Segment Information (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Reconciliation of consolidated net operating income
Consolidated net operating income	$ 86,021	$ 83,828
Less:
Interest expense	(34,144)	(32,393)
Deferred financing costs	(1,311)	(928)
Depreciation and amortization	(50,502)	(50,295)
Administrative expenses	(6,050)	(6,244)
Plus:
Interest income	483	441
Interest expense — financing obligation	(182)	0
Equity in income of real estate ventures	44	1,233
Net gain on sales of interests in real estate ventures	0	2,791
Gain (loss) on early extinguishment of debt	(248)	0
Income (loss) from continuing operations	(5,889)	(1,567)
Income from discontinued operations	15,225	1,077
Net income (loss)	$ 9,336	$ (490)