Note 8 - Derivatives and Hedging (Details Textual) $ in Millions	Jun. 30, 2026 USD ($)	Aug. 20, 2021 USD ($)
Number of Interest Rate Derivatives Held	6
Unsecured Term Notes Payable, at 30-day SOFR Average 1.20% Due August 20, 2026 [Member]
Debt Instrument, Face Amount		$ 15.0
Roanoke Gas Company [Member]
Number of Interest Rate Derivatives Held	2
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	$ 15.0
Derivative, Fixed Interest Rate	2.00%
Roanoke Gas Company [Member] \| Unsecured Debt [Member] \| Unsecured term note payable, at Term SOFR plus 1.00%, due October 1, 2028 [Member]
Debt Instrument, Face Amount	$ 10.0
Derivative, Fixed Interest Rate	2.49%
Roanoke Gas Company [Member] \| Unsecured Debt [Member] \| Unsecured Delayed-draw Term Note Payable at Term SOFR Plus 1.00%, Due August 20, 2029 [Member]
Debt Instrument, Face Amount	$ 15.0
Derivative, Fixed Interest Rate	5.13%
RGC Midstream LLC [Member] \| Interest Rate Swap [Member]
Number of Interest Rate Derivatives Held	3
RGC Midstream LLC [Member] \| Unsecured Term Notes [Member] \| Variable Rate Term Note 1 [Member]
Debt Instrument, Face Amount	$ 2.8
Derivative, Fixed Interest Rate	2.443%
RGC Midstream LLC [Member] \| Unsecured Term Notes [Member] \| Variable Rate Term Note 2 [Member]
Debt Instrument, Face Amount	$ 34.3
Derivative, Fixed Interest Rate	5.061%
RGC Midstream LLC [Member] \| Unsecured Term Notes [Member] \| Variable Rate Term Note 3 [Member]
Debt Instrument, Face Amount	$ 14.4
Derivative, Fixed Interest Rate	5.061%
RGC Midstream LLC [Member] \| Unsecured Term Notes [Member] \| Unsecured Term Note Payable at Term SOFR Plus 1.55%, Due September 5, 2032 [Member]
Debt Instrument, Face Amount	$ 37.1
RGC Midstream LLC [Member] \| Unsecured Term Notes [Member] \| Unsecured Term Note Payable at Term SOFR Plus 1.55%, Due September 5, 2032 2 [Member]
Debt Instrument, Face Amount	$ 14.4