Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Gross liability for unrecognized tax benefits	$ 608	$ 608	$ 353
Unrecognized tax benefits that would impact effective tax rate	500	500
Net liability for accrued interest and penalties	270	230
Interest and penalty expenses on unrecognised tax benefit	$ 40	$ 60