Postretirement benefits (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Oct. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Expenses recognized during period under the defined contributions plans	$ 150	$ 117	$ 119
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, benefits paid inclusive of settlements	213	29
Defined Benefit Plan, Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates [Abstract]
Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation	11
Effect of One Percentage Point Increase on Service and Interest Cost Components	1
Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation	9
Effect of One Percentage Point Decrease on Service and Interest Cost Components	$ 1
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Target Plan Asset Allocations Range Minimum	55.00%
Target Plan Asset Allocations Range Maximum	65.00%
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Accumulated Benefit Obligation	$ 3,800	$ 559
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year	27
Non-US [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Future Amortization of (Gain) Loss	3
UNITED STATES
Defined Benefit Plan, Plan Amendment [Abstract]
Effect of Plan Amendment on Accumulated Benefit Obligation				$ 496
UNITED STATES | Pension Plan [Member]
Defined Benefit Plan, Plan Amendment [Abstract]
Effect of Plan Amendment on Accumulated Benefit Obligation				113
UNITED STATES | Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Future Amortization of Prior Service (Cost) Credit	92
UNITED STATES | Postretirement Health Coverage [Member]
Defined Benefit Plan, Plan Amendment [Abstract]
Effect of Plan Amendment on Accumulated Benefit Obligation	$ 15			$ 383