Leases Maturities of Lease Liabilities (Details) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Operating Lease Liabilities, Payments Due [Abstract]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	$ 29,000,000
Lessee, Operating Lease, Liability, Payments, Due Year Two	34,000,000
Lessee, Operating Lease, Liability, Payments, Due Year Three	25,000,000
Lessee, Operating Lease, Liability, Payments, Due Year Four	21,000,000
Lessee, Operating Lease, Liability, Payments, Due Year Five	19,000,000
Lessee, Operating Lease, Liability, Payments, Due after Year Five	147,000,000
Operating Leases, Future Sublease Income	0	$ 0
Lessee, Operating Lease, Liability, Payments, Due	275,000,000
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(50,000,000)
Operating Lease, Liability	225,000,000
Finance Lease Liabilities, Payments, Due [Abstract]
Finance Lease, Liability, Payments, Remainder of Fiscal Year	31,000,000
Finance Lease, Liability, Payments, Due Year Two	43,000,000
Finance Lease, Liability, Payments, Due Year Three	41,000,000
Finance Lease, Liability, Payments, Due Year Four	32,000,000
Finance Lease, Liability, Payments, Due Year Five	23,000,000
Finance Lease, Liability, Payments, Due after Year Five	88,000,000
Finance Lease, Future Minimum Sublease Rentals	0
Finance Lease, Liability, Payments, Due	258,000,000
Finance Lease, Liability, Undiscounted Excess Amount	(95,000,000)
Finance Lease, Liability	163,000,000	$ 167,000,000
Finance lease commitments that have not yet commenced	$ 0