigation settlement expense	(7,500		)	—			—			—			(7,500		)
	Equity in income of unconsolidated joint ventures	323			—			—			—			323
		(7,292		)	—			(15,749		)	—			(23,041		)
	Income/(loss) from continuing operations	(7,500		)	(84		)	11,863			6,203			10,482
	Discontinued operations:
	Operating income	509			—			98			—			607
	Loss on sale of real estate assets	(254		)	—			—			—			(254		)
	Income from discontinued operations	255			—			98			—			353
	Net income/(loss)	(7,245		)	(84		)	11,961			6,203			10,835
	Less: Net income attributable to noncontrolling interest	—			—			(4		)	—			(4		)
	Net income/(loss) attributable to Piedmont	$	(7,245	)	$	(84	)	$	11,957		$	6,203		$	10,831
	Condensed Consolidated Statements of Income
	For the nine months ended September 30, 2013
	(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
	Revenues:
	Rental income	$	57,754		$	—		$	279,931		$	(3,830	)	$	333,855
Tenant reimbursements	12,018			—			65,357			(207		)	77,168
Property management fee revenue	—			—			11,392			(9,358		)	2,034
	69,772			—			356,680			(13,395		)	413,057
Expenses:
Property operating costs	31,107			—			147,014			(13,701		)	164,420
Depreciation	18,074			—			72,614			—			90,688
Amortization	3,926			—			30,318			—			34,244
General and administrative	16,024			249			18,896			(18,491		)	16,678
	69,131			249			268,842			(32,192		)	306,030
Real estate operating income/(loss)	641			(249		)	87,838			18,797			107,027
Other income (expense):
Interest expense	(15,478		)	—			(47,879		)	9,425			(53,932		)
Interest and other income/(expense)	7,834			128			(497		)	(9,425		)	(1,960		)
Litigation settlement recovery	1,250			—			—			—			1,250
Net casualty (loss)/recoveries	(239		)	—			6,300			—			6,061
Equity in income of unconsolidated joint ventures	604			—			—			—			604
Loss on consolidation	(898		)	—			—			—			(898		)
	(6,927		)	128			(42,076		)	—			(48,875		)
Income/(loss) from continuing operations	(6,286		)	(121		)	45,762			18,797			58,152
Discontinued operations:
Operating income, excluding impairment loss	503			—			606						1,109
Impairment loss	(6,402		)	—			—			—			(6,402		)
Gain/(loss) on sale of real estate assets	(9		)	—			16,267			—			16,258
Income/(loss) from discontinued operations	(5,908		)	—			16,873			—			10,965
Net income/(loss)	(12,194		)	(121		)	62,635			18,797			69,117
Less: Net income attributable to noncontrolling interest	—			—			(12		)	—			(12		)
Net income/(loss) attributable to Piedmont	$	(12,194	)	$	(121	)	$	62,623		$	18,797		$	69,105
Condensed Consolidated Statements of Income
For the nine months ended September 30, 2012
(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Revenues:
Rental income	$	55,272		$	—		$	260,287		$	(3,552	)	$	312,007
Tenant reimbursements	12,774			—			67,727			(211		)	80,290
Property management fee revenue	—			—			10,705			(8,985		)	1,720
	68,046			—			338,719			(12,748		)	394,017
Expenses:
Property operating costs	31,416			—			136,444			(13,292		)	154,568
Depreciation	17,439			—			64,282			—			81,721
Amortization	3,981			—			35,114			—			39,095
General and administrative	14,930			224			18,057			(17,582		)	15,629
	67,766			224			253,897			(30,874		)	291,013
Real estate operating income/(loss)	280			(224		)	84,822			18,126			103,004
Other income (expense):
Interest expense	(9,120		)	—			(48,965		)	9,358			(48,727		)
Interest and other income/(expense)	9,268			—			855			(9,358		)	765
Litigation settlement expense	(7,500		)	—			—			—			(7,500		)
Equity in income of unconsolidated joint ventures	739			—			—			—			739
	(6,613		)	—			(48,110		)	—			(54,723		)
Income/(loss) from continuing operations	(6,333		)	(224		)	36,712			18,126			48,281
Discontinued operations:
Operating income	2,795			—			119			—			2,914
Gain on sale of real estate assets	27,582			—			1			—			27,583
Income from discontinued operations	30,377			—			120			—			30,497
Net income/(loss)	24,044			(224		)	36,832			18,126			78,778
Less: Net income attributable to noncontrolling interest	—			—			(12		)	—			(12		)
Net income/(loss) attributable to Piedmont	$	24,044		$	(224	)	$	36,820		$	18,126		$	78,766
Condensed Consolidated Statements of Cash Flows	'
	Condensed Consolidated Statements of Cash Flows
	For the nine months ended September 30, 2013
	(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
	Net Cash Provided by Operating Activities	$	18,325		$	1,363		$	129,863		$	18,797		$	168,348
	Cash Flows from Investing Activities:
	Investment in real estate assets and real estate related intangibles, net of accruals	(5,858		)	—			(357,055		)	300			(362,613		)
	Intercompany note receivable	—			500			—			(500		)	—
	Assets assumed upon acquisition of joint ventures	18,045			—			(32,287		)	—			(14,242		)
	Net sales proceeds from wholly-owned properties	3,752			—			45,574			—			49,326
	Investments in unconsolidated joint ventures	(793		)	—			—			—			(793		)
	Deferred lease costs paid	(10,015		)	—			(18,334		)	—			(28,349		)
	Net cash (used in)/provided by investing activities	5,131			500			(362,102		)	(200		)	(356,671		)
	Cash Flows from Financing Activities:
	Deferred financing costs paid	(3,447		)	—			—			—			(3,447		)
	Proceeds from debt	832,603			—			—			—			832,603
	Repayments of debt	(426,000		)	—			—			—			(426,000		)
	Intercompany note payable	—			—			(500		)	500			—
	Costs of issuance of common stock	—			(91		)	—			—			(91		)
	Repurchases of common stock as part of announced plan	—			(111,625		)	—			—			(111,625		)
	Distributions to/repayments from affiliates	(476,887		)	209,855			286,129			(19,097		)	—
	Dividends paid and discount on dividend reinvestments	—			(100,094		)	(8		)	—			(100,102		)
	Net cash provided by/(used in) financing activities	(73,731		)	(1,955		)	285,621			(18,597		)	191,338
	Net increase/(decrease) in cash and cash equivalents	(50,275		)	(92		)	53,382			—			3,015
	Cash and cash equivalents, beginning of period	62,371			238			(49,652		)	—			12,957
	Cash and cash equivalents, end of period	$	12,096		$	146		$	3,730		$	—		$	15,972
	Condensed Consolidated Statements of Cash Flows
	For the nine months ended September 30, 2012
	(in thousands)	Issuer			Guarantor			Non-Guarantor Subsidiaries			Eliminations			Consolidated
	Net Cash Provided by Operating Activities	$	748		$	1,527		$	122,202		$	18,126		$	142,603
	Cash Flows from Investing Activities:
	Investment in real estate assets and real estate related intangibles, net of accruals	(16,558		)	—			(57,878		)	—			(74,436		)
	Intercompany note receivable	(3,100		)	—			—			3,100			—
	Net sales proceeds from wholly-owned properties	74,845			—			—			—			74,845
	Deferred lease costs paid	(2,837		)	—			(36,482		)	—			(39,319		)
	Net cash provided by/(used in) investing activities	52,350			—			(94,360		)	3,100			(38,910		)
	Cash Flows from Financing Activities:
	Deferred financing costs paid	(2,991		)	—			—			—			(2,991		)
	Proceeds from debt	365,000			—			—			—			365,000
	Repayments of debt	(216,500		)	—			(185,000		)	—			(401,500		)
	Intercompany note payable	—			—			3,100			(3,100		)	—
	Costs of issuance of common stock	—			(229		)	—			—			(229		)
	Repurchases of common stock as part of announced plan	—			(80,130		)	—			—			(80,130		)
	Distributions to/repayments from affiliates	(305,743		)	181,605			142,264			(18,126		)	—
	Dividends paid and discount on dividend reinvestments	—			(102,762		)	(8		)	—			(102,770		)
	Net cash used in financing activities	(160,234		)	(1,516		)	(39,644		)	(21,226		)	(222,620		)
	Net (decrease)/increase in cash and cash equivalents	(107,136		)	11			(11,802		)	—			(118,927		)
	Cash and cash equivalents, beginning of period	166,920			139			(27,369		)	—			139,690
	Cash and cash equivalents, end of period	$	59,784		$	150		$	(39,171	)	$	—		$	20,763

