Income Taxes - Components of Provision for Income Taxes (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Current
Federal	$ 31,787us-gaap_CurrentFederalTaxExpenseBenefit	$ 10,395us-gaap_CurrentFederalTaxExpenseBenefit
State	3,168	1,787	341
Total current tax expense	34,955us-gaap_CurrentIncomeTaxExpenseBenefit	12,182us-gaap_CurrentIncomeTaxExpenseBenefit	341us-gaap_CurrentIncomeTaxExpenseBenefit
Deferred
Federal	3,200	29,933	19,707
State	1,194	2,663	6,982
Total deferred tax expense (benefit)	4,394us-gaap_DeferredIncomeTaxExpenseBenefit	32,596us-gaap_DeferredIncomeTaxExpenseBenefit	26,689us-gaap_DeferredIncomeTaxExpenseBenefit
Income tax expense	$ 39,349us-gaap_IncomeTaxExpenseBenefit	$ 44,778us-gaap_IncomeTaxExpenseBenefit	$ 27,030us-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.