v3.25.4
Retirement benefits (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2025
Dec. 31, 2024
Other Postretirement Benefits        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Service cost $ 0 $ 0 $ 0 $ 0
Interest cost 0 0 1 1
Expected return on plan assets 0 0 0 0
Amortization of prior service cost 0 0 0 0
Amortization of net actuarial loss (gain) 0 0 (1) 0
Net periodic benefit cost (income) 0 0 0 1
United States | Pension Plans        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Service cost 6 7 12 14
Interest cost 42 46 84 92
Expected return on plan assets (58) (61) (116) (122)
Amortization of prior service cost 1 1 2 2
Amortization of net actuarial loss (gain) 1 2 2 4
Net periodic benefit cost (income) (8) (5) (16) (10)
Non-U.S. Pension Benefits | Pension Plans        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Service cost 5 5 11 11
Interest cost 19 19 37 38
Expected return on plan assets (22) (21) (45) (43)
Amortization of prior service cost 0 0 0 0
Amortization of net actuarial loss (gain) 1 1 3 3
Net periodic benefit cost (income) $ 3 $ 4 $ 6 $ 9