Organization_Details

Organization (Details)	0 Months Ended	9 Months Ended
	9-May-13	Sep. 30, 2013	Aug. 12, 2013
		subsidiary	property
		area
Real Estate Properties [Line Items]	'	'	'
Number of wholly-owned subsidiaries	'	2	'
Percentage ownership by sole general partner	100.00%	99.90%	'
Percentage ownership by sole limited partner	'	0.10%	'
Number of real estate properties	'	'	3
Number of metropolitan areas	'	18	'
Unconsolidated Joint Venture [Member]	'	'	'
Real Estate Properties [Line Items]	'	'	'
Number of real estate properties	'	2	'
Office properties [Member]	'	'	'
Real Estate Properties [Line Items]	'	'	'
Number of real estate properties	'	77	'
Square footage of real estate property	'	21,100,000	'
Percentage Leased as of Acquisition	'	86.70%	'

Summary_of_Significant_Account2

Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Details) (Minimum [Member])	9 Months Ended
	Sep. 30, 2013
Minimum [Member]	'
Income Tax For Real Estate Investment Trusts [Line Items]	'
Real estate investment trust status required taxable income distribution rate	90.00%

Acquisitions_Details

Acquisitions (Details) (USD $)

0 Months Ended

3 Months Ended

9 Months Ended

Aug. 12, 2013

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Mar. 04, 2013

Mar. 22, 2013

Aug. 12, 2013

Aug. 12, 2013

Aug. 12, 2013

Aug. 01, 2013

property

Arlington Gateway [Member]

Wayside, 5 and 15 [Member]

20/20 [Member]

5301 Maryland Way [Member]

4685 Investment Drive [Member]

Royal Lane [Member]

Joint_Venture

sqft

sqft

sqft

sqft

sqft

acre

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Rentable Square Feet

'

'

'

'

'

333,948

271,434

68,376

201,237

77,045

'

Acreage

'

'

'

'

'

'

'

'

'

'

10.59

Number of real estate properties

3

'

'

'

'

'

'

'

'

'

'

Number of unconsolidated joint venture partnerships

2

'

'

'

'

'

'

'

'

'

'

Percentage Leased as of Acquisition

'

'

'

'

'

99.00%

95.00%

89.00%

100.00%

100.00%

'

Purchase Price

'

'

'

'

'

$175,600,000

$69,300,000

$4,300,000

[1]

$18,500

[1]

$10,000

[1]

$2,600,000

Amount purchased of remaining minority interest

14,700,000

'

'

'

'

'

'

'

'

'

'

Loss on consolidation

'

($898,000)

$0

($898,000)

$0

'

'

'

'

'

'

[1]

Purchase price represents the estimated fair value of the respective property which was derived by reference to a credible, unrelated third-party offer and verified using discounted cash flow analysis. Under the terms of the respective joint venture agreements, Piedmont exercised its dissenter's right to buy out each of its co-venturers' interests based upon the terms of the third-party offer. The $0.9 million difference between the fair value of the properties acquired and the sum of Piedmont's previously recorded book value in investment in unconsolidated joint ventures plus cash consideration paid for the interests was recorded as a loss on consolidation in Piedmont's consolidated statement of operations for the three months ended September 30, 2013.

Debt_Narrative_Details

Debt (Narrative) (Details) (USD $)	0 Months Ended	3 Months Ended			9 Months Ended
	9-May-13	Sep. 30, 2013		Sep. 30, 2012	Sep. 30, 2013		Sep. 30, 2012
Debt Instrument [Line Items]	'	'		'	'		'
Percentage ownership in operating partnership	100.00%	'		'	99.90%		'
Settlement of forward starting interest rate swaps	'	'		'	($672,000)		$0
Interest payments on debt facilities	'	15,500,000		15,700,000	47,300,000		47,100,000
Interest Costs Capitalized	'	'		'	0		'
Senior Notes [Member] | $350 Million Senior Notes [Member]	'	'		'	'		'
Debt Instrument [Line Items]	'	'		'	'		'
Face amount of debt instument	350,000,000	350,000,000		'	350,000,000		'
Rate	'	3.40%	[1],[2]	'	3.40%	[1],[2]	'
Proceeds from debt	348,600,000	'		'	'		'
Discount on notes payable	1,400,000	'		'	'		'
Term of notes	'10 years	'		'	'		'
Senior Notes [Member] | $350 Million Senior Notes [Member] | Forward Starting Interest Rate Swap [Member]	'	'		'	'		'
Debt Instrument [Line Items]	'	'		'	'		'
Number of Interest Rate Derivatives Settled During the Period	'	'		'	2		'
Notional amount of forward starting swap agreements	250,000,000	'		'	'		'
Settlement of forward starting interest rate swaps	700,000	'		'	'		'
Senior Notes [Member] | $350 Million Senior Notes [Member] | Forward Starting Rate Swap 1 [Member]	'	'		'	'		'
Debt Instrument [Line Items]	'	'		'	'		'
Notional amount of forward starting swap agreements	220,000,000	'		'	'		'
Senior Notes [Member] | $350 Million Senior Notes [Member] | Forward Starting Rate Swap 2 [Member]	'	'		'	'		'
Debt Instrument [Line Items]	'	'		'	'		'
Notional amount of forward starting swap agreements	30,000,000	'		'	'		'
Unsecured Debt [Member] | $500 Million Unsecured Line of Credit [Member]	'	'		'	'		'
Debt Instrument [Line Items]	'	'		'	'		'
Face amount of debt instument	'	500,000,000		'	500,000,000		'
Net borrowings	'	'		'	484,000,000		'
Repayments	'	'		'	426,000,000		'
Borrowing capacity of line of credit	'	$500,000,000		'	$500,000,000		'
[1]	The $350 Million Senior Notes have a fixed coupon rate of 3.40%, however, as a result of the issuance of the notes at a discount, Piedmont recognizes an effective interest rate on this debt issuance of 3.45%.
[2]	All of Piedmont’s outstanding debt as of September 30, 2013 and December 31, 2012 is interest-only debt.

