Postretirement benefits Schedule of Health Care Cost Trend Rates (Details) - Other Postretirement Benefits Plan [Member]	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
UNITED STATES
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]
Health Care Cost Trend Rate	7.01%	7.28%	6.50%
Ultimate Health Care Cost Trend Rate	4.50%	4.50%	4.50%
Year that Rate Reaches Ultimate Trend Rate	2038	2038	2026
Non-US [Member]
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]
Health Care Cost Trend Rate	6.61%	6.61%
Ultimate Health Care Cost Trend Rate	4.50%	4.50%
Year that Rate Reaches Ultimate Trend Rate	2029	2029