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Note 4 - Regulatory Matters (Details Textual) |  |  |  |  |  | 12 Months Ended |  |
--- | --- | --- | --- | --- | --- | --- | --- | ---
Dec. 02, 2025 USD ($) | Sep. 26, 2025 USD ($) | May 30, 2025 USD ($) | Oct. 16, 2024 USD ($) | Feb. 02, 2024 USD ($) | Sep. 30, 2025 USD ($) | Sep. 30, 2024 USD ($) | Sep. 30, 2022 | Jun. 02, 2022
Public Utilities, Requested Rate Increase (Decrease), Amount |  |  |  |  | $ 4,330,000 |  |  |  |
Public Utilities, Approved Return on Equity, Percentage |  |  |  | 9.90% | 9.44% |  |  |  |
Public Utilities, Requested Return on Equity, Percentage |  |  |  |  | 10.35% |  |  |  |
Public Utilities, Approved Rate Increase (Decrease), Amount |  |  |  | $ 4,080,000.00 |  |  |  |  |
RNG Rider Revenue Requirement |  |  | $ 1,660,000 |  |  |  |  |  |
RNG Rider Impact to Customers |  |  | 699,000 |  |  |  |  |  |
SAVE Annual Revenues |  | $ 2,610,000 | 2,640,000 |  |  |  |  |  |
Recovery Costs, SAVE Eligible Expenses |  |  | $ 10,330,000 |  |  |  |  |  |
Number of Locations, Natural Gas Delivery Assets, Requested Acquisition |  |  |  |  |  |  |  |  | 5
Number of Locations, Natural Gas Delivery Assets, Approved Acquisition |  |  |  |  |  | 1 | 1 | 2 |
Natural Gas Delivery Assets [Member] | Housing Authority Management [Member] |  |  |  |  |  |  |  |  |
Asset Acquisition, Recognized Pre-tax Gain |  |  |  |  |  | $ 762,000 | $ 782,000 |  |
Subsequent Event [Member] |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount | $ 4,300,000 |  |  |  |  |  |  |  |

X
- Definition Amount of recognized pre-tax gain from the acquisition of assets. + References No definition available. + Details
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- Definition Number of locations where the request for asset acquisition of natural gas delivery has been approved. + References No definition available. + Details
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- Definition Number of locations where the acquisition of assets related to natural gas delivery has been requested. + References No definition available. + Details
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