Guarantor and Non-Guarantor Financial Information (Condensed Consolidated Balance Sheets) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Assets:
Land	$ 614,934	$ 617,138
Buildings and improvements, less accumulated depreciation	2,723,163	2,754,106
Intangible lease assets, less accumulated amortization	78,700	99,695
Construction in progress	8,957	34,814
Real estate assets held for sale, net	0	225,939
Total real estate assets	3,425,754	3,731,692
Investments in and amounts due from unconsolidated joint ventures	49	7,360
Cash and cash equivalents	36,108	6,992	$ 6,032	$ 5,441
Tenant and straight-line rent receivables, net	195,411	190,283
Advances to affiliates	0	0
Investment in subsidiary	0	0
Note receivable	0	0
Prepaid expenses, restricted cash, escrows, and other assets	29,492	24,413
Goodwill	98,918	98,918
Interest rate swaps	34	0
Deferred lease costs, net	274,884	298,695
Other assets held for sale, net	0	9,815
Total assets	4,060,650	4,368,168
Liabilities:
Debt, net	1,703,586	2,020,475
Accounts payable, accrued expenses, and accrued capital expenditures	108,120	165,410
Advances from affiliates	0	0
Deferred income	29,970	28,406
Intangible lease liabilities, net	41,064	48,005
Interest rate swaps	3,915	8,169
Total liabilities	1,886,655	2,270,465
Stockholders’ Equity:
Common stock	1,453	1,452
Additional paid-in capital	3,676,706	3,673,128
Cumulative distributions in excess of earnings	(1,511,428)	(1,580,863)
Other comprehensive loss income	5,400	2,104
Piedmont stockholders’ equity	2,172,131	2,095,821
Noncontrolling interest	1,864	1,882
Total stockholders’ equity	2,173,995	2,097,703		2,123,420
Total liabilities and stockholders’ equity	4,060,650	4,368,168
Eliminations
Assets:
Land	0	0
Buildings and improvements, less accumulated depreciation	(300)	(300)
Intangible lease assets, less accumulated amortization	0	0
Construction in progress	0	0
Real estate assets held for sale, net		0
Total real estate assets	(300)	(300)
Investments in and amounts due from unconsolidated joint ventures	0	0
Cash and cash equivalents	0	0	0	0
Tenant and straight-line rent receivables, net	0	0
Advances to affiliates	(7,834,144)	(7,779,751)
Investment in subsidiary	(3,539,122)	(3,630,745)
Note receivable	(233,410)	(184,700)
Prepaid expenses, restricted cash, escrows, and other assets	(809)	(1,897)
Goodwill	0	0
Interest rate swaps	0
Deferred lease costs, net	0	0
Other assets held for sale, net		0
Total assets	(11,607,785)	(11,597,393)
Liabilities:
Debt, net	(233,410)	(184,700)
Accounts payable, accrued expenses, and accrued capital expenditures	(809)	(1,897)
Advances from affiliates	(7,932,399)	(7,878,007)
Deferred income	0	0
Intangible lease liabilities, net	0	0
Interest rate swaps	0	0
Total liabilities	(8,166,618)	(8,064,604)
Stockholders’ Equity:
Common stock	0	0
Additional paid-in capital	(3,539,122)	(3,630,745)
Cumulative distributions in excess of earnings	97,955	97,956
Other comprehensive loss income	0	0
Piedmont stockholders’ equity	(3,441,167)	(3,532,789)
Noncontrolling interest	0	0
Total stockholders’ equity	(3,441,167)	(3,532,789)
Total liabilities and stockholders’ equity	(11,607,785)	(11,597,393)
Issuer
Assets:
Land	43,929	46,133
Buildings and improvements, less accumulated depreciation	206,700	228,194
Intangible lease assets, less accumulated amortization	317	725
Construction in progress	797	145
Real estate assets held for sale, net		0
Total real estate assets	251,743	275,197
Investments in and amounts due from unconsolidated joint ventures	49	7,360
Cash and cash equivalents	25,884	3,674	3,591	2,174
Tenant and straight-line rent receivables, net	17,556	20,159
Advances to affiliates	6,257,405	6,464,135
Investment in subsidiary	0	0
Note receivable	88,910	88,910
Prepaid expenses, restricted cash, escrows, and other assets	4,905	6,189
