Income Taxes (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Net income attributable to Piedmont	$ 29,623,000	$ 19,096,000	$ 35,358,000	$ 14,651,000	$ 14,438,000	$ 10,830,000	$ 30,708,000	$ 37,228,000	$ 98,728,000	$ 93,204,000	$ 225,041,000
Depreciation and amortization expense for financial reporting purposes in excess of amounts for income tax purposes									42,374,000	35,125,000	47,346,000
Rental income accrued for income tax purposes less than amounts for financial reporting purposes									(25,964,000)	(10,422,000)	(9,380,000)
Net amortization of above/below-market lease intangibles for financial reporting purposes in excess of amounts for income tax purposes									(4,701,000)	(5,324,000)	(6,605,000)
Gain on disposal of property for financial reporting purposes in excess of amounts for income tax purposes									(35,153,000)	(7,967,000)	(66,410,000)
Taxable income of Piedmont Washington Properties, Inc., in excess of amount for financial reporting purposes									0	2,662,000	4,515,000
Other expenses for financial reporting purposes in excess of amounts for income tax purposes									9,045,000	14,361,000	(2,072,000)
Income tax basis net income, prior to dividends paid deduction									84,329,000	121,639,000	192,435,000
Ordinary income									64.00%	73.00%	61.00%
Return of capital									36.00%	11.00%	12.00%
Capital gains									0.00%	16.00%	27.00%
Common Stock Dividends, Percent									100.00%	100.00%	100.00%
Tax basis of total assets	4,500,000,000				4,100,000,000				4,500,000,000	4,100,000,000
Accrued interest and penalties related to uncertain tax positions	$ 6,700,000				$ 6,700,000				$ 6,700,000	$ 6,700,000