Postretirement benefit plans (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2	$ 2
Interest cost	6	6
Expected return on plan assets	(6)	(4)
Recognized net actuarial losses (gains)	1	2
Amortization of prior service cost (credit)	0	0
Net periodic benefit costs (credits)	3	6
U.S. | Retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0
Interest cost	3	3
Expected return on plan assets	(3)	(3)
Recognized net actuarial losses (gains)	0	0
Amortization of prior service cost (credit)	0	0
Net periodic benefit costs (credits)	0	0
Non-U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	4	4
Interest cost	16	14
Expected return on plan assets	(19)	(18)
Recognized net actuarial losses (gains)	(1)	1
Amortization of prior service cost (credit)	1	0
Net periodic benefit costs (credits)	$ 1	$ 1