Income Taxes (Schedule of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred Income Tax Sources
Inventories	$ 4,140	$ 330
Environmental costs	3,042	1,013
Accrued liabilities	7,012	4,927
Post-retirement and post-employment employee benefits	1,510	896
Net operating loss carryforwards	18,428	29,544
Pension liabilities	96,982	98,556
Impairments of long-lived assets	3,245	0
Minimum tax credit carryforwards	3,146	7,356
R&D state credit carryforwards	1,172	0
Miscellaneous / Other items, net	9,137	7,009
Deferred income tax assets before valuation allowance	147,814	149,631
Valuation allowance	(5,815)	(4,267)
Deferred income tax assets	141,999	145,364
Property, plant and equipment	(14,717)	(15,112)
Intangible assets	(31,822)	(9,847)
Undistributed foreign earnings	(181)	(256)
Other items, net	(373)	0
Deferred tax liabilities (foreign amounts principally related to long-lived assets	(47,093)	(25,215)
Net deferred income tax assets	94,906	120,149
Foreign:
Deferred income tax liabilities, net	(2,826)	(402)
Foreign Tax Authority
Deferred Income Tax Sources
Inventories	35	0
Miscellaneous / Other items, net	25	0
Valuation allowance	(2,487)	(1,340)
Deferred tax liabilities (foreign amounts principally related to long-lived assets	(3,008)	(402)
Foreign:
Trade receivables	18	0
Net operating loss carryforwards	2,591	1,340
Foreign deferred income tax assets	182	0
Deferred income tax liabilities, net	$ (2,826)	$ (402)