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Subsequent Event (Narrative) (Details) - USD ($) $ in Millions |  | 9 Months Ended
--- | --- | ---
Oct. 28, 2025 | Sep. 30, 2025 | Sep. 30, 2024
Subsequent Event [Line Items] |  |  |
Payment to renewable generation asset developer |  | $ 1,091.7 | $ 478.8
Investment Company, Committed Capital | $ 1,325.0 |  |
Business Combination, Price of Acquisition, Expected | $ 35.2 |  |
NIPSCO Holdings II |  |  |
Subsequent Event [Line Items] |  |  |
Subsidiary, Ownership Percentage, Parent | 19.90% |  |
Subsidiary, Ownership Percentage, Noncontrolling Owner | 14.90% |  |
Investment Company, Committed Capital | $ 175.0 |  |
Generation Holdings II |  |  |
Subsequent Event [Line Items] |  |  |
Subsidiary, Ownership Percentage, Parent | 17.50% |  |

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- Definition Purchase price of expected business acquisition prior to consideration being transferred. Excludes asset acquisition. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479328/805-10-50-7 + Details
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- Definition Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 830 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481674/830-30-50-2 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 855 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147483399/855-10-50-2 + Details
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- Details
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- Details
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