Supplemental Disclosure to Statements of Cash Flows (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Supplemental Disclosure to Statements of Cash Flows [Abstract]
Write-off of fully depreciated property and deferred costs	$ 7,643	$ 14,125
Write Off Of Depreciated Property And Deferred Costs Due To Sale	3,331	0
writeoff origination cost	(2,771)	0
Preferred Stock Redemption Discount	$ 2,771	$ 0