OTHER ASSETS (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025	Dec. 31, 2025	Dec. 31, 2024
Asset Acquisition [Line Items]
Capital contributions	$ 19.4	$ 21.8	$ 19.4	$ 21.8	$ 21.3	$ 23.0
Losses of non-consolidated affiliates	(0.9)	(1.0)	(3.3)	(2.4)
Supply contracts	937.6	986.4	937.6	986.4	996.0
Pension assets	132.9	69.1	132.9	69.1	106.8
Capital contributions	19.4	21.8	19.4	21.8	21.3	$ 23.0
Other	68.6	93.1	68.6	93.1	85.9
Other assets	1,158.5	1,170.4	1,158.5	1,170.4	$ 1,210.0
Amortization of Supply Contracts	21.6	20.9	65.0	62.7
Hidrogenii
Asset Acquisition [Line Items]
Capital contributions	1.9	1.6	1.9	1.6
Losses of non-consolidated affiliates			(3.8)	(2.8)
Other	0.5			0.4
Capital contributions	1.9	$ 1.6	$ 1.9	1.6
Other	$ 0.5			$ 0.4
Nilico Hydrogen Holdings LLC \| Hidrogenii
Asset Acquisition [Line Items]
Equity Method Investment, Ownership Percentage	50.00%		50.00%
Equity Method Investment, Ownership Percentage	50.00%		50.00%
PLug Power LA LLC \| Hidrogenii
Asset Acquisition [Line Items]
Equity Method Investment, Ownership Percentage	50.00%		50.00%
Equity Method Investment, Ownership Percentage	50.00%		50.00%

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