Leases - Lease Position (Details) - USD ($) $ in Millions |
Dec. 31, 2019 |
Dec. 31, 2018 |
|---|---|---|
| Assets | ||
| Operating lease assets | $ 5,627 | $ 5,994 |
| Finance lease assets | 1,062 | 490 |
| Total lease assets | 6,689 | 6,484 |
| Liabilities | ||
| Current operating lease liabilities | 801 | 955 |
| Current finance lease liabilities | 233 | 109 |
| Noncurrent operating lease liabilities | 5,294 | 5,801 |
| Noncurrent finance lease liabilities | 821 | 294 |
| Total lease liabilities | $ 7,149 | $ 7,159 |
| Operating leases, weighted-average remaining lease term | 12 years | 12 years |
| Finance leases, Operating leases, weighted-average remaining lease term | 5 years | 7 years |
| Operating leases, weighted-average discount rate | 3.73% | 3.69% |
| Finance leases, weighted-average discount rate | 3.46% | 5.23% |