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OPERATIONS AND SIGNIFICANT ACCOUNTING POLICIES - Supplemental Statement of Cash Flows Information (Details) - USD ($) $ in Millions | 9 Months Ended
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Sep. 30, 2025 | Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract] |  |
Cash Paid for Interest – Net of Amounts Capitalized | $ 64.0 | $ 59.5
Cash Paid for Income Taxes – Net | 15.9 | 7.0
Noncash Investing and Financing Activities |  |
Increase in Accounts Payable for Capital Additions to Property, Plant and Equipment | 3.4 | 13.5
Capitalized Asset Retirement Costs | 2.6 | 51.0
AFUDC–Equity | $ 4.0 | $ 4.0

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