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Note 12 - Employee Benefit Plans (Tables)

12 Months Ended

Sep. 30, 2025

Notes Tables

Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan [Table Text Block]

		Pension Plan								Postretirement Plan
		2025				2024				2025				2024
Accumulated benefit obligation		$	26,298,490			$	26,859,162			$	10,462,318			$	10,842,455
Change in benefit obligation:
Benefit obligation at beginning of year		$	29,873,428			$	26,747,624			$	10,842,455			$	11,248,448
Service cost			387,429				324,265				4,376				30,398
Interest cost			1,410,406				1,468,822				507,423				613,477
Actuarial loss (gain)			(752,215	)			2,613,621				(297,327	)			(540,914	)
Benefit payments, net of retiree contributions			(1,439,028	)			(1,280,904	)			(594,609	)			(508,954	)
Benefit obligation at end of year		$	29,480,020			$	29,873,428			$	10,462,318			$	10,842,455
Change in fair value of plan assets:
Fair value of plan assets at beginning of year		$	31,054,138			$	26,878,661			$	15,078,281			$	13,019,313
Actual return on plan assets, net of taxes			872,291				5,456,381				907,150				2,567,922
Employer contributions			—				—				—				—
Benefit payments, net of retiree contributions			(1,439,028	)			(1,280,904	)			(594,609	)			(508,954	)
Fair value of plan assets at end of year		$	30,487,401			$	31,054,138			$	15,390,822			$	15,078,281
Funded status		$	1,007,381			$	1,180,710			$	4,928,504			$	4,235,826
Amounts recognized in the consolidated balance sheet consist of:
Benefit plan assets under other non-current assets		$	1,007,381			$	1,180,710			$	4,928,504			$	4,235,826
Amounts recognized in accumulated other comprehensive income:
Net actuarial loss (gain), net of tax		$	923,823			$	432,149			$	(520,987	)		$	(227,071	)
Total amounts included in accumulated other comprehensive income, net of tax		$	923,823			$	432,149			$	(520,987	)		$	(227,071	)
Amounts deferred to a regulatory asset (liability):
Net actuarial loss (gain)		$	2,199,542			$	3,041,666			$	(3,879,294	)		$	(4,032,929	)
Amounts recognized as regulatory assets (liabilities)		$	2,199,542			$	3,041,666			$	(3,879,294	)		$	(4,032,929	)

Defined Benefit Plan, Assumptions [Table Text Block]

		Pension Plan								Postretirement Plan
		2025				2024				2025				2024
Assumptions used to determine benefit obligations:
Discount rate			5.29	%			4.83	%			5.16	%			4.83	%
Expected rate of compensation increase			4.00	%			4.00	%			N/A				N/A
Assumptions used to determine benefit costs:
Discount rate			4.83	%			5.63	%			4.83	%			5.63	%
Expected long-term rate of return on plan assets			4.95	%			4.50	%			4.95	%			4.21	%
Expected rate of compensation increase			4.00	%			4.00	%			N/A				N/A

Schedule of Net Benefit Costs [Table Text Block]

		Pension Plan								Postretirement Plan
		2025				2024				2025				2024
Service cost		$	387,429			$	324,265			$	4,376			$	30,398
Interest cost			1,410,406				1,468,822				507,423				613,477
Expected return on plan assets			(1,503,902	)			(1,179,830	)			(729,708	)			(533,249	)
Recognized loss (gain)			59,423				316,522				(232,611	)			(40,597	)
Net periodic benefit cost (income)		$	353,356			$	929,779			$	(450,520	)		$	70,029

Schedule of Health Care Cost Trend Rates [Table Text Block]

		Pre 65								Post 65
		2025				2024				2025				2024
Health care cost trend rate assumed for next year			7.00	%			7.00	%			5.60	%			5.60	%
Rate to which the cost trend is assumed to decline (the ultimate trend rate)			4.00	%			4.00	%			4.00	%			4.00	%
Year that the rate reaches the ultimate trend rate		2075				2075				2075				2075

Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates [Table Text Block]

		1% Increase				1% Decrease
Effect on total service and interest cost components		$	58,000			$	(50,000	)
Effect on accumulated postretirement benefit obligation			1,113,000				(955,000	)

Schedule of Allocation of Plan Assets [Table Text Block]

