FAIR VALUE MEASUREMENTS, INVESTMENTS AND NOTES RECEIVABLE - Narrative (Details) $ in Millions	12 Months Ended
Dec. 31, 2024 USD ($) aircraft
Fair Value [Line Items]
Investments in securities accounted for under the equity method	$ 241
Carrying amount of loan receivable	$ 72
Champlain
Fair Value [Line Items]
Number of regional aircraft \| aircraft	57
Republic
Fair Value [Line Items]
Number of regional aircraft \| aircraft	66
Republic
Fair Value [Line Items]
Ownership stake	19.00%
Champlain
Fair Value [Line Items]
Ownership stake	40.00%
UAV Fund
Fair Value [Line Items]
Ownership stake	33.00%
Other Investments
Fair Value [Line Items]
Carrying value of other investment	$ 264
Mesa
Fair Value [Line Items]
Variable interest	10.00%
Corporate Debt
Fair Value [Line Items]
Available for sale investment maturity term (less than)	2 years

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Fair Value [Line Items]

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Amortized cost excluding accrued interest, after allowance for credit loss, of financing receivable. Excludes net investment in lease.

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Number of aircraft operated by the carrier.

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Percentage of the Variable Interest Entity's (VIE) voting interest owned by (or beneficial interest in) the reporting entity (directly or indirectly).

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