Income Taxes (Deferred Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Deferred employee benefits	$ 46,539	$ 82,836
Inventories	5,528	9,694
Tax loss and credit carryforwards	20,813	19,216
Accrued liabilities and other items	7,031	12,433
Total deferred tax assets	79,911	124,179
Deferred tax liabilities:
Property, plant and equipment	(10,756)	(15,653)
Intangibles	(40,258)	(48,785)
Other items	(4,020)	(3,100)
Total deferred tax liabilities	(55,034)	(67,538)
Net deferred tax assets before valuation allowance	24,877	56,641
Valuation allowance	(5,298)	(4,143)
Net deferred tax assets after valuation allowance	19,579	52,498
Change in valuation allowance	1,200
Pre-tax income (loss) from foreign operations	700	$ (5,000)	$ (4,300)
Undistributed earnings from foreign subsidiaries	23,200
Delamac
Deferred tax liabilities:
Net deferred tax assets	$ 1,600