LEASES - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($) lease aircraft transaction airport
Lessee, Lease, Description [Line Items]
Leases that have not yet commenced | $	$ 242
Aircraft sale leaseback
Lessee, Lease, Description [Line Items]
Sale leaseback transactions | $	$ 2,800
Number of aircraft in sale-leaseback transactions | aircraft	85
Number of sale-leaseback transactions that did not qualify as sale | transaction	74
Number of sale-leaseback transactions that qualified as sale | transaction	11
Minimum
Lessee, Lease, Description [Line Items]
Leases that have not yet commenced, term of contract	7 years
Maximum
Lessee, Lease, Description [Line Items]
Leases that have not yet commenced, term of contract	10 years
Aircraft
Lessee, Lease, Description [Line Items]
Number of leases	221
Number of finance leases	105
Number of operating leases	116
Lease component of purchase agreements, number of aircraft | aircraft	115
Aircraft | Minimum
Lessee, Lease, Description [Line Items]
Remaining term of operating leases	1 month
Remaining term of finance leases	1 month
Aircraft | Maximum
Lessee, Lease, Description [Line Items]
Remaining term of operating leases	13 years
Remaining term of finance leases	13 years
Airport Facilities
Lessee, Lease, Description [Line Items]
Number of airports with facility space under lease | airport	300
Airport Facilities | Minimum
Lessee, Lease, Description [Line Items]
Remaining term of operating leases	1 month
Airport Facilities | Maximum
Lessee, Lease, Description [Line Items]
Remaining term of operating leases	29 years
Other Ground Property and Equipment | Minimum
Lessee, Lease, Description [Line Items]
Remaining term of operating leases	1 month
Remaining term of finance leases	1 month
Other Ground Property and Equipment | Maximum
Lessee, Lease, Description [Line Items]
Remaining term of operating leases	7 years
Remaining term of finance leases	7 years