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, 2019	Sep. 30, 2018	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Computed income taxes at statutory rate	$ 6,627	$ 7,443	$ 12,750
Increase (decrease) in taxes resulting from -
State and local income taxes	577	982	1,093
U.S. tax law change		(2,655)
One-time repatriation tax		876
Foreign-Derived Intangible Income tax	(294)
Global Intangible Low Taxed Income tax	1,119
Foreign tax credit	(990)	(15)	(57)
Foreign tax rate differences	46	(104)	(281)
Qualified domestic production incentives		(550)	(1,012)
Uncertain tax position activity	126	(62)	134
Goodwill impairment charge			2,320
Valuation allowance	106	(40)
Stock-based compensation	(33)	447
Other, net	(109)	209	(75)
Income Tax Provision	$ 7,175	$ 6,531	$ 14,872
Computed income taxes at statutory rate	21.00%	24.50%	35.00%
State and local income taxes, rate	1.80%	3.20%	3.00%
U.S. tax law change, rate		(8.70%)
One-time repatriation tax, rate		2.90%
Foreign-Derived Intangible Income tax, rate	(0.90%)
Global Intangible Low Taxed Income tax, rate	3.60%
Foreign tax credit, rate	(3.10%)		(0.20%)
Foreign tax rate differences, rate	0.10%	(0.30%)	(0.80%)
Qualified domestic production incentives, rate		(1.80%)	(2.80%)
Uncertain tax position activity, rate	0.40%	(0.20%)	0.40%
Goodwill impairment charge, rate			6.40%
Valuation allowance, rate	0.30%	(0.10%)
Stock-based compensation, rate	(0.10%)	1.40%
Other, net, rate	(0.40%)	0.60%	(0.20%)
Total, rate	22.70%	21.50%	40.80%