Liability Maturity (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	$ 251
Lessee, Operating Lease, Liability, Payments, Due Year Two	216
Lessee, Operating Lease, Liability, Payments, Due Year Three	187
Lessee, Operating Lease, Liability, Payments, Due Year Four	143
Lessee, Operating Lease, Liability, Payments, Due Year Five	88
Lessee, Operating Lease, Liability, Payments, Due after Year Five	292
Lessee, Operating Lease, Liability, Payments, Due	1,177
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(181)
Operating Lease, Liability	$ 996
Operating Leases, Future Minimum Payments Due, Next Twelve Months		$ 214
Operating Leases, Future Minimum Payments, Due in Two Years		149
Operating Leases, Future Minimum Payments, Due in Three Years		121
Operating Leases, Future Minimum Payments, Due in Four Years		95
Operating Leases, Future Minimum Payments, Due in Five Years		52
Operating Leases, Future Minimum Payments, Due Thereafter		177
Operating Leases, Future Minimum Payments Due		$ 808