Postretirement benefits Components of net periodic benefit costs (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	$ 2	$ 1
Non-service (benefit) cost	(25)	(55)
Net periodic benefit cost (benefit)	(23)	(54)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	0	0
Interest cost	0	0
Expected return on plan assets	(1)	0
Defined Benefit Plan, Amortization of Gain (Loss)	0	0
Amortization of prior service cost	0	0
Settlements	0	0
Non-service (benefit) cost	(1)	0
Net periodic benefit cost (benefit)	(1)	0
Losses and loss expenses | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	0	0
Non-service (benefit) cost	(2)	(5)
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	1
Non-service (benefit) cost	(23)	(50)
Administrative Expense | Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	0	0
Non-service (benefit) cost	(1)	0
Foreign Plan [Member] | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	2	1
Interest cost	9	6
Expected return on plan assets	(12)	(11)
Defined Benefit Plan, Amortization of Gain (Loss)	0	0
Amortization of prior service cost	0	0
Settlements	0	0
Non-service (benefit) cost	(3)	(5)
Net periodic benefit cost (benefit)	(1)	(4)
UNITED STATES | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	0	0
Interest cost	34	21
Expected return on plan assets	(56)	(71)
Defined Benefit Plan, Amortization of Gain (Loss)	0	0
Amortization of prior service cost	0	0
Settlements	0	0
Non-service (benefit) cost	(22)	(50)
Net periodic benefit cost (benefit)	$ (22)	$ (50)