Postretirement benefits Components of net periodic benefit costs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	$ 1	$ 1	$ 2	$ 2
Non-service (benefit) cost	(54)	(52)	(109)	(103)
Net periodic benefit cost (benefit)	(53)	(51)	(107)	(101)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	0	0	0	0
Interest cost	1	0	1	0
Expected return on plan assets	(1)	0	(1)	0
Defined Benefit Plan, Amortization of Gain (Loss)	0	0	0	0
Amortization of prior service cost	0	(6)	0	(26)
Settlements	0	0	0	0
Non-service (benefit) cost	0	(6)	0	(26)
Net periodic benefit cost (benefit)	0	(6)	0	(26)
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	(5)	(4)	(10)	(9)
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	(1)	0	(3)
Administrative Expense | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	1	1	2	2
Non-service (benefit) cost	(49)	(48)	(99)	(94)
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	(5)	0	(23)
Foreign Plan [Member] | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	1	1	2	2
Interest cost	6	4	12	9
Expected return on plan assets	(11)	(11)	(22)	(22)
Defined Benefit Plan, Amortization of Gain (Loss)	0	1	0	2
Amortization of prior service cost	0	0	0	0
Settlements	0	0	0	0
Non-service (benefit) cost	(5)	(6)	(10)	(11)
Net periodic benefit cost (benefit)	(4)	(5)	(8)	(9)
UNITED STATES | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	0	0	0	0
Interest cost	22	17	43	35
Expected return on plan assets	(71)	(63)	(142)	(127)
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	(49)	(46)	(99)	(92)
Net periodic benefit cost (benefit)	$ (49)	$ (46)	$ (99)	$ (92)