Nature of the Business and Basis of Presentation (Details) - USD ($) $ in Thousands |
1 Months Ended | 3 Months Ended | 12 Months Ended | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Jul. 20, 2018 |
Jul. 31, 2018 |
Dec. 31, 2018 |
Sep. 30, 2018 |
Jun. 30, 2018 |
Mar. 31, 2018 |
Dec. 31, 2017 |
Sep. 30, 2017 |
Jun. 30, 2017 |
Mar. 31, 2017 |
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
|
| Sale of Equity | |||||||||||||
| Net proceeds after deducting underwriting discounts and commissions and other offering costs | $ 257,866 | ||||||||||||
| Recurring losses | $ (27,183) | $ (26,362) | $ (21,239) | $ (14,411) | $ (17,517) | $ (11,919) | $ (9,834) | $ (5,233) | (89,195) | $ (44,503) | $ (11,764) | ||
| Accumulated deficit | $ (150,082) | $ (60,979) | $ (150,082) | $ (60,979) | |||||||||
| Common stock | |||||||||||||
| Sale of Equity | |||||||||||||
| Shares issued (in shares) | 12,055,450 | ||||||||||||
| Conversion of redeemable convertible preferred stock to common stock (in shares) | 51,845,438 | 51,845,438 | 51,845,438 | ||||||||||
| IPO | |||||||||||||
| Sale of Equity | |||||||||||||
| Shares issued (in shares) | 12,055,450 | ||||||||||||
| Net proceeds after deducting underwriting discounts and commissions and other offering costs | $ 254,300 | ||||||||||||
| Conversion of redeemable convertible preferred stock to common stock (in shares) | 131,273 | ||||||||||||
| Overallotment | |||||||||||||
| Sale of Equity | |||||||||||||
| Shares issued (in shares) | 1,572,450 | ||||||||||||