Income Taxes (Details) - USD ($)	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
Income Taxes [Line Items]
Net income applicable to Piedmont	$ 45,410,000	$ 16,114,000	$ 10,942,000	$ 57,830,000	$ (31,383,000)	$ 126,133,000	$ 23,710,000	$ 15,104,000	$ 130,296,000	$ 133,564,000	$ 99,732,000
Depreciation and amortization expense recognized for financial reporting purposes in excess of amounts recognized for income tax purposes									54,420,000	62,916,000	69,214,000
Rental income accrued for income tax purposes less than amounts for financial reporting purposes									(9,681,000)	(25,432,000)	(18,964,000)
Net amortization of above/below-market lease intangibles for income tax purposes in excess of amounts for financial reporting purposes									(7,453,000)	(6,041,000)	(4,895,000)
Gain on disposal of property for financial reporting purposes less than/(in excess of) amounts for income tax purposes									(36,241,000)	10,068,000	(118,713,000)
Other expenses, including impairment loss on real estate assets, for financial reporting purposes in excess of/ (less than) amounts for income tax purposes									(37,394,000)	49,859,000	42,019,000
Income tax basis net income, prior to dividends paid deduction									$ 91,794,000	$ 225,082,000	$ 67,999,000
Ordinary income, Percent									100.00%	53.61%	81.77%
Return of capital, Percent									0.00%	0.00%	18.23%
Capital gains, Percent									0.00%	46.39%	0.00%
Common Stock Dividends, Percent									100.00%	100.00%	100.00%
Tax basis of total assets	3,600,000,000				4,200,000,000				$ 3,600,000,000	$ 4,200,000,000
Accrued interest and penalties related to uncertain tax positions	$ 2,400,000				$ 3,800,000				2,400,000	3,800,000
Recovery of tax expense, including potential interest and penalties									1,400,000	100,000	$ 0
Reduction to tax liability related to RIET subsidiary									200,000
Piedmont Washington Properties, Inc
Income Taxes [Line Items]
Taxable income (loss) in excess of/(less than) amount for financial reporting purposes									(2,089,000)	176,000	(1,042,000)
Piedmont Office Holdings, Inc
Income Taxes [Line Items]
Taxable income (loss) in excess of/(less than) amount for financial reporting purposes									$ (64,000)	$ (28,000)	$ 648,000