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Note 7 - Long-term Debt - Long-term Debt (Details) (Parentheticals)	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Roanoke Gas Company [Member] | Unsecured Senior Notes Payable [Member] | Unsecured Senior Notes Payable, at 4.26%, Due on September 18, 2034 [Member]
Stated rate	4.26%	4.26%
Roanoke Gas Company [Member] | Unsecured Senior Notes Payable [Member] | Unsecured Term Notes Payable, at 3.58%, Due on October 2, 2027 [Member]
Stated rate	3.58%	3.58%
Roanoke Gas Company [Member] | Unsecured Senior Notes Payable [Member] | Unsecured Term Notes Payable, at 4.41 %, Due on March 28, 2031 [Member]
Stated rate	4.41%	4.41%
Roanoke Gas Company [Member] | Unsecured Senior Notes Payable [Member] | Unsecured Term Notes Payable, at 3.60%, Due on December 6, 2029 [Member]
Stated rate	3.60%	3.60%
Roanoke Gas Company [Member] | Unsecured Senior Notes Payable [Member] | Unsecured Term Notes Payable, at 30-day SOFR Average 1.20% Due August 20, 2026 [Member]
Basis spread	1.20%	1.20%
Derivative fixed interest rate	2.00%	2.00%
Roanoke Gas Company [Member] | Unsecured Senior Notes Payable [Member] | Unsecured term note payable, at Term SOFR plus 1.00%, due October 1, 2028 [Member]
Basis spread	1.00%	1.00%
Derivative fixed interest rate	2.49%	2.49%
RGC Midstream LLC [Member] | Southgate Revolving Credit Facility [Member] | Revolving Credit Facility [Member]
Basis spread	1.75%	1.75%
RGC Midstream LLC [Member] | Boost Revolving Credit Facility [Member] | Revolving Credit Facility [Member]
Basis spread	1.75%	1.75%
RGC Midstream LLC [Member] | Revolving Credit Facility Retired September 5, 2025 [Member] | Revolving Credit Facility [Member]
Basis spread	2.215%	2.215%
RGC Midstream LLC [Member] | Unsecured Senior Notes Payable [Member] | Unsecured Term Note Payable Due September 5, 2032 [Member]
Basis spread	1.55%	1.55%
RGC Midstream LLC [Member] | Unsecured Senior Notes Payable [Member] | Unsecured Term Note Payable Due September 5, 2032 [Member] | Fourteen M Swap [Member]
Derivative fixed interest rate	3.24%	3.24%
RGC Midstream LLC [Member] | Unsecured Senior Notes Payable [Member] | Unsecured Term Note Payable Due September 5, 2032 [Member] | Four M Swap [Member]
Derivative fixed interest rate	2.443%	2.443%
RGC Midstream LLC [Member] | Unsecured Senior Notes Payable [Member] | Unsecured Term Note Payable Due September 5, 2032 [Member] | Twenty Point Six M Swap [Member]
Derivative fixed interest rate	5.061%	5.061%
RGC Midstream LLC [Member] | Unsecured Senior Notes Payable [Member] | Unsecured Term Note Payable Due September 5, 2032 2 [Member]
Basis spread	1.55%	1.55%
Derivative fixed interest rate	5.061%	5.061%
RGC Midstream LLC [Member] | Unsecured Senior Notes Payable [Member] | Unsecured Term Note Payable Retired September 5, 2025 [Member]
Stated rate	1.55%	1.55%
RGC Midstream LLC [Member] | Unsecured Senior Notes Payable [Member] | Unsecured Term Note Payable Retired September 5, 2025 2 [Member]
Basis spread	1.26448%	1.26448%
Derivative fixed interest rate	3.24%	3.24%
RGC Midstream LLC [Member] | Unsecured Senior Notes Payable [Member] | Unsecured Term Note Payable Retired September 5, 2025 3 [Member]
Basis spread	1.26448%	1.26448%
Derivative fixed interest rate	2.443%	2.443%

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- Definition

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+ References

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- Definition

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+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22)(a)(1))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1B

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