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Revenue Recognition Revenue Recognition (Allowance for Credit Losses) (Details) - USD ($) | 6 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Jun. 30, 2025 | Dec. 31, 2024 | Dec. 31, 2023
Accounts Receivable Allowance For Credit Loss [Line Items] |  |  |
Accounts Receivable, Allowance for Credit Loss | $ 27,300,000 | $ 23,700,000 | $ 22,900,000
Current period provisions | 27,500,000 | 38,800,000 |
Write-offs charged against allowance | 28,600,000 | 55,700,000 |
Recoveries of amounts previously written off | 4,700,000 | 17,700,000 |
Corporate and Other |  |  |
Accounts Receivable Allowance For Credit Loss [Line Items] |  |  |
Accounts Receivable, Allowance for Credit Loss | 0 | 0 | 800,000
Current period provisions | 0 | 0 |
Write-offs charged against allowance | 0 | (800,000) |
Recoveries of amounts previously written off | 0 | 0 |
Columbia Operations |  |  |
Accounts Receivable Allowance For Credit Loss [Line Items] |  |  |
Accounts Receivable, Allowance for Credit Loss | 11,400,000 | 9,800,000 | 10,200,000
Current period provisions | 20,400,000 | 26,700,000 |
Write-offs charged against allowance | 23,100,000 | 43,900,000 |
Recoveries of amounts previously written off | 4,300,000 | 16,800,000 |
NIPSCO Operations |  |  |
Accounts Receivable Allowance For Credit Loss [Line Items] |  |  |
Accounts Receivable, Allowance for Credit Loss | 15,900,000 | 13,900,000 | $ 11,900,000
Current period provisions | 7,100,000 | 12,100,000 |
Write-offs charged against allowance | 5,500,000 | 11,000,000.0 |
Recoveries of amounts previously written off | $ 400,000 | $ 900,000 |

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