Nature of the Business and Basis of Presentation (Details) - USD ($) $ in Thousands |
1 Months Ended | 3 Months Ended | 6 Months Ended | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Jul. 20, 2018 |
Jul. 31, 2018 |
Jun. 30, 2019 |
Mar. 31, 2019 |
Jun. 30, 2018 |
Mar. 31, 2018 |
Jun. 30, 2019 |
Jun. 30, 2018 |
Jan. 01, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| Sale of Equity | |||||||||||
| Net loss | $ (39,390) | $ (32,581) | $ (21,239) | $ (14,411) | $ (71,971) | $ (35,650) | |||||
| Accumulated deficit | $ (221,253) | $ (221,253) | $ (149,282) | $ (150,082) | $ (60,979) | ||||||
| Common stock | |||||||||||
| Sale of Equity | |||||||||||
| Conversion of redeemable convertible preferred stock to common stock (in shares) | 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 | ||||||||||
| IPO | Common stock | |||||||||||
| Sale of Equity | |||||||||||
| Shares issued (in shares) | 12,055,450 | ||||||||||
| Overallotment | |||||||||||
| Sale of Equity | |||||||||||
| Shares issued (in shares) | 1,572,450 | ||||||||||