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OPERATIONS AND SIGNIFICANT ACCOUNTING POLICIES - Other Current Liabilities (Details) - USD ($) $ in Millions | Sep. 30, 2025 | Dec. 31, 2024
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Organization, Consolidation and Presentation of Financial Statements [Abstract] |  |
Provision for Interim Rate Refund | $ 0.0 | $ 23.0
Customer Deposits | 9.3 | 7.8
PSAs | 5.8 | 5.9
Other | 60.3 | 81.2
Total Other Current Liabilities | $ 75.4 | $ 117.9

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