Stockholders' Equity - Reserve for Unissued Shares of Common Stock (Details) |
Dec. 31, 2015
shares
|
|---|---|
| Equity [Abstract] | |
| Outstanding stock options | 24,277,901 |
| Outstanding restricted stock units | 3,747,340 |
| Outstanding common stock warrants | 1,631,478 |
| Additional shares available for grant under equity plan | 3,095,368 |
| Total | 32,752,087 |