Leases and Capacity Purchase Agreements - Summary of Scheduled Future Minimum Lease Payments under Operating and Finance Leases (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Operating Leases
2023	$ 851
2024	736
2025	616
2026	597
2027	779
After 2027	3,190
Minimum lease payments	6,769
Imputed interest	(1,749)
Present value of minimum lease payments	5,020
Less: current maturities of lease obligations	(561)	$ (556)
Long-term lease obligations	4,459	5,152
Finance Leases
2023	114
2024	45
2025	39
2026	17
2027	10
After 2027	18
Minimum lease payments	243
Imputed interest	(24)
Present value of minimum lease payments	219
Less: current maturities of lease obligations	(104)	(76)
Long-term lease obligations	$ 115	$ 219