LEASES - Lease Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Lessee, Lease, Description [Line Items]
Operating Lease, Expense	$ 708	$ 654	$ 602
Sublease Income	15	16	14
Lease, Cost	693	638	588
Aircraft Leases [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Cost	$ 191	174	215
Operating Lease, Weighted Average Discount Rate, Percent	4.40%
Operating Lease, Weighted Average Remaining Lease Term	7 years 10 months 24 days
CPA Aircraft [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Cost	$ 100	80	80
Operating Lease, Weighted Average Discount Rate, Percent	7.00%
Operating Lease, Weighted Average Remaining Lease Term	8 years 9 months 18 days
Airport Facilities [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Cost	$ 384	379	288
Operating Lease, Weighted Average Discount Rate, Percent	4.40%
Operating Lease, Weighted Average Remaining Lease Term	7 years 10 months 24 days
Corporate real estate [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Cost	$ 33	$ 21	$ 19
Operating Lease, Weighted Average Discount Rate, Percent	4.70%
Operating Lease, Weighted Average Remaining Lease Term	27 years 6 months