Discontinued Operations (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			3 Months Ended					3 Months Ended		0 Months Ended	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011	Mar. 31, 2012 High Point Complex [Member]	Mar. 31, 2011 High Point Complex [Member]	Mar. 31, 2012 Retail Properties [Member] Properties	Mar. 31, 2011 Retail Properties [Member]	Dec. 31, 2011 Retail Properties [Member]	Mar. 31, 2012 Washington DC 1140 Connecticut Avenue and 1227 Twenty Fifth Street [Member]	Mar. 31, 2011 Washington DC 1140 Connecticut Avenue and 1227 Twenty Fifth Street [Member]	Jan. 06, 2012 West Mart 350 [Member] sqft	Mar. 31, 2012 West Mart 350 [Member]	Dec. 31, 2011 West Mart 350 [Member]
Disposal Group Including Discontinued Operation Additional Disclosures Abstract
Cash Sale of Real Estate						$ 83,670					$ 228,000
Square Footage of Real Estate Property Sold											1,200,000
Number of Real Estate Properties Sold						7
Discontinued Operation, Income (Loss) from Discontinued Operation Disclosures [Abstract]
Total revenues	1,320	16,215
Total expenses	422	13,661
Income from discontinued operations before gain on sale of real estate	898	2,554
Net gain on extinguishment of debt				0	83,907
Net gains on sale of real estate						906	5,303		0	45,862	54,911	54,911
Income (Loss) from Discontinued Operations	56,715	137,626
Disposal Group Including Discontinued Operation Unclassified Balance Sheet Disclosures Abstract
Assets related to discontinued operations	0		251,202			0		77,422				0	173,780
Liabilities related to discontinued operations	$ 0		$ 14,153			$ 0		$ 7,792				$ 0	$ 6,361