Net Loss Per Share - Schedule of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders (Detail) - USD ($) $ / shares in Units, $ in Thousands |
3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2015 |
Sep. 30, 2015 |
Jun. 30, 2015 |
Mar. 31, 2015 |
Dec. 31, 2014 |
Sep. 30, 2014 |
Jun. 30, 2014 |
Mar. 31, 2014 |
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
|
| Earnings Per Share [Abstract] | |||||||||||
| Net loss | $ (10,637) | $ (11,524) | $ (10,009) | $ (7,578) | $ (7,954) | $ (7,294) | $ (6,392) | $ (7,008) | $ (39,748) | $ (28,648) | $ (13,317) |
| Accretion of redeemable convertible preferred stock to redemption value | (11) | (27) | |||||||||
| Net loss attributable to common stockholders | $ (10,637) | $ (11,524) | $ (10,009) | $ (7,578) | $ (7,954) | $ (7,294) | $ (6,397) | $ (7,014) | $ (39,748) | $ (28,659) | $ (13,344) |
| Weighted average common shares outstanding, basic and diluted | 23,244,162 | 10,652,865 | 2,609,020 | ||||||||
| Net loss per share attributable to common stockholders, basic and diluted | $ (0.43) | $ (0.47) | $ (0.45) | $ (0.35) | $ (0.37) | $ (0.48) | $ (2.10) | $ (2.45) | $ (1.71) | $ (2.69) | $ (5.11) |