Property Table 3 - Schedule of Impairment on Real Estate (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Recovery of Impairment of Real Estate, net	$ 0	$ 0	$ (1,644)
Recovery of Provision for Impairment of Real Estate Including Discontinued Operations	913	14,934	27,283
105 Kendall Park Lane [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Recovery of Impairment of Real Estate, net	0	0	(1,718)
4001 North Norfleet Road [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Recovery of Impairment of Real Estate, net	0	0	74
Havertys Furniture [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Recovery of Provision for Impairment of Real Estate Including Discontinued Operations	0	0	(2,148)
25850 S. Ridgeland [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Recovery of Provision for Impairment of Real Estate Including Discontinued Operations	0	0	586
Metropolitan Park North [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Recovery of Provision for Impairment of Real Estate Including Discontinued Operations	0	0	28,781
Georgia Door Sales Distribution Center [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Recovery of Provision for Impairment of Real Estate Including Discontinued Operations	913	0	64
Marketplace at Northglenn [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Recovery of Provision for Impairment of Real Estate Including Discontinued Operations	$ 0	$ 14,934	$ 0