Debt_Details

Debt (Details) (USD $)	Sep. 30, 2013		9-May-13	Dec. 31, 2012
Debt Instrument [Line Items]	'		'	'
Weighted Average Rate	4.04%	[1],[2]	'	'
Amount Outstanding	$1,823,175,000	[2]	'	$1,416,525,000	[2]
Secured Debt [Member]	'		'	'
Debt Instrument [Line Items]	'		'	'
Weighted Average Rate	5.17%	[1],[2]	'	'
Amount Outstanding	987,525,000	[2]	'	987,525,000	[2]
Unsecured Debt [Member]	'		'	'
Debt Instrument [Line Items]	'		'	'
Weighted Average Rate	2.71%	[1],[2]	'	'
Amount Outstanding	835,650,000	[2]	'	429,000,000	[2]
Mortgage Note $200 Million [Member] | Secured Debt [Member]	'		'	'
Debt Instrument [Line Items]	'		'	'
Rate	4.87%	[1]	'	'
Amount Outstanding	200,000,000		'	200,000,000
Face amount of debt instument	200,000,000		'	'
Mortgage Note $25 Million [Member] | Secured Debt [Member]	'		'	'
Debt Instrument [Line Items]	'		'	'
Rate	5.70%	[1]	'	'
Amount Outstanding	25,000,000		'	25,000,000
Face amount of debt instument	25,000,000		'	'
Secured Pooled Facility [Member] | Secured Debt [Member]	'		'	'
Debt Instrument [Line Items]	'		'	'
Rate	4.84%	[1],[3]	'	'
Amount Outstanding	350,000,000		'	350,000,000
Number of properties in collateralized pool	9		'	'
Face amount of debt instument	350,000,000		'	'
Fixed-Rate $105 Million Loan [Member] | Secured Debt [Member]	'		'	'
Debt Instrument [Line Items]	'		'	'
Rate	5.29%	[1]	'	'
Amount Outstanding	105,000,000		'	105,000,000
Face amount of debt instument	105,000,000		'	'
Fixed-Rate $125 Million Loan [Member] | Secured Debt [Member]	'		'	'
Debt Instrument [Line Items]	'		'	'
Rate	5.50%	[1],[4]	'	'
Amount Outstanding	125,000,000		'	125,000,000
Number of properties in collateralized pool	4		'	'
Face amount of debt instument	125,000,000		'	'
Fixed-Rate $42.5 Million Loan [Member] | Secured Debt [Member]	'		'	'
Debt Instrument [Line Items]	'		'	'
Rate	5.70%	[1]	'	'
Amount Outstanding	42,525,000		'	42,525,000
Face amount of debt instument	42,500,000		'	'
WDC Mortgage Notes $140 Million[Member] | Secured Debt [Member]	'		'	'
Debt Instrument [Line Items]	'		'	'
Rate	5.76%	[1]	'	'
Amount Outstanding	140,000,000		'	140,000,000
Face amount of debt instument	140,000,000		'	'
$300 Million Unsecured Term Loan [Member] | Unsecured Debt [Member]	'		'	'
Debt Instrument [Line Items]	'		'	'
Amount Outstanding	300,000,000		'	300,000,000
Face amount of debt instument	300,000,000		'	'
Basis spread on variable rate	1.45%	[1],[5]	'	'
$500 Million Unsecured Line of Credit [Member] | Unsecured Debt [Member]	'		'	'
Debt Instrument [Line Items]	'		'	'
Line of credit, effective interest rate	1.36%	[1],[6]	'	'
Amount Outstanding	187,000,000		'	129,000,000
Face amount of debt instument	500,000,000		'	'
Borrowing capacity of line of credit	500,000,000		'	'
$500 Million Unsecured Line of Credit [Member] | Unsecured Debt [Member] | Minimum [Member]	'		'	'
Debt Instrument [Line Items]	'		'	'
LIBOR rate in effect	0.18%		'	'
$500 Million Unsecured Line of Credit [Member] | Unsecured Debt [Member] | Maximum [Member]	'		'	'
Debt Instrument [Line Items]	'		'	'
LIBOR rate in effect	0.19%		'	'
$350 Million Senior Notes [Member] | Senior Notes [Member]	'		'	'
Debt Instrument [Line Items]	'		'	'
Rate	3.40%	[1],[7]	'	'
Amount Outstanding	348,650,000		'	0
Face amount of debt instument	$350,000,000		$350,000,000	'
Effective interest rate	3.45%	[1]	'	'
Interest Rate Swap [Member] | $300 Million Unsecured Term Loan [Member] | Unsecured Debt [Member]	'		'	'
Debt Instrument [Line Items]	'		'	'
Effective interest rate	2.69%		'	'
LIBOR [Member] | $500 Million Unsecured Line of Credit [Member] | Unsecured Debt [Member]	'		'	'
Debt Instrument [Line Items]	'		'	'
Basis spread on variable rate	1.18%		'	'
[1]	All of Piedmont’s outstanding debt as of September 30, 2013 and December 31, 2012 is interest-only debt.
[2]	Weighted average is based on contractual balance of outstanding debt and interest rates in the table as of September 30, 2013, except for the $350 Million Senior Notes, which were issued at a discount (see footnote 7 below).
[3]	Nine property collateralized pool includes: 1200 Crown Colony Drive, Braker Pointe III, 2 Gatehall Drive, One and Two Independence Square, 2120 West End Avenue, 400 Bridgewater Crossing, 200 Bridgewater Crossing, and Fairway Center II.
[4]	Four property collateralized pool includes 1430 Enclave Parkway, Windy Point I and II, and 1055 East Colorado Boulevard.
[5]	The $300 Million Unsecured Term Loan has a stated variable rate; however, Piedmont entered into interest rate swap agreements which effectively fix, exclusive of changes to Piedmont's credit rating, the rate on this facility to 2.69%.
[6]	Piedmont may select from multiple interest rate options with each draw, including the prime rate and various-length LIBOR locks. All LIBOR selections are subject to an additional spread (1.175% as of September 30, 2013) over the selected rate based on Piedmont’s current credit rating. The outstanding balance as of September 30, 2013 consisted of 30-day LIBOR draws ranging from 0.18% to 0.19% (subject to the additional spread mentioned above).
[7]	The $350 Million Senior Notes have a fixed coupon rate of 3.40%, however, as a result of the issuance of the notes at a discount, Piedmont recognizes an effective interest rate on this debt issuance of 3.45%.

Derivative_Instruments_Details

Derivative Instruments (Details) (USD $)

9 Months Ended

3 Months Ended

9 Months Ended

12 Months Ended

0 Months Ended

0 Months Ended

9 Months Ended

Sep. 30, 2013

Sep. 30, 2012

Dec. 31, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

9-May-13

Sep. 30, 2013

9-May-13

Sep. 30, 2013

Interest Rate Swap [Member]

Interest Rate Swap [Member]

Interest Rate Swap [Member]

Interest Rate Swap [Member]

Interest Rate Swap 1 [Member]

Interest Rate Swap 2 [Member]

Interest Rate Swap 3 [Member]

Interest Rate Swap 4 [Member]

Forward Starting Interest Rate Swap [Member]

Forward Starting Interest Rate Swap 3 [Member]

Forward Starting Interest Rate Swap 4 [Member]

Forward Starting Interest Rate Swap 5 [Member]

Forward Starting Interest Rate Swap 6 [Member]

Credit Risk Contract [Member]

Debt [Member]

Unsecured Debt [Member]

Senior Notes [Member]

Senior Notes [Member]

Senior Notes [Member]

Senior Notes [Member]

Interest Expense [Member]

Interest Expense [Member]

Interest Expense [Member]

Interest Expense [Member]

contract

$300 Million Unsecured Term Loan [Member]

$350 Million Senior Notes [Member]

$350 Million Senior Notes [Member]

$350 Million Senior Notes [Member]

$350 Million Senior Notes [Member]

contract

Forward Starting Interest Rate Swap [Member]

Forward Starting Interest Rate Swap [Member]

agreement

Derivative [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of forward starting swaps

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4

'

'

'

'

Total notional value of forward starting swap agreements

$580,000,000

'

'

'

'

'

'

$125,000,000

$75,000,000

$50,000,000

$50,000,000

$530,000,000

$70,000,000

$70,000,000

$70,000,000

$70,000,000

'

'

$300,000,000

'

'

'

'

Face amount of debt instument

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

300,000,000

350,000,000

350,000,000

'

'

Total Number of Interest Rate Derivatives Entered During the Period

'

'

'

'

'

'

'

'

'

'

'

6

'

'

'

'

'

'

'

'

'

'

'

Number of Interest Rate Derivatives Settled During the Period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2

Notional amount of forward starting swap agreements

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

250,000,000

'

Settlement of forward starting interest rate swaps

-672,000

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

700,000

'

Term of notes

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'10 years

'

'

'

Hedged amount associated with potential issuance of long-term debt

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

280,000,000

'

'

'

'

'

Derivative, term of contract

'126 months

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Interest Rate Cash Flow Hedge Derivative at Fair Value, Net [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Gross derivative assets

19,192,000

'

1,075,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Gross derivative liabilities

-5,010,000

'

-8,235,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net derivative asset/(liability)

14,182,000

'

-7,160,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Amount of gain/(loss) recognized in OCI on derivative

'

'

'

-2,201,000

-2,756,000

19,659,000

-8,628,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Amount of previously recorded loss reclassified from accumulated OCI into interest expense

'

'

'

783,000

762,000

2,328,000

2,249,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Loss to be reclassified from accumulated other comprehensive loss to interest expense over next twelve months

5,900,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Assets needed for immediate settlement, aggregate fair value

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$5,100,000

'

'

'

'

'

'

