| Schedule of Long-Term Debt Instruments [Table Text Block] |
| | | June 30, 2026 | | | September 30, 2025 | |
| | | Principal | | | Unamortized Debt Issuance Costs | | | Principal | | | Unamortized Debt Issuance Costs | |
| Roanoke Gas: | | | | | | | | | | | | | | | | |
| Unsecured senior note payable at 4.26%, due September 18, 2034 | | $ | 30,500,000 | | | $ | 79,646 | | | $ | 30,500,000 | | | $ | 86,887 | |
| Unsecured term note payable at 3.58%, due October 2, 2027 | | | 8,000,000 | | | | 6,020 | | | | 8,000,000 | | | | 9,632 | |
| Unsecured term note payable at 4.41%, due March 28, 2031 | | | 10,000,000 | | | | 14,880 | | | | 10,000,000 | | | | 17,229 | |
| Unsecured term note payable at 3.60%, due December 6, 2029 | | | 10,000,000 | | | | 12,330 | | | | 10,000,000 | | | | 14,971 | |
| Unsecured term note payable at 30-day SOFR plus 1.20%, due August 20, 2026 (swap rate at 2.00%) | | | 15,000,000 | | | | — | | | | 15,000,000 | | | | — | |
| Unsecured term note payable at Term SOFR plus 1.00%, due October 1, 2028 (swap rate at 2.49%) | | | 10,000,000 | | | | 15,972 | | | | 10,000,000 | | | | 22,612 | |
| Unsecured delayed-draw term note payable at Term SOFR plus 1.00%, due August 20, 2029 (swap rate at 5.13%) | | | — | | | | 20,908 | | | | — | | | | — | |
| Midstream: | | | | | | | | | | | | | | | | |
| Unsecured term note payable at Term SOFR plus 1.55%, due September 5, 2032 ($2.8M swap rate at 2.443% and $34.3M swap rate at 5.061%) | | | 37,062,832 | | | | 130,124 | | | | 38,600,000 | | | | 171,362 | |
| Unsecured term note payable at Term SOFR plus 1.55%, due September 5, 2032 (swap rate at 5.061%) | | | 14,402,655 | | | | 50,566 | | | | 15,000,000 | | | | 66,592 | |
| Revolving credit facility at Term SOFR plus 1.75%, due September 5, 2030 ("Southgate") | | | 405,233 | | | | 4,706 | | | | 4,215 | | | | 5,553 | |
| Revolving credit facility at Term SOFR plus 1.75%, due September 5, 2030 ("Boost") | | | 614,942 | | | | 9,285 | | | | — | | | | 10,956 | |
| Total long-term debt | | | 135,985,662 | | | | 344,437 | | | | 137,104,215 | | | | 405,794 | |
| Less: current maturities of long-term debt | | | (2,846,018 | ) | | | — | | | | (2,846,018 | ) | | | — | |
| Total long-term debt, net current maturities | | $ | 133,139,644 | | | $ | 344,437 | | | $ | 134,258,197 | | | $ | 405,794 | |
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