Leases (Schedule of Prior Year Maturities) (Details) $ in Millions |
Dec. 31, 2018
USD ($)
|
|---|---|
| Leases [Abstract] | |
| Operating Leases, Future Minimum Payments Due, Next Twelve Months | $ 160 |
| Operating Leases, Future Minimum Payments, Due in Two Years | 125 |
| Operating Leases, Future Minimum Payments, Due in Three Years | 77 |
| Operating Leases, Future Minimum Payments, Due in Four Years | 49 |
| Operating Leases, Future Minimum Payments, Due in Five Years | 28 |
| Operating Leases, Future Minimum Payments, Due Thereafter | $ 118 |