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v3.25.3

Notes Payable and Credit Agreements - Short-term Borrowings (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024
Short-Term Debt [Line Items] |  |
Highest borrowings outstanding | $ 1,348.0 |
Lowest borrowings outstanding | 896.0 |
Weighted average borrowings | $ 1,085.7 |
Weighted average interest rate | 4.40% |
Borrowings outstanding | $ 1,317.0 | $ 947.0
Weighted average interest rate | 4.50% | 5.20%
Spire Note [Member] | Spire Missouri [Member] |  |
Short-Term Debt [Line Items] |  |
Highest borrowings outstanding | $ 615.0 |
Lowest borrowings outstanding | 299.5 |
Weighted average borrowings | $ 482.6 |
Weighted average interest rate | 4.40% |
Borrowings outstanding | $ 566.3 | $ 495.3
Weighted average interest rate | 4.70% | 5.20%
Spire Note [Member] | Spire Alabama Inc [Member] |  |
Short-Term Debt [Line Items] |  |
Highest borrowings outstanding | $ 130.6 |
Lowest borrowings outstanding | 1.2 |
Weighted average borrowings | $ 50.8 |
Weighted average interest rate | 4.40% |
Borrowings outstanding | $ 130.1 | $ 48.4
Weighted average interest rate | 4.70% | 5.20%
Parent Company [Member] | Commercial Paper [Member] |  |
Short-Term Debt [Line Items] |  |
Highest borrowings outstanding | $ 1,348.0 |
Lowest borrowings outstanding | 896.0 |
Weighted average borrowings | $ 1,085.7 |
Weighted average interest rate | 4.40% |
Borrowings outstanding | $ 1,317.0 | $ 947.0
Weighted average interest rate | 4.50% | 5.20%

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