Leases - Maturity Schedules (Details) $ in Millions	Mar. 31, 2019 USD ($)
Operating leases
2019 (excluding the three months ended March 31, 2019)	$ 85
2020	91
2021	69
2022	48
2023	34
Thereafter	55
Total future undiscounted lease payments	382
Less imputed interest	(25)
Total reported lease liability	357
Finance leases
2019 (excluding the three months ended March 31, 2019)	1
2020	1
2021	0
2022	0
2023	0
Thereafter	0
Total future undiscounted lease payments	2
Less imputed interest	0
Total reported lease liability	$ 2