COMMITMENTS AND CONTINGENCIES - Aircraft-Related Commitments (Details)	Jun. 30, 2025 aircraft
Firm Orders
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	86
Options and Other Rights
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	93
B737 | Firm Orders
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	75
B737 | Options and Other Rights
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	88
B787-9 | Firm Orders
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	8
B787-9 | Options and Other Rights
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	5
E175 | Firm Orders
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	3
E175 | Options and Other Rights
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	0