Leases Maturity of Lease Liabilities (Details) $ in Millions	Sep. 30, 2019 USD ($)
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2019	$ 3
2020	9
2021	7
2022	5
2023	3
2024 and after	29
Total lease payments	55
Less: Interest	(14)
Present value of lease liabilities	41
Finance Lease, Liability, Payment, Due [Abstract]
2019	0
2020	1
2021	0
2022	0
2023	0
2024 and after	0
Total lease payments	1
Less: Interest	0
Present value of lease liabilities	1
Lease Liabilities, Payments Due [Abstract]
2019	3
2020	10
2021	7
2022	5
2023	3
2024 and after	29
Lease, Liability, Payments Due	56
Lease, liability, undiscounted excess amount	(14)
Total lease liabilities	$ 42