Investments and Fair Value Measurement - Fair Value of Unobservable Inputs, Liabilities (Details) $ in Millions |
9 Months Ended |
|---|---|
|
Sep. 30, 2019
USD ($)
| |
| Warrants | |
| Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] | |
| Balance as of December 31, 2018 | $ 52 |
| Vesting of share warrants | 1 |
| Exercise of vested share warrants | (53) |
| Change in fair value | 0 |
| Settlement of derivative liability | 0 |
| Balance as of September 30, 2019 | 0 |
| Convertible Debt Embedded Derivative | |
| Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] | |
| Balance as of December 31, 2018 | 2,018 |
| Vesting of share warrants | 0 |
| Exercise of vested share warrants | 0 |
| Change in fair value | (58) |
| Settlement of derivative liability | (1,960) |
| Balance as of September 30, 2019 | $ 0 |