Income Taxes (Details 3) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013		Jan. 31, 2013
Net Deferred Tax Liability
Deferred tax liabilities	$ 1,423,173		$ 1,832,038
Deferred tax assets	985,356		1,410,914
Less: valuation allowance	(48,077)	[1]	(53,282)	[1]
Net deferred tax assets	937,279		1,357,632
Total	$ 485,894		$ 474,406

[1] The valuation allowance is related to state net operating losses and bonus depreciation, general business credits and charitable contributions.