Basis of Presentation and Summary of Significant Accounting Policies - Accounting for Share-Based Compensation (Details) - USD ($) $ in Thousands |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2021 |
Jun. 30, 2020 |
Jun. 30, 2021 |
Jun. 30, 2020 |
|
| Basis of Presentation [Line Items] | ||||
| Share-based compensation expense | $ 10,216 | $ 7,359 | $ 18,621 | $ 13,012 |
| SBC - Research and development expenses | ||||
| Basis of Presentation [Line Items] | ||||
| Share-based compensation expense | 4,556 | 3,019 | 8,495 | 5,416 |
| SBC - General and administrative expenses | ||||
| Basis of Presentation [Line Items] | ||||
| Share-based compensation expense | $ 5,660 | $ 4,340 | $ 10,126 | $ 7,596 |