Restatement (Schedule of Previously Reported, Restatement Adjustments, and Restated Consolidated Statements of Operations) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Revenues:
Rental income													$ 459,890		$ 468,872		$ 454,635
Tenant reimbursements													93,961		113,881		109,548
Property management fee revenue													1,864		2,016		2,069
Total revenues	$ 143,911	$ 138,485	$ 135,307	$ 138,012	$ 139,461	$ 148,815	$ 146,734	$ 149,759	$ 146,711	$ 144,641	$ 138,580	$ 136,320	555,715		584,769		566,252
Expenses:
Property operating costs													218,934		242,022		239,431
Depreciation													127,733		134,503		138,596
Amortization													75,119		60,886		56,579
Impairment loss on real estate assets	0	22,951	10,950	0	0	37,105	6,196	0					33,901	[1]	43,301	[1]	0	[1]
General and administrative													29,244		30,346		23,825
Operating Expenses													484,931		511,058		458,431
Real estate operating income	26,633	2,988	14,791	26,372	28,938	(3,424)	19,983	28,214	28,789	27,199	26,556	25,277	70,784		73,711		107,821
Other income (expense):
Interest expense													(64,860)		(73,998)		(74,446)
Other income/(expense)													(13)		1,565		62
Net recoveries/(loss) from casualty events and litigation settlements													34		(278)		6,992
Equity in income/(loss) of unconsolidated joint ventures													362		553		(350)
Nonoperating Income (Expense)													(64,477)		(72,158)		(67,742)
Income from continuing operations	10,529	(13,065)	(1,553)	10,396	11,164	(21,318)	2,531	9,176	12,567	9,150	9,325	9,037	6,307		1,553		40,079
Discontinued operations:
Operating income													0		84		954
Gain/(loss) on sale of real estate assets													0		(1)		262
Income from discontinued operations	0	1	(1)	0	72	14	(3)	0	(42)	16	882	360	0		83		1,216
Gain/(loss) on sale of real estate assets	19,652	(57)	73,835	(20)	84,427	14,796	21,520	8,940	(8)	0	878	0	93,410		129,683		870
Net income	30,181	(13,121)	72,281	10,376	95,663	(6,508)	24,048	18,116	12,517	9,166	11,085	9,397	99,717		131,319		42,165
Less: Net loss/(income) applicable to noncontrolling interest													15		(15)		(15)
Net income applicable to Piedmont	$ 30,189	$ (13,107)	$ 72,278	$ 10,372	$ 95,660	$ (6,512)	$ 24,044	$ 18,112	$ 12,514	$ 9,162	$ 11,081	$ 9,393	$ 99,732		$ 131,304		$ 42,150
Per share information— basic and diluted:
Income from continuing operations and gain on sale of real estate assets (in dollars per share)													$ 0.69		$ 0.87		$ 0.26
Income from discontinued operations (in dollars per share)													0.00		0.00		0.01
Net income available to common stockholders (in dollars per share)	$ 0.21	$ (0.09)	$ 0.50	$ 0.07	$ 0.65	$ (0.05)	$ 0.15	$ 0.12	$ 0.08	$ 0.06	$ 0.07	$ 0.06	$ 0.69		$ 0.87		$ 0.27
Weighted-average shares outstanding - basic (in shares)													145,230,382		150,537,757		154,452,121
Weighted-average shares outstanding - diluted (in shares)													145,634,953		150,880,116		154,585,273
Scenario, Previously Reported [Member]
Revenues:
Rental income													$ 459,890		$ 468,872		$ 454,635
Tenant reimbursements													93,961		113,881		109,548
Property management fee revenue													1,864		2,016		2,069
Total revenues													555,715		584,769		566,252
Expenses:
Property operating costs													218,934		242,022		239,431
Depreciation													127,733		134,503		138,596
Amortization													75,119		60,886		56,579
Impairment loss on real estate assets													30,898		40,169		0
General and administrative													29,244		30,346		23,825
Operating Expenses													481,928		507,926		458,431
Real estate operating income													73,787		76,843		107,821
Other income (expense):
Interest expense													(64,860)		(73,998)		(74,446)
Other income/(expense)													(13)		1,565		62
Net recoveries/(loss) from casualty events and litigation settlements													34		(278)		6,992
Equity in income/(loss) of unconsolidated joint ventures													362		553		(350)
Nonoperating Income (Expense)													(64,477)		(72,158)		(67,742)
Income from continuing operations													9,310		4,685		40,079
Discontinued operations:
Operating income													0		84		954
Gain/(loss) on sale of real estate assets													0		(1)		1,198
Income from discontinued operations													0		83		2,152
Gain/(loss) on sale of real estate assets													98,562		168,237		1,132
Net income													107,872		173,005		43,363
Less: Net loss/(income) applicable to noncontrolling interest													15		(15)		(15)
Net income applicable to Piedmont													$ 107,887		$ 172,990		$ 43,348
Per share information— basic and diluted:
Income from continuing operations and gain on sale of real estate assets (in dollars per share)													$ 0.74		$ 1.15		$ 0.27
Income from discontinued operations (in dollars per share)													0.00		0.00		0.01
Net income available to common stockholders (in dollars per share)													$ 0.74		$ 1.15		$ 0.28
Weighted-average shares outstanding - basic (in shares)													145,230,382		150,537,757		154,452,121
Weighted-average shares outstanding - diluted (in shares)													145,634,953		150,880,116		154,585,273
Restatement Adjustment [Member]
Revenues:
Rental income													$ 0		$ 0		$ 0
Tenant reimbursements													0		0		0
Property management fee revenue													0		0		0
Total revenues													0		0		0
Expenses:
Property operating costs													0		0		0
Depreciation													0		0		0
Amortization													0		0		0
Impairment loss on real estate assets													3,003		3,132		0
General and administrative													0		0		0
Operating Expenses													3,003		3,132		0
Real estate operating income													(3,003)		(3,132)		0
Other income (expense):
Interest expense													0		0		0
Other income/(expense)													0		0		0
Net recoveries/(loss) from casualty events and litigation settlements													0		0		0
Equity in income/(loss) of unconsolidated joint ventures													0		0		0
Nonoperating Income (Expense)													0		0		0
Income from continuing operations													(3,003)		(3,132)		0
Discontinued operations:
Operating income													0		0		0
Gain/(loss) on sale of real estate assets													0		0		(936)
Income from discontinued operations													0		0		(936)
Gain/(loss) on sale of real estate assets													(5,152)		(38,554)		(262)
Net income													(8,155)		(41,686)		(1,198)
Less: Net loss/(income) applicable to noncontrolling interest													0		0		0
Net income applicable to Piedmont													$ (8,155)		$ (41,686)		$ (1,198)
Per share information— basic and diluted:
Income from continuing operations and gain on sale of real estate assets (in dollars per share)													$ (0.05)		$ (0.28)		$ (0.01)
Income from discontinued operations (in dollars per share)													0.00		0.00		0.00
Net income available to common stockholders (in dollars per share)													$ (0.05)		$ (0.28)		$ (0.01)
Weighted-average shares outstanding - basic (in shares)
Weighted-average shares outstanding - diluted (in shares)

[1] The fair value measurements used in the evaluation of the non-financial assets above are considered to be Level 1 valuations within the fair value hierarchy as defined by GAAP, as there are direct observations and transactions involving the assets by unrelated, third-party purchasers.