FAIR VALUE MEASUREMENTS (Measured on Recurring Basis) (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Other Assets | Pension Benefits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 19.7	$ 20.7
Fair Value, Measurements, Recurring [Member] | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	249.1	83.5
Derivative, Collateral, Right to Reclaim Cash	(197.2)	(71.5)
Derivative Liability	51.9	12.0
Fair Value, Measurements, Recurring [Member] | Commodity contracts | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	249.1	79.7
Fair Value, Measurements, Recurring [Member] | Commodity contracts | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	0.0	3.8
Fair Value, Measurements, Recurring [Member] | Commodity contracts | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	0.0	0.0
Fair Value, Measurements, Recurring [Member] | Catalyst financing arrangements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, Collateral, Right to Reclaim Cash	0.0	0.0
Obligations, Fair Value Disclosure	63.3	58.4
Fair Value, Measurements, Recurring [Member] | Catalyst financing arrangements | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Obligations, Fair Value Disclosure	0.0	0.0
Fair Value, Measurements, Recurring [Member] | Catalyst financing arrangements | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Obligations, Fair Value Disclosure	63.3	58.4
Fair Value, Measurements, Recurring [Member] | Catalyst financing arrangements | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Obligations, Fair Value Disclosure	0.0	0.0
Fair Value, Measurements, Recurring [Member] | Renewable energy credit and emissions obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, Collateral, Right to Reclaim Cash	0.0	0.0
Obligations, Fair Value Disclosure	1,141.0	953.9
Fair Value, Measurements, Recurring [Member] | Renewable energy credit and emissions obligations | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Obligations, Fair Value Disclosure	0.0	0.0
Fair Value, Measurements, Recurring [Member] | Renewable energy credit and emissions obligations | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Obligations, Fair Value Disclosure	1,141.0	953.9
Fair Value, Measurements, Recurring [Member] | Renewable energy credit and emissions obligations | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Obligations, Fair Value Disclosure	0.0	0.0
Fair Value, Measurements, Recurring [Member] | Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, Collateral, Right to Reclaim Cash	0.0	0.0
Obligations, Fair Value Disclosure	79.5	29.4
Fair Value, Measurements, Recurring [Member] | Contingent Consideration | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Obligations, Fair Value Disclosure	0.0	0.0
Fair Value, Measurements, Recurring [Member] | Contingent Consideration | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Obligations, Fair Value Disclosure	0.0	0.0
Fair Value, Measurements, Recurring [Member] | Contingent Consideration | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Obligations, Fair Value Disclosure	79.5	29.4
Fair Value, Measurements, Recurring [Member] | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	45.9	260.9
Fair Value, Measurements, Recurring [Member] | Money market funds | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	45.9	260.9
Fair Value, Measurements, Recurring [Member] | Money market funds | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0.0	0.0
Fair Value, Measurements, Recurring [Member] | Money market funds | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0.0	0.0
Fair Value, Measurements, Recurring [Member] | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	197.2	71.5
Derivative assets, Effect of Counter-party Netting	(197.2)	(71.5)
Derivative assets, Net Carrying Value on Balance Sheet	0.0	0.0
Fair Value, Measurements, Recurring [Member] | Commodity contracts | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	197.2	71.5
Fair Value, Measurements, Recurring [Member] | Commodity contracts | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	0.0	0.0
Fair Value, Measurements, Recurring [Member] | Commodity contracts | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	0.0	0.0
Fair Value, Measurements, Recurring [Member] | Derivatives included with inventory intermediation agreement obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	60.4	19.7
Derivative assets, Effect of Counter-party Netting	0.0	0.0
Derivative assets, Net Carrying Value on Balance Sheet	60.4	19.7
Fair Value, Measurements, Recurring [Member] | Derivatives included with inventory intermediation agreement obligations | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	0.0	0.0
Fair Value, Measurements, Recurring [Member] | Derivatives included with inventory intermediation agreement obligations | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	60.4	19.7
Fair Value, Measurements, Recurring [Member] | Derivatives included with inventory intermediation agreement obligations | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	$ 0.0	$ 0.0