Income Taxes - Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Unrecognized income tax benefits at beginning of year	$ 262	$ 517
Additions for tax positions of prior years	83
Reductions for tax positions of prior years	(100)
Additions for tax positions of current year	138
Tax examination and other settlements		(161)
Expiration of statute of limitations		(94)
Unrecognized income tax benefits at end of year	$ 383	$ 262