Income Taxes (Details 5) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Deferred tax assets:
Net operating loss carryforwards	$ 1,658,084	$ 1,826,597
Equity compensation	32,219	29,337
Deferred revenue	35,689	33,523
Tax credit and other attribute carryforwards	109,294	110,563
Insurance loss reserve	4,645	10,873
Accrued interest	224,959	55,143
Other	162,678	49,556
Subtotal	2,227,568	2,115,592
Valuation allowance	(1,547,441)	(1,520,852)
Deferred tax assets	680,127	594,740
Deferred tax liabilities:
Depreciation, amortization and depletion for tax in excess of book expense	967,689	945,888
Variable interest investments	85,979	144,020
Other	17,890
Deferred tax liability	1,071,558	1,089,908
Net deferred assets (liabilities)	(391,431)	(495,168)
Balance Sheet Summary :
Net current deferred asset	121,316	110,480
Net noncurrent deferred asset	6,491	4,408
Net current deferred liability	(3,075)	(10,721)
Net noncurrent deferred liability	(516,161)	(599,335)	(852,650)
Net deferred assets (liabilities)	$ (391,431)	$ (495,168)