Postretirement benefits Components of net periodic benefit costs (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	$ 2	$ 2
Non-service (benefit) cost	(31)	(25)
Net periodic benefit cost (benefit)	(29)	(23)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	0	0
Interest cost	1	0
Expected return on plan assets	(1)	(1)
Defined Benefit Plan, Amortization of Gain (Loss)	(1)	0
Amortization of prior service cost	0	0
Settlements	0	0
Non-service (benefit) cost	(1)	(1)
Net periodic benefit cost (benefit)	(1)	(1)
Losses and loss expenses | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	0	0
Non-service (benefit) cost	(3)	(2)
Losses and loss expenses | Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	0	0
Non-service (benefit) cost	0	0
Administrative Expense | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	2	2
Non-service (benefit) cost	(28)	(23)
Administrative Expense | Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	0	0
Non-service (benefit) cost	(1)	(1)
Foreign Plan [Member] | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	2	2
Interest cost	9	9
Expected return on plan assets	(13)	(12)
Defined Benefit Plan, Amortization of Gain (Loss)	1	0
Amortization of prior service cost	0	0
Settlements	0	0
Non-service (benefit) cost	(3)	(3)
Net periodic benefit cost (benefit)	(1)	(1)
UNITED STATES | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	0	0
Interest cost	33	34
Expected return on plan assets	(61)	(56)
Defined Benefit Plan, Amortization of Gain (Loss)	0	0
Amortization of prior service cost	0	0
Settlements	0	0
Non-service (benefit) cost	(28)	(22)
Net periodic benefit cost (benefit)	$ (28)	$ (22)