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Other Commitments And Contingencies (Narrative) (Details) $ in Millions							3 Months Ended
	Oct. 28, 2025 USD ($) Rate	Sep. 04, 2025 USD ($)	Jun. 18, 2025 USD ($)	May 31, 2025 USD ($)	Feb. 03, 2025 USD ($)	Jan. 15, 2025 USD ($)	Jun. 30, 2025 USD ($)	Sep. 30, 2025 USD ($) Rate	Dec. 31, 2024 USD ($)
Other Commitments And Contingencies [Line Items]
Guaranty Liabilities								$ 29.2	$ 1,127.5
Recorded reserves to cover environmental remediation at various sites								$ 84.6	91.8
Wind Power Purchase Agreement, Purchase Percentage | Rate								100.00%
Business Combination, Price of Acquisition, Expected	$ 35.2
Payments to Acquire Assets, Investing Activities			$ 262.4	$ 141.4	$ 217.6	$ 336.6
Contractual Obligation								$ 52.0	61.7
NIPSCO Holdings II
Other Commitments And Contingencies [Line Items]
Subsidiary, Ownership Percentage, Parent | Rate	19.90%
MGP Sites
Other Commitments And Contingencies [Line Items]
Number of waste disposal sites identified by program								51
Liability for Estimated Remediation Costs								$ 77.3	86.4
Reasonably possible remediation costs variance from reserve								16.5	16.3
CCR Remediation
Other Commitments And Contingencies [Line Items]
Accrual for Environmental Loss Contingencies, Period Increase (Decrease)							$ 38.8
Standby Letters of Credit
Other Commitments And Contingencies [Line Items]
Long-term Line of Credit								$ 119.0	$ 9.4
Payments to Acquire Assets, Investing Activities		$ 133.7

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Total costs accrued as of the balance sheet date for environmental loss contingencies.

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Purchase price of expected business acquisition prior to consideration being transferred. Excludes asset acquisition.

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