v3.26.3
REVENUE - Disclosure of revenue disaggregated by product (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Disaggregation of Revenue [Line Items]        
Total revenue $ 2,639 $ 2,166 $ 7,848 $ 6,248
Aerospace rolled products        
Disaggregation of Revenue [Line Items]        
Total revenue 329 264 1,008 798
Transportation, industry, defense and other rolled products        
Disaggregation of Revenue [Line Items]        
Total revenue 298 199 841 567
Packaging rolled products        
Disaggregation of Revenue [Line Items]        
Total revenue 1,187 984 3,421 2,764
Automotive rolled products        
Disaggregation of Revenue [Line Items]        
Total revenue 407 297 1,264 883
Specialty and other thin-rolled products        
Disaggregation of Revenue [Line Items]        
Total revenue 28 23 84 73
Automotive extruded products        
Disaggregation of Revenue [Line Items]        
Total revenue 241 259 769 742
Other extruded products        
Disaggregation of Revenue [Line Items]        
Total revenue $ 149 $ 140 $ 461 $ 421