Leases Maturity of Lease Liabilities (Details) $ in Millions	Mar. 31, 2019 USD ($)
Operating Lease Liabilities, Payments Due [Abstract]
2019	$ 7
2020	8
2021	5
2022	3
2023	1
2024 and after	0
Total lease payments	24
Less: Interest	(1)
Present value of lease liabilities	23
Finance Lease Liabilities, Payments, Due [Abstract]
2019	0
2020	0
2021	0
2022	0
2023	0
2024 and after	0
Total lease payments	2
Less: Interest	0
Present value of lease liabilities	2
Lease, liability, undiscounted excess amount	(1)
Lease Liabilities, Payments Due [Abstract]
2019	7
2020	8
2021	6
2022	3
2023	1
2024 and after	0
Lease, Liability, Payments Due	25
Total lease liabilities	$ 24