Leases - Future Lease Payments Under Non-cancelable Leases (Details) $ in Millions	Dec. 31, 2019 USD ($)
Operating Leases
2020	$ 197
2021	146
2022	102
2023	68
2024	42
Thereafter	97
Total future undiscounted lease payments	652
Less imputed interest	(71)
Total operating lease liabilities	581
Finance Leases
2020	38
2021	34
2022	23
2023	15
2024	9
Thereafter	15
Total future undiscounted lease payments	134
Less imputed interest	(11)
Total finance lease liabilities	$ 123