Postretirement benefits Schedule of assumptions used to determine benefit obligation (Details)	Dec. 31, 2016	Dec. 31, 2015
Pension Plan [Member] | UNITED STATES
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Benefit Obligation, Discount Rate	4.14%
Benefit Obligation, Rate of Compensation Increase	4.00%
Pension Plan [Member] | Non-US [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Benefit Obligation, Discount Rate	2.83%	3.61%
Benefit Obligation, Rate of Compensation Increase	3.57%	3.05%
Other Postretirement Benefit Plan [Member] | UNITED STATES
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Benefit Obligation, Discount Rate	2.86%
Other Postretirement Benefit Plan [Member] | Non-US [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Benefit Obligation, Discount Rate	3.73%