v3.26.1
REVENUE - Disclosure of revenue disaggregated by product (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Disaggregation of Revenue [Line Items]        
Total revenue $ 2,748 $ 2,103 $ 5,209 $ 4,082
Aerospace rolled products        
Disaggregation of Revenue [Line Items]        
Total revenue 350 267 679 534
Transportation, industry, defense and other rolled products        
Disaggregation of Revenue [Line Items]        
Total revenue 288 200 543 368
Packaging rolled products        
Disaggregation of Revenue [Line Items]        
Total revenue 1,188 912 2,234 1,780
Automotive rolled products        
Disaggregation of Revenue [Line Items]        
Total revenue 454 295 857 586
Specialty and other thin-rolled products        
Disaggregation of Revenue [Line Items]        
Total revenue 31 26 56 50
Automotive extruded products        
Disaggregation of Revenue [Line Items]        
Total revenue 266 249 528 483
Other extruded products        
Disaggregation of Revenue [Line Items]        
Total revenue $ 171 $ 154 $ 312 $ 281