Income Taxes (Details 5) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Deferred tax assets:
Net operating loss carryforwards	$ 1,826,597	$ 2,009,318
Equity compensation	29,337	25,937
Deferred revenue	33,523	32,200
Tax credit and other attribute carryforwards	110,563	90,297
Insurance loss reserve	10,873	24,598
Other	104,699	114,043
Subtotal	2,115,592	2,296,393
Valuation allowance	(1,520,852)	(1,485,540)
Deferred tax assets	594,740	810,853
Deferred tax liabilities:
Depreciation, amortization and depletion for tax in excess of book expense	945,888	1,317,256
Variable interest investments	144,020	116,005
Other		34,822
Deferred tax liability	1,089,908	1,468,083
Net deferred assets (liabilities)	(495,168)	(657,230)
Balance Sheet Summary
Net current deferred asset	110,480	127,874
Net noncurrent deferred asset	4,408	13,090
Net current deferred liability	(10,721)	(269)
Net noncurrent deferred liability	(599,335)	(797,925)
Net deferred assets (liabilities)	$ (495,168)	$ (657,230)