Guarantor and Non-Guarantor Financial Information - Condensed Consolidated Statements of Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended				12 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013		Dec. 31, 2013
Revenues:
Rental income	$ 114,529		$ 115,170		$ 338,720		$ 329,177
Tenant reimbursements	29,579		27,329		79,253		76,895
Property management fee revenue	533		890		1,568		2,034
Total revenues	144,641		143,389		419,541		408,106
Expenses:
Property operating costs	62,027		58,137		177,434		162,516
Depreciation	35,366		30,295		103,154		89,289
Amortization	14,235		13,685		42,407		33,895
General and administrative	5,814		5,849		17,514		16,677
Operating Expenses	117,442		107,966		340,509		302,377
Real estate operating income	27,199		35,423		79,032		105,729
Other income (expense):
Interest expense	(18,654)		(19,331)		(55,592)		(53,932)
Other income/(expense)	524		(596)		68		(1,944)
Net recoveries from casualty events and litigation settlements	(8)		3,919		4,514		7,311
Equity in income/(loss) of unconsolidated joint ventures	89		46		(510)		604
Loss on consolidation	0		(898)		0		(898)
Nonoperating Income (Expense)	(18,049)		(16,860)		(51,520)		(48,859)
Income from continuing operations	9,150		18,563		27,512		56,870
Discontinued operations:
Operating income	16		537		996		2,391
Impairment loss	0	[1]	0	[1]	0	[1]	(6,402)	[1]
Gain on sale of real estate assets, net	0		0		1,198		16,258
Income from discontinued operations	16		537		2,194		12,247
Gain on sale of real estate assets	0		0		1,140		0
Net income	9,166		19,100		30,846		69,117
Less: Net income attributable to noncontrolling interest	(4)		(4)		(12)		(12)
Net income attributable to Piedmont	9,162		19,096		30,834		69,105		98,728
Issuer [Member]
Revenues:
Rental income	19,178		19,165		53,687		53,181
Tenant reimbursements	4,526		3,964		12,304		11,764
Property management fee revenue	0		0		0		0
Total revenues	23,704		23,129		65,991		64,945
Expenses:
Property operating costs	11,355		10,300		31,730		29,129
Depreciation	5,963		5,607		17,453		16,704
Amortization	1,225		1,293		3,441		3,711
General and administrative	5,638		5,632		17,057		16,023
Operating Expenses	24,181		22,832		69,681		65,567
Real estate operating income	(477)		297		(3,690)		(622)
Other income (expense):
Interest expense	(12,776)		(6,444)		(34,378)		(15,478)
Other income/(expense)	3,433		2,263		8,993		7,835
Net recoveries from casualty events and litigation settlements	(8)		(85)		1,344		1,011
Equity in income/(loss) of unconsolidated joint ventures	89		46		(510)		604
Loss on consolidation			(898)				(898)
Nonoperating Income (Expense)	(9,262)		(5,118)		(24,551)		(6,926)
Income from continuing operations	(9,739)		(4,821)		(28,241)		(7,548)
Discontinued operations:
Operating income	16		583		957		1,765
Impairment loss							(6,402)
Gain on sale of real estate assets, net					451		(9)
Income from discontinued operations	16		583		1,408		(4,646)
Gain on sale of real estate assets					0
Net income	(9,723)		(4,238)		(26,833)		(12,194)
Less: Net income attributable to noncontrolling interest	0		0		0		0
Net income attributable to Piedmont	(9,723)		(4,238)		(26,833)		(12,194)
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	74		64		218		249
Operating Expenses	74		64		218		249
Real estate operating income	(74)		(64)		(218)		(249)
Other income (expense):
Interest expense	0		0		0		0
Other income/(expense)	35		42		105		128
Net recoveries from casualty events and litigation settlements	0		0		1,479		0
Equity in income/(loss) of unconsolidated joint ventures	0		0		0		0
Loss on consolidation			0				0
Nonoperating Income (Expense)	35		42		1,584		128
Income from continuing operations	(39)		(22)		1,366		(121)
Discontinued operations:
Operating income	0		0		0		0
Impairment loss							0
