Income Taxes (Components of the Net Deferred Tax Asset and Related Valuation Allowance) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Income Taxes
Allowances, accruals and other items not currently deductible	$ 17,673	$ 13,165
Net operating loss carryforwards	16,279	173,062
Current deferred liabilities	(17,345)	(9,044)
Subtotal	16,607	177,183
Less: Valuation allowance	(517)	(13,491)
Net short-term deferred tax assets	16,090	163,692
Net operating loss carryforwards	48,962	157,869
Basis step-up from corporate restructuring and tax planning strategies	0	22,123
Accrued asset retirement obligations	50,131	98,519
Stock-based compensation	26,993	23,428
Deferred revenue	20,896	77,564
Items not currently deductible and other	27,396	148,709
Depreciation and amortization	31,264	(372,117)
Deferred rent	(9,987)	(88,623)
Other	(2,031)	(42,354)
Subtotal	193,624	25,118
Less: Valuation Allowance	(5,321)	(34,716)
Net long-term deferred tax (liabilities) assets	$ 188,303	$ (9,598)