Variable_Interest_Entities_Det

Variable Interest Entities (Details) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Eye Street 1201 NW Associates LLC [Member]	'	'
Variable Interest Entity [Line Items]	'	'
Piedmont’s % Ownership of Entity	49.50%	'
Net Carrying Amount	($4.50)	($5.70)
Variable interst entity, cash flow percent entitled to entity	100.00%	'
Eye Street 1225 NW Associates LLC [Member]	'	'
Variable Interest Entity [Line Items]	'	'
Piedmont’s % Ownership of Entity	49.50%	'
Net Carrying Amount	-0.4	-0.1
Variable interst entity, cash flow percent entitled to entity	100.00%	'
Piedmont 500 W. Monroe Fee LLC [Member]	'	'
Variable Interest Entity [Line Items]	'	'
Piedmont’s % Ownership of Entity	100.00%	'
Net Carrying Amount	228	194
Suwanee Gateway One LLC [Member]	'	'
Variable Interest Entity [Line Items]	'	'
Piedmont’s % Ownership of Entity	100.00%	'
Net Carrying Amount	7.4	7.6
Medici Atlanta LLC [Member]	'	'
Variable Interest Entity [Line Items]	'	'
Piedmont’s % Ownership of Entity	100.00%	'
Net Carrying Amount	14.5	13.7
TownPark 400, LLC [Member]	'	'
Variable Interest Entity [Line Items]	'	'
Piedmont’s % Ownership of Entity	100.00%	'
Net Carrying Amount	$22.10	$23.50

Fair_Value_Measurement_of_Fina2

Fair Value Measurement of Financial Instruments (Details) (USD $)	Sep. 30, 2013		Dec. 31, 2012
In Thousands, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Interest rate swaps	$19,192		$1,075
Interest rate swap liability	5,010		8,235
Carrying Value [Member]	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Cash and cash equivalents	15,972	[1]	12,957	[1]
Tenant receivables, net	31,006	[1]	25,038	[1]
Restricted cash and escrows	385	[1]	334	[1]
Interest rate swaps	19,192		1,075
Accounts payable and accrued expenses	22,229	[1]	23,113	[1]
Debt	1,823,175		1,416,525
Interest Rate Swap [Member] | Carrying Value [Member]	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Interest rate swap liability	5,010		8,235
Level 1 [Member] | Estimated Fair Value [Member]	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Cash and cash equivalents	15,972	[1]	12,957	[1]
Tenant receivables, net	31,006	[1]	25,038	[1]
Restricted cash and escrows	385	[1]	334	[1]
Accounts payable and accrued expenses	22,229	[1]	23,113	[1]
Level 2 [Member] | Estimated Fair Value [Member]	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Interest rate swaps	19,192		1,075
Debt	1,836,413		1,470,002
Level 2 [Member] | Interest Rate Swap [Member] | Estimated Fair Value [Member]	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Interest rate swap liability	$5,010		$8,235
[1]	For the periods presented, the carrying value of these financial instruments approximates estimated fair value due to their short-term maturity.

Commitments_and_Contingencies_1

Commitments and Contingencies (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Loss Contingencies [Line Items]	'	'	'	'
Letter of credit, renewal period	'	'	'1 year	'
Letter of Credit 1, July 2013 [Member]	'	'	'	'
Loss Contingencies [Line Items]	'	'	'	'
Letters of credit outstanding	$7,696,547.95	'	$7,696,547.95	'
Letter of Credit 2, July 2013 [Member]	'	'	'	'
Loss Contingencies [Line Items]	'	'	'	'
Letters of credit outstanding	9,033,164	'	9,033,164	'
Letter of Credit 3, July 2013 [Member]	'	'	'	'
Loss Contingencies [Line Items]	'	'	'	'
Letters of credit outstanding	382,556	'	382,556	'
Tenant Audits and Disputes [Member]	'	'	'	'
Loss Contingencies [Line Items]	'	'	'	'
Tenant audit dispute expense	500,000	200,000	600,000	200,000
Unsecured Debt [Member] | $500 Million Unsecured Line of Credit [Member]	'	'	'	'
Loss Contingencies [Line Items]	'	'	'	'
Face amount of debt instument	500,000,000	'	500,000,000	'
Non-Incremental Capital Expenditures [Member]	'	'	'	'
Loss Contingencies [Line Items]	'	'	'	'
Potential obligations for tenant improvements	93,700,000	'	93,700,000	'
Incremental Capital Expenditures [Member]	'	'	'	'
Loss Contingencies [Line Items]	'	'	'	'
Potential obligations for tenant improvements	$23,600,000	'	$23,600,000	'

Discontinued_Operations_Detail

Discontinued Operations (Details) (USD $)	3 Months Ended		9 Months Ended		0 Months Ended					3 Months Ended	0 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Mar. 19, 2012		31-May-12	Sep. 21, 2012	Mar. 28, 2013	Mar. 31, 2013	1-May-13
					Portland Portfolio [Member]		26200 Enterprise Way [Member]	110 & 112 Hidden Lake Circle Buildings [Member]	1111 Durham Avenue [Member]	1111 Durham Avenue [Member]	1200 Enclave Parkway [Member]
					property
					acre
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'	'	'	'		'	'	'	'	'
Gain/(Loss) on Sale	$0	($254,000)	$16,258,000	$27,583,000	$17,823,000	[1]	$10,013,000	($259,000)	($9,000)	'	$16,267,000
Net Sales Proceeds	'	'	49,326,000	74,845,000	43,832,000	[1]	24,412,000	25,595,000	3,752,000	'	45,574,000
Number of Real Estate Properties Sold	'	'	'	'	4		'	'	'	'	'
Area of Land (in acres)	'	'	'	'	18.19		'	'	'	'	'
Impairment loss	0	0	-6,402,000	0	'		'	'	'	-6,400,000	'
Sale price	'	'	'	'	'		'	'	4,000,000	'	'
Revenues:	'	'	'	'	'		'	'	'	'	'
Rental income	516,000	2,388,000	2,693,000	8,403,000	'		'	'	'	'	'
Tenant reimbursements	91,000	410,000	650,000	1,298,000	'		'	'	'	'	'
Revenue	607,000	2,798,000	3,343,000	9,701,000	'		'	'	'	'	'
Expenses:	'	'	'	'	'		'	'	'	'	'
Property operating costs	316,000	1,262,000	1,448,000	3,834,000	'		'	'	'	'	'
Depreciation	141,000	732,000	687,000	2,379,000	'		'	'	'	'	'
Amortization	21,000	159,000	138,000	527,000	'		'	'	'	'	'
General and administrative	0	38,000	2,000	47,000	'		'	'	'	'	'
Expenses	478,000	2,191,000	2,275,000	6,787,000	'		'	'	'	'	'
Other income (expense):	'	'	'	'	'		'	'	'	'	'
Interest and other income/(expense)	-1,000	0	24,000	0	'		'	'	'	'	'
Net recoveries of casualty loss	0	0	17,000	0	'		'	'	'	'	'
Other income (expense)	-1,000	0	41,000	0	'		'	'	'	'	'
Operating income, excluding gain/(loss) on sale	128,000	607,000	1,109,000	2,914,000	'		'	'	'	'	'
Income from discontinued operations	$128,000	$353,000	$10,965,000	$30,497,000	'		'	'	'	'	'
[1]	The Portland Portfolio consisted of four office properties known as the Deschutes building, the Rhein building, the Rogue building, and the Willamette building, as well as 18.19 acres of adjoining, undeveloped land.

