Income Taxes (Components of Deferred Income Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Deferred income tax assets:
Pension	$ 9,644	$ 12,317
Non-pension postretirement benefits	21,751	24,326
Other accrued liabilities	20,432	18,726
Receivables	2,341	1,798
Net operating loss and charitable contribution carry forwards	25,754	33,531
Tax credits	10,245	10,320
Total deferred income tax assets	90,167	101,018
Deferred income tax liabilities:
Property, plant and equipment	22,882	20,986
Inventories	2,378	5,037
Intangibles and other	7,883	7,581
Total deferred income tax liabilities	33,143	33,604
Net deferred income tax asset (liability):
Net deferred income tax asset before valuation allowance	57,024	67,414
Valuation allowance	(11,184)	(66,486)	$ (46,048)	$ (77,629)
Net deferred income tax asset (liability)	$ 45,840	$ 928