Income Taxes (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income (loss) before income taxes
United States	$ (11,987,000)	$ (18,998,000)	$ (37,682,000)
Foreign	1,820,000	2,894,000	5,294,000
Loss before income taxes	(10,167,000)	(16,104,000)	(32,388,000)
Current:
State	59,000	84,000	82,000
Foreign	780,000	641,000	738,000
Total current	839,000	725,000	820,000
Deferred:
Foreign	260,000	315,000	826,000
Total deferred	260,000	315,000	826,000
Income tax provision	1,099,000	1,040,000	1,646,000
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	(3,558,000)	(5,636,000)	(11,336,000)
State income taxes	38,000	55,000	53,000
Unrecognized tax benefits	184,000	(293,000)	(832,000)
Effect of change in valuation allowance	(6,835,000)	5,975,000	12,662,000
Foreign income tax rate differentials	259,000	(1,244,000)	(788,000)
Unremitted earnings of foreign subsidiaries	(758,000)	961,000
Foreign dividend			383,000
Stock options	686,000	450,000	1,298,000
Deemed distribution from foreign subsidiaries	607,000	316,000	149,000
Discrete items, net	9,143,000
Other, net	1,333,000	456,000	57,000
Income tax provision	1,099,000	1,040,000	1,646,000
Significant components of current deferred income taxes
Accrued compensation	65,000	43,000
Inventories	9,808,000	16,540,000
Warranty	486,000	591,000
Other	1,620,000	2,671,000
Deferred taxes, gross	11,979,000	19,845,000
Valuation allowance	(10,975,000)	(18,059,000)
Deferred taxes, net	1,004,000	1,786,000
Significant components of long-term deferred income taxes
Federal net operating loss carryforwards	105,119,000	104,370,000
State net operating loss carryforwards	2,210,000	2,250,000
Foreign net operating loss carryforwards	1,280,000	1,421,000
Unremitted earnings of foreign subsidiaries	(8,800,000)	(9,661,000)
Intangible assets	383,000	532,000
Property, plant and equipment	4,548,000	4,796,000
Stock compensation	5,198,000	4,896,000
Warranty		(56,000)
Other	(2,328,000)	(2,406,000)
Deferred taxes, gross	129,572,000	129,499,000
Valuation allowance	(128,982,000)	(129,409,000)
Deferred taxes, net	590,000	90,000
Deferred tax assets	141,600,000
United States
Tax credit carryforwards
Tax credit carryforwards	16,669,000	17,814,000
State
Tax credit carryforwards
Tax credit carryforwards	$ 5,293,000	$ 5,543,000