DEBT - Long-term Debt (Details)	1 Months Ended	3 Months Ended
	Dec. 31, 2019 USD ($) aircraft	Mar. 31, 2026 USD ($) aircraft	Sep. 30, 2025 USD ($) aircraft	Mar. 31, 2025 USD ($) aircraft	Dec. 31, 2025 USD ($) aircraft	Dec. 31, 2024 USD ($) aircraft	Mar. 31, 2022 USD ($) aircraft
DEBT
Number of aircraft | aircraft		72		66	70	63
Long-term debt, gross		$ 309,635,000			$ 326,410,000
Repayments of long-term debt		$ 16,776,000		$ 14,829,000
Owned Aircraft Held for Operating Lease | Other Property
DEBT
Property, plant and equipment, number of aircraft refinanced | aircraft			5
Number of aircraft | aircraft		2
Owned Aircraft Held for Operating Lease | Other Property
DEBT
Number of aircraft | aircraft		2		4	2	4
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%
Margin (as a percent)		2.60%
Delayed Draw Term Loan Facility
DEBT
Long-term debt, gross		$ 104,012,000			106,610,000
2022-1 EETC | Notes payable
DEBT
Face amount							$ 188,277,000
Long-term debt, gross		$ 104,111,000			118,288,000
Number of aircraft financed by debt | aircraft							13
Weighted average interest rate		5.04%
2022-1 EETC | Notes payable | Maximum
DEBT
Interest rate		5.75%
2022-1 EETC | Notes payable | Minimum
DEBT
Interest rate		4.84%
2019-1 EETC | Notes payable
DEBT
Face amount	$ 248,587,000
Long-term debt, gross		$ 101,512,000			$ 101,512,000
Weighted average interest rate		5.56%
Number of used aircrafts purchased or refinanced | aircraft	13
2019-1 EETC | Notes payable | Maximum
DEBT
Interest rate		7.10%
2019-1 EETC | Notes payable | Minimum
DEBT
Interest rate		4.13%
Notes payable under the Company's 2019-1 EETC agreement | Notes payable
DEBT
Face amount						$ 60,000,000