Income Taxes - Components of Deferred Tax Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Deferred income tax assets:
Net operating loss carryforwards and credits	$ 17,539	$ 19,552
Acquired intangible assets	6,444	7,543
Reserves and accruals	1,565	1,656
Share-based compensation	2,877	2,775
Depreciation	407	346
Total deferred income tax assets	28,832us-gaap_DeferredTaxAssetsGross	31,872us-gaap_DeferredTaxAssetsGross
Deferred income tax liabilities:
Acquired intangible assets	(18)	(96)
Other	(144)us-gaap_DeferredTaxLiabilitiesOther	(4)us-gaap_DeferredTaxLiabilitiesOther
Total deferred income tax liabilities	(162)us-gaap_DeferredIncomeTaxLiabilities	(100)us-gaap_DeferredIncomeTaxLiabilities
Valuation allowance	(1,500)	(1,500)	(37,726)	(39,049)
Deferred income tax asset , net	$ 27,170us-gaap_DeferredTaxAssetsLiabilitiesNet	$ 30,272us-gaap_DeferredTaxAssetsLiabilitiesNet

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Amount 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 temporary differences from intangible assets including goodwill.

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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 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 from property, plant, and equipment.

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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 warranty reserves.

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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 intangible assets other than goodwill.

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Amount of deferred tax liability attributable to taxable temporary differences not separately disclosed.

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