INCOME TAXES - Summary of Current and Deferred Income Tax Provision (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current:
Federal	$ 0	$ 0	$ (730)
State	128	118	123
Foreign	559	277	507
Total current income tax provision	687	395	(100)
Deferred:
Federal	0	0	0
State	0	0	0
Foreign	(2,335)	262	353
Total deferred income tax provision	(2,335)	262	353
Income tax (benefit) expense	$ (1,648)	$ 657	$ 253