Net (Loss) Income Per Share - Calculation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands |
3 Months Ended | 9 Months Ended | 12 Months Ended | |||
|---|---|---|---|---|---|---|
Sep. 30, 2021 |
Sep. 30, 2020 |
Sep. 30, 2021 |
Sep. 30, 2020 |
Dec. 31, 2020 |
Dec. 31, 2019 |
|
| Earnings Per Share [Abstract] | ||||||
| Net (loss) income | $ (34,527) | $ 12,758 | $ (400,555) | $ (10,001) | $ (136,392) | $ (363,737) |
| Net (loss) income attributable to common stockholders | $ (34,527) | $ 4,966 | $ (400,555) | $ (10,001) | $ (136,392) | $ (363,737) |
| Basic weighted average number of common shares and common shares equivalents outstanding (in shares) | 414,572,706 | 88,863,244 | 410,417,493 | 88,616,116 | 88,691,582 | 87,829,419 |
| Diluted weighted average number of common shares and common shares equivalents outstanding (in shares) | 414,572,706 | 248,133,335 | 410,417,493 | 88,616,116 | 88,691,582 | 87,829,419 |
| Net (loss) income per share attributable to common stockholders - basic (in dollars per share) | $ (0.08) | $ 0.06 | $ (0.98) | $ (0.11) | $ (1.54) | $ (4.14) |
| Net (loss) income per share attributable to common stockholders - diluted (in dollars per share) | $ (0.08) | $ 0.02 | $ (0.98) | $ (0.11) | $ (1.54) | $ (4.14) |