Guarantor and Non-Guarantor Financial Information - Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Net income applicable to Piedmont	$ 162,478	$ 8,422	$ 8,153	$ 50,208	$ 45,410	$ 16,114	$ 10,942	$ 57,830	$ 229,261	$ 130,296	$ 133,564
Effective portion of gain/(loss) on derivative instruments that are designated and qualify as cash flow hedges (See Note 5)									(5,659)	692	2,479
Plus: Reclassification of net (gain)/loss included in net income									(1,836)	(300)	3,502
Other comprehensive income									(7,495)	392	6,060
Comprehensive income applicable to Piedmont									221,766	130,688	139,624
Reportable Legal Entities | Piedmont (Parent) (Guarantor)
Condensed Financial Statements, Captions [Line Items]
Net income applicable to Piedmont									229,261	130,296	(347)
Effective portion of gain/(loss) on derivative instruments that are designated and qualify as cash flow hedges (See Note 5)									(5,659)	692
Plus: Reclassification of net (gain)/loss included in net income									(1,836)	(300)
Other comprehensive income									(7,495)	392
Comprehensive income applicable to Piedmont									221,766	130,688
Reportable Legal Entities | Piedmont OP (the Issuer)
Condensed Financial Statements, Captions [Line Items]
Net income applicable to Piedmont									198,591	129,611	(28,451)
Effective portion of gain/(loss) on derivative instruments that are designated and qualify as cash flow hedges (See Note 5)									(5,659)	692
Plus: Reclassification of net (gain)/loss included in net income									(1,836)	(300)
Other comprehensive income									(7,495)	392
Comprehensive income applicable to Piedmont									191,096	130,003
Reportable Legal Entities | Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income applicable to Piedmont									286,213	179,622	162,362
Effective portion of gain/(loss) on derivative instruments that are designated and qualify as cash flow hedges (See Note 5)									0	0
Plus: Reclassification of net (gain)/loss included in net income									0	0
Other comprehensive income									0	0
Comprehensive income applicable to Piedmont									286,213	179,622
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net income applicable to Piedmont									(484,804)	(309,233)	$ 0
Effective portion of gain/(loss) on derivative instruments that are designated and qualify as cash flow hedges (See Note 5)									5,659	(692)
Plus: Reclassification of net (gain)/loss included in net income									1,836	300
Other comprehensive income									7,495	(392)
Comprehensive income applicable to Piedmont									$ (477,309)	$ (309,625)