Goodwill	98,918	98,918
Interest rate swaps	34
Deferred lease costs, net	13,927	16,550
Other assets held for sale, net		0
Total assets	6,759,331	6,981,092
Liabilities:
Debt, net	1,511,587	1,701,933
Accounts payable, accrued expenses, and accrued capital expenditures	16,546	17,365
Advances from affiliates	790,748	708,340
Deferred income	3,728	5,206
Intangible lease liabilities, net	0	0
Interest rate swaps	3,915	8,169
Total liabilities	2,326,524	2,441,013
Stockholders’ Equity:
Common stock	0	0
Additional paid-in capital	3,534,946	3,626,564
Cumulative distributions in excess of earnings	892,461	911,411
Other comprehensive loss income	5,400	2,104
Piedmont stockholders’ equity	4,432,807	4,540,079
Noncontrolling interest	0	0
Total stockholders’ equity	4,432,807	4,540,079
Total liabilities and stockholders’ equity	6,759,331	6,981,092
Guarantor
Assets:
Land	0	0
Buildings and improvements, less accumulated depreciation	0	0
Intangible lease assets, less accumulated amortization	0	0
Construction in progress	0	0
Real estate assets held for sale, net		0
Total real estate assets	0	0
Investments in and amounts due from unconsolidated joint ventures	0	0
Cash and cash equivalents	150	150	150	150
Tenant and straight-line rent receivables, net	0	0
Advances to affiliates	1,576,739	1,315,616
Investment in subsidiary	3,538,945	3,630,564
Note receivable	0	0
Prepaid expenses, restricted cash, escrows, and other assets	38	0
Goodwill	0	0
Interest rate swaps	0
Deferred lease costs, net	0	0
Other assets held for sale, net		0
Total assets	5,115,872	4,946,330
Liabilities:
Debt, net	0	0
Accounts payable, accrued expenses, and accrued capital expenditures	652	31,230
Advances from affiliates	5,226,546	5,071,521
Deferred income	0	0
Intangible lease liabilities, net	0	0
Interest rate swaps	0	0
Total liabilities	5,227,198	5,102,751
Stockholders’ Equity:
Common stock	1,453	1,452
Additional paid-in capital	3,679,578	3,676,000
Cumulative distributions in excess of earnings	(3,792,357)	(3,833,873)
Other comprehensive loss income	0	0
Piedmont stockholders’ equity	(111,326)	(156,421)
Noncontrolling interest	0	0
Total stockholders’ equity	(111,326)	(156,421)
Total liabilities and stockholders’ equity	5,115,872	4,946,330
Non-Guarantor Subsidiaries
Assets:
Land	571,005	571,005
Buildings and improvements, less accumulated depreciation	2,516,763	2,526,212
Intangible lease assets, less accumulated amortization	78,383	98,970
Construction in progress	8,160	34,669
Real estate assets held for sale, net		225,939
Total real estate assets	3,174,311	3,456,795
Investments in and amounts due from unconsolidated joint ventures	0	0
Cash and cash equivalents	10,074	3,168	$ 2,291	$ 3,117
Tenant and straight-line rent receivables, net	177,855	170,124
Advances to affiliates	0	0
Investment in subsidiary	177	181
Note receivable	144,500	95,790
Prepaid expenses, restricted cash, escrows, and other assets	25,358	20,121
Goodwill	0	0
Interest rate swaps	0
Deferred lease costs, net	260,957	282,145
Other assets held for sale, net		9,815
Total assets	3,793,232	4,038,139
Liabilities:
Debt, net	425,409	503,242
Accounts payable, accrued expenses, and accrued capital expenditures	91,731	118,712
Advances from affiliates	1,915,105	2,098,146
Deferred income	26,242	23,200
Intangible lease liabilities, net	41,064	48,005
Interest rate swaps	0	0
Total liabilities	2,499,551	2,791,305
Stockholders’ Equity:
Common stock	0	0
Additional paid-in capital	1,304	1,309
Cumulative distributions in excess of earnings	1,290,513	1,243,643
Other comprehensive loss income	0	0
Piedmont stockholders’ equity	1,291,817	1,244,952
Noncontrolling interest	1,864	1,882
Total stockholders’ equity	1,293,681	1,246,834
Total liabilities and stockholders’ equity	$ 3,793,232	$ 4,038,139