Commitment, Contingencies And Guarantees: Manufactured Gas Plants (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023
Loss Contingencies [Line Items]
Regulatory assets	$ 427.7	$ 480.1
Accrued liabilities	302.2	293.3
Environmental
Loss Contingencies [Line Items]
Regulatory assets	10.7	$ 2.9
Manufactured Gas Plant
Loss Contingencies [Line Items]
Insurance Settlements Receivable, Noncurrent	1.5
Site remediation cost	7.4
Manufactured Gas Plant \| Black Hills Energy - Iowa Gas
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies, Gross	9.7
Manufactured Gas Plant \| Environmental
Loss Contingencies [Line Items]
Regulatory assets	10.7
Manufactured Gas Plant \| Gas Utilities \| Black Hills Energy - Nebraska Gas
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies, Gross	$ 0.6

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Carrying amount due after one year of the balance sheet date (or one operating cycle, if longer) of amount due in settlement of a claim for reimbursement from an insurance company when the Company has suffered a loss covered under an insurance policy.

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