		Pension Plan												Postretirement Plan
		Target				2025				2024				Target				2025				2024
Asset category:
Equity securities			25	%			23	%			25	%			30	%			38	%			48	%
Debt securities			75	%			77	%			75	%			70	%			53	%			36	%
Cash			—	%			—	%			—	%			—	%			9	%			16	%

						Pension Plan
						Fair Value Measurements - September 30, 2025
		Fair Value				Level 1				Level 2				Level 3
Asset Class:
Cash		$	27,603			$	27,603			$	—			$	—
Common and Collective Trust and Pooled Funds:
Bond Funds			19,460,378				—				19,460,378				—
Mutual Funds:
Domestic Fixed Income			3,901,202				3,901,202				—				—
Equities
Domestic Large Cap Growth			2,161,688				2,161,688				—				—
Domestic Large Cap Value			2,470,055				2,470,055				—				—
Domestic Small/Mid Cap Core			1,023,627				1,023,627				—				—
Foreign Large Cap Growth			442,847				442,847				—				—
Foreign Large Cap Value			469,821				469,821				—				—
Foreign Large Cap Core			530,180				530,180				—				—
Total		$	30,487,401			$	11,027,023			$	19,460,378			$	—

						Pension Plan
						Fair Value Measurements - September 30, 2024
		Fair Value				Level 1				Level 2				Level 3
Asset Class:
Cash		$	142,921			$	142,921			$	—			$	—
Common and Collective Trust and Pooled Funds:
Bond Funds			19,505,237				—				19,505,237				—
Mutual Funds:
Domestic Fixed Income			3,791,697				3,791,697				—				—
Equities
Domestic Large Cap Growth			2,073,092				2,073,092				—				—
Domestic Large Cap Value			2,469,045				2,469,045				—				—
Domestic Small/Mid Cap Core			1,297,579				1,297,579				—				—
Foreign Large Cap Growth			498,732				498,732				—				—
Foreign Large Cap Value			482,222				482,222				—				—
Foreign Large Cap Core			793,613				793,613				—				—
Total		$	31,054,138			$	11,548,901			$	19,505,237			$	—

						Postretirement Plan
						Fair Value Measurements - September 30, 2025
		Fair Value				Level 1				Level 2				Level 3
Asset Class:
Cash		$	1,462,600			$	1,462,600			$	—			$	—
Mutual Funds:
Bonds
Domestic Fixed Income			8,089,514				8,089,514				—				—
Equities
Domestic Large Cap Growth			1,340,584				1,340,584				—				—
Domestic Large Cap Value			2,799,537				2,799,537				—				—
Domestic Small/Mid Cap Core			453,828				453,828				—				—
Foreign Large Cap Growth			217,707				217,707				—				—
Foreign Large Cap Core			1,027,052				1,027,052				—				—
Total		$	15,390,822			$	15,390,822			$	—			$	—

						Postretirement Plan
						Fair Value Measurements - September 30, 2024
		Fair Value				Level 1				Level 2				Level 3
Asset Class:
Cash		$	2,381,909			$	2,381,909			$	—			$	—
Mutual Funds:
Bonds
Domestic Fixed Income			5,457,976				5,457,976				—				—
Equities
Domestic Large Cap Growth			2,412,824				2,412,824				—				—
Domestic Large Cap Value			1,996,262				1,996,262				—				—
Domestic Small/Mid Cap Core			738,393				738,393				—				—
Foreign Large Cap Growth			532,391				532,391				—				—
Foreign Large Cap Value			652,023				652,023				—				—
Foreign Large Cap Core			906,503				906,503				—				—
Total		$	15,078,281			$	15,078,281			$	—			$	—

Schedule of Expected Benefit Payments [Table Text Block]

			Pension				Postretirement
Fiscal year ending September 30			Plan				Plan
2026			$	1,463,000			$	728,140
2027				1,560,000				753,633
2028				1,630,000				747,643
2029				1,701,000				773,121
2030				1,780,000				760,210
2031 - 2035				9,733,000				3,794,802

NQDC Plan [Member]

Notes Tables

Defined Contribution Plan Disclosures [Table Text Block]

		2025				2024
Beginning deferred compensation balance		$	113,600			$	47,674
Employer contributions			80,510				52,400
Earnings			7,084				13,526
Ending deferred compensation balance		$	201,194			$	113,600

The 401K Plan [Member]

Notes Tables

Defined Contribution Plan Disclosures [Table Text Block]

		Years Ended September 30
		2025				2024
Matching contribution		$	466,630			$	427,022
Discretionary contribution			137,114				112,207

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