Postretirement benefits Schedule of Net Funded Status (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Plan [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Service Cost	$ 69	$ 80	$ 93
Pension Plan [Member] | UNITED STATES
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation, beginning of year	3,285	3,035
Service Cost	57	63	75
Interest Cost	105	105	103
Actuarial Loss (gain)	(214)	232
Defined Benefit Plan, Benefit Obligation, Benefits Paid	(108)	(132)
Amendments	0	0
Curtailments	0	0
Settlements, Benefit obligations	(33)	(18)
Foreign currency revaluation, benefit obligations	0	0
Benefit Obligation, end of year	3,092	3,285	3,035
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	3,109	2,765
Actual Return on Plan Assets	(218)	441
Employer Contributions	34	53
Benefits Paid	(108)	(132)
Settlements	(33)	(18)
Foreign currency revaluation, Plan Assets	0	0
Plan assets at fair value, end of year	2,784	3,109	2,765
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(308)	(176)
Pension Plan [Member] | Non-US [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation, beginning of year	1,077	1,025
Service Cost	12	17	18
Interest Cost	27	27	30
Actuarial Loss (gain)	(71)	(4)
Defined Benefit Plan, Benefit Obligation, Benefits Paid	(26)	(28)
Amendments	4	0
Curtailments	0	(32)
Settlements, Benefit obligations	(27)	(8)
Foreign currency revaluation, benefit obligations	(54)	80
Benefit Obligation, end of year	942	1,077	1,025
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	1,172	962
Actual Return on Plan Assets	(63)	100
Employer Contributions	14	63
Benefits Paid	(26)	(28)
Settlements	(27)	(8)
Foreign currency revaluation, Plan Assets	(62)	83
Plan assets at fair value, end of year	1,008	1,172	962
Defined Benefit Plan, Funded (Unfunded) Status of Plan	66	95
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation, beginning of year	137	165
Service Cost	1	2	10
Interest Cost	3	4	17
Actuarial Loss (gain)	(20)	(2)
Defined Benefit Plan, Benefit Obligation, Benefits Paid	(15)	(14)
Amendments	0	(23)
Curtailments	0	2
Settlements, Benefit obligations	0	0
Foreign currency revaluation, benefit obligations	7	3
Benefit Obligation, end of year	113	137	165
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	157	159
Actual Return on Plan Assets	1	6
Employer Contributions	0	6
Benefits Paid	(15)	(14)
Settlements	0	0
Foreign currency revaluation, Plan Assets	0	0
Plan assets at fair value, end of year	143	157	$ 159
Defined Benefit Plan, Funded (Unfunded) Status of Plan	$ 30	$ 20