Acquisitions (Summary Of Preliminary Estimated Fair Values Of The Assets Acquired And Liabilities Assumed) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011
Acquisitions [Abstract]
Cash and cash equivalents	$ 3,531
Accounts and notes receivable	741
Inventory	88
Prepaid expenses, deferred costs, and other current assets	1,297
Property and equipment	9,961
Intangible assets	46,000
Goodwill	104,135
Other assets	9
Total assets acquired	165,762
Accounts payable	4,405
Accrued liabilities	4,200
Asset retirement obligations	1,902
Deferred tax liability, net	5,755
Other long-term liabilities	4,500
Total liabilities assumed	20,762
Net assets acquired	$ 145,000