Common Stock Reserved for Issuance - Schedule of Common Stock Reserved for Future Issuance (Detail) - shares	Dec. 31, 2016	Dec. 31, 2015
Class Of Stock [Line Items]
Total shares of common stock reserved	10,822,328	9,833,252
Shares available for future stock option grants
Class Of Stock [Line Items]
Total shares of common stock reserved	2,168,391	3,166,968
ESPP shares available for issuance
Class Of Stock [Line Items]
Total shares of common stock reserved	667,670	285,621
Warrant to purchase common stock
Class Of Stock [Line Items]
Total shares of common stock reserved	1,707,736	326,991
Options To Purchase Common Stock
Class Of Stock [Line Items]
Total shares of common stock reserved	6,127,291	6,053,672
Shares issuable upon settlement of restricted stock units outstanding
Class Of Stock [Line Items]
Total shares of common stock reserved	151,240