Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands |
3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2019 |
Sep. 30, 2019 |
Jun. 30, 2019 |
Mar. 31, 2019 |
Dec. 31, 2018 |
Sep. 30, 2018 |
Jun. 30, 2018 |
Mar. 31, 2018 |
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| Statements of Operations Data: | |||||||||||
| Total operating expenses | $ 45,428 | $ 48,482 | $ 41,285 | $ 34,406 | $ 29,122 | $ 27,554 | $ 20,384 | $ 14,603 | $ 169,601 | $ 91,663 | $ 43,264 |
| Loss from operations | (45,428) | (48,482) | (41,285) | (34,406) | (29,122) | (27,554) | (20,384) | (14,603) | (169,601) | (91,663) | (43,264) |
| Net loss attributable to common stockholders | $ (44,472) | $ (47,015) | $ (39,390) | $ (32,581) | $ (27,183) | $ (26,362) | $ (21,239) | $ (14,411) | $ (163,458) | $ (89,195) | $ (44,503) |
| Net loss per share attributable to common stockholders, basic and diluted | $ (0.56) | $ (0.59) | $ (0.50) | $ (0.42) | $ (0.35) | $ (0.42) | $ (2.43) | $ (1.72) | $ (2.08) | $ (2.27) | $ (5.55) |