Income Taxes - Components of Deferred Tax Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Deferred tax assets:
Reserves and accruals	$ 31,999	$ 31,208	$ 33,741
Net operating loss carryovers	27,522	24,852	27,431
Research and development credit carryovers	13,704	13,500	12,136
Deferred stock-based compensation	7,684	6,643	6,063
Other tax credits	2,207	2,764	2,813
Total deferred tax assets	83,116	78,967	82,184
Valuation allowance	(34,347)	(28,354)	(26,557)
Net deferred tax assets	48,769	50,613	55,627
Deferred tax liabilities:
Depreciation and amortization	(5,485)	(5,434)	(3,320)
Intangibles	(11,656)	(17,668)	(26,172)
Other	(483)	(135)	(1,066)
Net deferred tax liabilities	$ (17,624)	$ (23,237)	$ (30,558)