Gain on sale of real estate assets, net					0		0
Income from discontinued operations	0		0		0		0
Gain on sale of real estate assets					0
Net income	(39)		(22)		1,366		(121)
Less: Net income attributable to noncontrolling interest	0		0		0		0
Net income attributable to Piedmont	(39)		(22)		1,366		(121)
Non-Guarantor Subsidiaries [Member]
Revenues:
Rental income	96,656		97,387		289,507		279,826
Tenant reimbursements	25,167		23,433		67,268		65,338
Property management fee revenue	4,098		4,003		12,208		11,392
Total revenues	125,921		124,823		368,983		356,556
Expenses:
Property operating costs	55,868		52,606		161,754		147,088
Depreciation	29,403		24,688		85,701		72,585
Amortization	13,010		12,392		38,966		30,184
General and administrative	6,951		6,469		20,762		18,896
Operating Expenses	105,232		96,155		307,183		268,753
Real estate operating income	20,689		28,668		61,800		87,803
Other income (expense):
Interest expense	(9,013)		(16,028)		(30,616)		(47,879)
Other income/(expense)	191		240		372		(482)
Net recoveries from casualty events and litigation settlements	0		4,004		1,691		6,300
Equity in income/(loss) of unconsolidated joint ventures	0		0		0		0
Loss on consolidation			0				0
Nonoperating Income (Expense)	(8,822)		(11,784)		(28,553)		(42,061)
Income from continuing operations	11,867		16,884		33,247		45,742
Discontinued operations:
Operating income	0		(46)		39		626
Impairment loss							0
Gain on sale of real estate assets, net					747		16,267
Income from discontinued operations	0		(46)		786		16,893
Gain on sale of real estate assets					1,140
Net income	11,867		16,838		35,173		62,635
Less: Net income attributable to noncontrolling interest	(4)		(4)		(12)		(12)
Net income attributable to Piedmont	11,863		16,834		35,161		62,623
Eliminations [Member]
Revenues:
Rental income	(1,305)		(1,382)		(4,474)		(3,830)
Tenant reimbursements	(114)		(68)		(319)		(207)
Property management fee revenue	(3,565)		(3,113)		(10,640)		(9,358)
Total revenues	(4,984)		(4,563)		(15,433)		(13,395)
Expenses:
Property operating costs	(5,196)		(4,769)		(16,050)		(13,701)
Depreciation	0		0		0		0
Amortization	0		0		0		0
General and administrative	(6,849)		(6,316)		(20,523)		(18,491)
Operating Expenses	(12,045)		(11,085)		(36,573)		(32,192)
Real estate operating income	7,061		6,522		21,140		18,797
Other income (expense):
Interest expense	3,135		3,141		9,402		9,425
Other income/(expense)	(3,135)		(3,141)		(9,402)		(9,425)
Net recoveries from casualty events and litigation settlements	0		0		0		0
Equity in income/(loss) of unconsolidated joint ventures	0		0		0		0
Loss on consolidation			0				0
Nonoperating Income (Expense)	0		0		0		0
Income from continuing operations	7,061		6,522		21,140		18,797
Discontinued operations:
Operating income	0		0		0		0
Impairment loss							0
Gain on sale of real estate assets, net					0		0
Income from discontinued operations	0		0		0		0
Gain on sale of real estate assets					0
Net income	7,061		6,522		21,140		18,797
Less: Net income attributable to noncontrolling interest	0		0		0		0
Net income attributable to Piedmont	$ 7,061		$ 6,522		$ 21,140		$ 18,797

[1] Piedmont sold the 1111 Durham Avenue building in South Plainfield, New Jersey and recorded an impairment charge of $6.4 million based on the difference between carrying value and fair value of the asset at the time it was reclassified from real estate assets held-for-use (at cost) to real estate assets held for sale (at estimated fair value). The fair value measurement used in the evaluation of this non-financial asset was based upon the amount set forth in the purchaser's original letter of intent which approximated the land value of the asset due to the age of construction and lack of near term leasing prospects for the building.