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Significant Accounting Policies - Estimated Useful Lives of Assets and Considering Residual Value (Detail)
 12 Months Ended
Dec. 31, 2020
Disclosure of detailed information about property, plant and equipment [line items]  
Residual Value 15.00%
Airframe and engines [member]  
Disclosure of detailed information about property, plant and equipment [line items]  
Estimated useful life (years) 27 years
Residual Value 15.00%
Major maintenance events [member] | Bottom of range [member]  
Disclosure of detailed information about property, plant and equipment [line items]  
Estimated useful life (years) 3 years
Major maintenance events [member] | Top of range [member]  
Disclosure of detailed information about property, plant and equipment [line items]  
Estimated useful life (years) 16 years
Ground equipment [member]  
Disclosure of detailed information about property, plant and equipment [line items]  
Estimated useful life (years) 10 years
Furniture, fixture, equipment and other [member] | Bottom of range [member]  
Disclosure of detailed information about property, plant and equipment [line items]  
Estimated useful life (years) 5 years
Furniture, fixture, equipment and other [member] | Top of range [member]  
Disclosure of detailed information about property, plant and equipment [line items]  
Estimated useful life (years) 10 years
Leasehold improvements [member]  
Disclosure of detailed information about property, plant and equipment [line items]  
Estimated useful lives Lesser of remaining lease term and estimated useful life of the leasehold improvement