Stockholders' Equity - Summary of Stock Option Activity (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options outstanding at December 31, 2014 | shares	8,006,380
Options granted | shares	1,628,402
Options exercised | shares	(949,252)
Options canceled | shares	(508,162)
Options outstanding at December 31, 2015 | shares	8,177,368
Options vested and expected to vest at December 31, 2015 | shares	7,752,480
Options exercisable at December 31, 2015 | shares	4,950,680
Options outstanding, Weighted-Average Exercise per Share Price, Beginning Balance | $ / shares	$ 8.90
Options granted, Weighted-Average Exercise per Share Price | $ / shares	9.95
Options exercised, Weighted-Average Exercise per Share Price | $ / shares	6.21
Options canceled, Weighted-Average Exercise per Share Price | $ / shares	11.91
Options outstanding, Weighted-Average Exercise per Share Price, Ending Balance | $ / shares	9.24
Options vested and expected to vest at December 31, 2015, Weighted-Average Exercise Per Share Price | $ / shares	9.15
Options exercisable at December 31, 2015, Weighted-Average Exercise per Share Price | $ / shares	$ 7.97
Options outstanding, Weighted Average Remaining Contractual Term, Ending	6 years 6 months 22 days
Options vested and expected to vest at December, 31, 2015, Weighted Average Remaining Contractual Term	6 years 4 months 24 days
Options exercisable at December, 31, 2015, Weighted Average Remaining Contractual Term	4 years 11 months 1 day
Options outstanding, Aggregate Intrinsic Value | $	$ 14,074
Options vested and expected to vest at December 31, 2015, Aggregate Intrinsic Value | $	14,042
Options exercisable at December 31, 2015, Aggregate Intrinsic Value | $	$ 13,119