Earnings per Share Data - Basic and Diluted Earnings Per Share (Detail) - USD ($)	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Net income	$ 2,489,000	$ 313,000	[1]
Common Shares:
Weighted-average common shares outstanding	14,586,000	14,541,000
Effect of dilutive stock options	134,000	158,000
Weighted-average diluted shares outstanding	14,720,000	14,699,000
Basic:
Net income per share	$ 0.17	$ 0.02
Diluted:
Net income per share	$ 0.17	$ 0.02

[1] The balances as of September 30, 2018 and December 31, 2018, and the amounts for the quarter ended December 31, 2018, have been adjusted to reflect the change in inventory accounting method, as described in Note 3 to the Condensed Consolidated Financial Statements.