Real Estate Assets (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Dispositions [Abstract]
Gain on disposition of property	$ 5,947,000	$ (37,000)	$ 5,947,000	$ (37,000)
Impairments [Abstract]
Impairments of real estate assets	588,000	0	588,000	0
Atlanta, GA Land Disposition (6/2014) [Member]
Dispositions [Abstract]
Number of land parcels sold	2		2
Proceeds received from sale of real estate	9,500,000
Gain on disposition of property	5,900,000
Greensboro, NC Office Property Impairment (6/2014) [Member]
Impairments [Abstract]
Impairments of real estate assets	$ 600,000