Fair Value Measurement - Convertible Notes (Details) - Convertible Notes - USD ($) |
12 Months Ended | |
|---|---|---|
Dec. 31, 2020 |
Dec. 31, 2019 |
|
| Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] | ||
| Fair value, liability, beginning balance | $ 39,020,000 | $ 0 |
| Exercise of warrants | 268,925,000 | 38,520,000 |
| Conversion of convertible notes into common stock | (270,794,684) | (481,728) |
| Change in fair value | 160,549,684 | 981,728 |
| Fair value, liability, ending balance | $ 197,700,000 | $ 39,020,000 |