Summary of Income Tax Expense (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Current Income Tax Expense:
Federal	$ 41,946us-gaap_CurrentFederalTaxExpenseBenefit	$ 91,664us-gaap_CurrentFederalTaxExpenseBenefit	$ 116,234us-gaap_CurrentFederalTaxExpenseBenefit
State	8,682	9,393	10,819
Current Income Tax Expense (Benefit), Total	50,628us-gaap_CurrentIncomeTaxExpenseBenefit	101,057us-gaap_CurrentIncomeTaxExpenseBenefit	127,053us-gaap_CurrentIncomeTaxExpenseBenefit
Deferred Income Tax (Benefit):
Federal	(3,314)	(35,941)	(23,035)
State	(3,843)	(822)	(206)
Deferred Income Tax Expense (Benefit), Total	(7,157)us-gaap_DeferredIncomeTaxExpenseBenefit	(36,763)us-gaap_DeferredIncomeTaxExpenseBenefit	(23,241)us-gaap_DeferredIncomeTaxExpenseBenefit
INCOME TAXES	$ 43,471us-gaap_IncomeTaxExpenseBenefit	$ 64,294us-gaap_IncomeTaxExpenseBenefit	$ 103,812us-gaap_IncomeTaxExpenseBenefit

Amount of current federal tax expense (benefit) pertaining to income (loss) from continuing operations.

Amount of current income tax expense (benefit) pertaining to taxable income (loss) from continuing operations.

Amount of current state and local tax expense (benefit) pertaining to income (loss) from continuing operations.

Amount of deferred federal income tax expense (benefit) pertaining to income (loss) from continuing operations.

Amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations.

Amount of deferred state and local tax expense (benefit) pertaining to income (loss) from continuing operations.