Convertible Preferred Stock and Stockholders' Equity (Deficit) - Summary of Stock Option Activity (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Total Options, Beginning balance	1,859,034	790,590	690,223
Total Options, Granted	822,250	1,212,000	316,935
Total Options, Exercised	(21,029)	(81,056)	(174,447)
Total Options, Cancelled	(195,406)	(62,500)	(42,121)
Total Options, Ending balance	2,464,849	1,859,034	790,590
Total Options, Vested or expected to vest	2,288,775
Total Options, Exercisable	1,071,325
Weighted-Average Exercise Price, Beginning balance	$ 6.84	$ 4.01	$ 0.80
Weighted-Average Exercise Price, Granted	6.03	8.41	9.44
Weighted-Average Exercise Price, Exercised	1.04	1.10	0.24
Weighted-Average Exercise Price, Cancelled	7.79	9.09	7.86
Weighted-Average Exercise Price, Ending balance	6.54	$ 6.84	$ 4.01
Weighted-Average Exercise Price, Vested	6.58
Weighted-Average Exercise Price, Vested, Exercisable	$ 5.75
Weighted-Average Remaining Contractual Term Outstanding	7 years 10 months 13 days
Weighted-Average Remaining Contractual Term Vested or expected to vest	7 years 9 months 7 days
Weighted-Average Remaining Contractual Term Exercisable	6 years 7 months 28 days