v3.26.1
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Reclassification (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Mar. 31, 2026
Jun. 30, 2025
Mar. 31, 2025
Jun. 30, 2026
Jun. 30, 2025
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)            
Commodity cash flow hedges $ 745.7   $ 747.7   $ 1,408.7 $ 1,468.7
Total before tax (119.1)   (103.0)   (225.6) (175.4)
Tax effect 0.5   2.5   9.9 9.1
Net Income (Loss) (119.6) $ (115.9) (105.5) $ (79.0) (235.5) (184.5)
Cash flow hedging items | Reclassified from AOCI to net income (loss)            
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)            
Total before tax     0.8     1.1
Tax effect     (0.1)     (0.1)
Net Income (Loss)     0.7     1.0
Cash flow hedging items | Reclassified from AOCI to net income (loss) | Commodity cash flow hedges            
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)            
Commodity cash flow hedges     0.8     1.1
Accumulated Defined Benefit Plans Adjustment Attributable to Parent | Reclassified from AOCI to net income (loss)            
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)            
Total before tax (1.8)   (1.7)   (4.1) (2.7)
Tax effect 0.4   0.2   0.9 0.6
Net Income (Loss) (1.4)   (1.5)   (3.2) (2.1)
Prior service credit | Reclassified from AOCI to net income (loss)            
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)            
Prior service credit (0.2)   (0.2)   (0.4) (0.5)
Net actuarial gain | Reclassified from AOCI to net income (loss)            
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)            
Net actuarial gain (1.5)   (0.7)   (3.0) (1.4)
Net curtailment and settlement gain | Reclassified from AOCI to net income (loss)            
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)            
Net curtailment and settlement gain $ (0.1)   $ (0.8)   $ (0.7) $ (0.8)