Income Taxes - Income Tax Provision (Benefit) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Current income tax provision:
Federal	$ 18,722us-gaap_CurrentFederalTaxExpenseBenefit	$ 1,745us-gaap_CurrentFederalTaxExpenseBenefit	$ 303us-gaap_CurrentFederalTaxExpenseBenefit
State	3,131	404	88
Total	21,853us-gaap_CurrentIncomeTaxExpenseBenefit	2,149us-gaap_CurrentIncomeTaxExpenseBenefit	391us-gaap_CurrentIncomeTaxExpenseBenefit
Deferred income tax provision (benefit):
Federal	3,118	(11,182)	510
State	456	(1,516)	108
Total	3,574us-gaap_DeferredIncomeTaxExpenseBenefit	(12,698)us-gaap_DeferredIncomeTaxExpenseBenefit	618us-gaap_DeferredIncomeTaxExpenseBenefit
Total income tax provision (benefit)	$ 25,427us-gaap_IncomeTaxExpenseBenefit	$ (10,549)us-gaap_IncomeTaxExpenseBenefit	$ 1,009us-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.