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Note 12 - Income Taxes (Details Textual) - USD ($) $ in Thousands | 12 Months Ended |  |
--- | --- | --- | ---
Sep. 30, 2022 | Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2019
Unrecognized Tax Benefits that Would Impact Effective Tax Rate | $ 4,000 | $ 3,600 |  |
Unrecognized Tax Benefits, Interest on Income Taxes Accrued | 0 | 0 |  |
Spire Missouri [Member] |  |  |  |
Regulatory Order, Excess Deferred Income Tax Returned to Customers | 9,900 | 8,400 |  |
Unrecognized Tax Benefits that Would Impact Effective Tax Rate | 3,700 | 3,300 |  |
Unrecognized Tax Benefits, Ending Balance | 19,300 | 16,100 | $ 13,000 | $ 10,400
Spire Alabama Inc [Member] |  |  |  |
Unrecognized Tax Benefits, Ending Balance | $ 0 | $ 0 | $ 0 |

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