Leases - Schedule of Lease Assets and Liabilities (Details) - USD ($) $ in Millions |
Dec. 31, 2020 |
Dec. 31, 2019 |
|---|---|---|
| Leases [Abstract] | ||
| ROU assets | $ 1,393 | $ 1,289 |
| Lease liabilities (short-term) | 321 | 269 |
| Lease liabilities (long-term) | $ 1,114 | $ 1,030 |
| ROU assets, statement of financial position | us-gaap:OtherAssetsNoncurrent | us-gaap:OtherAssetsNoncurrent |
| Lease liabilities (short-term), statement of financial position | us-gaap:OtherLiabilitiesCurrent | us-gaap:OtherLiabilitiesCurrent |
| Lease liabilities (long-term), statement of financial position | us-gaap:OtherLiabilitiesNoncurrent | us-gaap:OtherLiabilitiesNoncurrent |