INCOME TAXES - Provision for income taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current:
Federal	$ 5,778	$ 5,953	$ 3,960
State	913	707	415
Foreign	1,623	1,853	1,025
Current income tax expense	8,314	8,513	5,400
Deferred:
Federal	548	283	(238)
State	47	32	(28)
Foreign	(22)	(168)	41
Deferred income tax expense	573	147	(225)
Income tax expense	$ 8,887	$ 8,660	$ 5,175