Assets Held for Sale - Additional Information (Detail) $ in Thousands		3 Months Ended		6 Months Ended
	May 29, 2024 USD ($)	Mar. 31, 2024 USD ($) AirCraft Engine	Dec. 31, 2023 Airframes AirCraft Engine	Mar. 31, 2024 USD ($) Airframes AirCraft Engine	Sep. 30, 2023 USD ($)
Long Lived Assets Held For Sale [Line Items]
Gross proceeds from sale of asset		$ 54,200
Proceeds from sale of asset		15,900
Assets held for sale		41,970		$ 41,970	$ 12,000
Number of engines held to sale | Engine			48	36
Current Assets [Member]
Long Lived Assets Held For Sale [Line Items]
Assets held for sale		38,300		$ 38,300
Noncurrent Assets [Member]
Long Lived Assets Held For Sale [Line Items]
Assets held for sale		$ 42,000		$ 42,000
CRJ-900 Aircraft [Member]
Long Lived Assets Held For Sale [Line Items]
Number of engine sold | Engine		12
Number of aircrafts held for sale | AirCraft		15	15	15
Gross proceeds from sale of asset		$ 54,200
Proceeds from sale of asset		15,900
Assets held for sale		$ 80,300		$ 80,300
Number of airframes without engines | Airframes			11	11
CF34-8C Aircraft [Member] | Subsequent Event [Member]
Long Lived Assets Held For Sale [Line Items]
Gross proceeds from sale of asset	$ 8,800