Leases - Additional Information (Detail)	3 Months Ended
	Dec. 31, 2022 USD ($) AirCraft	Dec. 31, 2021 USD ($)
Lessee, Lease, Description [Line Items]
Number of leased aircraft | AirCraft	17
Aggregate rental expense under all operating aircraft, equipment and facility leases | $	$ 6,907,000	$ 11,848,000
Weighted average remaining lease term Operating leases	6 years
Weighted average discount rate Operating leases	4.80%
Impairment of certain operating lease ROU assets | $		$ 0
RASPRO Aircraft Lease Agreement [Member]
Lessee, Lease, Description [Line Items]
Number of aircraft lease terminated | AirCraft	15
Buyout pricing | $	$ 25,000,000
RASPRO Aircraft Lease Agreement [Member] | CRJ-900 Aircraft [Member]
Lessee, Lease, Description [Line Items]
Number of leased aircraft | AirCraft	15