Pension and Other Postretirement Benefits (Details 3) - Pension Plan [Member] - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation, related to pension plans with benefit obligations in excess of plan assets	$ 352,251	$ 450,673
Fair value of plan assets, related to pension plans with benefit obligations in excess of plan assets	293,292	370,616
Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation, related to pension plans with benefit obligations in excess of plan assets	311,320	389,613
Fair value of plan assets, related to pension plans with benefit obligations in excess of plan assets	267,087	331,260
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation, related to pension plans with benefit obligations in excess of plan assets	40,931	61,060
Fair value of plan assets, related to pension plans with benefit obligations in excess of plan assets	$ 26,205	$ 39,356