Leases - Future Maturities of Lease Liabilities - ASC 842 (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Operating Leases
2020	$ 242
2021	192
2022	141
2023	109
2024	81
Thereafter	359
Total Lease Payments	1,124
Less: Imputed Interest	257
Total Operating Lease Liabilities	867
Finance Leases
2020	25
2021	35
2022	22
2023	21
2024	20
Thereafter	690
Total Lease Payments	813
Less: Imputed Interest	564
Total Finance Lease Liabilities	$ 249	$ 37