Income Taxes (Schedule of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Line Items]
Tax loss carryforwards	$ 23,400	$ 27,800
Unrepatriated foreign earnings	5,800
Domestic Tax Authority [Member]
Income Tax Disclosure [Line Items]
Total deferred tax assets	70,431	99,481
Total deferred tax liabilities	25,334	54,112
Net deferred tax asset	45,097	45,369
Non-U.S. [Member]
Income Tax Disclosure [Line Items]
Total deferred tax assets	16,575	15,205
Total deferred tax liabilities	2,597	6,774
Net deferred tax asset	13,978	12,308
Noncurrent Assets [Member] | Domestic Tax Authority [Member]
Income Tax Disclosure [Line Items]
Accounts receivable	557	1,155
Inventories	1,109	1,193
Deferred compensation	3,300	7,533
Depreciation and amortization		2,786
Postretirement benefits	18,286	26,602
Tax loss carryforwards	1,368	1,760
Tax credit carryforwards	41,920	50,624
Other	3,891	7,828
Deferred tax assets before valuation allowance	70,431	99,481
Less: valuation allowance
Total deferred tax assets	70,431	99,481
Noncurrent Assets [Member] | Non-U.S. [Member]
Income Tax Disclosure [Line Items]
Accounts receivable	1,341	1,381
Inventories	961	1,868
Deferred compensation	1,362
Depreciation and amortization	3,211	2,564
Postretirement benefits	1,464	2,067
Tax loss carryforwards	22,639	26,084
Tax credit carryforwards	1,654	1,186
Other		2,876
Deferred tax assets before valuation allowance	32,632	38,026
Less: valuation allowance	(16,057)	(22,821)
Total deferred tax assets	16,575	15,205
Noncurrent Liabilities [Member] | Domestic Tax Authority [Member]
Income Tax Disclosure [Line Items]
Unrepatriated foreign earnings	914	1,602
Depreciation and amortization	20,170	43,156
Deferred Gain	4,169	7,156
Other	81	2,198
Total deferred tax liabilities	25,334	54,112
Noncurrent Liabilities [Member] | Non-U.S. [Member]
Income Tax Disclosure [Line Items]
Unrepatriated foreign earnings
Depreciation and amortization
Deferred Gain
Other	2,597	2,897
Total deferred tax liabilities	$ 2,597	$ 2,897