Pension and Other Postretirement Benefits (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Contribution expense	$ 6,874	$ 6,921	$ 6,644
Retirement Savings Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Annual retirement contribution percent	4.00%
Pensions [Member]
Defined Benefit Plan Disclosure [Line Items]
Total accumulated benefit obligation	$ 511,977	457,539
Estimated future employer contributions in next fiscal year	4,399
Curtailment gain	0	0	7,217
Estimated net actuarial loss for the defined benefit pension plans that will be amortized from accumulated other non-owner changes to equity into net periodic benefit cost in 2017	13,712
Estimated prior service cost for the defined benefit pension plans that will be amortized from accumulated other non-owner changes to equity into net periodic benefit cost (credit) in 2017	307
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Curtailment gain	0	$ 0	0
Estimated net actuarial loss for the defined benefit pension plans that will be amortized from accumulated other non-owner changes to equity into net periodic benefit cost in 2017	27
Estimated prior service cost for the defined benefit pension plans that will be amortized from accumulated other non-owner changes to equity into net periodic benefit cost (credit) in 2017	$ 88
Health care cost trend rate assumed	6.78%	7.30%
Ultimate health care cost trend rate	4.50%
Facility Closing [Member]
Defined Benefit Plan Disclosure [Line Items]
Curtailment gain		$ 7,217	7,217
Facility Closing [Member] | Pensions [Member]
Defined Benefit Plan Disclosure [Line Items]
Curtailment gain			$ 7,217
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%