Pension and Other Postretirement Benefits (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Contribution expense	$ 5,301	$ 6,874	$ 6,921
Pensions [Member]
Defined Benefit Plan Disclosure [Line Items]
Total accumulated benefit obligation	545,918	511,977
Estimated future employer contributions in next fiscal year	4,692
Curtailment gain (loss)	(484)	0	0
Settlement gain (loss)	(549)	(340)	0
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Curtailment gain (loss)	0	0	0
Settlement gain (loss)	$ 0	$ 0	$ 0
Health care cost trend rate assumed	5.70%	6.24%
Ultimate health care cost trend rate	4.50%
Equity Securities [Member] | Pensions [Member]
Defined Benefit Plan Disclosure [Line Items]
The weighted-average target investment allocations in equity securities	65.00%
Fixed Income Securities [Member] | Pensions [Member]
Defined Benefit Plan Disclosure [Line Items]
The weighted-average target investment allocations in equity securities	35.00%