Pension and Postretirement Benefit Plans - Significant Weighted Average Assumptions Used in Measurement of Pension Obligations (Details) - Pension Plan [Member]	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
UNITED STATES
Pension benefit obligations:
Discount rate	3.55%	3.92%	4.13%
Net periodic benefit cost:
Discount rate	3.24%	3.29%	3.81%
Expected return on plan assets	6.00%	6.50%	7.00%
Foreign Plan [Member]
Pension benefit obligations:
Discount rate	2.25%	2.48%	2.83%
Net periodic benefit cost:
Discount rate	2.34%	2.56%	3.75%
Rate of compensation increase	3.33%	3.12%	4.83%
Expected return on plan assets	5.92%	5.42%	5.87%