AIRCRAFT - Aircraft Fleet (Details) - aircraft	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Movement in Property, Plant and Equipment [Roll Forward]
Balance at beginning of period	48	43
Additions	6	2
Reclassifications	0	0
Removals	(1)	0
Balance at end of period	53	45
Number of aircraft modified to finance leases	2
Reclassifications, net change	1
Passenger
Movement in Property, Plant and Equipment [Roll Forward]
Balance at beginning of period	36	31
Additions	6	2
Reclassifications	0	0
Removals	(1)	0
Balance at end of period	41	33
Number of aircraft modified to finance leases	2
Passenger | Owned
Movement in Property, Plant and Equipment [Roll Forward]
Balance at beginning of period	21	14
Additions	5	0
Reclassifications	1	6
Removals	(1)	0
Balance at end of period	26	20
Passenger | Finance leases
Movement in Property, Plant and Equipment [Roll Forward]
Balance at beginning of period	9	5
Additions	1	2
Reclassifications	1	0
Removals	0	0
Balance at end of period	11	7
Passenger | Operating leases
Movement in Property, Plant and Equipment [Roll Forward]
Balance at beginning of period	6	12
Additions	0	0
Reclassifications	(2)	(6)
Removals	0	0
Balance at end of period	4	6
Cargo | Aircraft Operated for Amazon
Movement in Property, Plant and Equipment [Roll Forward]
Balance at beginning of period	12	12
Additions	0	0
Reclassifications	0	0
Removals	0	0
Balance at end of period	12	12