Income Taxes - Components of Deferred Tax Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax Disclosure [Abstract]
Net operating loss carryforwards and credits	$ 19,552	$ 24,883
Acquired intangible assets	7,543	8,121
Reserves and accruals	1,656	2,149
Share-based compensation	2,775	2,438
Depreciation	346	268
Total deferred income tax assets	31,872	37,859
Deferred income tax liabilities:
Acquired intangible assets	(96)	(213)
Other	(4)	(6)
Total deferred income tax liabilities	(100)	(219)
Valuation allowance	(1,500)	(37,726)	(39,049)	(39,373)
Deferred income tax asset (liability), net	$ 30,272	$ (86)