Impairment Loss on Real Estate Assets (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Jul. 31, 2016 property
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment loss on real estate assets	[1]	$ 30,898	$ 40,169	$ 0
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Eastpoint I & II [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment loss on real estate assets	[2]	0	5,354	0
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | 2 Gatehall Drive [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment loss on real estate assets	[2]	0	34,815	0
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | 150 West Jefferson [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment loss on real estate assets	[2]	5,972	0	0
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | 9200 and 9211 Corporate Boulevard [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment loss on real estate assets	[3]	22,590	0	0
Number of assets sold | property					2
Impairment loss		22,600
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | 9221 Corporate Boulevard [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment loss on real estate assets	[4]	2,336	$ 0	$ 0
Loss on impairment		$ 2,300

[1] The fair value measurements used in the evaluation of the non-financial assets above are considered to be Level 1 valuations within the fair value hierarchy as defined by GAAP, as there are direct observations and transactions involving the assets by unrelated, third-party purchasers.

[2] Piedmont recognized an impairment loss on real estate assets based upon the difference between the carrying value of the asset and the contracted sales price, less estimated selling costs.

[3] Piedmont elected to sell its remaining two assets and exit the Rockville, Maryland sub-market of Washington, D.C, after selling the 9221 Corporate Boulevard building in July 2016 (mentioned above). Upon management's change in its hold period assumption for the assets from a long-term hold to a near-term sale, Piedmont recognized an impairment loss of approximately $22.6 million. The impairment loss was calculated as the difference between the carrying value of the asset and the anticipated contracted sales price, less estimated selling costs.

[4] Piedmont, using a probability-weighted model heavily weighted towards the short-term sale of the 9221 Corporate Boulevard building in Rockville, Maryland, determined that the carrying value would not be recovered from the undiscounted future operating cash flows expected from the use of the asset and its eventual disposition. As a result, Piedmont recognized a loss on impairment of approximately $2.3 million during the year ended December 31, 2016 calculated as the difference between the carrying value of the asset and the anticipated contract sales price, less estimated selling costs.