Income Taxes - Tax Effects (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income (loss) before income taxes
United States	$ 12,708	$ (11,987)	$ (18,998)
Foreign	2,497	1,820	2,894
Income (loss) before income taxes	15,205	(10,167)	(16,104)
Current:
State	(33)	59	84
Foreign	374	780	641
Total current	341	839	725
Deferred:
Foreign	186	260	315
Total deferred	186	260	315
Income tax provision	527	1,099	1,040
Reconciliations of income taxes at the United States Federal statutory rate to the effective income tax rate
Income tax benefit at the United States statutory rate	5,322	(3,558)	(5,636)
State income taxes	(22)	38	55
Unrecognized tax benefits	(174)	184	(293)
Effect of change in valuation allowance	(5,676)	(6,835)	5,975
Foreign income tax rate differentials	600	259	(1,244)
Unremitted earnings of foreign subsidiaries	(102)	(758)	961
Stock options	379	686	450
Deemed distribution from foreign subsidiaries		607	316
Discrete items, net	(540)	9,143
Other, net	740	1,333	456
Income tax provision	527	1,099	$ 1,040
Significant components of current deferred income taxes
Accrued compensation	1,082	65
Inventories	2,541	9,808
Warranty	1,214	486
Other	1,237	1,620
Deferred taxes, gross	6,074	11,979
Valuation allowance	(6,335)	(10,975)
Deferred taxes, net	(261)	1,004
Significant components of long-term deferred income taxes
Federal net operating loss carryforwards	101,479	105,119
State net operating loss carryforwards	1,636	2,210
Foreign net operating loss carryforwards	810	1,280
Unremitted earnings of foreign subsidiaries	(8,632)	(8,800)
Intangible assets	286	383
Property, plant and equipment	9,331	4,548
Stock compensation	6,001	5,198
Other	(3,945)	(2,328)
Deferred taxes, gross	127,273	129,572
Valuation allowance	(125,928)	(128,982)
Deferred taxes, net	1,345	590
Deferred tax assets	124,200
United States
Tax credit carryforwards
Tax credit carryforwards	16,343	16,669
State
Tax credit carryforwards
Tax credit carryforwards	$ 3,964	$ 5,293