FAIR VALUE MEASUREMENTS (Measured on Recurring Basis) (Details) - USD ($) $ in Millions | Mar. 31, 2024 | Dec. 31, 2023 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative assets, Effect of Counter-party Netting | $ (0.9) | $ (23.7) |
Derivative, Collateral, Obligation to Return Cash | 0.9 | 23.7 |
Other Assets | Pension Benefits | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Defined Benefit Plan, Plan Assets, Amount | 19.2 | 18.8 |
Fair Value, Measurements, Recurring | Commodity contracts | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative Liability, Fair Value, Amount Not Offset Against Collateral | 67.5 | 46.9 |
Derivative, Collateral, Right to Reclaim Cash | (67.5) | (46.9) |
Derivative Liability | 0 | 0 |
Fair Value, Measurements, Recurring | 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 | 66.9 | 46.9 |
Fair Value, Measurements, Recurring | 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 | 0.6 | 0 |
Fair Value, Measurements, Recurring | 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 |
Fair Value, Measurements, Recurring | 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 |
Obligations, Fair Value Disclosure | 460.4 | 429.8 |
Fair Value, Measurements, Recurring | 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 |
Fair Value, Measurements, Recurring | 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 | 460.4 | 429.8 |
Fair Value, Measurements, Recurring | 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 |
Fair Value, Measurements, Recurring | Contingent consideration obligation | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative, Collateral, Right to Reclaim Cash | 0 | 0 |
Obligations, Fair Value Disclosure | 18.3 | 21.6 |
Fair Value, Measurements, Recurring | Contingent consideration obligation | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Obligations, Fair Value Disclosure | 0 | 0 |
Fair Value, Measurements, Recurring | Contingent consideration obligation | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Obligations, Fair Value Disclosure | 0 | 0 |
Fair Value, Measurements, Recurring | Contingent consideration obligation | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Obligations, Fair Value Disclosure | 18.3 | 21.6 |
Fair Value, Measurements, Recurring | Money market funds | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash and cash equivalents | 51.6 | 130.3 |
Fair Value, Measurements, Recurring | Money market funds | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash and cash equivalents | 51.6 | 130.3 |
Fair Value, Measurements, Recurring | Money market funds | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash and cash equivalents | 0 | 0 |
Fair Value, Measurements, Recurring | Money market funds | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash and cash equivalents | 0 | 0 |
Fair Value, Measurements, Recurring | Commodity contracts | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative Asset, Fair Value, Amount Not Offset Against Collateral | 81.6 | 80.1 |
Derivative assets, Effect of Counter-party Netting | (67.5) | (46.9) |
Derivative assets, Net Carrying Value on Balance Sheet | 14.1 | 33.2 |
Derivative, Collateral, Obligation to Return Cash | 67.5 | 46.9 |
Fair Value, Measurements, Recurring | 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 | 80.2 | 80.1 |
Fair Value, Measurements, Recurring | 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 | 1.4 | 0 |
Fair Value, Measurements, Recurring | 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 |