Leases Lease Liability Maturities (Details) $ in Millions	Mar. 31, 2019 USD ($)
Operating Lease Liabilities, Payments Due [Abstract]
Remainder of 2019	$ 141
2020	168
2021	146
2022	124
2023	79
Thereafter	194
Total lease payments	852
Less: imputed interest	(144)
Operating lease liability	708
Finance Lease Liabilities, Payments, Due [Abstract]
Remainder of 2019	13
2020	18
2021	14
2022	13
2023	12
Thereafter	68
Total lease payments	138
Less: imputed interest	(43)
Financing lease liability	$ 95