Pension, Post-Retirement and Post-Employment Plans - Key Assumptions Used to Determine Benefit Obligations (Details)	Dec. 31, 2017	Dec. 31, 2016
Pension Plan and SERP | Domestic
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	3.70%	4.20%
Rate of compensation increase	3.50%	3.50%
Pension Plan and SERP | Foreign
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	3.00%	2.30%
Rate of compensation increase	3.40%	3.00%
Post-retirement Medical Benefits | Domestic
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	3.70%	4.20%
Post-retirement Medical Benefits | Foreign
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	9.90%	12.20%