Leases (Future Minimum Payments) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Operating
2021	$ 372
2022	315
2023	260
2024	209
2025	197
2026	916
Total minimum payments	2,269
Less amounts representing interest	380
Present value of minimum payments	1,889	$ 1,994
Finance
2021	17
2022	7
2023	2
2024	1
2025	1
2026	0
Total minimum payments	28
Less amounts representing interest	2
Present value of minimum payments	$ 26	$ 44