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Note 1 - Summary of Significant Accounting Policies (Details Textual)	12 Months Ended
	Sep. 30, 2025 USD ($) shares	Sep. 30, 2024 USD ($) shares	Sep. 24, 2021 USD ($)	Aug. 20, 2021 USD ($)	Jun. 30, 2019
Number of Major Customers	62,500
Remaining Amounts of Regulatory Assets for which No Return on Investment During Recovery Period is Provided	$ 5,897,920
Regulatory Utility Assets Provision, Period (Year)	5 years
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service	3.26%	3.26%
Unbilled Receivables, Current	$ 1,373,512	$ 1,294,798
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares) | shares	1,926	2,542
Number of Pipelines	3
Number of States in which Entity Operates	2
Unsecured Term Notes Payable, at 30-day SOFR Average 1.20% Due August 20, 2026 [Member]
Debt Instrument, Face Amount				$ 15,000,000
Subsequent Letter of Commitment to Refinance [Member]
Debt Instrument, Face Amount	$ 53,600,000
Roanoke Gas Company [Member] | Unsecured Debt [Member] | Unsecured Term Notes Payable, at 30-day SOFR Average 1.20% Due August 20, 2026 [Member]
Debt Instrument, Face Amount				$ 15,000,000
Derivative, Fixed Interest Rate				2.00%
Roanoke Gas Company [Member] | Unsecured Debt [Member] | Unsecured Term Notes Payable, at 30-day LIBOR Plus 100 Basis Points, Due October 1, 2028 [Member]
Debt Instrument, Face Amount			$ 10,000,000
Derivative, Fixed Interest Rate			2.49%
RGC Midstream LLC [Member] | Unsecured Term Notes [Member] | Variable Rate Term Note 1 [Member]
Debt Instrument, Face Amount	14,000,000
Derivative, Fixed Interest Rate					3.24%
RGC Midstream LLC [Member] | Unsecured Term Notes [Member] | Variable Rate Term Note 2 [Member]
Debt Instrument, Face Amount	4,000,000
Derivative, Fixed Interest Rate					2.443%
RGC Midstream LLC [Member] | Unsecured Term Notes [Member] | Variable Rate Term Note 3 [Member]
Debt Instrument, Face Amount	20,600,000
Derivative, Fixed Interest Rate					5.061%
RGC Midstream LLC [Member] | Unsecured Term Notes [Member] | Variable Rate Term Note 4 [Member]
Debt Instrument, Face Amount	15,000,000
Derivative, Fixed Interest Rate					5.061%
RGC Midstream LLC [Member] | Unsecured Term Notes [Member] | Subsequent Letter of Commitment to Refinance [Member]
Debt Instrument, Face Amount	$ 53,600,000
Energy Related Derivative [Member]
Derivative, Number of Instruments Held	0	0
Interest Rate Swap [Member]
Derivative, Number of Instruments Held	6
Interest Rate Swap [Member] | Roanoke Gas Company [Member]
Derivative, Number of Instruments Held	2
Interest Rate Swap [Member] | RGC Midstream LLC [Member]
Derivative, Number of Instruments Held	4
Customer Concentration Risk [Member] | Revenue from Contract with Customer Benchmark [Member]
Number of Major Customers	0	0
Customer Concentration Risk [Member] | Revenue from Contract with Customer Benchmark [Member] | Minimum [Member]
Concentration Risk, Percentage	5.00%	5.00%
Operations and Maintenance Expense [Member]
Amortization of Regulatory Asset	$ 101,141	$ 116,085
Other Income [Member]
Amortization of Regulatory Asset	131,673	211,863
Interest Expense [Member]
Amortization of Regulatory Asset	$ 114,187	$ 114,187

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