Postretirement benefit plans - Expense Related to Defined Benefit and Retiree Health Care Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2	$ 4	$ 6	$ 12
Interest cost	7	8	21	20
Expected return on plan assets	(6)	(6)	(17)	(22)
Recognized net actuarial losses (gains)	2	1	5	2
Amortization of prior service cost (credit)	0	0	0	0
Net periodic benefit costs (credits)	5	7	15	12
Settlement losses	0	16	1	29
Total, including other postretirement losses (gains)	5	23	16	41
U.S. | Retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	1	1	2
Interest cost	4	3	11	8
Expected return on plan assets	(4)	(3)	(13)	(9)
Recognized net actuarial losses (gains)	(1)	0	(4)	0
Amortization of prior service cost (credit)	0	(1)	0	(1)
Net periodic benefit costs (credits)	(1)	0	(5)	0
Settlement losses	0	0	0	0
Total, including other postretirement losses (gains)	(1)	0	(5)	0
Non-U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	4	6	12	19
Interest cost	14	7	43	26
Expected return on plan assets	(16)	(15)	(48)	(50)
Recognized net actuarial losses (gains)	3	1	9	1
Amortization of prior service cost (credit)	1	0	1	0
Net periodic benefit costs (credits)	6	(1)	17	(4)
Settlement losses	0	1	1	10
Total, including other postretirement losses (gains)	$ 6	$ 0	$ 18	$ 6