v3.25.2
Pension and postretirement benefits - Components of plan benefit expense (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 29, 2025
Mar. 30, 2024
Pension    
Defined Benefit Plan Disclosure [Line Items]    
Service cost $ 2 $ 2
Interest cost 7 7
Expected return on plan assets (8) (9)
Amortization of unrecognized prior service cost 1 1
Total expense (income) 2 1
Nonpension postretirement    
Defined Benefit Plan Disclosure [Line Items]    
Service cost 1 1
Interest cost 6 6
Expected return on plan assets (15) (15)
Amortization of unrecognized prior service cost (2) (2)
Total expense (income) $ (10) $ (10)