Components of Income Tax Expense (Benefit) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Expenses [Line Items]
Current income tax expense (benefit), Federal	$ 9,326us-gaap_CurrentFederalTaxExpenseBenefit	$ 13,674us-gaap_CurrentFederalTaxExpenseBenefit	$ 75,867us-gaap_CurrentFederalTaxExpenseBenefit
Current income tax expense (benefit), State	828	2,368	5,885
Current income tax expense (benefit), Total	10,154us-gaap_CurrentIncomeTaxExpenseBenefit	16,042us-gaap_CurrentIncomeTaxExpenseBenefit	81,752us-gaap_CurrentIncomeTaxExpenseBenefit
Deferred income tax expense (benefit), Federal	(2,280)	(144,771)	8,576
Deferred income tax expense (benefit), State	(931)	(6,266)	(2,815)
Deferred income tax expense (benefit), Total	(3,211)us-gaap_DeferredIncomeTaxExpenseBenefit	(151,037)us-gaap_DeferredIncomeTaxExpenseBenefit	5,761us-gaap_DeferredIncomeTaxExpenseBenefit
Income tax expense (benefit)	$ 6,943us-gaap_IncomeTaxExpenseBenefit	$ (134,995)us-gaap_IncomeTaxExpenseBenefit	$ 87,513us-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.