Guarantor and Non-Guarantor Financial Information (Cash Flows) (Details) - USD ($)	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	$ 160,243,000	$ 138,322,000
Cash Flows from Investing Activities:
Investment in real estate assets and real estate related intangibles	(383,512,000)	(73,174,000)
Intercompany note receivable		0
Net sales proceeds from wholly-owned properties	180,975,000	419,554,000
Note receivable issuance	0	(3,200,000)
Deferred lease costs paid	(16,632,000)	(15,831,000)
Distributions from subsidiaries	0	0
Net cash (used in)/provided by investing activities	(219,169,000)	327,349,000
Cash Flows from Financing Activities:
Debt issuance and other costs paid	(91,000)	(947,000)
Proceeds from debt	550,000,000	820,061,000
Repayments of debt	(358,041,000)	(833,005,000)
Costs of issuance of common stock	(259,000)	0
Intercompany note payable		0
Value of shares withheld to pay tax obligations related to employee stock compensation	(3,295,000)	(2,219,000)
Repurchases of common stock as part of announced plan	(16,899,000)	(266,062,000)
Distributions	(106,419,000)	(184,073,000)
Net cash provided by/(used in) financing activities	64,996,000	(466,245,000)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	6,070,000	(574,000)
Cash, cash equivalents, and restricted cash and escrows, beginning of period	6,034,000	8,755,000
Cash, cash equivalents, and restricted cash and escrows, end of period	12,104,000	8,181,000
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	(138,471,000)	(204,920,000)
Cash Flows from Investing Activities:
Investment in real estate assets and real estate related intangibles	0	0
Intercompany note receivable		(88,000,000)
Net sales proceeds from wholly-owned properties	0	0
Note receivable issuance		0
Deferred lease costs paid	0	0
Distributions from subsidiaries	(269,382,000)	(427,417,000)
Net cash (used in)/provided by investing activities	(269,382,000)	(515,417,000)
Cash Flows from Financing Activities:
Debt issuance and other costs paid	0	0
Proceeds from debt	0	0
Repayments of debt	0	0
Costs of issuance of common stock	0
Intercompany note payable		88,000,000
Value of shares withheld to pay tax obligations related to employee stock compensation	0	0
Repurchases of common stock as part of announced plan	0	0
Distributions	408,371,000	632,337,000
Net cash provided by/(used in) financing activities	408,371,000	720,337,000
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	518,000	0
Cash, cash equivalents, and restricted cash and escrows, beginning of period	(518,000)	0
Cash, cash equivalents, and restricted cash and escrows, end of period	0	0
Piedmont (Parent) (Guarantor) | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	72,694,000	89,540,000
Cash Flows from Investing Activities:
Investment in real estate assets and real estate related intangibles	0	0
Intercompany note receivable		0
Net sales proceeds from wholly-owned properties	0	0
Note receivable issuance		0
Deferred lease costs paid	0	0
Distributions from subsidiaries	54,151,000	362,784,000
Net cash (used in)/provided by investing activities	54,151,000	362,784,000
Cash Flows from Financing Activities:
Debt issuance and other costs paid	0	0
Proceeds from debt	0	0
Repayments of debt	0	0
Costs of issuance of common stock	(259,000)
Intercompany note payable		0
Value of shares withheld to pay tax obligations related to employee stock compensation	(3,295,000)	(2,219,000)
Repurchases of common stock as part of announced plan	(16,899,000)	(266,062,000)
Distributions	(106,392,000)	(184,043,000)
Net cash provided by/(used in) financing activities	(126,845,000)	(452,324,000)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	0	0
Cash, cash equivalents, and restricted cash and escrows, beginning of period	150,000	150,000
Cash, cash equivalents, and restricted cash and escrows, end of period	150,000	150,000
Piedmont OP (the Issuer) | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	43,676,000	89,639,000
Cash Flows from Investing Activities:
Investment in real estate assets and real estate related intangibles	(13,561,000)	(6,074,000)
Intercompany note receivable		88,000,000
Net sales proceeds from wholly-owned properties	128,000	36,572,000
Note receivable issuance		0
Deferred lease costs paid	(1,210,000)	(1,826,000)
Distributions from subsidiaries	215,231,000	64,633,000
Net cash (used in)/provided by investing activities	200,588,000	181,305,000
Cash Flows from Financing Activities:
Debt issuance and other costs paid	(91,000)	(947,000)
Proceeds from debt	550,000,000	820,061,000
Repayments of debt	(357,000,000)	(832,000,000)
Costs of issuance of common stock	0
Intercompany note payable		0
Value of shares withheld to pay tax obligations related to employee stock compensation	0	0
Repurchases of common stock as part of announced plan	0	0
Distributions	(431,416,000)	(258,907,000)
Net cash provided by/(used in) financing activities	(238,507,000)	(271,793,000)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	5,757,000	(849,000)
Cash, cash equivalents, and restricted cash and escrows, beginning of period	32,000	3,906,000
Cash, cash equivalents, and restricted cash and escrows, end of period	5,789,000	3,057,000
Non-Guarantors | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	182,344,000	164,063,000
Cash Flows from Investing Activities:
Investment in real estate assets and real estate related intangibles	(369,951,000)	(67,100,000)
Intercompany note receivable		0
Net sales proceeds from wholly-owned properties	180,847,000	382,982,000
Note receivable issuance		(3,200,000)
Deferred lease costs paid	(15,422,000)	(14,005,000)
Distributions from subsidiaries	0	0
Net cash (used in)/provided by investing activities	(204,526,000)	298,677,000
Cash Flows from Financing Activities:
Debt issuance and other costs paid	0	0
Proceeds from debt	0	0
Repayments of debt	(1,041,000)	(1,005,000)
Costs of issuance of common stock	0
Intercompany note payable		(88,000,000)
Value of shares withheld to pay tax obligations related to employee stock compensation	0	0
Repurchases of common stock as part of announced plan	0	0
Distributions	23,018,000	(373,460,000)
Net cash provided by/(used in) financing activities	21,977,000	(462,465,000)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	(205,000)	275,000
Cash, cash equivalents, and restricted cash and escrows, beginning of period	6,370,000	4,699,000
Cash, cash equivalents, and restricted cash and escrows, end of period	$ 6,165,000	$ 4,974,000