Income Taxes - Components of Consolidated Income Tax Expense (Benefit) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Current:
Federal	$ 20,811us-gaap_CurrentFederalTaxExpenseBenefit	$ 15,270us-gaap_CurrentFederalTaxExpenseBenefit	$ 7,373us-gaap_CurrentFederalTaxExpenseBenefit
State	684	504	302
Total Current	21,495us-gaap_CurrentIncomeTaxExpenseBenefit	15,774us-gaap_CurrentIncomeTaxExpenseBenefit	7,675us-gaap_CurrentIncomeTaxExpenseBenefit
Deferred:
Federal	(821)	(207)	115
State	(591)
Total Deferred	(1,412)us-gaap_DeferredIncomeTaxExpenseBenefit	(207)us-gaap_DeferredIncomeTaxExpenseBenefit	115us-gaap_DeferredIncomeTaxExpenseBenefit
Income tax expense, Total	$ 20,083us-gaap_IncomeTaxExpenseBenefit	$ 15,567us-gaap_IncomeTaxExpenseBenefit	$ 7,790us-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.