Leases - Undiscounted Cash Flows under ASC 842 (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Operating Leases
2020	$ 24
2020	16
2021	12
2022	7
2023	4
Thereafter	2
Total minimum lease payments	65
Less: amount of lease payments representing interest	(7)
Present value of future minimum lease payments	58
Less: current obligations under leases	(20)
Long-term lease obligations	38
Finance Lease, Liability, Payment, Due [Abstract]
2020	60
2020	54
2021	23
2022	0
2023	0
Thereafter	0
Total minimum lease payments	137
Less: amount of lease payments representing interest	(7)
Present value of future minimum lease payments	130
Less: current obligations under leases	(55)	$ (17)
Long-term lease obligations	$ 75	$ 30