COMMITMENTS AND CONTINGENCIES - Aircraft Commitments by Fleet Type (Details) (Details) - Future aircraft purchase commitments	Mar. 31, 2023 aircraft
Future Purchase Commitments
Aircraft purchase commitments, minimum quantity required	322
A220-300
Future Purchase Commitments
Aircraft purchase commitments, minimum quantity required	59
A321-200neo
Future Purchase Commitments
Aircraft purchase commitments, minimum quantity required	130
A330-900neo
Future Purchase Commitments
Aircraft purchase commitments, minimum quantity required	17
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