Summary of Significant Accounting Policies - Summary of Original Cost of Company's Fixed Assets and Accumulated Depreciation or Amortization (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Property, Plant, and Equipment [Line Items]
Accumulated Depreciation/ Amortization	$ 222,864	$ 217,938
Property, Plant and Equipment, Excluding Construction in Progress
Property, Plant, and Equipment [Line Items]
Original Cost	261,653	262,158
Accumulated Depreciation/ Amortization	222,864	217,938
Aircraft
Property, Plant, and Equipment [Line Items]
Original Cost	65,098	65,480
Accumulated Depreciation/ Amortization	56,577	55,544
Spare engines
Property, Plant, and Equipment [Line Items]
Original Cost	157,996	157,997
Accumulated Depreciation/ Amortization	138,947	135,278
Rotable parts
Property, Plant, and Equipment [Line Items]
Original Cost	29,688	29,823
Accumulated Depreciation/ Amortization	19,276	19,223
Ground equipment
Property, Plant, and Equipment [Line Items]
Original Cost	2,952	2,953
Accumulated Depreciation/ Amortization	2,556	2,466
Office equipment
Property, Plant, and Equipment [Line Items]
Original Cost	4,782	4,782
Accumulated Depreciation/ Amortization	4,596	4,547
Leasehold improvements
Property, Plant, and Equipment [Line Items]
Original Cost	1,137	1,123
Accumulated Depreciation/ Amortization	$ 912	$ 880