Guarantor and Non-Guarantor Financial Information - Condensed Consolidated Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Revenues:
Rental income	$ 117,454	$ 113,287	$ 235,261	$ 224,191
Tenant reimbursements	28,813	24,745	60,203	49,674
Property management fee revenue	467	548	1,029	1,035
Total revenues	146,734	138,580	296,493	274,900
Expenses:
Property operating costs	61,479	57,136	125,715	115,407
Depreciation	36,039	34,144	72,271	67,788
Amortization	14,955	13,599	29,625	28,172
Impairment loss on real estate asset	5,354	0	5,354	0
General and administrative	8,083	7,145	14,490	11,700
Operating expenses	125,910	112,024	247,455	223,067
Real estate operating income	20,824	26,556	49,038	51,833
Other income (expense):
Interest expense	(18,172)	(18,012)	(37,188)	(36,938)
Other income/(expense)	596	(366)	415	(456)
Net recoveries from casualty events and litigation settlements	0	1,480	0	4,522
Equity in income/(loss) of unconsolidated joint ventures	124	(333)	283	(599)
Nonoperating income (expense)	(17,452)	(17,231)	(36,490)	(33,471)
Income from continuing operations	3,372	9,325	12,548	18,362
Discontinued operations:
Operating income/(loss)	(3)	514	(3)	980
Gain on sale of real estate assets	0	1,304	0	1,198
Income/(loss) from discontinued operations	(3)	1,818	(3)	2,178
Gain on sale of real estate assets	26,611	1,140	36,684	1,140
Net income	29,980	12,283	49,229	21,680
Less: Net income attributable to noncontrolling interest	(4)	(4)	(8)	(8)
Net income attributable to Piedmont	29,976	12,279	49,221	21,672	$ 43,348
Issuer [Member]
Revenues:
Rental income	17,046	17,109	35,983	34,510
Tenant reimbursements	3,557	3,917	7,802	7,778
Property management fee revenue	0	0	0	0
Total revenues	20,603	21,026	43,785	42,288
Expenses:
Property operating costs	9,550	10,330	20,211	20,375
Depreciation	5,159	5,650	10,961	11,490
Amortization	1,096	1,105	2,350	2,217
Impairment loss on real estate asset	5,354		5,354
General and administrative	7,904	6,949	14,104	11,418
Operating expenses	29,063	24,034	52,980	45,500
Real estate operating income	(8,460)	(3,008)	(9,195)	(3,212)
Other income (expense):
Interest expense	(13,441)	(12,482)	(26,630)	(21,602)
Other income/(expense)	3,392	2,797	6,159	5,560
Net recoveries from casualty events and litigation settlements		1		1,352
Equity in income/(loss) of unconsolidated joint ventures	124	(333)	283	(599)
Nonoperating income (expense)	(9,925)	(10,017)	(20,188)	(15,289)
Income from continuing operations	(18,385)	(13,025)	(29,383)	(18,501)
Discontinued operations:
Operating income/(loss)	(2)	461	(2)	941
Gain on sale of real estate assets		557		451
Income/(loss) from discontinued operations	(2)	1,018	(2)	1,392
Gain on sale of real estate assets	26,611	0	36,684	0
Net income	8,224	(12,007)	7,299	(17,109)
Less: Net income attributable to noncontrolling interest	0	0	0	0
Net income attributable to Piedmont	8,224	(12,007)	7,299	(17,109)
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
Impairment loss on real estate asset	0		0
General and administrative	84	66	195	143
Operating expenses	84	66	195	143
Real estate operating income	(84)	(66)	(195)	(143)
Other income (expense):
Interest expense	0	0	0	0
Other income/(expense)	0	35	0	69
Net recoveries from casualty events and litigation settlements		1,479		1,479
Equity in income/(loss) of unconsolidated joint ventures	0	0	0	0
Nonoperating income (expense)	0	1,514	0	1,548
Income from continuing operations	(84)	1,448	(195)	1,405
Discontinued operations:
Operating income/(loss)	0	0	0	0
Gain on sale of real estate assets		0		0
Income/(loss) from discontinued operations	0	0	0	0
Gain on sale of real estate assets	0	0	0	0
Net income	(84)	1,448	(195)	1,405
Less: Net income attributable to noncontrolling interest	0	0	0	0
Net income attributable to Piedmont	(84)	1,448	(195)	1,405
Non-Guarantor Subsidiaries [Member]
Revenues:
Rental income	101,137	97,694	200,714	192,850
Tenant reimbursements	25,427	20,921	52,700	42,100
Property management fee revenue	4,501	3,939	8,940	8,110
Total revenues	131,065	122,554	262,354	243,060
Expenses:
Property operating costs	57,046	52,008	115,541	105,886
Depreciation	30,880	28,494	61,310	56,298
Amortization	13,859	12,494	27,275	25,955
Impairment loss on real estate asset	0		0
General and administrative	9,263	7,851	16,988	13,812
Operating expenses	111,048	100,847	221,114	201,951
Real estate operating income	20,017	21,707	41,240	41,109
Other income (expense):
Interest expense	(7,769)	(8,664)	(16,717)	(21,603)
Other income/(expense)	242	(64)	415	182
Net recoveries from casualty events and litigation settlements		0		1,691
Equity in income/(loss) of unconsolidated joint ventures	0	0	0	0
Nonoperating income (expense)	(7,527)	(8,728)	(16,302)	(19,730)
Income from continuing operations	12,490	12,979	24,938	21,379
Discontinued operations:
Operating income/(loss)	(1)	53	(1)	39
Gain on sale of real estate assets		747		747
Income/(loss) from discontinued operations	(1)	800	(1)	786
Gain on sale of real estate assets	0	1,140	0	1,140
Net income	12,489	14,919	24,937	23,305
Less: Net income attributable to noncontrolling interest	(4)	(4)	(8)	(8)
Net income attributable to Piedmont	12,485	14,915	24,929	23,297
Eliminations [Member]
Revenues:
Rental income	(729)	(1,516)	(1,436)	(3,169)
Tenant reimbursements	(171)	(93)	(299)	(204)
Property management fee revenue	(4,034)	(3,391)	(7,911)	(7,075)
Total revenues	(4,934)	(5,000)	(9,646)	(10,448)
Expenses:
Property operating costs	(5,117)	(5,202)	(10,037)	(10,854)
Depreciation	0	0	0	0
Amortization	0	0	0	0
Impairment loss on real estate asset	0		0
General and administrative	(9,168)	(7,721)	(16,797)	(13,673)
Operating expenses	(14,285)	(12,923)	(26,834)	(24,527)
Real estate operating income	9,351	7,923	17,188	14,079
Other income (expense):
Interest expense	3,038	3,134	6,159	6,267
Other income/(expense)	(3,038)	(3,134)	(6,159)	(6,267)
Net recoveries from casualty events and litigation settlements		0		0
Equity in income/(loss) of unconsolidated joint ventures	0	0	0	0
Nonoperating income (expense)	0	0	0	0
Income from continuing operations	9,351	7,923	17,188	14,079
Discontinued operations:
Operating income/(loss)	0	0	0	0
Gain on sale of real estate assets		0		0
Income/(loss) from discontinued operations	0	0	0	0
Gain on sale of real estate assets	0	0	0	0
Net income	9,351	7,923	17,188	14,079
Less: Net income attributable to noncontrolling interest	0	0	0	0
Net income attributable to Piedmont	$ 9,351	$ 7,923	$ 17,188	$ 14,079