Leases Lease maturities (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Leases [Abstract]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	$ 9
Finance Lease, Liability, Payments, Remainder of Fiscal Year	0
Lessee, Operating Lease, Liability, Payments, Due Year Two	37
Finance Lease, Liability, Payments, Due Year Two	2
Lessee, Operating Lease, Liability, Payments, Due Year Three	34
Finance Lease, Liability, Payments, Due Year Three	1
Lessee, Operating Lease, Liability, Payments, Due Year Four	30
Finance Lease, Liability, Payments, Due Year Four	1
Lessee, Operating Lease, Liability, Payments, Due Year Five	28
Finance Lease, Liability, Payments, Due Year Five	0
Lessee, Operating Lease, Liability, Payments, Due after Year Five	126
Finance Lease, Liability, Payments, Due after Year Five	0
Lessee, Operating Lease, Liability, Payments, Due	264
Finance Lease, Liability, Payment, Due	4
Operating lease, Future Minimum Payments, Interest Included in Payments	(66)
Capital Leases, Future Minimum Payments, Interest Included in Payments	0
Operating Leases, Future Minimum Payments Due	198	$ 235
Capital Leases, Future Minimum Payments Due	$ 4