Segment Information Segment Information (Reconciliation of Consolidated Net Operating Income) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 Reportable_Segments	Mar. 31, 2012
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Consolidated net operating income	$ 85,112	$ 81,645
Less:
Interest expense	(30,914)	(34,144)
Interest expense — amortization of deferred financing costs	(1,161)	(1,311)
Depreciation and amortization	(49,861)	(48,096)
Administrative expenses	(6,551)	(6,050)
Plus:
Interest income	58	483
Interest expense — financing obligation	(218)	(182)
Equity in income of real estate ventures	1,535	44
Loss on early extinguishment of debt	(3)	(248)
Loss from continuing operations	(2,003)	(7,859)
Income (Loss) from Discontinued Operations	5,922	17,195
Net income (loss)	$ 3,919	$ 9,336
Number of Reportable Segments	7