Fair value of financial assets and liabilities - Unobservable inputs of the warrant liability (Details) |
Dec. 31, 2018
$ / shares
|
Jul. 30, 2018
$ / shares
|
Jul. 24, 2018
$ / shares
|
|---|---|---|---|
| Initial public offering | |||
| Unobservable inputs of the warrant liability | |||
| Fair value of series seed preferred stock (in price per share) | $ 15.00 | $ 15.00 | $ 15.00 |
| Risk-free interest rate | |||
| Unobservable inputs of the warrant liability | |||
| Warrant liability inputs | 2.81 | ||
| Expected dividend yield | |||
| Unobservable inputs of the warrant liability | |||
| Warrant liability inputs | 0 | ||
| Expected term | |||
| Unobservable inputs of the warrant liability | |||
| Warrant liability inputs | 7.2 | ||
| Expected volatility | |||
| Unobservable inputs of the warrant liability | |||
| Warrant liability inputs | 64.4 |