Income Taxes (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Line Items]
Net income applicable to Piedmont	$ (31,383,000)	$ 126,133,000	$ 23,710,000	$ 15,104,000	$ 30,189,000	$ (13,107,000)	$ 72,278,000	$ 10,372,000	$ 133,564,000	$ 99,732,000	$ 131,304,000
Depreciation and amortization expense recognized for financial reporting purposes in excess of/(less than) amounts recognized for income tax purposes									62,916,000	69,214,000	(1,717,000)
Rental income accrued for income tax purposes less than amounts for financial reporting purposes									(25,432,000)	(18,964,000)	(12,123,000)
Net amortization of above/below-market lease intangibles for income tax purposes in excess of amounts for financial reporting purposes									(6,041,000)	(4,895,000)	(4,614,000)
Gain on disposal of property for financial reporting purposes less than/(in excess of) amounts for income tax purposes									10,068,000	(118,713,000)	(43,493,000)
Other expenses, including impairment loss on real estate assets, for financial reporting purposes in excess of amounts for income tax purposes									49,859,000	42,019,000	54,425,000
Income tax basis net income, prior to dividends paid deduction									$ 225,082,000	$ 67,999,000	$ 126,273,000
Ordinary income, Percent									53.61%	81.77%	31.75%
Return of capital, Percent									0.00%	18.23%	0.00%
Capital gains, Percent									46.39%	0.00%	68.25%
Common Stock Dividends, Percent									100.00%	100.00%	100.00%
Tax basis of total assets	4,200,000,000				4,300,000,000				$ 4,200,000,000	$ 4,300,000,000
Accrued interest and penalties related to uncertain tax positions	$ 3,800,000				$ 3,800,000				3,800,000	3,800,000
Recovery of tax expense, including potential interest and penalties									100,000	0	$ 0
Piedmont Washington Properties, Inc
Income Taxes [Line Items]
Taxable income (loss) in excess of/(less than) amount for financial reporting purposes									176,000	(1,042,000)	2,491,000
Piedmont Office Holdings, Inc
Income Taxes [Line Items]
Taxable income (loss) in excess of/(less than) amount for financial reporting purposes									$ (28,000)	$ 648,000	$ 0