Income Taxes (Deferred Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, Not Subject to Expiration	$ 24,300
Deferred tax assets:
Deferred employee benefits	30,701	$ 36,678
Tax loss and credit carryforwards	33,065	19,449
Accrued liabilities and other items	17,420	14,044
Total deferred tax assets	81,186	70,171
Deferred tax liabilities:
Property, plant and equipment	(5,379)	(6,410)
Intangibles	(32,398)	(27,147)
Other items	(765)	(226)
Deferred Tax Liabilities, Gross	38,542	33,783
Net Deferred Tax Assets Before Valuation Allowance	42,644	36,388
Valuation allowance	(10,216)	(8,142)
Net deferred tax assets after valuation allowance	32,428	28,246
Pre-tax income (loss) from foreign operations	$ 36,900	$ 4,000	$ (27,100)