Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2021 |
Dec. 31, 2020 |
Dec. 31, 2019 |
|
| Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] | |||
| Unrecognized tax benefits at beginning of year | $ 2,293 | $ 1,797 | $ 394 |
| Gross increases - current year tax positions | 239 | 353 | 1,566 |
| Gross increases - prior year tax positions | 134 | 191 | 16 |
| Gross decreases - prior year tax positions | (9) | (48) | (36) |
| Gross decreases - settlements with tax authorities | 0 | 0 | (143) |
| Unrecognized tax benefits at end of year | $ 2,657 | $ 2,293 | $ 1,797 |