EQUITY-BASED COMPENSATION - Equity Options Changed During Period (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Equity Options
Granted (in shares)	0	0
Equity options
Equity Options
Beginning balance (in shares)	3,797,319
Forfeited (in shares)	(22,437)
Expired (in shares)	(255,723)
Ending balance (in shares)	3,519,159	3,797,319
Ending balance, exercisable (in shares)	3,515,784
Nonvested at end of period (in shares)	3,375
Weighted-average Grant Date Value
Beginning balance (in dollars per share)	$ 8.19
Forfeited (in dollars per share)	8.42
Expired (in dollars per share)	2.81
Ending balance (in dollars per share)	8.58	$ 8.19
Ending balance, exercisable	8.58
Weighted-average Exercise Price
Beginning balance (in dollars per share)	15.95
Forfeited (in dollars per share)	18.52
Expired (in dollars per share)	13.47
Ending balance (in dollars per share)	16.11	$ 15.95
Ending balance, exercisable	16.11
Nonvested at end of period (in dollar per share)	$ 22.22
Weighted-average Remaining Contractual Term (Years)
Outstanding	3 years 3 months 18 days	4 years 2 months 12 days
Ending balance, exercisable	3 years 3 months 18 days
Aggregate Intrinsic Value
Beginning balance, outstanding	$ 509
Ending balance, outstanding		$ 509