Postretirement benefit plans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1	$ 2	$ 5	$ 6
Interest cost	6	7	19	19
Expected return on plan assets	(3)	(7)	(13)	(18)
Recognized net actuarial losses (gains)	1	1	5	3
Amortization of prior service cost (credit)	0	0	0	0
Net periodic benefit costs (credits)	5	3	16	10
Settlement losses	4	0	7	0
Total, including other postretirement losses (gains)	9	3	23	10
U.S. | Retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	1	1
Interest cost	3	4	9	10
Expected return on plan assets	(2)	(4)	(8)	(13)
Recognized net actuarial losses (gains)	0	(1)	(1)	(2)
Amortization of prior service cost (credit)	0	0	0	0
Net periodic benefit costs (credits)	1	(1)	1	(4)
Settlement losses	0	0	0	0
Total, including other postretirement losses (gains)	1	(1)	1	(4)
Non-U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	4	4	11	12
Interest cost	16	15	45	42
Expected return on plan assets	(20)	(22)	(55)	(60)
Recognized net actuarial losses (gains)	1	3	3	9
Amortization of prior service cost (credit)	0	1	0	1
Net periodic benefit costs (credits)	1	1	4	4
Settlement losses	0	0	0	0
Total, including other postretirement losses (gains)	$ 1	$ 1	$ 4	$ 4