Discontinued Operations and Assets Held for Sale (Table Illustration of Discontinued Operations in Income Statement) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Discontinued Operations
Revenues	$ 1,234	$ 52,170
Operating expenses	(815)	(25,273)
Depreciation and amortization on discontinued operations	(643)	(17,159)
Operating income (loss)	(224)	9,738
Interest expense	(525)	(15,141)
Loss before gain on sales	(749)	(5,403)
Gain on sale of depreciable properties	6,476	11,603
Income from discontinued operations	$ 5,727	$ 6,200