COMMITMENTS AND CONTINGENCIES - Aircraft-Related Commitments (Details)	Jun. 30, 2026 aircraft
Firm Orders
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	181
Options and Other Rights
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	71
B737 | Firm Orders
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	168
B737 | Options and Other Rights
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	71
B787 | Firm Orders
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	12
B787 | Options and Other Rights
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	0
E175 | Firm Orders
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	1
E175 | Options and Other Rights
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	0