v3.25.2
Pension and Postretirement Plans (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Postretirement Benefits        
Defined Benefit Plan Disclosure [Line Items]        
Interest cost $ 1 $ 1 $ 2 $ 3
Expected return on plan assets (3) (3) (8) (7)
Amortization of prior service credit (2) (1) (4) (4)
Net periodic benefit cost (4) (3) (10) (8)
United States | Pension Plan        
Defined Benefit Plan Disclosure [Line Items]        
Interest cost 16 20 49 59
Expected return on plan assets (24) (30) (73) (90)
Net periodic benefit cost (8) (10) (24) (31)
Foreign Plan | Pension Plan        
Defined Benefit Plan Disclosure [Line Items]        
Service cost 5 4 13 12
Interest cost 16 17 48 51
Expected return on plan assets (20) (18) (58) (54)
Net periodic benefit cost $ 1 $ 3 $ 3 $ 9