Loss Per Share - Summary of Anti-dilutive Securities (Details) - shares |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
|
| Employee Options | |||
| Earnings Per Share [Line Items] | |||
| Antidilutive securities excluded from computation of earnings per share | 12,243,526 | 14,646,720 | 10,976,480 |
| Restricted Stock Units | |||
| Earnings Per Share [Line Items] | |||
| Antidilutive securities excluded from computation of earnings per share | 100,383 | 195,937 | 501,480 |
| Restricted Stock Awards | |||
| Earnings Per Share [Line Items] | |||
| Antidilutive securities excluded from computation of earnings per share | 61,880 | 61,880 | |
| Warrants | |||
| Earnings Per Share [Line Items] | |||
| Antidilutive securities excluded from computation of earnings per share | 6,720,000 | 5,120,000 | |