Income Taxes - Earnings Before Income Taxes and Related Provision for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Domestic	$ 9,068	$ 23,954	$ 27,787
Foreign	50,225	7,603	2,593
Earnings Before Income Taxes	59,293	31,557	30,380
Federal
Current	1,173	5,001	6,030
Fixed asset basis differences and depreciation	960	288	410
Intangible asset basis differences and amortization	753	(797)	(4,052)
Currently non-deductible expenses and reserves	(1,001)	241	1,206
Stock-based compensation	(41)	(109)	1,379
Net operating loss carryforwards utilized	26	69	61
Tax credit carryforwards utilized			181
Other, net	47	(169)	(148)
Subtotal	1,917	4,524	5,067
State and local	1,170	834	1,066
Foreign	10,020	1,817	398
Income Tax Provision	$ 13,107	$ 7,175	$ 6,531