SEGMENT INFORMATION (Details 2) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	$ 83,853				$ 90,270				$ 83,853	$ 90,270	$ 96,663
Sales	90,175	$ 84,991	$ 78,197	$ 64,557	86,794	$ 67,211	$ 70,186	$ 67,822	317,920	292,013	315,249
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	33,101				35,166				33,101	35,166	37,607
Sales									90,783	87,122	103,650
Other North America
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	0				0				0	0	0
Sales									9,165	5,546	4,820
North America
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	33,101				35,166				33,101	35,166	37,607
Sales									99,948	92,668	108,470
England
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	180				340				180	340	555
Sales									6,733	7,925	12,780
Germany
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	1,333				1,333				1,333	1,333	1,388
Sales									34,712	38,573	34,830
FRANCE
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	100				79				100	79	74
Sales									9,433	10,201	9,397
ITALY
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	0				0				0	0	0
Sales									6,694	4,729	5,159
Switzerland
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	22,529				28,025				22,529	28,025	30,322
Sales									5,927	5,211	7,613
Other Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	0				0				0	0	0
Sales									27,830	24,743	27,490
Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	24,142				29,777				24,142	29,777	32,339
Sales									91,329	91,382	97,269
China
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	9,345				9,242				9,345	9,242	10,515
Sales									101,719	94,816	92,727
Taiwan
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	14,645				13,534				14,645	13,534	13,453
Sales									6,605	2,957	3,772
INDIA
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	2,620				2,551				2,620	2,551	2,749
Sales									5,030	3,722	4,356
Other Asia
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	0				0				0	0	0
Sales									13,289	6,468	8,655
Asia
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	$ 26,610				$ 25,327				26,610	25,327	26,717
Sales									$ 126,643	$ 107,963	$ 109,510