CONCENTRATION OF RISK - Revenues by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Concentration Risk [Line Items]
Revenues	$ 30,214	$ 39,419	$ 124,309	$ 128,734
South Korea [Member]
Concentration Risk [Line Items]
Revenues	24,852	34,514	111,994	110,547
China [Member]
Concentration Risk [Line Items]
Revenues	2,095	843	5,663	1,523
Japan [Member]
Concentration Risk [Line Items]
Revenues	1,230	3,274	3,334	13,931
Other Non-U.S. Locations [Member]
Concentration Risk [Line Items]
Revenues	396	523	1,416	1,726
Total Non-U.S. Locations [Member]
Concentration Risk [Line Items]
Revenues	28,573	39,154	122,407	127,727
UNITED STATES
Concentration Risk [Line Items]
Revenues	$ 1,641	$ 265	$ 1,902	$ 1,007