Consolidated Balance Sheet Components - Accrued and Other Current Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Accrued Liabilities and Other Liabilities [Abstract]
Accrued expenses	$ 3,352	$ 2,295
Derivative liability	1,002	0
Income tax payable	317	325
Short-term deferred rent	297	226
Short-term stock repurchase liability	767	521
Other	641	594
Total accrued and other current liabilities	$ 6,376	$ 3,961