v3.26.1
Derivatives, Hedging Programs and Other Financial Instruments - Summary of (Gain) Loss Associated with Derivative Contracts (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Derivative Instruments Gain Loss [Line Items]        
Total of income and expense line items presented in our Statements of Consolidated Income in which the effects of cash flow hedges are recorded $ 1,057.6 $ 722.8 $ 2,000.8 $ 1,396.2
Cash Flow Hedges        
Derivative Instruments Gain Loss [Line Items]        
Total of income and expense line items presented in our Statements of Consolidated Income in which the effects of cash flow hedges are recorded 1,057.6 722.8 2,000.8 1,396.2
Cash Flow Hedges | Designated as Hedging Instrument        
Derivative Instruments Gain Loss [Line Items]        
Total gain recognized in our Statements of Consolidated Income related to cash flow hedges $ (12.8) $ (2.5) $ (22.1) $ (8.0)
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Total of income and expense line items presented in our Statements of Consolidated Income in which the effects of cash flow hedges are recorded Total of income and expense line items presented in our Statements of Consolidated Income in which the effects of cash flow hedges are recorded Total of income and expense line items presented in our Statements of Consolidated Income in which the effects of cash flow hedges are recorded Total of income and expense line items presented in our Statements of Consolidated Income in which the effects of cash flow hedges are recorded
Cash Flow Hedges | Designated as Hedging Instrument | Aluminum        
Derivative Instruments Gain Loss [Line Items]        
Total gain recognized in our Statements of Consolidated Income related to cash flow hedges $ (14.8) $ (2.2) $ (23.3) $ (7.4)
Cash Flow Hedges | Designated as Hedging Instrument | Alloying Metals        
Derivative Instruments Gain Loss [Line Items]        
Total gain recognized in our Statements of Consolidated Income related to cash flow hedges (0.7) (0.5) (1.2) (0.9)
Cash Flow Hedges | Designated as Hedging Instrument | Foreign exchange contracts        
Derivative Instruments Gain Loss [Line Items]        
Total gain recognized in our Statements of Consolidated Income related to cash flow hedges   (0.1) 0.0  
Cash Flow Hedges | Designated as Hedging Instrument | Natural Gas        
Derivative Instruments Gain Loss [Line Items]        
Total gain recognized in our Statements of Consolidated Income related to cash flow hedges 0.5 $ 0.3 0.2 $ 0.3
Cash Flow Hedges | Designated as Hedging Instrument | Electricity        
Derivative Instruments Gain Loss [Line Items]        
Total gain recognized in our Statements of Consolidated Income related to cash flow hedges $ 2.2   $ 2.2