DEBT - Long-term Debt (Details)	1 Months Ended	3 Months Ended	9 Months Ended
	Dec. 31, 2019 USD ($) aircraft	Sep. 30, 2025 USD ($) aircraft	Sep. 30, 2025 USD ($) aircraft	Sep. 30, 2024 USD ($) aircraft	Dec. 31, 2024 USD ($) aircraft	Dec. 31, 2023 aircraft	Mar. 31, 2023 USD ($) aircraft	Mar. 31, 2022 USD ($) aircraft
DEBT
Number of aircraft | aircraft		70	70	63	63	60
Long-term debt, gross		$ 304,099,000	$ 304,099,000		$ 330,122,000
Repayments of long-term debt			$ 80,023,000	$ 60,776,000
Owned Aircraft Held for Operating Lease | Other Property
DEBT
Property, plant and equipment, number of aircraft refinanced | aircraft		5	5
Number of aircraft | aircraft		3	3		4		5
Owned Aircraft Held for Operating Lease | Other Property
DEBT
Number of aircraft | aircraft				5		5
Number of aircraft with expiring lease term | aircraft		3	3
Term Loan
DEBT
Face amount		$ 108,000,000	$ 108,000,000
Repayments of long-term debt		$ 20,953,000
Debt instrument, interest rate, effective percentage		5.98%	5.98%
Margin (as a percent)			2.60%
Payments of debt issuance costs		$ 1,059,000
Line of credit facility, amount available		54,000,000	$ 54,000,000
Gain (loss) on extinguishment of debt		(391,000)
Term Loan | Notes payable
DEBT
Face amount							$ 119,200,000
Delayed Draw Term Loan Facility
DEBT
Long-term debt, gross		54,000,000	54,000,000		$ 0
2022-1 EETC | Notes payable
DEBT
Face amount								$ 188,277,000
Long-term debt, gross		$ 118,288,000	$ 118,288,000		138,532,000
Number of aircraft financed by debt | aircraft								13
Weighted average interest rate		5.04%	5.04%
2022-1 EETC | Notes payable | Maximum
DEBT
Interest rate		5.75%	5.75%
2022-1 EETC | Notes payable | Minimum
DEBT
Interest rate		4.84%	4.84%
2019-1 EETC | Notes payable
DEBT
Face amount	$ 248,587,000
Long-term debt, gross		$ 131,811,000	$ 131,811,000		158,510,000
Weighted average interest rate		5.43%	5.43%
Number of used aircrafts purchased or refinanced | aircraft	13
2019-1 EETC | Notes payable | Maximum
DEBT
Interest rate		7.10%	7.10%
2019-1 EETC | Notes payable | Minimum
DEBT
Interest rate		4.13%	4.13%
Notes payable under the Company's 2019-1 EETC agreement | Notes payable
DEBT
Face amount					$ 60,000,000