AIRCRAFT - Aircraft Fleet (Details) - aircraft	3 Months Ended	9 Months Ended
	Mar. 31, 2022	Sep. 30, 2022	Sep. 30, 2021
Movement in Property, Plant and Equipment [Roll Forward]
Balance at beginning of period	48	48	43
Additions		7	4
Reclassifications		0	0
Removals		(1)	0
Balance at end of period		54	47
Number of aircraft modified to finance leases	2
Number of aircraft finance lease purchase options exercised		2
Reclassifications, net change		0
Passenger
Movement in Property, Plant and Equipment [Roll Forward]
Balance at beginning of period	36	36	31
Additions		7	4
Reclassifications		0	0
Removals		(1)	0
Balance at end of period		42	35
Number of aircraft modified to finance leases		2
Passenger | Owned
Movement in Property, Plant and Equipment [Roll Forward]
Balance at beginning of period	21	21	14
Additions		5	1
Reclassifications		4	6
Removals		(1)	0
Balance at end of period		29	21
Passenger | Finance leases
Movement in Property, Plant and Equipment [Roll Forward]
Balance at beginning of period	9	9	5
Additions		2	3
Reclassifications		0	0
Removals		0	0
Balance at end of period		11	8
Passenger | Operating leases
Movement in Property, Plant and Equipment [Roll Forward]
Balance at beginning of period	6	6	12
Additions		0	0
Reclassifications		(4)	(6)
Removals		0	0
Balance at end of period		2	6
Cargo | Aircraft Operated for Amazon
Movement in Property, Plant and Equipment [Roll Forward]
Balance at beginning of period	12	12	12
Additions		0	0
Reclassifications		0	0
Removals		0	0
Balance at end of period		12	12