Income Taxes - Reconciliation of Provision for Income Taxes (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule Of Income Taxes [Line Items]
Provision for income taxes at U.S. Federal statutory rate	$ (3,180)	$ 4,071	$ 1,904
State taxes	(604)	1,053	(469)
Differential in rates on foreign earnings	(5,181)	(9,924)	(1,842)
Losses for which no benefit is taken	7,279	9,185	6,880
Change in valuation allowance	(1,104)		(450)
Change in liabilities for uncertain tax positions	1,708	(1,540)	1,261
Non-deductible stock-based compensation	1,996	1,882	1,940
Research credits		(2,138)	(1,404)
Non-deductible acquisition related expenses			1,289
Non-deductible meals and entertainment	232	237	165
Adjustments related to tax positions taken during prior years	619	(255)
Foreign income inclusion	317		403
Adjustment related to property and equipment			182
Tax-exempt investment income	(248)	(71)	(180)
Other	18	354	95
Total provision for income taxes	$ 1,852	$ 2,854	$ 9,774

Income Tax Reconciliation Deductions Plant Related Items

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Income tax reconciliation for losses.

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The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing operations.

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to changes in the valuation allowance for deferred tax assets in the period.

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement for the period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to the extraterritorial income exclusion deduction received under enacted tax laws.

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The portion of the difference, between total income tax expense or benefit as reported in the Income Statement for the period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations, that is attributable to total foreign income tax expense or benefit. The foreign income tax expense or benefit difference represents the income tax expense or benefit at applicable domestic statutory income tax rates applied to foreign earnings or loss for the period versus the foreign income tax expense or benefit calculated by applying the appropriate foreign tax rates.

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement for the period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to nondeductible meal and entertainment expenses under enacted tax laws.

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The portion of the difference, between total income tax expense or benefit as reported in the Income Statement for the year/accounting period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations, that is attributable to all other items not otherwise listed in the existing taxonomy.

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement for the current period and the expected income tax expense or benefit computed attributable to revisions of previously reported income tax expense.

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The sum of the differences between total income tax expense or benefit as reported in the Income Statement and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to changes in all income tax contingencies, whether recorded or adjusted, during the period.

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to research tax credits generated or utilized under enacted tax laws during the period.

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement for the period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to income that is exempt from income taxes under enacted tax laws.

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