Summary of Significant Accounting Policies - Schedule of Property and Equipment Useful Lives (Detail) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Original Cost	$ 265,728	$ 265,280
Accumulated Depreciation/ Amortization	213,934	193,457
Aircraft
Property, Plant and Equipment [Line Items]
Original Cost	66,390	67,459
Accumulated Depreciation/ Amortization	53,921	48,011
Spare engines
Property, Plant and Equipment [Line Items]
Original Cost	160,694	160,694
Accumulated Depreciation/ Amortization	133,166	119,575
Rotable parts
Property, Plant and Equipment [Line Items]
Original Cost	29,837	28,335
Accumulated Depreciation/ Amortization	19,037	18,512
Ground equipment
Property, Plant and Equipment [Line Items]
Original Cost	2,912	2,912
Accumulated Depreciation/ Amortization	2,433	2,277
Office equipment
Property, Plant and Equipment [Line Items]
Original Cost	4,772	4,757
Accumulated Depreciation/ Amortization	4,521	4,391
Leasehold improvements
Property, Plant and Equipment [Line Items]
Original Cost	1,123	1,123
Accumulated Depreciation/ Amortization	$ 856	$ 691