Leases Future minimum payments on noncancellable operating leases (Details) $ in Millions |
Dec. 31, 2018
USD ($)
|
|---|---|
| Leases [Abstract] | |
| Operating Leases, Future Minimum Payments Due | $ 975 |
| 2019 | 275 |
| 2020 | 146 |
| 2021 | 122 |
| 2022 | 100 |
| 2023 | 78 |
| Thereafter | $ 254 |