Stockholders' equity (deficit) (Details) |
12 Months Ended | ||
|---|---|---|---|
|
Dec. 31, 2015
Vote
shares
|
Jan. 31, 2015
shares
|
Dec. 31, 2014
shares
|
|
| Class of Stock | |||
| Common stock reserved for future issuance | 6,253,651 | 25,722,026 | |
| Options issued and outstanding | 3,659,713 | 1,923,332 | |
| Options available for grant under stock option plan | 2,268,938 | 276,805 | |
| ESPP | |||
| Class of Stock | |||
| Common stock reserved for future issuance | 325,000 | 325,000 | |
| Convertible preferred stock | |||
| Class of Stock | |||
| Common stock reserved for future issuance | 23,521,889 | ||
| Common stock | |||
| Class of Stock | |||
| Number of votes for each share | Vote | 1 |