SUPPLEMENTAL CASH FLOW INFORMATION (Details) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2025	Jun. 30, 2024
Supplemental Cash Flow Information [Abstract]
Cash paid for interest, net of amount capitalized	$ 47.0	$ 47.0
Cash paid for income taxes, net	9.8	2.1
Cash received from sale of production tax credits	9.7	14.5
Significant non-cash investing and financing transactions
Accounts payable related to construction costs	45.8	30.0
Liabilities accrued for software licensing agreements	$ 4.3	$ 0.0

Future cash outflow to pay for purchases of fixed assets that have occurred.

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Amount, after refund, of cash paid to foreign, federal, state, and local jurisdictions as income tax.

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Future cash outflow to pay for software licensing agreements already signed.

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Cash received during the period from the sale of production tax credits to third parties.

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