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, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Revenues:
Rental income	$ 111,767	$ 117,454	$ 226,505	$ 235,261
Tenant reimbursements	23,086	28,813	45,837	60,203
Property management fee revenue	454	467	977	1,029
Total revenues	135,307	146,734	273,319	296,493
Expenses:
Property operating costs	52,280	61,479	106,468	125,715
Depreciation	31,556	36,039	63,338	72,271
Amortization	17,402	14,955	35,208	29,625
Impairment loss on real estate assets	8,308	5,354	8,308	5,354
General and administrative	8,328	8,083	16,192	14,490
Operating expenses	117,874	125,910	229,514	247,455
Real estate operating income	17,433	20,824	43,805	49,038
Other income (expense):
Interest expense	(16,413)	(18,172)	(32,798)	(37,188)
Other income/(expense)	(41)	596	253	415
Equity in income of unconsolidated joint ventures	111	124	226	283
Other income (expense)	(16,343)	(17,452)	(32,319)	(36,490)
Income from continuing operations	1,090	3,372	11,486	12,548
Discontinued operations:
Operating loss	(1)	(3)	(1)	(3)
Loss from discontinued operations	(1)	(3)	(1)	(3)
Gain on sale of real estate assets	78,987	26,611	78,967	36,684
Net income	80,076	29,980	90,452	49,229
Net income applicable to noncontrolling interest	(4)	(4)	(8)	(8)	$ (15)
Net income applicable to Piedmont	80,072	29,976	90,444	49,221	$ 172,990
Eliminations [Member]
Revenues:
Rental income	(754)	(729)	(1,518)	(1,436)
Tenant reimbursements	(76)	(171)	(169)	(299)
Property management fee revenue	(3,724)	(4,034)	(7,518)	(7,911)
Total revenues	(4,554)	(4,934)	(9,205)	(9,646)
Expenses:
Property operating costs	(4,595)	(5,117)	(9,274)	(10,037)
Depreciation	0	0	0	0
Amortization	0	0	0	0
Impairment loss on real estate assets	0	0	0	0
General and administrative	(10,096)	(9,168)	(19,558)	(16,797)
Operating expenses	(14,691)	(14,285)	(28,832)	(26,834)
Real estate operating income	10,137	9,351	19,627	17,188
Other income (expense):
Interest expense	2,423	3,038	4,966	6,159
Other income/(expense)	(2,423)	(3,038)	(4,966)	(6,159)
Equity in income of unconsolidated joint ventures	0	0	0	0
Other income (expense)	0	0	0	0
Income from continuing operations	10,137	9,351	19,627	17,188
Discontinued operations:
Operating loss	0	0	0	0
Loss from discontinued operations	0	0	0	0
Gain on sale of real estate assets	0	0	0	0
Net income	10,137	9,351	19,627	17,188
Net income applicable to noncontrolling interest	0	0	0	0
Net income applicable to Piedmont	10,137	9,351	19,627	17,188
Issuer [Member]
Revenues:
Rental income	14,661	17,046	30,127	35,983
Tenant reimbursements	3,753	3,557	7,026	7,802
Property management fee revenue	0	0	0	0
Total revenues	18,414	20,603	37,153	43,785
Expenses:
Property operating costs	8,307	9,550	16,659	20,211
Depreciation	4,476	5,159	9,376	10,961
Amortization	941	1,096	1,991	2,350
Impairment loss on real estate assets	5,972	5,354	5,972	5,354
General and administrative	8,119	7,904	15,718	14,104
Operating expenses	27,815	29,063	49,716	52,980
Real estate operating income	(9,401)	(8,460)	(12,563)	(9,195)
Other income (expense):
Interest expense	(12,170)	(13,441)	(24,360)	(26,630)
Other income/(expense)	1,735	3,392	4,400	6,159
Equity in income of unconsolidated joint ventures	111	124	226	283
Other income (expense)	(10,324)	(9,925)	(19,734)	(20,188)
Income from continuing operations	(19,725)	(18,385)	(32,297)	(29,383)
Discontinued operations:
Operating loss	0	(2)	0	(2)
Loss from discontinued operations	0	(2)	0	(2)
Gain on sale of real estate assets	32,017	26,611	32,012	36,684
Net income	12,292	8,224	(285)	7,299
Net income applicable to noncontrolling interest	0	0	0	0
Net income applicable to Piedmont	12,292	8,224	(285)	7,299
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 assets	0	0	0	0
General and administrative	92	84	168	195
Operating expenses	92	84	168	195
Real estate operating income	(92)	(84)	(168)	(195)
Other income (expense):
Interest expense	0	0	0	0
Other income/(expense)	282	0	282	0
Equity in income of unconsolidated joint ventures	0	0	0	0
Other income (expense)	282	0	282	0
Income from continuing operations	190	(84)	114	(195)
Discontinued operations:
Operating loss	0	0	0	0
Loss from discontinued operations	0	0	0	0
Gain on sale of real estate assets	0	0	0	0
Net income	190	(84)	114	(195)
Net income applicable to noncontrolling interest	0	0	0	0
Net income applicable to Piedmont	190	(84)	114	(195)
Non-Guarantor Subsidiaries [Member]
Revenues:
Rental income	97,860	101,137	197,896	200,714
Tenant reimbursements	19,409	25,427	38,980	52,700
Property management fee revenue	4,178	4,501	8,495	8,940
Total revenues	121,447	131,065	245,371	262,354
Expenses:
Property operating costs	48,568	57,046	99,083	115,541
Depreciation	27,080	30,880	53,962	61,310
Amortization	16,461	13,859	33,217	27,275
Impairment loss on real estate assets	2,336	0	2,336	0
General and administrative	10,213	9,263	19,864	16,988
Operating expenses	104,658	111,048	208,462	221,114
Real estate operating income	16,789	20,017	36,909	41,240
Other income (expense):
Interest expense	(6,666)	(7,769)	(13,404)	(16,717)
Other income/(expense)	365	242	537	415
Equity in income of unconsolidated joint ventures	0	0	0	0
Other income (expense)	(6,301)	(7,527)	(12,867)	(16,302)
Income from continuing operations	10,488	12,490	24,042	24,938
Discontinued operations:
Operating loss	(1)	(1)	(1)	(1)
Loss from discontinued operations	(1)	(1)	(1)	(1)
Gain on sale of real estate assets	46,970	0	46,955	0
Net income	57,457	12,489	70,996	24,937
Net income applicable to noncontrolling interest	(4)	(4)	(8)	(8)
Net income applicable to Piedmont	$ 57,453	$ 12,485	$ 70,988	$ 24,929