Guarantor and Non-Guarantor Financial Information - Consolidating Statements of Comprehensive 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
Condensed Financial Statements, Captions [Line Items]
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
Effective portion of gain/(loss) on derivative instruments that are designated and qualify as cash flow hedges (See Note 5)									692	2,479	(4,126)
Plus: Reclassification of net (gain)/loss included in net income									(300)	3,502	4,548
Other comprehensive income									392	6,060	443
Comprehensive income applicable to Piedmont									130,688	139,624	100,175
Reportable Legal Entities | Piedmont (Parent) (Guarantor)
Condensed Financial Statements, Captions [Line Items]
Net income applicable to Piedmont									130,296	(347)	(29)
Effective portion of gain/(loss) on derivative instruments that are designated and qualify as cash flow hedges (See Note 5)									692
Plus: Reclassification of net (gain)/loss included in net income									(300)
Other comprehensive income									392
Comprehensive income applicable to Piedmont									130,688
Reportable Legal Entities | Piedmont OP (the Issuer)
Condensed Financial Statements, Captions [Line Items]
Net income applicable to Piedmont									129,611	(28,451)	(27,735)
Effective portion of gain/(loss) on derivative instruments that are designated and qualify as cash flow hedges (See Note 5)									692
Plus: Reclassification of net (gain)/loss included in net income									(300)
Other comprehensive income									392
Comprehensive income applicable to Piedmont									130,003
Reportable Legal Entities | Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income applicable to Piedmont									179,622	162,362	91,835
Effective portion of gain/(loss) on derivative instruments that are designated and qualify as cash flow hedges (See Note 5)									0
Plus: Reclassification of net (gain)/loss included in net income									0
Other comprehensive income									0
Comprehensive income applicable to Piedmont									179,622
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net income applicable to Piedmont									(309,233)	$ 0	$ 35,661
Effective portion of gain/(loss) on derivative instruments that are designated and qualify as cash flow hedges (See Note 5)									(692)
Plus: Reclassification of net (gain)/loss included in net income									300
Other comprehensive income									(392)
Comprehensive income applicable to Piedmont									$ (309,625)