Discontinued_Operations_Discon

Discontinued Operations Discontinued Operations - Assets Held-for-Sale (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'
Real estate assets held for sale, net	$19,734	$18,941
Other assets held for sale, net	1,960	793
350 Spectrum Loop building [Member]	'	'
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'
Real estate assets held for sale, net	19,734	18,941
Straight-line rent	1,018	793
Deferred lease costs, less accumulated amortization of $78 and $0 as of September 30, 2013 and December 31, 2012, respectively	942	0
Accumulated amortization on deferred lease costs	78	0
Other assets held for sale, net	1,960	793
Land [Member] | 350 Spectrum Loop building [Member]	'	'
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'
Real estate assets held for sale, net	2,185	2,186
Building and improvements [Member] | 350 Spectrum Loop building [Member]	'	'
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'
Real estate assets held for sale, net	16,332	16,755
Accumulated depreciation (building improvements)	6,737	6,313
Construction in progress [Member] | 350 Spectrum Loop building [Member]	'	'
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'
Real estate assets held for sale, net	$1,217	$0

Stock_Based_Compensation_Rollf

Stock Based Compensation (Rollforward of Deferred Stock Awards) (Details) (Stock Awards [Member], USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Stock Awards [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]	'	'	'	'
Unvested Deferred Stock Awards, Beginning of period (in shares)	'	'	318,893	'
Deferred Stock Awards Granted (in shares)	'	'	161,257	'
Deferred Stock Awards Vested (in shares)	'	'	-204,295	'
Deferred Stock Awards Forfeited (in shares)	'	'	-2,862	'
Unvested Deferred Stock Awards, End of period (in shares)	272,993	'	272,993	'
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]	'	'	'	'
Unvested Deferred Stock Awards, Weighted-Average Grant Date Fair Value, Beginning of period (in dollars per share)	'	'	$18.41	'
Deferred Stock Awards Granted, Weighted-Average Grant Date Fair Value (in dollars per share)	$0	$17.10	$19.47	$17.48
Deferred Stock Awards Vested, Weighted-Average Grant Date Fair Value (in dollars per share)	'	'	$18.93	'
Deferred Stock Awards Forfeited, Weighted-Average Grant Date Fair Value (in dollars per share)	'	'	$18.55	'
Unvested Deferred Stock Awards, Weighted-Average Grant Date Fair Value, End of period (in dollars per share)	$18.64	'	$18.64	'

Stock_Based_Compensation_Addit

Stock Based Compensation (Additional Information Regarding Stock Award Activity) (Details) (Stock Awards [Member], USD $)	3 Months Ended				9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Stock Awards [Member]	'		'		'		'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'		'		'		'
Weighted-Average Grant Date Fair Value of Shares Granted During the Period	$0		$17.10		$19.47		$17.48
Total Grant Date Fair Value of Shares Vested During the Period	$28		$28		$3,867		$5,241
Share-based Liability Awards Paid During the Period	$0	[1]	$0	[1]	$103	[1]	$798	[1]
[1]	Amounts reflect the issuance of performance share awards during the period.

Stock_Based_Compensation_Outst

Stock Based Compensation (Outstanding Employee Deferred Stock Awards) (Details) (USD $)

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Apr. 05, 2011

Sep. 30, 2013

Apr. 05, 2011

Sep. 30, 2013

Apr. 04, 2012

Sep. 30, 2013

Apr. 04, 2012

Sep. 30, 2013

Apr. 02, 2013

Sep. 30, 2013

Apr. 02, 2013

Stock Awards [Member]

Stock Awards [Member]

Stock Awards, Granted April 5, 2011 [Member]

Stock Awards, Granted April 5, 2011 [Member]

Stock Awards 2, Granted April 5, 2011 [Member]

Stock Awards 2, Granted April 5, 2011 [Member]

Stock Awards 1, Granted April 4, 2012 [Member]

Stock Awards 1, Granted April 4, 2012 [Member]

Stock Awards 2, Granted April 4, 2012 [Member]

Stock Awards 2, Granted April 4, 2012 [Member]

Stock Awards, Granted April 2, 2013 [Member]

Stock Awards, Granted April 2, 2013 [Member]

Stock Awards 2, Granted April 2, 2013 [Member]

Stock Awards 2, Granted April 2, 2013 [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net Shares Granted

'

'

'

116,116

[1]

'

0

[1]

'

191,786

[1]

'

0

[1]

'

146,679

[1]

'

0

[1]

Grant Date Fair Value

$18.64

$18.41

'

$19.40

'

$18.27

'

$17.53

'

$17.42

'

$19.47

'

$18.91

Of the shares granted, % vested

'

'

25.00%

'

'

'

25.00%

'

'

'

25.00%

'

'

'

Of the shares granted, % expected to vest in one year

'

'

25.00%

'

'

'

25.00%

'

'

'

25.00%

'

'

'

Of the shares granted, % expected to vest in two years

'

'

25.00%

'

'

'

25.00%

'

'

'

25.00%

'

'

'

Of the shares granted, % expected to vest in three years

'

'

25.00%

'

'

'

25.00%

'

'

'

25.00%

'

'

'

Unvested Shares

272,993

318,893

37,196

'

0

[2]

'

116,289

'

0

[2]

'

119,508

'

0

[2]

'

[1]

Amounts reflect the total grant, net of shares surrendered upon vesting to satisfy required minimum tax withholding obligations through September 30, 2013.

[2]

Estimated based on Piedmont's cumulative total stockholder return ("TSR") for the respective performance period through September 30, 2013. As of September 30, 2013, Piedmont's TSR for each of these respective plans was below threshold. Such estimates are subject to change in future periods based on both Piedmont's and its peers' stock performance and dividends paid.

Stock_Based_Compensation_Narra

Stock Based Compensation (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, except Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Compensation expense related to stock awards	$0.70	$0.90	$3	$3.10
Total shares issued to employees, directors, and officers	'	'	147,515	'
Unrecognized compensation cost related to nonvested	2.5	'	2.5	'
Unrecognized compensation cost related to nonvested, weighted-average vesting period (in years)	'	'	'1 year	'
Amortization of Nonvested Shares [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Compensation expense related to stock awards	'	'	$1.80	$1.80
Stock Awards [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Award vesting period (in years)	'	'	'3 years	'
Period of predetermined peer group's total stockholder return	'	'	'3 years	'

Earnings_Per_Share_Details

Earnings Per Share (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]	'	'	'	'
Weighted-average common shares – basic	164,683,173	168,805,589	166,597,577	171,162,281
Restricted stock awards (in shares)	113,102	123,450	136,887	132,817
Weighted-average common shares – diluted	164,796,275	168,929,039	166,734,464	171,295,098

