Leases - Components of Operating and Finance Lease Costs (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Leases [Abstract]
Operating lease costs	$ 8,517	$ 37,637
Variable and short-term lease costs	3,691	5,783
Interest expense on finance lease liabilities	4,492	547
Amortization expense of finance lease assets	13,414	2,705
Total lease costs	$ 30,114	$ 46,672