Note 11 - Other Comprehensive Income (Loss) - Schedule of Other Comprehensive Income and Loss (Details) - USD ($)	3 Months Ended	6 Months Ended
Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2025	Mar. 31, 2024
Unrealized gains (losses), before tax	$ (165,869)		$ 802,399		$ 528,308	$ (33,672)
Unrealized gains (losses), tax	42,695		(206,537)		(135,986)	8,668
Unrealized gains (losses), after tax	(123,174)		595,862		392,322	(25,004)
Transfer of realized gains to interest expense, before tax	(327,190)		(533,706)		(711,463)	(1,078,889)
Transfer of realized gains to interest expense, tax	84,218		137,376		183,130	277,705
Transfer of realized gains to interest expense, after tax	(242,972)		(396,330)		(528,333)	(801,184)
Net interest rate swaps, before tax	(493,059)		268,693		(183,155)	(1,112,561)
Net interest rate swaps, tax	126,913		(69,161)		47,144	286,373
Interest rate swaps	(366,146)		199,532		(136,011)	(826,188)
Amortization of net actuarial gains, before tax	(10,377)		16,015		(20,755)	32,030
Amortization of net actuarial gains, tax	2,671		(4,122)		5,342	(8,244)
Amortization of net actuarial gains, after tax	(7,706)		11,893		(15,413)	23,786
Other comprehensive income (loss), before tax	(503,436)		(284,708)		(203,910)	(1,080,531)
Other comprehensive income (loss), tax	129,584		(73,283)		52,486	278,129
Other comprehensive income (loss), after tax	(373,852)	$ 222,428	211,425	$ (1,013,827)	(151,424)	(802,402)
Unrealized gains (losses), before tax	(165,869)		802,399		528,308	(33,672)
Amortization of net actuarial gains (losses), after tax	(7,706)		11,893		(15,413)	23,786
Other comprehensive income (loss), before tax	503,436		284,708		203,910	1,080,531
Other comprehensive income (loss), tax	$ 129,584		$ (73,283)		$ 52,486	$ 278,129

Amount before tax of other comprehensive income (loss) attributable to parent entity.

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