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, 2017		$ 128,918,000		$ 11,178,000		$ 116,299,000		$ 1,215,000		$ 226,000
Beginning balance, shares at Sep. 30, 2017								12,154,829		2,263,857
Inventory accounting method change at Sep. 30, 2017	[1]	2,708,000				2,708,000
Beginning balance adjusted at Sep. 30, 2017	[1]	131,626,000		11,178,000		119,007,000		$ 1,215,000		$ 226,000
Beginning balance adjusted, shares at Sep. 30, 2017	[1]							12,154,829		2,263,857
Net income	[1]	12,694,000				12,694,000
Stock-based compensation		71,000		71,000
Stock options exercised		$ 626,000		613,000				$ 10,000		$ 3,000
Stock options exercised, shares		122,508						97,508		25,000
Ending balance at Sep. 30, 2018		$ 145,017,000	[2]	11,862,000	[1]	131,701,000	[1]	$ 1,225,000	[1]	$ 229,000	[1]
Ending 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

[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 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.