EMPLOYEE BENEFIT PLAN - (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Percent of employees gross pay eligible for matching	100.00%
Percentage of first elective contributions	6.00%
Discretionary contribution amount	$ 0.8	$ 0.9	$ 0.6

Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

No definition available.

Name:	us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration