Income Taxes - Components of Deferred Income Taxes (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Non-deductible reserves and accruals	$ 10,164	$ 7,239
Stock compensation	5,086	4,539
Other assets	838us-gaap_DeferredTaxAssetsOther
Net operating loss and other carryforwards	9,070	10,830
Gross deferred tax asset	25,158us-gaap_DeferredTaxAssetsGross	22,608us-gaap_DeferredTaxAssetsGross
Less - valuation allowance	(1,565)	(2,200)	(2,086)	(3,077)
Sub-total	23,593us-gaap_DeferredTaxAssetsNet	20,408us-gaap_DeferredTaxAssetsNet
Depreciation and amortization	(799)	(2,945)
Goodwill amortization	(5,224)	(5,401)
Other liabilities		(2,134)us-gaap_DeferredTaxLiabilitiesOther
Deferred commissions	(5,399)	(5,080)
Net deferred tax asset	$ 12,171us-gaap_DeferredTaxAssetsLiabilitiesNet	$ 4,848us-gaap_DeferredTaxAssetsLiabilitiesNet

Amount of deferred tax liability attributable to taxable temporary differences from depreciation and amortization.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards, net of deferred tax liability attributable to taxable temporary differences.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences not separately disclosed.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from share-based compensation.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from loss reserves other than estimated credit losses.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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Amount of deferred tax liability attributable to taxable temporary differences from capitalized costs.

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Amount of deferred tax liability attributable to taxable temporary differences from goodwill.

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