Net Loss Per Share Attributable to Common Stockholders - Schedule of Basic and Diluted Net Loss Per Common Share (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 attributable to common stockholders | $ (39,594) | $ (23,342) | $ (17,143) | ||||||||
| Weighted-average number of common shares — basic and diluted | 27,346,780 | 27,307,103 | 26,690,673 | 20,350,557 | 20,125,009 | 20,124,574 | 16,883,716 | 786,986 | 25,431,332 | 14,548,516 | 684,330 |
| Net loss per share attributable to common stockholders — basic and diluted | $ (0.39) | $ (0.39) | $ (0.37) | $ (0.41) | $ (0.37) | $ (0.28) | $ (0.44) | $ (3.70) | $ (1.56) | $ (1.60) | $ (25.05) |