Discontinued Operations (Details) (USD $)	3 Months Ended		6 Months Ended		0 Months Ended	6 Months Ended	0 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jan. 17, 2014 Woodbranch Building	Jun. 30, 2014 Woodbranch Building	Jan. 31, 2014 Mesa Corporate Center	Jun. 30, 2014 Mesa Corporate Center
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gross proceeds from sale of real estate discontinued operations					$ 15,000,000		$ 13,200,000
Net proceeds from the sale					13,900,000		12,100,000
Gain on sale of real estate from discontinued operations	$ 0	$ 0	$ 10,463,000	$ 542,000		$ 9,974,000		$ 489,000