Retirement Benefit Plans - Assumptions Used (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
United States | Pension Plan [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Assumptions used calculating benefit obligation, discount rate	3.55%	3.94%
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Assumptions used calculating net periodic benefit cost, discount rate	3.94%	4.15%	3.89%
Assumptions used calculating net periodic benefit cost, expected long-term return on assets	6.01%	6.70%	6.71%
United States | U.S. other postretirement benefit plans [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Assumptions used calculating benefit obligation, discount rate	3.32%	3.61%
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Assumptions used calculating net periodic benefit cost, discount rate	3.61%	3.84%	3.50%
Non-US [Member] | Pension Plan [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Assumptions used calculating benefit obligation, discount rate	2.25%	2.25%
Assumptions used calculating benefit obligation, rate of compensation increase	2.98%	3.00%
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Assumptions used calculating net periodic benefit cost, discount rate	2.25%	2.99%	2.84%
Assumptions used calculating net periodic benefit cost, rate of compensation increase	3.00%	3.01%	2.84%
Assumptions used calculating net periodic benefit cost, expected long-term return on assets	5.68%	6.41%	6.53%