Balance Sheet Components - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Balance Sheet Related Disclosures [Abstract]
Remaining contractual maturities of available-for-sale-securities	less than two years
Realized gains (losses) on available-for-sale securities	$ 0
Cash, cash equivalents, and short-term investments	71,900,000
Cash portion included in cash, cash equivalents and short-term investments	600,000
Cash equivalents and short-term investments	71,300,000
Property and equipment depreciation and amortization expense	$ 404,000	$ 361,000	$ 281,000