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Note 7 - Shareholders' Equity (Details Textual) - USD ($)	1 Months Ended	3 Months Ended				6 Months Ended		8 Months Ended	15 Months Ended
	Dec. 31, 2022	Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2022	Feb. 25, 2022	Feb. 24, 2022
Payments for Repurchase of Common Stock						$ 382,000	$ 136,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)		0		0		0	0
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Forfeitures in Period (in shares)		0		0		2,000	0
Share-Based Payment Arrangement, Expense		$ 0		$ 345,000		$ 0	$ 733,000
Share-Based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount	$ 0	$ 0		$ 0		$ 0	$ 0		$ 0
Plan1989 [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number, Ending Balance (in shares)	229,000	229,000		231,000		229,000	231,000		229,000
Treasury Stock, Common [Member]
Treasury Stock, Shares, Acquired (in shares)		87,407	39,965	10,457	13,647
Common Class A [Member] \| Plan1989 [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price, Ending Balance (in dollars per share)	$ 6.05	$ 6.05		$ 6.05		$ 6.05	$ 6.05		$ 6.05
Common Class A [Member] \| Plan1997 [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number, Ending Balance (in shares)	2,000	2,000		2,000		2,000	2,000		2,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price, Ending Balance (in dollars per share)	$ 2.74	$ 2.74		$ 2.74		$ 2.74	$ 2.74		$ 2.74
Common Class A [Member] \| Treasury Stock, Common [Member]
Treasury Stock, Shares, Acquired (in shares)		87,407		10,457		127,372	24,104
Payments for Repurchase of Common Stock		$ 249,000		$ 54,000		$ 382,000	$ 136,000
Share Repurchase Plan Renewal December2012 December2020 [Member]
Stock Repurchase Program, Authorized Amount	$ 5,000,000.0	$ 5,000,000.0				$ 5,000,000.0			$ 5,000,000.0	$ 5,000,000.0	$ 2,750,000
Monthly Dividends Paid [Member]
Common Stock, Dividends, Per Share, Cash Paid (in dollars per share)	$ 0.0075							$ 0.0050	$ 0.0075