Note 1 - Summary of Significant Accounting Policies - Reconciliation of Accumulated Comprehensive Income (Loss) (Details) - USD ($)	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Balance	$ 100,732,625	$ 93,090,656
Other comprehensive income (loss)	(926,718)	288,925
Balance	108,136,775	100,732,625
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]
Balance	3,428,922	3,563,341
Other comprehensive income (loss)	(1,897,273)	(134,419)
Balance	1,531,649	3,428,922
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member]
Balance	(1,175,633)	(1,598,977)
Other comprehensive income (loss)	970,555	423,344
Balance	(205,078)	(1,175,633)
AOCI Attributable to Parent [Member]
Balance	2,253,289	1,964,364
Other comprehensive income (loss)	(926,718)	288,925
Balance	$ 1,326,571	$ 2,253,289