Stockholders' Equity - Summary of Stock Option Activity (Detail)	6 Months Ended
	Jun. 30, 2017 $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Total Options, Beginning balance | shares	3,393,813
Total Options, Granted | shares	1,059,100
Total Options, Exercised | shares	(51,757)
Total Options, Cancelled | shares	(72,412)
Total Options, Ending balance | shares	4,328,744
Weighted-Average Exercise Price, Beginning balance | $ / shares	$ 5.10
Weighted-Average Exercise Price, Granted | $ / shares	4.43
Weighted-Average Exercise Price, Exercised | $ / shares	1.15
Weighted-Average Exercise Price, Cancelled | $ / shares	4.42
Weighted-Average Exercise Price, Ending balance | $ / shares	$ 5.00