Property Transactions (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Components of Income (Loss) from Discontinued Operations
Rental property revenues	$ 11,115	$ 17,806	$ 21,543
Other income	98	35	53
Rental property operating expenses	4,474	6,515	8,571
Depreciation and amortization	3,887	6,643	8,052
Interest expense			(1,634)
Income (loss) from discontinued operations	$ 2,852	$ 4,683	$ 3,339