Leases, Commitments, Guarantees and Contingencies - Operating Leases (Details) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2025 USD ($) aircraft	Dec. 31, 2024
Lessee, Lease, Description [Line Items]
Lease term		5 years
Purchase obligation | $	$ 2,434,032
Minimum
Lessee, Lease, Description [Line Items]
Purchase obligation | $	50,000
Maximum
Lessee, Lease, Description [Line Items]
Purchase obligation | $	$ 60,000
E175
Lessee, Lease, Description [Line Items]
Number of aircraft under purchase agreement	74
Number of additional aircrafts with secured delivery positions	44
CRJ 900
Lessee, Lease, Description [Line Items]
Number of used aircraft acquired	21
United | E175
Lessee, Lease, Description [Line Items]
Number of aircrafts to be purchased and placed into service	13
Alaska | E175
Lessee, Lease, Description [Line Items]
Number of aircrafts to be purchased and placed into service	1
Delta | E175
Lessee, Lease, Description [Line Items]
Number of aircrafts to be purchased and placed into service	16