Pension and Other Postretirement Benefits (Details 4) - Pensions [Member] - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets [Abstract]
Accumulated benefit obligation	$ 392,515	$ 375,201
Fair value of plan assets	333,913	313,461
U.S. [Member]
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets [Abstract]
Accumulated benefit obligation	340,158	322,999
Fair value of plan assets	298,966	282,213
Foreign Plan [Member]
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets [Abstract]
Accumulated benefit obligation	52,357	52,202
Fair value of plan assets	$ 34,947	$ 31,248