GEOGRAPHIC AND CUSTOMER CONCENTRATION INFORMATION - Summary of Geographic Information Relating to Property and Equipment (Details) - USD ($) $ in Thousands	Jun. 28, 2015	Dec. 31, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	$ 9,587	$ 7,534
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	4,294	4,140
Germany
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	5,099	3,185
Others
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	$ 194	$ 209