REVENUES - Schedule of Disaggregation of Revenue (Details) $ in Millions		12 Months Ended
		Dec. 31, 2025 USD ($) aircraft	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Disaggregation of Revenue [Line Items]
Revenues	[1]	$ 1,676.5	$ 1,474.0	$ 1,429.1
Regional jet service revenue		1,346.4	1,165.9	1,111.6
Lease revenue		304.4	288.6	305.7
Other revenue		$ 25.7	19.5	11.8
American Airlines
Disaggregation of Revenue [Line Items]
Number of aircraft leased | aircraft		31
American Airlines
Disaggregation of Revenue [Line Items]
Revenues		$ 723.6	627.4	659.0
Delta Air Lines
Disaggregation of Revenue [Line Items]
Revenues		409.7	378.2	334.1
United Airlines
Disaggregation of Revenue [Line Items]
Revenues		517.5	448.9	424.2
Other Airlines
Disaggregation of Revenue [Line Items]
Revenues		$ 25.7	$ 19.5	$ 11.8

[1] Substantially all of the Company’s revenues are derived from related parties during the years ended December 31, 2025, 2024, and 2023. Refer to Note 16, Related Party Transactions and Note 5, Revenue Recognition.