Consolidated Statements of Shareholders' Equity - USD ($)		Total	Capital in Excess of Par Value [Member]	Retained Earnings [Member]	Common Stock [Member]	Class B Stock [Member]
Beginning balance at Sep. 30, 2018	[1]	$ 145,017,000	$ 11,862,000	$ 131,701,000	$ 1,225,000	$ 229,000
Beginning balance, shares at Sep. 30, 2018	[1]				12,252,337	2,288,857
Net income		10,196,000		10,196,000
Stock-based compensation		71,000	71,000
Stock options exercised		$ 231,000	226,000		$ 3,000	$ 2,000
Stock options exercised, shares		45,000			25,000	20,000
Ending balance at Sep. 30, 2019		$ 155,515,000	12,159,000	141,897,000	$ 1,228,000	$ 231,000
Ending balance, shares at Sep. 30, 2019					12,277,337	2,308,857
Net income		5,531,000		5,531,000
Stock-based compensation		71,000	71,000
Stock options exercised		$ 103,000	101,000		$ 1,000	$ 1,000
Stock options exercised, shares		20,000			10,000	10,000
Ending balance at Sep. 30, 2020		$ 161,220,000	$ 12,331,000	$ 147,428,000	$ 1,229,000	$ 232,000
Ending balance, shares at Sep. 30, 2020					12,287,337	2,318,857

[1] The balances as of 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.