Postretirement benefits Components of net periodic benefit costs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	$ 2	$ 1	$ 4	$ 2
Non-service (benefit) cost	(26)	(54)	(51)	(109)
Net periodic benefit cost (benefit)	(24)	(53)	(47)	(107)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	0	0	0	0
Interest cost	1	1	1	1
Expected return on plan assets	(1)	(1)	(2)	(1)
Defined Benefit Plan, Amortization of Gain (Loss)	0	0	0	0
Amortization of prior service cost	0	0	0	0
Settlements	0	0	0	0
Non-service (benefit) cost	0	0	(1)	0
Net periodic benefit cost (benefit)	0	0	(1)	0
Losses and loss expenses | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	0	0	0	0
Non-service (benefit) cost	(3)	(5)	(5)	(10)
Losses and loss expenses | Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	0	0	0	0
Non-service (benefit) cost	0	0	0	0
Administrative Expense | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	2	1	4	2
Non-service (benefit) cost	(23)	(49)	(46)	(99)
Administrative Expense | Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	0	0	0	0
Non-service (benefit) cost	0	0	(1)	0
Foreign Plan [Member] | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	2	1	4	2
Interest cost	9	6	18	12
Expected return on plan assets	(13)	(11)	(25)	(22)
Defined Benefit Plan, Amortization of Gain (Loss)	0	0	0	0
Amortization of prior service cost	0	0	0	0
Settlements	0	0	0	0
Non-service (benefit) cost	(4)	(5)	(7)	(10)
Net periodic benefit cost (benefit)	(2)	(4)	(3)	(8)
UNITED STATES | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	0	0	0	0
Interest cost	34	22	68	43
Expected return on plan assets	(56)	(71)	(112)	(142)
Defined Benefit Plan, Amortization of Gain (Loss)	0	0	0	0
Amortization of prior service cost	0	0	0	0
Settlements	0	0	0	0
Non-service (benefit) cost	(22)	(49)	(44)	(99)
Net periodic benefit cost (benefit)	$ (22)	$ (49)	$ (44)	$ (99)