Income Taxes - Summary of Reconciliation of Changes in Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Unrecognized tax benefits, beginning balance	$ 2,887	$ 2,871	$ 2,323
Increases in tax positions for prior years	53	15	58
Decreases in tax positions for prior years	(35)	(8)	(1)
Increases in tax positions for current year	519	458	664
Lapse of the statute of limitations	(631)	(449)	(173)
Unrecognized tax benefits, ending balance	$ 2,793	$ 2,887	$ 2,871