EMPLOYEE BENEFIT PLANS - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Retirement Benefits [Abstract]
Service period, minimum	3 months
Employees eligible age under plan, minimum	21 years
Maximum annual contribution per employee	100.00%
Vesting period of employer's matching contributions	5 years
Contributions by employer	$ 300	$ 400
Expected employer's contributions in 2018	$ 24