Income Taxes - Provision for Income Taxes (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]
Federal, current	$ 247,898us-gaap_CurrentFederalTaxExpenseBenefit	$ 138,343us-gaap_CurrentFederalTaxExpenseBenefit	$ 261,552us-gaap_CurrentFederalTaxExpenseBenefit
State, current	30,790	223	20,337
Foreign, current	19,235us-gaap_CurrentForeignTaxExpenseBenefit	10,464us-gaap_CurrentForeignTaxExpenseBenefit	3,199us-gaap_CurrentForeignTaxExpenseBenefit
Total current	297,923us-gaap_CurrentIncomeTaxExpenseBenefit	149,030us-gaap_CurrentIncomeTaxExpenseBenefit	285,088us-gaap_CurrentIncomeTaxExpenseBenefit
Federal, deferred	94,991	36,157	(23,052)
State, deferred	3,958	(39)	(10,440)
Foreign, deferred	(8,085)	20,446	8,218
Total deferred	90,864us-gaap_DeferredIncomeTaxExpenseBenefit	56,564us-gaap_DeferredIncomeTaxExpenseBenefit	(25,274)us-gaap_DeferredIncomeTaxExpenseBenefit
Total provision for income taxes	$ 388,787us-gaap_IncomeTaxExpenseBenefit	$ 205,594us-gaap_IncomeTaxExpenseBenefit	$ 259,814us-gaap_IncomeTaxExpenseBenefit

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