Leases - Maturities (Details) $ in Millions	Mar. 31, 2019 USD ($)
Leases [Abstract]
Operating Leases, Remainder of 2019	$ 37
Operating Leases, 2020	44
Operating Leases, 2021	37
Operating Leases, 2022	27
Operating Leases, 2023	20
Operating Leases, Thereafter	57
Operating Leases, Total lease payments	222
Operating Leases, Less: interest	36
Operating Leases, Present value of lease liabilities	186
Finance Leases, Remainder of 2019	4
Finance Leases, 2020	4
Finance Leases, 2021	4
Finance Leases, 2022	4
Finance Leases, 2023	3
Finance Leases, Thereafter	15
Finance Leases, Total lease payments	34
Finance Leases, Less: interest	5
Finance Leases, Present value of lease liabilities	$ 29