OPERATIONS AND SIGNIFICANT ACCOUNTING POLICIES - Supplemental Statement of Cash Flows Information (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash Paid for Interest – Net of Amounts Capitalized	$ 40.5	$ 36.8
Cash Paid for Income Taxes – Net	11.1	5.7
Noncash Investing and Financing Activities
Increase in Accounts Payable for Capital Additions to Property, Plant and Equipment	13.6	5.8
Capitalized Asset Retirement Costs	2.6	50.0
AFUDC–Equity	$ 2.7	$ 2.5