Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Losses	$ 9,557	$ 9,985
Compensation related deductions	4,437	2,915
Tax credits	2,318	2,409
Restructuring related liabilities	471	294
Inventory	5,869	4,415
Depreciation		503
Amortization	3,082	3,205
Warranty	1,049	1,127
Other	1,688	1,281
Total deferred tax assets	28,471	26,134
Valuation allowance on deferred tax assets	(13,014)	(12,537)
Net deferred tax assets	15,457	13,597
Deferred tax liabilities:
Equity-method investment	(1,370)	(1,733)
Depreciation	(749)
Amortization	(4,162)	(2,791)
Unrealized currency gains/losses	(659)	(1,292)
Other	(1,218)	(345)
Total deferred tax liabilities	(8,158)	(6,161)
Net deferred income tax assets (liabilities)	$ 7,299	$ 7,436