Income Taxes (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
Income Taxes [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
Depreciation and amortization expense recognized for financial reporting purposes in excess of amounts recognized for income tax purposes									10,381	54,420	62,916
Rental income accrued for income tax purposes less than amounts for financial reporting purposes									(34,804)	(9,681)	(25,432)
Net amortization of above/below-market lease intangibles for income tax purposes in excess of amounts for financial reporting purposes									(7,698)	(7,453)	(6,041)
Gain on disposal of property for financial reporting purposes less than/(in excess of) amounts for income tax purposes									(85,463)	(36,241)	10,068
Other expenses, including impairment loss on real estate assets, for financial reporting purposes in excess of/ (less than) amounts for income tax purposes									23,127	(37,394)	49,859
Income tax basis net income, prior to dividends paid deduction									$ 135,390	$ 91,794	$ 225,082
Ordinary income, Percent									29.82%	100.00%	53.61%
Return of capital, Percent									0.00%	0.00%	0.00%
Capital gains, Percent									70.18%	0.00%	46.39%
Common Stock Dividends, Percent									100.00%	100.00%	100.00%
Tax basis of total assets	3,300,000				3,600,000				$ 3,300,000	$ 3,600,000
Accrued interest and penalties related to uncertain tax positions	$ 1,000				$ 2,400				1,000	2,400
Recovery of tax expense, including potential interest and penalties									1,400	1,400	$ 100
Piedmont Washington Properties, Inc
Income Taxes [Line Items]
Taxable income for subsidiary in excess of/(less than) amount for financial reporting purposes									411	(2,089)	176
Piedmont Office Holdings, Inc
Income Taxes [Line Items]
Taxable income for subsidiary in excess of/(less than) amount for financial reporting purposes									$ 175	$ (64)	$ (28)