EMPLOYEE BENEFIT PLANS - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Contribution Plan Disclosure [Line Items]
Employee benefit plan expenses	$ 2,213	$ 2,053	$ 1,430
Profit Sharing Plan
Defined Contribution Plan Disclosure [Line Items]
Minimum term employees required to work to be eligible in plan	30 days
Minimum age eligibility of employee	18 years