Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Losses	$ 9,407	$ 9,557
Compensation related deductions	3,687	4,437
Tax credits	2,594	2,318
Unrealized currency gains/losses	183
Restructuring related liabilities	172	471
Inventory	3,400	5,869
Amortization		3,082
Warranty	768	1,049
Other		1,688
Total deferred tax assets	20,211	28,471
Valuation allowance on deferred tax assets	(12,811)	(13,014)
Net deferred tax assets	7,400	15,457
Deferred tax liabilities:
Equity-method investment		(1,370)
Depreciation	(1,353)	(749)
Amortization	(23,496)	(4,162)
Unrealized currency gains/losses		(659)
Other	(1,171)	(1,218)
Total deferred tax liabilities	(26,020)	(8,158)
Net deferred income tax (liabilities)	$ (18,620)
Net deferred income tax assets		$ 7,299