Guarantor and Non-Guarantor Financial Information - Cash Flows (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided By/(Used In) Operating Activities	$ 208,484,000	$ 202,869,000	$ 242,805,000
Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	(429,753,000)	(224,019,000)	(115,093,000)
Net sale proceeds from wholly-owned properties	589,767,000	575,227,000	375,518,000
Intercompany note receivable		0	0
Net sale proceeds received from unconsolidated joint ventures	0	0	12,334,000
Note receivable issuance	0	(3,200,000)	0
Note receivable payment	0	3,200,000	0
Investments in unconsolidated joint ventures			(1,162,000)
Deferred lease costs paid	(25,639,000)	(27,430,000)	(30,985,000)
Distributions from subsidiaries	0	0
Net cash provided by/(used in) investing activities	134,375,000	323,778,000	240,612,000
Cash Flows from Financing Activities:
Debt issuance costs paid	(151,000)	(1,040,000)	(132,000)
Proceeds from debt	592,000,000	977,062,000	180,000,000
Repayments of debt	(798,019,000)	(1,020,455,000)	(476,401,000)
Intercompany note payable		0	0
Costs of issuance of common stock	(710,000)	(85,000)	(182,000)
Value of shares withheld for payment of taxes related to employee stock compensation	(3,295,000)	(2,219,000)	(3,403,000)
Repurchases of common stock as part of announced plan	(16,899,000)	(298,538,000)	(60,474,000)
(Distributions to)/repayments from affiliates			0
Dividends paid and discount on dividend reinvestments	(106,433,000)	(184,093,000)	(122,274,000)
Net cash used in financing activities	(333,507,000)	(529,368,000)	(482,866,000)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	9,352,000	(2,721,000)	551,000
Cash, cash equivalents, and restricted cash and escrows, beginning of year	6,034,000	8,755,000	8,204,000
Cash, cash equivalents, and restricted cash and escrows, end of year	15,386,000	6,034,000	8,755,000
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided By/(Used In) Operating Activities	(484,275,000)	(309,741,000)	0
Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	0	0	0
Net sale proceeds from wholly-owned properties	0	0	0
Intercompany note receivable		(88,000,000)	48,610,000
Net sale proceeds received from unconsolidated joint ventures			0
Note receivable issuance		0
Note receivable payment		0
Investments in unconsolidated joint ventures			0
Deferred lease costs paid	0	0	0
Distributions from subsidiaries	89,631,000	(354,540,000)
Net cash provided by/(used in) investing activities	89,631,000	(442,540,000)	48,610,000
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)
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
Dividends paid and discount on dividend reinvestments	395,162,000	663,763,000	0
Net cash used in financing activities	395,162,000	751,763,000	(48,610,000)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	518,000	(518,000)	0
Cash, cash equivalents, and restricted cash and escrows, beginning of year	(518,000)	0	0
Cash, cash equivalents, and restricted cash and escrows, end of year	0	(518,000)	0
Piedmont (Parent) (Guarantor) | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided By/(Used In) Operating Activities	236,214,000	135,755,000	5,497,000
Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	0	0	0
Net sale proceeds from wholly-owned properties	0	0	0
Intercompany note receivable		0	0
Net sale proceeds received from unconsolidated joint ventures			0
Note receivable issuance		0
Note receivable payment		0
Investments in unconsolidated joint ventures			0
Deferred lease costs paid	0	0	0
Distributions from subsidiaries	(108,918,000)	349,135,000
Net cash provided by/(used in) investing activities	(108,918,000)	349,135,000	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
Costs of issuance of common stock	(710,000)	(85,000)	(182,000)
Value of shares withheld for payment of taxes related to employee stock compensation	(3,295,000)	(2,219,000)	(3,403,000)
Repurchases of common stock as part of announced plan	(16,899,000)	(298,538,000)	(60,474,000)
(Distributions to)/repayments from affiliates			180,791,000
Dividends paid and discount on dividend reinvestments	(106,392,000)	(184,048,000)	(122,229,000)
Net cash used in financing activities	(127,296,000)	(484,890,000)	(5,497,000)
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	220,068,000	141,293,000	(18,989,000)
Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	(16,020,000)	(14,479,000)	(1,614,000)
Net sale proceeds from wholly-owned properties	113,000	36,572,000	23,028,000
Intercompany note receivable		88,000,000	100,000
Net sale proceeds received from unconsolidated joint ventures			12,334,000
Note receivable issuance		0
Note receivable payment		0
Investments in unconsolidated joint ventures			(1,162,000)
Deferred lease costs paid	(3,220,000)	(3,090,000)	(4,081,000)
Distributions from subsidiaries	19,287,000	5,405,000
Net cash provided by/(used in) investing activities	160,000	112,408,000	28,605,000
Cash Flows from Financing Activities:
Debt issuance costs paid	(151,000)	(1,040,000)	(132,000)
Proceeds from debt	592,000,000	977,062,000	180,000,000
Repayments of debt	(797,000,000)	(1,019,000,000)	(335,000,000)
Intercompany note payable		0	(14,289,000)
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
Dividends paid and discount on dividend reinvestments	(5,420,000)	(214,596,000)	0
Net cash used in financing activities	(210,571,000)	(257,574,000)	(9,402,000)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	9,657,000	(3,873,000)	214,000
Cash, cash equivalents, and restricted cash and escrows, beginning of year	34,000	3,907,000	3,693,000
Cash, cash equivalents, and restricted cash and escrows, end of year	9,691,000	34,000	3,907,000
Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided By/(Used In) Operating Activities	236,477,000	235,562,000	256,297,000
Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	(413,733,000)	(209,540,000)	(113,479,000)
Net sale proceeds from wholly-owned properties	589,654,000	538,655,000	352,490,000
Intercompany note receivable		0	(48,710,000)
Net sale proceeds received from unconsolidated joint ventures			0
Note receivable issuance		(3,200,000)
Note receivable payment		3,200,000
Investments in unconsolidated joint ventures			0
Deferred lease costs paid	(22,419,000)	(24,340,000)	(26,904,000)
Distributions from subsidiaries	0	0
Net cash provided by/(used in) investing activities	153,502,000	304,775,000	163,397,000
Cash Flows from Financing Activities:
Debt issuance costs paid	0	0	0
Proceeds from debt	0	0	0
Repayments of debt	(1,019,000)	(1,455,000)	(141,401,000)
Intercompany note payable		(88,000,000)	62,899,000
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)
Dividends paid and discount on dividend reinvestments	(389,783,000)	(449,212,000)	(45,000)
Net cash used in financing activities	(390,802,000)	(538,667,000)	(419,357,000)
Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows	(823,000)	1,670,000	337,000
Cash, cash equivalents, and restricted cash and escrows, beginning of year	6,368,000	4,698,000	4,361,000
Cash, cash equivalents, and restricted cash and escrows, end of year	$ 5,545,000	$ 6,368,000	$ 4,698,000