RELATED PARTY TRANSACTIONS (Summary of Related Party Transactions) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Transactions under commercial agreements:
Sales	$ 7,904.3	$ 7,066.4
St. Bernard Renewables LLC \| Equity Method Investment, Nonconsolidated Investee or Group of Investees
Transactions under commercial agreements:
Sales	21.6	13.4
Purchases	(157.5)	(60.3)
St. Bernard Renewables LLC \| Equity Method Investment, Nonconsolidated Investee or Group of Investees \| General and Administrative Expense \| Operating agreement
Reimbursements under related party agreements:
Transactions with related party	70.1	40.0
St. Bernard Renewables LLC \| Equity Method Investment, Nonconsolidated Investee or Group of Investees \| General and Administrative Expense \| Omnibus agreement
Reimbursements under related party agreements:
Transactions with related party	1.0	1.0
St. Bernard Renewables LLC \| Equity Method Investment, Nonconsolidated Investee or Group of Investees \| General and Administrative Expense \| Common asset use and servitude agreement
Reimbursements under related party agreements:
Transactions with related party	2.0	2.2
St. Bernard Renewables LLC \| Equity Method Investment, Nonconsolidated Investee or Group of Investees \| Cost of Sales \| Lease Agreements
Reimbursements under related party agreements:
Transactions with related party	$ 0.0	$ (5.3)