Income Taxes - Reconciliation of Provision (Benefit) for Income Taxes (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Tax at statutory rate	35.00%	35.00%	35.00%
State taxes, net of federal benefit	3.00%	2.00%	7.00%
Uncertain tax positions	(22.00%)
IRS audit resolution	11.00%
Change in valuation allowance	2.00%
Other, net	0.00%
Income tax expense	29.00%	37.00%	42.00%
Tax at statutory rate	$ 47,922	$ 41,968	$ 22,645
State taxes, net of federal benefit	4,357	2,893	4,793
Uncertain tax positions	(30,961)
IRS audit resolution	15,505
Change in valuation allowance	2,165	(264)	(242)
Other, net	361	181	(166)
Income tax expense	$ 39,349us-gaap_IncomeTaxExpenseBenefit	$ 44,778us-gaap_IncomeTaxExpenseBenefit	$ 27,030us-gaap_IncomeTaxExpenseBenefit

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to changes in the valuation allowance for deferred tax assets.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to income tax contingencies. Includes, but not limited to, domestic tax contingency, foreign tax contingency, state and local tax contingency, and other contingencies.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to increase (decrease) in the valuation allowance for deferred tax assets.

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