Pension Plans Weighted Average Assumptions Used to Determine Net Periodic Pension Cost (Details) |
12 Months Ended | |
|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
|
| United States Pension Plan of US Entity [Member] | ||
| Defined Benefit Plan Disclosure [Line Items] | ||
| Discount rate | 3.83% | |
| Expected long-term return on plan assets | 5.75% | |
| Foreign Pension Plan [Member] | ||
| Defined Benefit Plan Disclosure [Line Items] | ||
| Discount rate | 1.91% | 2.63% |
| Expected long-term return on plan assets | 3.58% | 4.19% |
| Rate of compensation increase | 2.89% | 2.77% |