Employee Benefits Plans (Details 4)	Dec. 31, 2017	Dec. 31, 2016
United States
Summary of weighted-average actuarial assumptions used in determining funded status
Discount rate	3.70%	4.20%
Rate of increase in compensation levels	3.00%	3.00%
Foreign Plan
Summary of weighted-average actuarial assumptions used in determining funded status
Discount rate	2.70%	3.90%
Rate of increase in compensation levels	3.10%	3.10%