Real Estate And Accumulated Depreciation (Changes In Accumulated Depreciation) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010		Dec. 31, 2009
Real Estate And Accumulated Depreciation [Abstract]
Balance, beginning of year	$ 841,801	$ 733,142		$ 636,970
Depreciation	143,093	126,249		120,002
Disposals associated with deconsolidation of the VIE		(13,627)	[1]
Disposals and retirements	(1,135)	(3,963)		(23,830)
Balance, end of year	$ 983,759	$ 841,801		$ 733,142

[1] Refer to Note 4 for discussion of the Company's sale of its general partnership interest in the VIE and the resulting deconsolidation of the VIE.