Leases Maturities of Lease Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	$ 8	$ 4
Lessee, Operating Lease, Liability, Payments, Due Year Two	8
Finance Lease, Liability, Payments, Due Year Two	16
Finance Lease, Liability, Payments, Due Year Two	16
Lessee, Operating Lease, Liability, Payments, Due Year Three	8
Finance Lease, Liability, Payments, Due Year Three	16
Lessee, Operating Lease, Liability, Payments, Due Year Four	8
Finance Lease, Liability, Payments, Due Year Four	14
Lessee, Operating Lease, Liability, Payments, Due Year Five	7
Finance Lease, Liability, Payments, Due Year Five	14
Lessee, Operating Lease, Liability, Payments, Due after Year Five	46
Finance Lease, Liability, Payments, Due after Year Five	235
Lessee, Operating Lease, Liability, Payments, Due	85
Finance Lease, Liability, Payment, Due	311
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(34)
Finance Lease, Liability, Undiscounted Excess Amount	(160)
Operating Lease, Liability	51
Finance Lease, Liability	$ 151