Leases Lease, Operating and Finance Lease Maturity (Details) $ in Millions	Sep. 30, 2019 USD ($)
Operating and Finance Lease Maturity [Abstract]
Lessee, Operating Lease, Liability, Payments, Due Next Rolling Twelve Months	$ 185
Lessee, Operating Lease, Liability, Payments, Due in Rolling Year Two	194
Lessee, Operating Lease, Liability, Payments, Due in Rolling Year Three	179
Lessee, Operating Lease, Liability, Payments, Due in Rolling Year Four	158
Lessee, Operating Lease, Liability, Payments, Due in Rolling Year Five	140
Lessee, Operating Lease, Liability, Payments, Due after Rolling Year Five	518
Lessee, Operating Lease, Liability, Payments, Due	1,374
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(185)
Operating Lease, Liability	1,189
Finance Lease, Liability, Payments, Due in Next Rolling Twelve Months	5
Finance Lease, Liability, Payments, Due in Rolling Year Two	5
Finance Lease, Liability, Payments, Due in Rolling Year Three	5
Finance Lease, Liability, Payments, Due in Rolling Year Four	5
Finance Lease, Liability, Payments, Due in Rolling Year Five	3
Finance Lease, Liability, Payments, Due in Rolling after Year Five	11
Finance Lease, Liability, Payment, Due	34
Finance Lease, Liability, Undiscounted Excess Amount	(8)
Finance Lease, Liability	26
Operating and Finance Lease, Liability, Payments Due in Next Rolling Twelve Months	190
Operating and Finance Lease, Liability, Payments Due in Rolling Year Two	199
Operating and Finance Lease, Liability, Payments Due in Rolling Year Three	184
Operating and Finance Lease, Liability, Payments Due in Rolling Year Four	163
Operating and Finance Lease, Liability, Payments Due in Rolling Year Five	143
Operating and Finance Lease, Liability, Payments Due in Rolling After Year Five	529
Operating and Finance Lease, Liability, Payments, Due	1,408
Operating and Finance Lease, Liability, Undiscounted Excess Amount	(193)
Operating and Finance Lease Liabilities	$ 1,215