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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
	Sep. 30, 2021
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 the 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

X

- 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=123364984&loc=d3e1205-110223

+ Details

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X

- 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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