Note 12 - Employee Benefit Plans - Schedule of Components of Net Periodic Pension and Postretirement Benefit Cost (Details) - USD ($)	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Pension Plan [Member]
Service cost	$ 324,265	$ 366,537
Interest cost	1,468,822	1,372,098
Expected return on plan assets	(1,179,830)	(1,232,597)
Recognized loss (gain)	316,522	316,724
Net periodic benefit cost	929,779	822,762
Other Postretirement Benefits Plan [Member]
Service cost	30,398	45,897
Interest cost	613,477	620,622
Expected return on plan assets	(533,249)	(464,046)
Recognized loss (gain)	(40,597)	0
Net periodic benefit cost	$ 70,029	$ 202,473