Guarantor and Non-Guarantor Financial Information - Condensed Consolidated Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues:
Rental income									$ 411,667	$ 455,125	$ 439,918
Tenant reimbursements									92,743	98,139	94,901
Total revenues	$ 137,185	$ 129,708	$ 129,174	$ 129,900	$ 139,444	$ 137,587	$ 148,679	$ 148,463	525,967	574,173	555,715
Expenses:
Property operating costs									209,338	222,441	220,796
Depreciation									107,956	119,288	127,733
Amortization									63,295	75,367	75,119
Impairment loss on real estate assets									0	46,461	33,901
General and administrative									29,713	29,319	27,382
Operating Expenses									410,302	492,876	484,931
Real estate operating income									115,665	81,297	70,784
Other income (expense):
Interest expense									(61,023)	(68,124)	(64,860)
Other income/(expense)									1,638	657	(13)
Net recoveries from casualty events									0	0	34
Equity in income of unconsolidated joint ventures									0	3,845	362
Loss on extinguishment of debt									(1,680)	0	0
Gain on sale of real estate assets, net	30,505	0	(23)	45,209	(77)	109,512	6,492	(53)	75,691	115,874	93,410
Nonoperating Income (Expense)									14,626	52,252	28,933
Net income									130,291	133,549	99,717
Income from subsidiaries									0
Net income	45,409	16,114	10,940	57,828	(31,388)	126,129	23,707	15,101	130,291	133,549	99,717
Net loss applicable to noncontrolling interest									5	15	15
Net income applicable to Piedmont	$ 45,410	$ 16,114	$ 10,942	$ 57,830	$ (31,383)	$ 126,133	$ 23,710	$ 15,104	130,296	133,564	99,732
Eliminations
Revenues:
Rental income									(2,027)	(1,791)	(2,631)
Tenant reimbursements									(446)	(474)	(498)
Total revenues									(18,141)	(18,735)	(18,162)
Expenses:
Property operating costs									(18,141)	(18,735)	(18,377)
Depreciation									0	0	0
Amortization									0	0	0
Impairment loss on real estate assets									0	0	0
General and administrative									0	0	(35,446)
Operating Expenses									(18,141)	(18,735)	(53,823)
Real estate operating income									0	0	35,661
Other income (expense):
Interest expense									7,630	15,360	11,884
Other income/(expense)									(7,630)	(15,360)	(11,884)
Net recoveries from casualty events											0
Equity in income of unconsolidated joint ventures										0	0
Loss on extinguishment of debt									0
Gain on sale of real estate assets, net									0	0	0
Nonoperating Income (Expense)									0	0	0
Net income									0	0	35,661
Income from subsidiaries									(309,233)
Net income									(309,233)
Net loss applicable to noncontrolling interest									0	0	0
Net income applicable to Piedmont									(309,233)	0	35,661
Piedmont (Parent) (Guarantor) | Reportable Legal Entities
Revenues:
Rental income									0	0	0
Tenant reimbursements									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									0	0	0
General and administrative									289	347	311
Operating Expenses									289	347	311
Real estate operating income									(289)	(347)	(311)
Other income (expense):
Interest expense									0	0	0
Other income/(expense)									0	0	282
Net recoveries from casualty events											0
Equity in income of unconsolidated joint ventures										0	0
Loss on extinguishment of debt									0
Gain on sale of real estate assets, net									0	0	0
Nonoperating Income (Expense)									0	0	282
Net income									(289)	(347)	(29)
Income from subsidiaries									130,585
Net income									130,296
Net loss applicable to noncontrolling interest									0	0	0
Net income applicable to Piedmont									130,296	(347)	(29)
Piedmont OP (the Issuer) | Reportable Legal Entities
Revenues:
Rental income									35,221	42,407	53,527
Tenant reimbursements									9,489	11,702	14,295
Total revenues									44,840	54,253	69,088
Expenses:
Property operating costs									19,583	22,805	33,829
Depreciation									11,514	12,995	16,657
Amortization									1,990	3,049	3,715
Impairment loss on real estate assets									0	87	8,259
General and administrative									6,576	6,443	26,452
Operating Expenses									39,663	45,379	88,912
Real estate operating income									5,177	8,874	(19,824)
Other income (expense):
Interest expense									(54,095)	(56,769)	(49,108)
Other income/(expense)									144	9,168	9,560
Net recoveries from casualty events											0
Equity in income of unconsolidated joint ventures										3,845	362
Loss on extinguishment of debt									(1,680)
Gain on sale of real estate assets, net									1,417	6,431	31,275
Nonoperating Income (Expense)									(54,214)	(37,325)	(7,911)
Net income									(49,037)	(28,451)	(27,735)
Income from subsidiaries									178,648
Net income									129,611
Net loss applicable to noncontrolling interest									0	0	0
Net income applicable to Piedmont									129,611	(28,451)	(27,735)
Non-Guarantor Subsidiaries | Reportable Legal Entities
Revenues:
Rental income									378,473	414,509	389,022
Tenant reimbursements									83,700	86,911	81,104
Total revenues									499,268	538,655	504,789
Expenses:
Property operating costs									207,896	218,371	205,344
Depreciation									96,442	106,293	111,076
Amortization									61,305	72,318	71,404
Impairment loss on real estate assets									0	46,374	25,642
General and administrative									22,848	22,529	36,065
Operating Expenses									388,491	465,885	449,531
Real estate operating income									110,777	72,770	55,258
Other income (expense):
Interest expense									(14,558)	(26,715)	(27,636)
Other income/(expense)									9,124	6,849	2,029
Net recoveries from casualty events											34
Equity in income of unconsolidated joint ventures										0	0
Loss on extinguishment of debt									0
Gain on sale of real estate assets, net									74,274	109,443	62,135
Nonoperating Income (Expense)									68,840	89,577	36,562
Net income									179,617	162,347	91,820
Income from subsidiaries									0
Net income									179,617
Net loss applicable to noncontrolling interest									5	15	15
Net income applicable to Piedmont									179,622	162,362	91,835
Management Service
Revenues:
Property management fee revenue									1,450	1,735	1,914
Management Service | Eliminations
Revenues:
Property management fee revenue									(15,668)	(16,470)	(15,033)
Management Service | Piedmont (Parent) (Guarantor) | Reportable Legal Entities
Revenues:
Property management fee revenue									0	0	0
Management Service | Piedmont OP (the Issuer) | Reportable Legal Entities
Revenues:
Property management fee revenue									0	0	0
Management Service | Non-Guarantor Subsidiaries | Reportable Legal Entities
Revenues:
Property management fee revenue									17,118	18,205	16,947
Other property related income
Revenues:
Property management fee revenue									20,107	19,174	18,982
Other property related income | Eliminations
Revenues:
Property management fee revenue									0	0	0
Other property related income | Piedmont (Parent) (Guarantor) | Reportable Legal Entities
Revenues:
Property management fee revenue									0	0	0
Other property related income | Piedmont OP (the Issuer) | Reportable Legal Entities
Revenues:
Property management fee revenue									130	144	1,266
Other property related income | Non-Guarantor Subsidiaries | Reportable Legal Entities
Revenues:
Property management fee revenue									$ 19,977	$ 19,030	$ 17,716