Income Taxes Schedule of Current and Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost	$ 1,295	$ 2,281
Deferred Tax Assets, Operating Loss Carryforwards	40,572	36,145
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Pensions	3,363	2,338
Deferred Tax Assets, Inventory	841	3,031
Deferred Tax Assets, Deferred Income	4,519	11,998
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Employee Bonuses	1,112	1,908
Deferred Tax Assets, Other	2,118	3,624
Deferred Tax Assets, Gross	53,820	61,325
Deferred Tax Assets, Valuation Allowance	(32,267)	(26,120)
Deferred Tax Assets, Net of Valuation Allowance	21,553	35,205
Deferred Tax Liabilities, Property, Plant and Equipment	2,605	2,266
Deferred Tax Liabilities, Foreign Other	3,448	1,538
Deferred Tax Liabilities, Other	62	212
Deferred Tax Liabilities, Net	6,115	4,016
Deferred Tax Assets, Net of Valuation Allowance, Noncurrent	18,841	32,197
Deferred Tax Assets, Net	$ 15,438	$ 31,189