Leases - Maturities of Financing and Operating Lease Liabilities (Details) $ in Millions	Dec. 31, 2019 USD ($)
Finance Leases
2020	$ 71
2021	67
2022	64
2023	70
2024	49
Thereafter	82
Total lease payments	403
Less: interest	(57)
Present value of lease liabilities	346
Operating Leases
2020	553
2021	503
2022	405
2023	316
2024	226
Thereafter	662
Total lease payments	2,665
Less: interest	(421)
Present value of lease liabilities	$ 2,244