Pension Plans Weighted Average Assumptions Used to Determine Benefit Obligations (Details) |
Dec. 31, 2017 |
Dec. 31, 2016 |
|---|---|---|
| United States Pension Plan of US Entity [Member] | ||
| Defined Benefit Plan Disclosure [Line Items] | ||
| Discount rate | 3.73% | |
| Foreign Pension Plan [Member] | ||
| Defined Benefit Plan Disclosure [Line Items] | ||
| Discount rate | 1.96% | 1.91% |
| Rate of compensation increase | 2.31% | 2.89% |