Guarantor and Non-Guarantor Financial Information - Condensed Consolidated Statements of Cash Flows (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided By/(Used In) Operating Activities	$ 202,869,000	$ 242,805,000	$ 231,847,000
Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	(224,019,000)	(115,093,000)	(459,896,000)
Intercompany note receivable	0	0	0
Net sale proceeds from wholly-owned properties	575,227,000	375,518,000	365,918,000
Net sale proceeds received from unconsolidated joint ventures	0	12,334,000	0
Note receivable issuance	(3,200,000)	0	0
Note receivable repayment	3,200,000	0	0
Investments in unconsolidated joint ventures		(1,162,000)
Deferred lease costs paid	(27,430,000)	(30,985,000)	(25,896,000)
Distributions from subsidiaries	0
Net cash provided by/(used in) investing activities	323,778,000	240,612,000	(119,874,000)
Cash Flows from Financing Activities:
Debt issuance costs paid	(1,040,000)	(132,000)	(264,000)
Proceeds from debt	977,062,000	180,000,000	695,000,000
Repayments of debt	(1,020,455,000)	(476,401,000)	(706,875,000)
Intercompany note payable	0	0	0
Costs of issuance of common stock	(85,000)	(182,000)	(342,000)
Value of shares withheld for payment of taxes related to employee stock compensation	(2,219,000)	(3,403,000)	(2,344,000)
Repurchases of common stock as part of announced plan	(298,538,000)	(60,474,000)	(7,943,000)
(Distributions to)/repayments from affiliates		0	0
Distributions	(184,093,000)	(122,274,000)	(91,616,000)
Net cash used in financing activities	(529,368,000)	(482,866,000)	(114,384,000)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	(2,721,000)	551,000	(2,411,000)
Cash, cash equivalents, and restricted cash and escrows, beginning of year	8,755,000	8,204,000	10,615,000
Cash, cash equivalents, and restricted cash and escrows, end of year	6,034,000	8,755,000	8,204,000
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided By/(Used In) Operating Activities	(309,741,000)	0	35,660,000
Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	0	0	0
Intercompany note receivable	(88,000,000)	48,610,000	71,460,000
Net sale proceeds from wholly-owned properties	0	0	0
Net sale proceeds received from unconsolidated joint ventures		0
Note receivable issuance	0
Note receivable repayment	0
Investments in unconsolidated joint ventures		0
Deferred lease costs paid	0	0	0
Distributions from subsidiaries	(354,540,000)
Net cash provided by/(used in) investing activities	(442,540,000)	48,610,000	71,460,000
Cash Flows from Financing Activities:
Debt issuance costs paid	0	0	0
Proceeds from debt	0	0	0
Repayments of debt	0	0	0
Intercompany note payable	88,000,000	(48,610,000)	(71,460,000)
Costs of issuance of common stock	0	0	0
Value of shares withheld for payment of taxes related to employee stock compensation	0	0	0
Repurchases of common stock as part of announced plan	0	0	0
(Distributions to)/repayments from affiliates		0	35,660,000
Distributions	663,763,000	0	0
Net cash used in financing activities	751,763,000	(48,610,000)	(107,120,000)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	(518,000)	0	0
Cash, cash equivalents, and restricted cash and escrows, beginning of year	0	0	0
Cash, cash equivalents, and restricted cash and escrows, end of year	(518,000)	0	0
Piedmont (Parent) (Guarantor) | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided By/(Used In) Operating Activities	135,755,000	5,497,000	5,214,000
Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	0	0	0
Intercompany note receivable	0	0	0
Net sale proceeds from wholly-owned properties	0	0	0
Net sale proceeds received from unconsolidated joint ventures		0
Note receivable issuance	0
Note receivable repayment	0
Investments in unconsolidated joint ventures		0
Deferred lease costs paid	0	0	0
Distributions from subsidiaries	349,135,000
Net cash provided by/(used in) investing activities	349,135,000	0	0
Cash Flows from Financing Activities:
Debt issuance costs paid	0	0	0
Proceeds from debt	0	0	0
Repayments of debt	0	0	0
Intercompany note payable	0	0	0
