STOCK-BASED COMPENSATION - Restricted Stock Units Narrative and Activity (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares shares
Additional disclosures
Average vesting period for recognition of unrecognized compensation expense	2 years
Performance-based Restricted Stock Units
Additional disclosures
Unrecognized compensation expense | $	$ 2,800
Average vesting period for recognition of unrecognized compensation expense	2 years 28 days
The 2004 Plan | Restricted stock units
Number of Shares
Granted (in shares)	0
The 2014 Plan | Restricted stock units
Number of Shares
Non-vested restricted stock units at the beginning of the period (in shares)	1,166,046
Granted (in shares)	1,897,661
Vested (in shares)	(539,898)
Forfeited (in shares)	(585,021)
Non-vested restricted stock units at the end of the period (in shares)	1,938,788
Weighted Average Grant Date Fair Value Per Share
Non-vested restricted stock units at the beginning of the period (in dollars per share) | $ / shares	$ 10.69
Granted (in dollars per share) | $ / shares	6.84
Vested (in dollars per share) | $ / shares	9.77
Forfeited (in dollars per share) | $ / shares	9.05
Non-vested restricted stock units at the end of the period (in dollars per share) | $ / shares	$ 6.94
Weighted Average Remaining Contractual Term (in years)
Non-vested restricted stock units at the end of the period	1 year 2 months 27 days
Additional disclosures
Total fair value of awards vested | $	$ 3,100
The 2014 Plan | Restricted stock units | Vesting Period One
Stock-based compensation
Vesting period	3 years
Annual vesting percentage	33.00%
The 2014 Plan | Restricted stock units | Vesting Period Two
Stock-based compensation
Vesting period	4 years
Annual vesting percentage	25.00%
The 2014 Plan | Performance-based Restricted Stock Units
Stock-based compensation
Vesting period	3 years
Number of Shares
Non-vested restricted stock units at the beginning of the period (in shares)	0
Granted (in shares)	523,187
Vested (in shares)	0
Forfeited (in shares)	(148,363)
Non-vested restricted stock units at the end of the period (in shares)	374,824
Weighted Average Grant Date Fair Value Per Share
Non-vested restricted stock units at the beginning of the period (in dollars per share) | $ / shares	$ 0.00
Granted (in dollars per share) | $ / shares	10.58
Vested (in dollars per share) | $ / shares	0.00
Forfeited (in dollars per share) | $ / shares	11.68
Non-vested restricted stock units at the end of the period (in dollars per share) | $ / shares	$ 10.14
Weighted Average Remaining Contractual Term (in years)
Non-vested restricted stock units at the end of the period	2 years 1 month 2 days
Aggregate Intrinsic Value | $	$ 1,353
The 2014 Plan | Performance-based Restricted Stock Units | Minimum
Stock-based compensation
Annual vesting percentage	0.00%
The 2014 Plan | Performance-based Restricted Stock Units | Maximum
Stock-based compensation
Annual vesting percentage	200.00%