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INCOME TAX EXPENSE - Reconciliation of Taxes from Federal Statutory Rate to Total Income Tax Expense (Details) - USD ($) $ in Millions | 3 Months Ended
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Mar. 31, 2025 | Mar. 31, 2024
Reconciliation of Taxes from Federal Statutory Rate to Total Income Tax Expense [Abstract] |  |
Income Before Income Taxes | $ 42.2 | $ 41.0
Statutory Federal Income Tax Rate | 21.00% | 21.00%
Income Taxes Computed at Statutory Federal Rate | $ 8.9 | $ 8.6
Increase (Decrease) in Income Tax Due to: |  |
State Income Taxes – Net of Federal Income Tax Benefit | 4.8 | 4.6
Production Tax Credits | (4.8) | (11.6)
Investment Tax Credits | (2.8) | (0.3)
Regulatory Differences – Excess Deferred Tax | (2.6) | (3.5)
Non-Controlling Interest in Subsidiaries | 4.0 | 2.8
AFUDC – Equity | (0.4) | (0.6)
Nondeductible Portion of Transaction Costs | 0.3 | 0.0
Other | 0.1 | 4.0
Total Income Tax Expense | $ 7.5 | $ 4.0

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