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Summary of Significant Accounting Policies - Summary of Estimated Useful Lives of Various Classifications of Property and Equipment (Detail) | 12 Months Ended
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Sep. 30, 2019
Buildings [Member] |
Property Plant And Equipment [Line Items] |
Property and Equipment, Estimated Useful Life | 30 years
Aircraft [Member] |
Property Plant And Equipment [Line Items] |
Property and Equipment, Estimated Useful Life | 25 years from manufacture date
Flight Equipment [Member] | Minimum [Member] |
Property Plant And Equipment [Line Items] |
Property and Equipment, Estimated Useful Life | 7 years
Flight Equipment [Member] | Maximum [Member] |
Property Plant And Equipment [Line Items] |
Property and Equipment, Estimated Useful Life | 20 years
Equipment [Member] | Minimum [Member] |
Property Plant And Equipment [Line Items] |
Property and Equipment, Estimated Useful Life | 5 years
Equipment [Member] | Maximum [Member] |
Property Plant And Equipment [Line Items] |
Property and Equipment, Estimated Useful Life | 9 years
Furniture and Fixtures [Member] | Minimum [Member] |
Property Plant And Equipment [Line Items] |
Property and Equipment, Estimated Useful Life | 3 years
Furniture and Fixtures [Member] | Maximum [Member] |
Property Plant And Equipment [Line Items] |
Property and Equipment, Estimated Useful Life | 5 years
Vehicles [Member] |
Property Plant And Equipment [Line Items] |
Property and Equipment, Estimated Useful Life | 5 years
Rotable Spare Parts [Member] |
Property Plant And Equipment [Line Items] |
Property and Equipment, Estimated Useful Life | Life of the aircraft or term of the lease, whichever is less
Leasehold Improvements [Member] |
Property Plant And Equipment [Line Items] |
Property and Equipment, Estimated Useful Life | Life of the aircraft or term of the lease, whichever is less

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- Definition Describes the periods of time over which an entity anticipates to receive utility from its property, plant and equipment (that is, the periods of time over which an entity allocates the initial cost of its property, plant and equipment). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 35 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=68071081&loc=d3e1205-110223 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=84158767&loc=d3e18780-107790 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment. + References No definition available. + Details
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