Investments and Fair Value Measurement - Summary of Amortized Cost, Unrealized Gains and Losses of Financial Assets (Details) - Recurring - USD ($) $ in Millions |
Dec. 31, 2019 |
Dec. 31, 2018 |
|---|---|---|
| Debt Securities, Available-for-sale [Line Items] | ||
| Amortized Cost | $ 2,894 | $ 2,305 |
| Unrealized Gains | 61 | 65 |
| Unrealized Losses | 0 | 0 |
| Fair Value | 2,955 | 2,370 |
| Commercial paper | ||
| Debt Securities, Available-for-sale [Line Items] | ||
| Amortized Cost | 233 | 0 |
| Unrealized Gains | 0 | 0 |
| Unrealized Losses | 0 | 0 |
| Fair Value | 233 | 0 |
| U.S. government and agency securities | ||
| Debt Securities, Available-for-sale [Line Items] | ||
| Amortized Cost | 153 | 0 |
| Unrealized Gains | 0 | 0 |
| Unrealized Losses | 0 | 0 |
| Fair Value | 153 | 0 |
| Corporate bonds | ||
| Debt Securities, Available-for-sale [Line Items] | ||
| Amortized Cost | 199 | 0 |
| Unrealized Gains | 0 | 0 |
| Unrealized Losses | 0 | 0 |
| Fair Value | 199 | 0 |
| Corporate Debt Securities | ||
| Debt Securities, Available-for-sale [Line Items] | ||
| Amortized Cost | 2,309 | 2,305 |
| Unrealized Gains | 61 | 65 |
| Unrealized Losses | 0 | 0 |
| Fair Value | $ 2,370 | $ 2,370 |