COMMITMENTS AND CONTINGENCIES - Aircraft Purchase Commitments by Fleet Type (Details) - Aircraft purchase commitments	Dec. 31, 2023 aircraft
Future Purchase Commitments
Aircraft purchase commitments, minimum quantity required	312
A220-300
Future Purchase Commitments
Aircraft purchase commitments, minimum quantity required	77
A321-200neo
Future Purchase Commitments
Aircraft purchase commitments, minimum quantity required	107
A330-900neo
Future Purchase Commitments
Aircraft purchase commitments, minimum quantity required	12
A350-900
Future Purchase Commitments
Aircraft purchase commitments, minimum quantity required	16
B-737-10
Future Purchase Commitments
Aircraft purchase commitments, minimum quantity required	100