Guarantor_and_NonGuarantor_Fin2

Guarantor and Non-Guarantor Financial Information - Condensed Consolidated Balance Sheets (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified
Assets:	'	'	'	'
Land	$675,281	$627,351	'	'
Buildings and improvements, less accumulated depreciation	3,049,905	2,891,323	'	'
Intangible lease assets, less accumulated amortization	66,870	54,744	'	'
Construction in progress	61,162	20,373	'	'
Real estate assets held for sale, net	19,734	18,941	'	'
Total real estate assets	3,872,952	3,612,732	'	'
Investments in and amounts due from unconsolidated joint ventures	18,668	37,689	'	'
Cash and cash equivalents	15,972	12,957	20,763	139,690
Tenant and straight-line rent receivables, net	166,493	146,544	'	'
Advances to affiliates	0	0	'	'
Investment in subsidiary	0	0	'	'
Notes receivable	0	0	'	'
Prepaid expenses, restricted cash, escrows, and other assets	17,995	13,356	'	'
Goodwill	180,097	180,097	'	'
Interest rate swaps	19,192	1,075	'	'
Deferred financing costs, net	7,990	6,454	'	'
Deferred lease costs, net	275,234	243,178	'	'
Other assets held for sale, net	1,960	793	'	'
Total assets	4,576,553	4,254,875	'	'
Liabilities:	'	'	'	'
Secured and unsecured debt	1,823,175	1,416,525	'	'
Accounts payable, accrued expenses, and accrued capital expenditures	159,675	127,263	'	'
Advances from affiliates	0	0	'	'
Deferred income	26,575	21,552	'	'
Intangible lease liabilities, net	41,435	40,805	'	'
Interest rate swaps	5,010	8,235	'	'
Total liabilities	2,055,870	1,614,380	'	'
Stockholders’ Equity:	'	'	'	'
Common stock	1,613	1,676	'	'
Additional paid-in capital	3,668,424	3,667,051	'	'
Cumulative distributions in excess of earnings	-1,165,794	-1,022,681	'	'
Other comprehensive income/(loss)	14,827	-7,160	'	'
Piedmont stockholders’ equity	2,519,070	2,638,886	'	'
Noncontrolling interest	1,613	1,609	'	'
Total stockholders’ equity	2,520,683	2,640,495	'	2,773,428
Total liabilities and stockholders’ equity	4,576,553	4,254,875	'	'
Issuer [Member]	'	'	'	'
Assets:	'	'	'	'
Land	88,054	91,782	'	'
Buildings and improvements, less accumulated depreciation	492,098	511,793	'	'
Intangible lease assets, less accumulated amortization	2,547	3,265	'	'
Construction in progress	2,546	1,056	'	'
Real estate assets held for sale, net	19,734	18,941	'	'
Total real estate assets	604,979	626,837	'	'
Investments in and amounts due from unconsolidated joint ventures	18,668	37,689	'	'
Cash and cash equivalents	12,096	62,371	59,784	166,920
Tenant and straight-line rent receivables, net	35,914	33,495	'	'
Advances to affiliates	5,110,420	4,623,173	'	'
Investment in subsidiary	0	0	'	'
Notes receivable	160,000	160,000	'	'
Prepaid expenses, restricted cash, escrows, and other assets	5,671	4,218	'	'
Goodwill	180,097	180,097	'	'
Interest rate swaps	19,192	1,075	'	'
Deferred financing costs, net	6,703	4,292	'	'
Deferred lease costs, net	36,293	31,357	'	'
Other assets held for sale, net	1,960	793	'	'
Total assets	6,191,993	5,765,397	'	'
Liabilities:	'	'	'	'
Secured and unsecured debt	859,540	452,890	'	'
Accounts payable, accrued expenses, and accrued capital expenditures	20,937	20,443	'	'
Advances from affiliates	306,636	274,159	'	'
Deferred income	8,533	5,991	'	'
Intangible lease liabilities, net	6	24	'	'
Interest rate swaps	5,010	8,235	'	'
Total liabilities	1,200,662	761,742	'	'
Stockholders’ Equity:	'	'	'	'
Common stock	0	0	'	'
Additional paid-in capital	4,035,964	4,068,844	'	'
Cumulative distributions in excess of earnings	940,540	941,971	'	'
Other comprehensive income/(loss)	14,827	-7,160	'	'
Piedmont stockholders’ equity	4,991,331	5,003,655	'	'
Noncontrolling interest	0	0	'	'
Total stockholders’ equity	4,991,331	5,003,655	'	'
Total liabilities and stockholders’ equity	6,191,993	5,765,397	'	'
Guarantor [Member]	'	'	'	'
Assets:	'	'	'	'
Land	0	0	'	'
Buildings and improvements, less accumulated depreciation	0	0	'	'
Intangible lease assets, less accumulated amortization	0	0	'	'
Construction in progress	0	0	'	'
Real estate assets held for sale, net	0	0	'	'
Total real estate assets	0	0	'	'
Investments in and amounts due from unconsolidated joint ventures	0	0	'	'
Cash and cash equivalents	146	238	150	139
Tenant and straight-line rent receivables, net	0	0	'	'
Advances to affiliates	1,293,461	1,300,158	'	'
Investment in subsidiary	4,035,964	4,068,844	'	'
Notes receivable	2,000	2,500	'	'
Prepaid expenses, restricted cash, escrows, and other assets	47	15	'	'
Goodwill	0	0	'	'
Interest rate swaps	0	0	'	'
Deferred financing costs, net	0	0	'	'
Deferred lease costs, net	0	0	'	'
Other assets held for sale, net	0	0	'	'
Total assets	5,331,618	5,371,755	'	'
Liabilities:	'	'	'	'
Secured and unsecured debt	0	0	'	'
Accounts payable, accrued expenses, and accrued capital expenditures	1,360	645	'	'
Advances from affiliates	4,807,113	4,636,936	'	'
Deferred income	0	0	'	'
Intangible lease liabilities, net	0	0	'	'
Interest rate swaps	0	0	'	'
Total liabilities	4,808,473	4,637,581	'	'
Stockholders’ Equity:	'	'	'	'
Common stock	1,613	1,676	'	'
Additional paid-in capital	3,668,424	3,667,051	'	'
Cumulative distributions in excess of earnings	-3,146,892	-2,934,553	'	'
Other comprehensive income/(loss)	0	0	'	'
Piedmont stockholders’ equity	523,145	734,174	'	'
Noncontrolling interest	0	0	'	'
Total stockholders’ equity	523,145	734,174	'	'
Total liabilities and stockholders’ equity	5,331,618	5,371,755	'	'
Non-Guarantor Subsidiaries [Member]	'	'	'	'
Assets:	'	'	'	'
Land	587,227	535,569	'	'
Buildings and improvements, less accumulated depreciation	2,558,107	2,379,530	'	'
Intangible lease assets, less accumulated amortization	64,323	51,479	'	'
Construction in progress	58,616	19,317	'	'
Real estate assets held for sale, net	0	0	'	'
Total real estate assets	3,268,273	2,985,895	'	'
Investments in and amounts due from unconsolidated joint ventures	0	0	'	'
Cash and cash equivalents	3,730	-49,652	-39,171	-27,369
Tenant and straight-line rent receivables, net	130,579	113,049	'	'
Advances to affiliates	-1,086,177	-908,506	'	'
Investment in subsidiary	199	200	'	'
Notes receivable	23,890	23,890	'	'
Prepaid expenses, restricted cash, escrows, and other assets	13,218	10,071	'	'
Goodwill	0	0	'	'
Interest rate swaps	0	0	'	'
Deferred financing costs, net	1,287	2,162	'	'
Deferred lease costs, net	238,941	211,821	'	'
Other assets held for sale, net	0	0	'	'
Total assets	2,593,940	2,388,930	'	'
Liabilities:	'	'	'	'
Secured and unsecured debt	1,149,525	1,150,025	'	'
Accounts payable, accrued expenses, and accrued capital expenditures	138,319	107,123	'	'
Advances from affiliates	244,499	135,940	'	'
Deferred income	18,042	15,561	'	'
Intangible lease liabilities, net	41,429	40,781	'	'
Interest rate swaps	0	0	'	'
Total liabilities	1,591,814	1,449,430	'	'
Stockholders’ Equity:	'	'	'	'
Common stock	0	0	'	'
Additional paid-in capital	199	200	'	'
Cumulative distributions in excess of earnings	1,000,314	937,691	'	'
Other comprehensive income/(loss)	0	0	'	'
Piedmont stockholders’ equity	1,000,513	937,891	'	'
Noncontrolling interest	1,613	1,609	'	'
Total stockholders’ equity	1,002,126	939,500	'	'
Total liabilities and stockholders’ equity	2,593,940	2,388,930	'	'
Eliminations [Member]	'	'	'	'
Assets:	'	'	'	'
Land	0	0	'	'
Buildings and improvements, less accumulated depreciation	-300	0	'	'
Intangible lease assets, less accumulated amortization	0	0	'	'
Construction in progress	0	0	'	'
Real estate assets held for sale, net	0	0	'	'
Total real estate assets	-300	0	'	'
Investments in and amounts due from unconsolidated joint ventures	0	0	'	'
Cash and cash equivalents	0	0	0	0
Tenant and straight-line rent receivables, net	0	0	'	'
Advances to affiliates	-5,317,704	-5,014,825	'	'
Investment in subsidiary	-4,036,163	-4,069,044	'	'
Notes receivable	-185,890	-186,390	'	'
Prepaid expenses, restricted cash, escrows, and other assets	-941	-948	'	'
Goodwill	0	0	'	'
Interest rate swaps	0	0	'	'
Deferred financing costs, net	0	0	'	'
Deferred lease costs, net	0	0	'	'
Other assets held for sale, net	0	0	'	'
Total assets	-9,540,998	-9,271,207	'	'
Liabilities:	'	'	'	'
Secured and unsecured debt	-185,890	-186,390	'	'
Accounts payable, accrued expenses, and accrued capital expenditures	-941	-948	'	'
Advances from affiliates	-5,358,248	-5,047,035	'	'
Deferred income	0	0	'	'
Intangible lease liabilities, net	0	'	'	'
Interest rate swaps	0	0	'	'
Total liabilities	-5,545,079	-5,234,373	'	'
Stockholders’ Equity:	'	'	'	'
Common stock	0	0	'	'
Additional paid-in capital	-4,036,163	-4,069,044	'	'
Cumulative distributions in excess of earnings	40,244	32,210	'	'
Other comprehensive income/(loss)	0	0	'	'
Piedmont stockholders’ equity	-3,995,919	-4,036,834	'	'
Noncontrolling interest	0	0	'	'
Total stockholders’ equity	-3,995,919	-4,036,834	'	'
Total liabilities and stockholders’ equity	($9,540,998)	($9,271,207)	'	'

