STOCK-BASED COMPENSATION AND EMPLOYEE BENEFIT PLANS - Defined Contribution 401(k) Profit Sharing Plan (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) hour	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Defined contribution plan, eligibility, hours of service (in hours) | hour	1,000
Defined Contribution 401(k) Profit Sharing Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Defined contribution plan, employer matching contribution, percent of employees' gross pay	5.00%
Defined contribution plan, cost | $	$ 2.7	$ 2.5	$ 2.2