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GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)
12 Months Ended
Dec. 31, 2023
Accounting Policies [Abstract]  
Property, Plant and Equipment [Table Text Block]
Property and equipment are recorded at cost and depreciated using the straight-line method over their estimated useful lives less an estimated salvage value, which are as follows:
Estimated Useful LifeEstimated Salvage Value
Aircraft and other flight equipment: 
B737 and E175 aircraft
20 to 25 years
10%
Buildings
25 to 40 years
10%
Minor building and land improvements10 years—%
Capitalized leases and leasehold improvementsGenerally shorter of lease term or
estimated useful life
—%
Computer hardware and software
3 to 10 years
—%
Other furniture and equipment
5 to 10 years
—%