GEOGRAPHIC AND CUSTOMER CONCENTRATION INFORMATION - Summary of Net Revenue by Geographic Areas Based on the Installation Locations of the Systems and the Location of Services Rendered (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 27, 2015	Jun. 28, 2015	Mar. 29, 2015	Dec. 31, 2014	Sep. 28, 2014	Jun. 29, 2014	Mar. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue	$ 32,049	$ 38,894	$ 43,334	$ 58,254	$ 54,747	$ 38,430	$ 42,029	$ 43,198	$ 172,532	$ 178,404	$ 119,434
Geographic concentration risk | Net revenue
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk percentage									100.00%	100.00%	100.00%
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue									$ 25,061	$ 25,716	$ 12,350
United States | Geographic concentration risk | Net revenue
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk percentage									15.00%	14.00%	10.00%
Korea
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue									$ 73,798	$ 87,585	$ 22,173
Korea | Geographic concentration risk | Net revenue
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk percentage									43.00%	49.00%	19.00%
Taiwan
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue									$ 17,537	$ 32,304	$ 50,782
Taiwan | Geographic concentration risk | Net revenue
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk percentage									10.00%	18.00%	43.00%
China
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue									$ 29,209	$ 17,369	$ 20,250
China | Geographic concentration risk | Net revenue
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk percentage									17.00%	10.00%	17.00%
Other Asia
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue									$ 19,560	$ 6,869	$ 8,740
Other Asia | Geographic concentration risk | Net revenue
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk percentage									11.00%	4.00%	7.00%
Europe and others
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue									$ 7,367	$ 8,561	$ 5,139
Europe and others | Geographic concentration risk | Net revenue
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk percentage									4.00%	5.00%	4.00%