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Commitment, Contingencies And Guarantees: Manufactured Gas Plants (Details) - USD ($) $ in Millions | 9 Months Ended |
--- | --- | ---
Sep. 30, 2025 | Dec. 31, 2024
Loss Contingencies [Line Items] |  |
Regulatory assets | $ 391.2 | $ 427.7
Manufactured Gas Plant | Black Hills Energy - Iowa Gas |  |
Loss Contingencies [Line Items] |  |
Insurance Settlements Receivable, Noncurrent | 1.5 |
Accrual for Environmental Loss Contingencies, Gross, Total |  | $ 9.7
Site remediation cost | 11.5 |
Insurance recovery asset | 1.5 |
Regulatory assets | $ 11.5 |

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