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GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)
12 Months Ended
Dec. 31, 2019
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: 
Boeing 737, Airbus A319/A320, and E175 aircraft20-25 years10%  
Bombardier Q400 aircraft15 years5%  
Buildings25 - 40 years10%  
Minor building and land improvements10 years—%  
Capitalized leases and leasehold improvementsGenerally shorter of lease term or
estimated useful life
—%  
Computer hardware and software3-10 years—%  
Other furniture and equipment5-10 years—%