Nature of Operations and Summary of Significant Accounting Policies - Basic and Diluted EPS (Detail) - USD ($)	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Net income (loss)	$ 10,196,000	$ 12,694,000	[1]
Net Income Diluted	$ 10,196,000	$ 12,694,000
Weighted average common shares outstanding	14,551,000	14,492,000
Common Stock Equivalents	157,000	231,000
Diluted shares outstanding	14,708,000	14,723,000
Basic earnings per common share:
Basic earnings per share	$ 0.70	$ 0.88	[2]
Diluted earnings per common share:
Diluted earnings per share	$ 0.69	$ 0.86	[2]

[1] The balances as of September 30, 2017 and 2018, and the amounts for the year ended September 30, 2018, have been adjusted to reflect the change in inventory accounting method, as described in Notes 1 and 2 to the Consolidated Financial Statements.

[2] The amounts for the year ended September 30, 2018 have been adjusted to reflect the change in inventory accounting method, as described in Notes 1 and 2 to the Consolidated Financial Statements.