Discontinued Operations (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		0 Months Ended	3 Months Ended	0 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 28, 2013 1111 Durham Avenue [Member]	Mar. 31, 2013 1111 Durham Avenue [Member]	May 01, 2013 1200 Enclave Parkway [Member]	Nov. 01, 2013 350 Spectrum Loop building [Member]	Dec. 30, 2013 8700 South Price Road [Member]	Mar. 19, 2014 11107 and 11109 Sunset Hills Road [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(Loss) on Sale	$ (106)	$ 0	$ (9)		$ 16,246	$ 7,959	$ 7,096	$ (106)
Net Sales Proceeds	22,322	3,403	3,752		45,552	29,676	16,691	22,322
Impairment loss	0	(6,402)		(6,400)
Revenues:
Rental income	1,174	2,928
Tenant reimbursements	112	434
Revenue	1,286	3,362
Expenses:
Property operating costs	505	1,486
Depreciation	83	859
Amortization	223	169
General and administrative	3	1
Expenses	814	2,515
Other income/(expense)
Other income/(expense)	(6)	12
Other income (expense)	(6)	12
Operating income, excluding gain/(loss) on sale	466	859
Income/(loss) from discontinued operations	$ 360	$ (5,543)