Guarantor_and_NonGuarantor_Fin3

Guarantor and Non-Guarantor Financial Information - Condensed Consolidated Statements of Income (Details) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Revenues:	'	'	'	'	'
Rental income	$116,810	$104,948	$333,855	$312,007	'
Tenant reimbursements	27,418	27,132	77,168	80,290	'
Property management fee revenue	890	520	2,034	1,720	'
Total revenues	145,118	132,600	413,057	394,017	'
Expenses:	'	'	'	'	'
Property operating costs	58,767	50,483	164,420	154,568	'
Depreciation	30,785	27,921	90,688	81,721	'
Amortization	13,878	15,165	34,244	39,095	'
General and administrative	5,841	5,508	16,678	15,629	'
Operating Expenses	109,271	99,077	306,030	291,013	'
Real estate operating income	35,847	33,523	107,027	103,004	'
Other income (expense):	'	'	'	'	'
Interest expense	-19,331	-16,247	-53,932	-48,727	'
Interest and other income/(expense)	-611	383	-1,960	765	'
Litigation settlement expense	'	-7,500	'	-7,500	'
Litigation settlement recovery/(expense)	0	-7,500	1,250	-7,500	'
Net recoveries of casualty loss	3,919	0	6,061	0	'
Equity in income of unconsolidated joint ventures	46	323	604	739	'
Loss on consolidation	-898	0	-898	0	'
Nonoperating Income (Expense)	-16,875	-23,041	-48,875	-54,723	'
Income from continuing operations	18,972	10,482	58,152	48,281	'
Discontinued operations:	'	'	'	'	'
Operating income	128	607	1,109	2,914	'
Impairment loss	0	0	-6,402	0	'
Gain/(loss) on sale of real estate assets	0	-254	16,258	27,583	'
Income from discontinued operations	128	353	10,965	30,497	'
Net income	19,100	10,835	69,117	78,778	'
Less: Net income attributable to noncontrolling interest	-4	-4	-12	-12	'
Net income attributable to Piedmont	19,096	10,831	69,105	78,766	93,204
Issuer [Member]	'	'	'	'	'
Revenues:	'	'	'	'	'
Rental income	20,700	18,889	57,754	55,272	'
Tenant reimbursements	4,035	4,655	12,018	12,774	'
Property management fee revenue	0	0	0	0	'
Total revenues	24,735	23,544	69,772	68,046	'
Expenses:	'	'	'	'	'
Property operating costs	10,939	11,279	31,107	31,416	'
Depreciation	6,068	6,200	18,074	17,439	'
Amortization	1,353	1,378	3,926	3,981	'
General and administrative	5,624	4,895	16,024	14,930	'
Operating Expenses	23,984	23,752	69,131	67,766	'
Real estate operating income	751	-208	641	280	'
Other income (expense):	'	'	'	'	'
Interest expense	-6,444	-3,360	-15,478	-9,120	'
Interest and other income/(expense)	2,262	3,245	7,834	9,268	'
Litigation settlement expense	'	-7,500	'	-7,500	'
Litigation settlement recovery/(expense)	'	'	1,250	'	'
Net recoveries of casualty loss	-85	'	-239	'	'
Equity in income of unconsolidated joint ventures	46	323	604	739	'
Loss on consolidation	-898	'	-898	'	'
Nonoperating Income (Expense)	-5,119	-7,292	-6,927	-6,613	'
Income from continuing operations	-4,368	-7,500	-6,286	-6,333	'
Discontinued operations:	'	'	'	'	'
Operating income	131	509	503	2,795	'
Impairment loss	'	'	-6,402	'	'
Gain/(loss) on sale of real estate assets	'	-254	-9	27,582	'
Income from discontinued operations	131	255	-5,908	30,377	'
Net income	-4,237	-7,245	-12,194	24,044	'
Less: Net income attributable to noncontrolling interest	0	0	0	0	'
Net income attributable to Piedmont	-4,237	-7,245	-12,194	24,044	'
Guarantor [Member]	'	'	'	'	'
Revenues:	'	'	'	'	'
Rental income	0	0	0	0	'
Tenant reimbursements	0	0	0	0	'
Property management fee revenue	0	0	0	0	'
Total revenues	0	0	0	0	'
Expenses:	'	'	'	'	'
Property operating costs	0	0	0	0	'
Depreciation	0	0	0	0	'
Amortization	0	0	0	0	'
General and administrative	64	84	249	224	'
Operating Expenses	64	84	249	224	'
Real estate operating income	-64	-84	-249	-224	'
Other income (expense):	'	'	'	'	'
Interest expense	0	0	0	0	'
Interest and other income/(expense)	42	0	128	0	'
Litigation settlement expense	'	0	'	0	'
Litigation settlement recovery/(expense)	'	'	0	'	'
Net recoveries of casualty loss	0	'	0	'	'
Equity in income of unconsolidated joint ventures	0	0	0	0	'
Loss on consolidation	0	'	0	'	'
Nonoperating Income (Expense)	42	0	128	0	'
Income from continuing operations	-22	-84	-121	-224	'
Discontinued operations:	'	'	'	'	'
Operating income	0	0	0	0	'
Impairment loss	'	'	0	'	'
Gain/(loss) on sale of real estate assets	'	0	0	0	'
Income from discontinued operations	0	0	0	0	'
Net income	-22	-84	-121	-224	'
Less: Net income attributable to noncontrolling interest	0	0	0	0	'
Net income attributable to Piedmont	-22	-84	-121	-224	'
Non-Guarantor Subsidiaries [Member]	'	'	'	'	'
Revenues:	'	'	'	'	'
Rental income	97,492	87,448	279,931	260,287	'
Tenant reimbursements	23,452	22,547	65,357	67,727	'
Property management fee revenue	4,003	3,634	11,392	10,705	'
Total revenues	124,947	113,629	356,680	338,719	'
Expenses:	'	'	'	'	'
Property operating costs	52,597	44,006	147,014	136,444	'
Depreciation	24,717	21,721	72,614	64,282	'
Amortization	12,525	13,787	30,318	35,114	'
General and administrative	6,469	6,503	18,896	18,057	'
Operating Expenses	96,308	86,017	268,842	253,897	'
Real estate operating income	28,639	27,612	87,838	84,822	'
Other income (expense):	'	'	'	'	'
Interest expense	-16,028	-16,041	-47,879	-48,965	'
Interest and other income/(expense)	226	292	-497	855	'
Litigation settlement expense	'	0	'	0	'
Litigation settlement recovery/(expense)	'	'	0	'	'
Net recoveries of casualty loss	4,004	'	6,300	'	'
Equity in income of unconsolidated joint ventures	0	0	0	0	'
Loss on consolidation	0	'	0	'	'
Nonoperating Income (Expense)	-11,798	-15,749	-42,076	-48,110	'
Income from continuing operations	16,841	11,863	45,762	36,712	'
Discontinued operations:	'	'	'	'	'
Operating income	-3	98	606	119	'
Impairment loss	'	'	0	'	'
Gain/(loss) on sale of real estate assets	'	0	16,267	1	'
Income from discontinued operations	-3	98	16,873	120	'
Net income	16,838	11,961	62,635	36,832	'
Less: Net income attributable to noncontrolling interest	-4	-4	-12	-12	'
Net income attributable to Piedmont	16,834	11,957	62,623	36,820	'
Eliminations [Member]	'	'	'	'	'
Revenues:	'	'	'	'	'
Rental income	-1,382	-1,389	-3,830	-3,552	'
Tenant reimbursements	-69	-70	-207	-211	'
Property management fee revenue	-3,113	-3,114	-9,358	-8,985	'
Total revenues	-4,564	-4,573	-13,395	-12,748	'
Expenses:	'	'	'	'	'
Property operating costs	-4,769	-4,802	-13,701	-13,292	'
Depreciation	0	0	0	0	'
Amortization	0	0	0	0	'
General and administrative	-6,316	-5,974	-18,491	-17,582	'
Operating Expenses	-11,085	-10,776	-32,192	-30,874	'
Real estate operating income	6,521	6,203	18,797	18,126	'
Other income (expense):	'	'	'	'	'
Interest expense	3,141	3,154	9,425	9,358	'
Interest and other income/(expense)	-3,141	-3,154	-9,425	-9,358	'
Litigation settlement expense	'	0	'	0	'
Litigation settlement recovery/(expense)	'	'	0	'	'
Net recoveries of casualty loss	0	'	0	'	'
Equity in income of unconsolidated joint ventures	0	0	0	0	'
Loss on consolidation	0	'	0	'	'
Nonoperating Income (Expense)	0	0	0	0	'
Income from continuing operations	6,521	6,203	18,797	18,126	'
Discontinued operations:	'	'	'	'	'
Operating income	0	0	'	0	'
Impairment loss	'	'	0	'	'
Gain/(loss) on sale of real estate assets	'	0	0	0	'
Income from discontinued operations	0	0	0	0	'
Net income	6,521	6,203	18,797	18,126	'
Less: Net income attributable to noncontrolling interest	0	0	0	0	'
Net income attributable to Piedmont	$6,521	$6,203	$18,797	$18,126	'

