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OTHER ASSETS (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
OTHER ASSETS (Details) - USD ($) $ in Millions	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Other Assets [Abstract]
Supply contracts	$ 986.4	$ 1,067.2	$ 986.4	$ 1,067.2	$ 1,047.3
Pension assets	69.1	1.7	69.1	1.7	43.3
Capital contributions	21.8	0.0	21.8	0.0	23.0
Other	93.1	62.6	93.1	62.6	71.5
Other assets	1,170.4	1,131.5	1,170.4	1,131.5	1,185.1
Payments under other long-term supply contracts			0.0	58.6
Amortization of Supply Contracts	20.9	18.3	62.7	54.9
Asset Acquisition [Line Items]
Capital contributions	21.8	0.0	21.8	0.0	$ 23.0
Losses of non-consolidated affiliates	(1.0)	$ 0.0	(2.4)	$ 0.0
Hidrogenii
Other Assets [Abstract]
Capital contributions	1.6		1.6
Other(1)			0.4
Asset Acquisition [Line Items]
Capital contributions	$ 1.6		1.6
Losses of non-consolidated affiliates			(2.4)
Other(1)			$ 0.4
Nilico Hydrogen Holdings LLC \| Hidrogenii
Other Assets [Abstract]
Equity Method Investment, Ownership Percentage	50.00%		50.00%
Asset Acquisition [Line Items]
Equity Method Investment, Ownership Percentage	50.00%		50.00%
PLug Power LA LLC \| Hidrogenii
Other Assets [Abstract]
Equity Method Investment, Ownership Percentage	50.00%		50.00%
Asset Acquisition [Line Items]
Equity Method Investment, Ownership Percentage	50.00%		50.00%