Postemployment benefit plans (Details A 1) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Change in benefit obligation:
Actuarial losses (gains)	$ (833)	$ 383	$ 468
Components of net amount recognized in financial position:
Liability, Pension and Other Postretirement and Postemployment Benefits, Noncurrent	$ (5,592)	$ (6,872)
U.S. pensions
Weighted-average assumptions used to determine benefit obligation, end of year:
Discount rate (as a percent)	2.80%	2.40%
Rate of compensation increase (as a percent)	0.00%	0.00%
Accumulated benefit obligation, end of year	$ 17,895	$ 19,177
Change in benefit obligation:
Benefit obligation, beginning of year	19,177	17,773
Service cost	0	0	115
Interest cost	330	483	600
Plan amendments	0	0
Actuarial losses (gains)	(610)	1,922
Foreign currency exchange rates	0	0
Participant contributions	0	0
Benefits paid - gross	(996)	(997)
Less: federal subsidy on benefits paid	0	0
Curtailments, settlements and termination benefits	(6)	(4)
Benefit obligation, end of year	17,895	19,177	17,773
Change in plan assets:
Fair value of plan assets, beginning of year	17,589	15,994
Actual return on plan assets	595	2,552
Foreign currency exchange rates	0	0
Company contributions	45	44
Participant contributions	0	0
Benefits paid	(996)	(997)
Settlements and termination benefits	(6)	(4)
Fair value of plan assets, end of year	17,227	17,589	15,994
Funded Status, end of year
Over (under) funded status	(668)	(1,588)
Components of net amount recognized in financial position:
Other assets (non-current asset)	592	409
Accrued wages, salaries and employee benefits (current liability)	(45)	(44)
Liability for postemployment benefits (non-current liability)	(1,215)	(1,953)
Net liability recognized	(668)	(1,588)
Amounts recognized in Accumulated other comprehensive income (pre-tax) consist of:
Prior service cost (credit)	$ 0	$ 0
Non-U.S. pensions
Weighted-average assumptions used to determine benefit obligation, end of year:
Discount rate (as a percent)	1.80%	1.40%
Rate of compensation increase (as a percent)	2.00%	2.00%
Accumulated benefit obligation, end of year	$ 4,311	$ 4,680
Change in benefit obligation:
Benefit obligation, beginning of year	4,847	4,666
Service cost	57	55	80
Interest cost	53	68	94
Plan amendments	0	6
Actuarial losses (gains)	(142)	258
Foreign currency exchange rates	(154)	213
Participant contributions	4	4
Benefits paid - gross	(184)	(159)
Less: federal subsidy on benefits paid	0	0
Curtailments, settlements and termination benefits	(45)	(264)
Benefit obligation, end of year	4,436	4,847	4,666
Change in plan assets:
Fair value of plan assets, beginning of year	4,731	4,525
Actual return on plan assets	99	385
Foreign currency exchange rates	(139)	164
Company contributions	84	76
Participant contributions	4	4
Benefits paid	(184)	(159)
Settlements and termination benefits	(43)	(264)
Fair value of plan assets, end of year	4,552	4,731	4,525
Funded Status, end of year
Over (under) funded status	116	(116)
Components of net amount recognized in financial position:
Other assets (non-current asset)	538	556
Accrued wages, salaries and employee benefits (current liability)	(16)	(25)
Liability for postemployment benefits (non-current liability)	(406)	(647)
Net liability recognized	116	(116)
Amounts recognized in Accumulated other comprehensive income (pre-tax) consist of:
Prior service cost (credit)	$ 23	$ 24
Other postretirement benefits
Weighted-average assumptions used to determine benefit obligation, end of year:
Discount rate (as a percent)	2.70%	2.30%
Rate of compensation increase (as a percent)	4.00%	4.00%
Change in benefit obligation:
Benefit obligation, beginning of year	$ 4,051	$ 3,960
Service cost	100	94	80
Interest cost	64	103	136
Plan amendments	0	(8)
Actuarial losses (gains)	(211)	192
Foreign currency exchange rates	(15)	(25)
Participant contributions	48	44
Benefits paid - gross	(310)	(317)
Less: federal subsidy on benefits paid	9	8
Curtailments, settlements and termination benefits	0	0
Benefit obligation, end of year	3,736	4,051	3,960
Change in plan assets:
Fair value of plan assets, beginning of year	147	255
Actual return on plan assets	34	23
Foreign currency exchange rates	0	0
Company contributions	211	142
Participant contributions	48	44
Benefits paid	(310)	(317)
Settlements and termination benefits	0	0
Fair value of plan assets, end of year	130	147	$ 255
Funded Status, end of year
Over (under) funded status	(3,606)	(3,904)
Components of net amount recognized in financial position:
Other assets (non-current asset)	0	0
Accrued wages, salaries and employee benefits (current liability)	(240)	(186)
Liability for postemployment benefits (non-current liability)	(3,366)	(3,718)
Net liability recognized	(3,606)	(3,904)
Liability, Pension and Other Postretirement and Postemployment Benefits, Noncurrent	(67)	(63)
Amounts recognized in Accumulated other comprehensive income (pre-tax) consist of:
Prior service cost (credit)	(5)	(46)
Defined contribution
Components of net amount recognized in financial position:
Liability, Pension and Other Postretirement and Postemployment Benefits, Noncurrent	$ (538)	$ (491)