Investments and Fair Value Measurement - Fair Value of Unobservable Inputs, Liabilities (Details) - USD ($) $ in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2019 |
Dec. 31, 2018 |
|
| Warrants | ||
| Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] | ||
| Beginning balance | $ 52 | $ 125 |
| Vesting of share warrants | 1 | 41 |
| Exercise of vested share warrants | (53) | (2) |
| Change in fair value | 0 | (120) |
| Settlement of derivative liability | 0 | 8 |
| Ending balance | 0 | 52 |
| Convertible Debt Embedded Derivative | ||
| Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] | ||
| Beginning balance | 2,018 | 1,517 |
| Vesting of share warrants | 0 | 0 |
| Exercise of vested share warrants | 0 | 0 |
| Change in fair value | (58) | 0 |
| Settlement of derivative liability | (1,960) | 501 |
| Ending balance | $ 0 | $ 2,018 |