Impairment of Certain Real Estate Assets (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Aug. 12, 2013 property
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment losses included in continuing operations:	$ 1,242	$ 0	$ 0
Number of real estate properties				3
1111 Durham Avenue [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment losses recorded in discontinued operations:	6,402	0	0
11107 and 11109 Sunset Hills Road [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment losses included in continuing operations:	1,242	0	0
Piedmont's Investment in Fund 13 and REIT JV (at Piedmont's approximate 72% ownership) [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment losses recorded in equity in loss of unconsolidated joint ventures:	$ 4,402	$ 0	$ 0
Piedmont’s Approximate Ownership Percentage	72.00%
Number of real estate properties	2