INCOME TAXES - Components of Income Tax Expense (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal									$ 1,551	$ 355	$ 86
State and local									145	112	45
Foreign									76	(176)	222
Total current provision									1,772	291	353
Deferred:
Federal									215	(50)	(79)
State and local									5	6	0
Foreign									(38)	21	312
Total deferred provision									182	(23)	233
Total provision for income taxes	$ 369	$ 909	$ 464	$ 212	$ 73	$ 83	$ 178	$ (66)	$ 1,954	$ 268	$ 586