v3.26.1
REVENUE - Disclosure of revenue disaggregated by product (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Disaggregation of Revenue [Line Items]    
Total revenue $ 2,461 $ 1,979
Aerospace rolled products    
Disaggregation of Revenue [Line Items]    
Total revenue 329 267
Transportation, industry, defense and other rolled products    
Disaggregation of Revenue [Line Items]    
Total revenue 255 168
Packaging rolled products    
Disaggregation of Revenue [Line Items]    
Total revenue 1,046 868
Automotive rolled products    
Disaggregation of Revenue [Line Items]    
Total revenue 403 291
Specialty and other thin-rolled products    
Disaggregation of Revenue [Line Items]    
Total revenue 25 24
Automotive extruded products    
Disaggregation of Revenue [Line Items]    
Total revenue 262 234
Other extruded products    
Disaggregation of Revenue [Line Items]    
Total revenue $ 141 $ 127