Income Taxes - Reconciliation Between the Statutory U.S. Income Tax Rate and Effective Rate Derived by Dividing the Provision for Income Taxes by Earnings Before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Computed income taxes at statutory rate	$ 11,407	$ 18,995	$ 12,452
Increase (decrease) in taxes resulting from -
State and local income taxes	362	1,204	773
Foreign-Derived Intangible Income tax	0	(563)	(136)
Global Intangible Low Taxed Income ("GILTI") tax	6,924	8,061	4,970
Foreign tax credit	(6,572)	(7,802)	(4,767)
Foreign tax rate differences	(1,679)	(869)	(534)
DOJ Lead Care legal matter accrual	2,100	0	0
Uncertain tax position activity	166	205	62
Valuation allowance	197	729	229
Stock-based compensation	825	(498)	41
Transaction Costs			548
Unrepatriated earnings	(1,148)	680	185
Other, net	(330)	(1,098)	(716)
Income Tax Provision	$ 11,858	$ 19,044	$ 13,107
Computed income taxes at statutory rate	21.00%	21.00%	21.00%
State and local income taxes, rate	0.70%	1.30%	1.30%
Foreign-Derived Intangible Income tax, rate	0.00%	(0.60%)	(0.20%)
Global Intangible Low Taxed Income tax, rate	12.70%	8.90%	8.40%
Foreign tax credit, rate	(12.10%)	(8.60%)	(8.00%)
Foreign tax rate differences, rate	(3.10%)	(1.00%)	(0.90%)
DOJ LeadCare legal matter accrual, rate	3.90%
Uncertain tax position activity, rate	0.30%	0.20%	0.10%
Valuation allowance, rate	0.40%	0.80%	0.30%
Stock-based compensation, rate	1.50%	(0.50%)	0.10%
Transaction costs, rate			0.90%
Unrepatriated earnings, rate	(2.10%)	0.80%	0.30%
Other, net, rate	(0.60%)	(1.20%)	(1.20%)
Total, rate	21.80%	21.10%	22.10%