SEGMENT AND GEOGRAPHIC INFORMATION - Summary of Long-Lived Assets by Geographic Region (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Total	$ 31,440	$ 32,118	$ 30,824
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total	22,634	21,913	20,037
China
Revenues from External Customers and Long-Lived Assets [Line Items]
Total	5,727	7,950	9,585
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Total	$ 3,079	$ 2,255	$ 1,202