Costs of issuance of common stock	(85,000)	(182,000)	(342,000)
Value of shares withheld for payment of taxes related to employee stock compensation	(2,219,000)	(3,403,000)	(2,344,000)
Repurchases of common stock as part of announced plan	(298,538,000)	(60,474,000)	(7,943,000)
(Distributions to)/repayments from affiliates		(180,791,000)	(97,016,000)
Distributions	(184,048,000)	(122,229,000)	(91,601,000)
Net cash used in financing activities	(484,890,000)	(5,497,000)	(5,214,000)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	0	0	0
Cash, cash equivalents, and restricted cash and escrows, beginning of year	150,000	150,000	150,000
Cash, cash equivalents, and restricted cash and escrows, end of year	150,000	150,000	150,000
Piedmont OP (the Issuer) | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided By/(Used In) Operating Activities	141,293,000	(18,989,000)	(26,263,000)
Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	(14,479,000)	(1,614,000)	(5,060,000)
Intercompany note receivable	88,000,000	100,000	440,000
Net sale proceeds from wholly-owned properties	36,572,000	23,028,000	200,220,000
Net sale proceeds received from unconsolidated joint ventures		12,334,000
Note receivable issuance	0
Note receivable repayment	0
Investments in unconsolidated joint ventures		(1,162,000)
Deferred lease costs paid	(3,090,000)	(4,081,000)	(2,758,000)
Distributions from subsidiaries	5,405,000
Net cash provided by/(used in) investing activities	112,408,000	28,605,000	192,842,000
Cash Flows from Financing Activities:
Debt issuance costs paid	(1,040,000)	(132,000)	(264,000)
Proceeds from debt	977,062,000	180,000,000	695,000,000
Repayments of debt	(1,019,000,000)	(335,000,000)	(538,000,000)
Intercompany note payable	0	(14,289,000)	(9,600,000)
Costs of issuance of common stock	0	0	0
Value of shares withheld for payment of taxes related to employee stock compensation	0	0	0
Repurchases of common stock as part of announced plan	0	0	0
(Distributions to)/repayments from affiliates		(160,019,000)	312,218,000
Distributions	(214,596,000)	0	0
Net cash used in financing activities	(257,574,000)	(9,402,000)	(165,082,000)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	(3,873,000)	214,000	1,497,000
Cash, cash equivalents, and restricted cash and escrows, beginning of year	3,907,000	3,693,000	2,196,000
Cash, cash equivalents, and restricted cash and escrows, end of year	34,000	3,907,000	3,693,000
Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided By/(Used In) Operating Activities	235,562,000	256,297,000	217,236,000
Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	(209,540,000)	(113,479,000)	(454,836,000)
Intercompany note receivable	0	(48,710,000)	(71,900,000)
Net sale proceeds from wholly-owned properties	538,655,000	352,490,000	165,698,000
Net sale proceeds received from unconsolidated joint ventures		0
Note receivable issuance	(3,200,000)
Note receivable repayment	3,200,000
Investments in unconsolidated joint ventures		0
Deferred lease costs paid	(24,340,000)	(26,904,000)	(23,138,000)
Distributions from subsidiaries	0
Net cash provided by/(used in) investing activities	304,775,000	163,397,000	(384,176,000)
Cash Flows from Financing Activities:
Debt issuance costs paid	0	0	0
Proceeds from debt	0	0	0
Repayments of debt	(1,455,000)	(141,401,000)	(168,875,000)
Intercompany note payable	(88,000,000)	62,899,000	81,060,000
Costs of issuance of common stock	0	0	0
Value of shares withheld for payment of taxes related to employee stock compensation	0	0	0
Repurchases of common stock as part of announced plan	0	0	0
(Distributions to)/repayments from affiliates		340,810,000	(250,862,000)
Distributions	(449,212,000)	(45,000)	(15,000)
Net cash used in financing activities	(538,667,000)	(419,357,000)	163,032,000
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	1,670,000	337,000	(3,908,000)
Cash, cash equivalents, and restricted cash and escrows, beginning of year	4,698,000	4,361,000	8,269,000
Cash, cash equivalents, and restricted cash and escrows, end of year	$ 6,368,000	$ 4,698,000	$ 4,361,000