Guarantor_and_NonGuarantor_Fin4

Guarantor and Non-Guarantor Financial Information - Condensed Consolidated Statements of Cash Flows (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Condensed Financial Statements, Captions [Line Items]	'	'
Net cash provided by operating activities	$168,348	$142,603
Cash Flows from Investing Activities:	'	'
Investment in real estate assets and real estate related intangibles, net of accruals	-362,613	-74,436
Intercompany note receivable	0	0
Acquisition of unconsolidated joint ventures, net of cash assumed	-14,242	0
Net sales proceeds from wholly-owned properties	49,326	74,845
Investments in unconsolidated joint ventures	-793	0
Deferred lease costs paid	-28,349	-39,319
Net cash used in investing activities	-356,671	-38,910
Cash Flows from Financing Activities:	'	'
Deferred financing costs paid	-3,447	-2,991
Proceeds from debt	832,603	365,000
Repayments of debt	-426,000	-401,500
Intercompany note payable	0	0
Costs of issuance of common stock	-91	-229
Repurchases of common stock as part of announced plan	-111,625	-80,130
Distributions to/repayments from affiliates	0	0
Dividends paid and discount on dividend reinvestments	-100,102	-102,770
Net cash provided by/(used in) financing activities	191,338	-222,620
Net increase/(decrease) in cash and cash equivalents	3,015	-118,927
Cash and cash equivalents, beginning of period	12,957	139,690
Cash and cash equivalents, end of period	15,972	20,763
Issuer [Member]	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Net cash provided by operating activities	18,325	748
Cash Flows from Investing Activities:	'	'
Investment in real estate assets and real estate related intangibles, net of accruals	-5,858	-16,558
Intercompany note receivable	0	-3,100
Acquisition of unconsolidated joint ventures, net of cash assumed	18,045	'
Net sales proceeds from wholly-owned properties	3,752	74,845
Investments in unconsolidated joint ventures	-793	'
Deferred lease costs paid	-10,015	-2,837
Net cash used in investing activities	5,131	52,350
Cash Flows from Financing Activities:	'	'
Deferred financing costs paid	-3,447	-2,991
Proceeds from debt	832,603	365,000
Repayments of debt	-426,000	-216,500
Intercompany note payable	0	0
Costs of issuance of common stock	0	0
Repurchases of common stock as part of announced plan	0	0
Distributions to/repayments from affiliates	-476,887	-305,743
Dividends paid and discount on dividend reinvestments	0	0
Net cash provided by/(used in) financing activities	-73,731	-160,234
Net increase/(decrease) in cash and cash equivalents	-50,275	-107,136
Cash and cash equivalents, beginning of period	62,371	166,920
Cash and cash equivalents, end of period	12,096	59,784
Guarantor [Member]	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Net cash provided by operating activities	1,363	1,527
Cash Flows from Investing Activities:	'	'
Investment in real estate assets and real estate related intangibles, net of accruals	0	0
Intercompany note receivable	500	0
Acquisition of unconsolidated joint ventures, net of cash assumed	0	'
Net sales proceeds from wholly-owned properties	0	0
Investments in unconsolidated joint ventures	0	'
Deferred lease costs paid	0	0
Net cash used in investing activities	500	0
Cash Flows from Financing Activities:	'	'
Deferred financing costs paid	0	0
Proceeds from debt	0	0
Repayments of debt	0	0
Intercompany note payable	0	0
Costs of issuance of common stock	-91	-229
Repurchases of common stock as part of announced plan	-111,625	-80,130
Distributions to/repayments from affiliates	209,855	181,605
Dividends paid and discount on dividend reinvestments	-100,094	-102,762
Net cash provided by/(used in) financing activities	-1,955	-1,516
Net increase/(decrease) in cash and cash equivalents	-92	11
Cash and cash equivalents, beginning of period	238	139
Cash and cash equivalents, end of period	146	150
Non-Guarantor Subsidiaries [Member]	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Net cash provided by operating activities	129,863	122,202
Cash Flows from Investing Activities:	'	'
Investment in real estate assets and real estate related intangibles, net of accruals	-357,055	-57,878
Intercompany note receivable	0	0
Acquisition of unconsolidated joint ventures, net of cash assumed	-32,287	'
Net sales proceeds from wholly-owned properties	45,574	0
Investments in unconsolidated joint ventures	0	'
Deferred lease costs paid	-18,334	-36,482
Net cash used in investing activities	-362,102	-94,360
Cash Flows from Financing Activities:	'	'
Deferred financing costs paid	0	0
Proceeds from debt	0	0
Repayments of debt	0	-185,000
Intercompany note payable	-500	3,100
Costs of issuance of common stock	0	0
Repurchases of common stock as part of announced plan	0	0
Distributions to/repayments from affiliates	286,129	142,264
Dividends paid and discount on dividend reinvestments	-8	-8
Net cash provided by/(used in) financing activities	285,621	-39,644
Net increase/(decrease) in cash and cash equivalents	53,382	-11,802
Cash and cash equivalents, beginning of period	-49,652	-27,369
Cash and cash equivalents, end of period	3,730	-39,171
Eliminations [Member]	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Net cash provided by operating activities	18,797	18,126
Cash Flows from Investing Activities:	'	'
Investment in real estate assets and real estate related intangibles, net of accruals	300	0
Intercompany note receivable	-500	3,100
Acquisition of unconsolidated joint ventures, net of cash assumed	0	'
Net sales proceeds from wholly-owned properties	0	0
Investments in unconsolidated joint ventures	0	'
Deferred lease costs paid	0	0
Net cash used in investing activities	-200	3,100
Cash Flows from Financing Activities:	'	'
Deferred financing costs paid	0	0
Proceeds from debt	0	0
Repayments of debt	0	0
Intercompany note payable	500	-3,100
Costs of issuance of common stock	0	0
Repurchases of common stock as part of announced plan	0	0
Distributions to/repayments from affiliates	-19,097	-18,126
Dividends paid and discount on dividend reinvestments	0	0
Net cash provided by/(used in) financing activities	-18,597	-21,226
Net increase/(decrease) in cash and cash equivalents	0	0
Cash and cash equivalents, beginning of period	0	0
Cash and cash equivalents, end of period	$0	$0

Other_Subsequent_Events_Detail

Other Subsequent Events (Details) (Subsequent Event [Member], USD $)	0 Months Ended
In Millions, except Per Share data, unless otherwise specified	Oct. 30, 2013
Subsequent Event [Member]	'
Subsequent Event [Line Items]	'
Dividends declared (in dollars per share)	$0.20
Amount authorized for stock repurchase plan	$150
Period for stock repurchase plan	'2 years