Income Taxes (Details 2) (USD $)	Dec. 31, 2013	Jan. 31, 2013
Components of Deferred Income Tax Liability [Line Items]
Total	$ 485,894,000	$ 474,406,000
Temporary Differences [Member]
Components of Deferred Income Tax Liability [Line Items]
Depreciation	424,595,000	493,489,000
Capitalized costs	395,733,000	1,018,375,000
Tax loss carryforward	(99,138,000)	(161,758,000)
State loss carryforward, net of federal benefit	0	0
Valuation allowance	0	0
Federal tax credits and other carryforwards	0	0
Other comprehensive loss	(125,099,000)	(168,585,000)
Basis in unconsolidated entities	367,892,000	199,359,000
Other	370,743,000	(83,747,000)
Total	1,334,726,000	1,297,133,000
Deferred Tax [Member]
Components of Deferred Income Tax Liability [Line Items]
Depreciation	164,671,000	191,390,000
Capitalized costs	153,508,000	394,956,000
Tax loss carryforward	(34,698,000)	(56,615,000)
State loss carryforward, net of federal benefit	(21,170,000)	(23,974,000)
Valuation allowance	48,077,000	53,282,000
Federal tax credits and other carryforwards	(56,274,000)	(58,094,000)
Other comprehensive loss	(48,517,000)	(65,382,000)
Basis in unconsolidated entities	142,680,000	77,317,000
Other	137,617,000	(38,474,000)
Total	$ 485,894,000	$ 474,406,000