Stock-based compensation - Summary of Restricted Stock Unit Activity and Related Information (Details) - RSAs and RSUs - $ / shares |
3 Months Ended | 12 Months Ended |
|---|---|---|
Mar. 31, 2019 |
Mar. 31, 2020 |
|
| Shares of restricted stock outstanding | ||
| Beginning balance (in shares) | 2,036,124 | 2,786,398 |
| Granted (in shares) | 1,464,710 | 673,461 |
| Vested (in shares) | (396,514) | (762,818) |
| Canceled forfeited (in shares) | (317,922) | (385,273) |
| Ending balance (in shares) | 2,786,398 | 2,311,768 |
| Weighted-average grant date fair value | ||
| Beginning balance (in USD per share) | $ 20.01 | $ 13.26 |
| Granted (in USD per share) | 7.64 | 14.26 |
| Vested (in USD per share) | 21.79 | 15.97 |
| Canceled forfeited (in USD per share) | 20.06 | 12.66 |
| Ending balance (in USD per share) | $ 13.26 | $ 12.86 |