Commitments and Contingencies (Textuals) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Apr. 03, 2020	Dec. 31, 2018	Jan. 15, 2018	Aug. 31, 2008
Accruals and Payable and Other Long Term Liabilities
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	$ 6,049	$ 6,078		$ 5,531
Accrual for environmental loss contingencies, payments	165	569
Net additions to accrual	141	1,122
New Hartford
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	2,300
Accrual for environmental loss contingencies, payments	1,700
Accrual for payments due to customer under agreement	600
New Hartford | Liabilities, Other Accruals and Payables
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	100
Bloomfield
Loss Contingencies [Line Items]
Environmental liability, discounted amount						$ 10,300
Undiscounted estimated remediation liability	6,305					$ 20,800
Discount rate						8.00%
Accrual for environmental loss contingencies						$ 10,300
Accrual for environmental loss contingencies, payments	14,500
Accrual for payments due to customer under agreement	2,300
Bloomfield | Liabilities, Other Accruals and Payables
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	700
Offset Agreement [Member]
Loss Contingencies [Line Items]
Notional Amount of Nonderivative Instruments	$ 194,000
Notional Value of Contract, Percent	60.00%
Contractual Obligation					$ 324,000
Loss Contingency, Estimate of Possible Loss	$ 16,500
Contract with Customer, Liability	11,000
Employee-Related Tax Matter [Member]
Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss	0	$ 2,500	$ 1,300
Loss Contingency Accrual, Payments	700
Pension Costs [Member]
Loss Contingencies [Line Items]
Accrual for payments due to customer under agreement	$ 300