Stock-Based Compensation - Summary of Company's Stock Option Activity and Related Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Shares Available for Grant
Shares Available for Grant, Beginning balance	3,166,968	295,101	1,848,367
Shares Available for Grant, Additional authorized		4,708,447
Shares Available for Grant, Granted	(1,173,043)	(1,975,673)	(1,642,799)
Shares Available for Grant, Cancelled	325,706	139,093	89,533
Shares Available for Grant, RSUs Granted	(151,240)
Shares Available for Grant, Ending balance	2,168,391	3,166,968	295,101	1,848,367
Number of Stock Options Outstanding
Number of Stock Options Outstanding, Beginning balance	6,053,672	4,248,519	2,723,573
Number of Stock Options Outstanding, Granted	1,173,043	1,975,673	1,642,799
Number of Stock Options Outstanding, Exercised	(773,718)	(31,427)	(28,320)
Number of Stock Options Outstanding, Cancelled	(325,706)	(139,093)	(89,533)
Number of Stock Options Outstanding, Ending balance	6,127,291	6,053,672	4,248,519	2,723,573
Number of Stock Options Outstanding, Vested and exercisable	3,608,258
Number of Stock Options Outstanding, Vested and expected to vest	5,901,120
Weighted- Average Exercise Price
Weighted- Average Exercise Price, Beginning balance	$ 2.13	$ 0.76	$ 0.71
Weighted- Average Exercise Price, Granted	4.20	5.03	0.84
Weighted- Average Exercise Price, Exercised	0.70	0.76	0.73
Weighted- Average Exercise Price, Cancelled	4.31	1.46	0.74
Weighted- Average Exercise Price, Ending balance	2.60	$ 2.13	$ 0.76	$ 0.71
Weighted- Average Exercise Price, Vested and exercisable	1.66
Weighted- Average Exercise Price, Vested and expected to vest	$ 2.55
Weighted- Average Remaining Contractual Life (Years)
Options Outstanding, Weighted- Average Remaining Contractual Life (Years)	7 years 3 months 18 days	7 years 7 months 6 days	7 years 8 months 12 days	7 years 8 months 12 days
Weighted- Average Remaining Contractual Life (Years), Vested and exercisable	6 years 4 months 24 days
Weighted- Average Remaining Contractual Life (Years), Vested and expected to vest	7 years 3 months 18 days
Aggregate Intrinsic Value
Aggregate Intrinsic Value	$ 7,800	$ 20,605	$ 8,343	$ 138
Aggregate Intrinsic Value, Vested and exercisable	6,711
Aggregate Intrinsic Value, Vested and expected to vest	$ 7,688