STOCK-BASED COMPENSATION - SUMMARY OF TIME-BASED STOCK OPTIONS (Details) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares
Number of Shares Underlying Stock Options
Ending outstanding balance (in shares)	375
Weighted Average Exercise Price Per Share
Weighted average remaining contractual life, Outstanding	4 years 9 months 18 days	4 years 4 months 9 days
Stock options outstanding
Number of Shares Underlying Stock Options
Beginning outstanding balance (in shares)	828
Exercised (in shares)	(326)
Canceled or expired (in shares)	(127)
Ending outstanding balance (in shares)	375	828
Number of shares underlying stock options, Vested and expected to vest (in shares)	375
Number of shares underlying stock options, Exercisable (in shares)	158
Weighted Average Exercise Price Per Share
Beginning outstanding balance (in dollars per share) | $ / shares	$ 8.16
Exercised (in dollars per share) | $ / shares	8.79
Canceled or expired (in dollars per share) | $ / shares	7.46
Ending outstanding balance (in dollars per share) | $ / shares	7.85	$ 8.16
Weighted average exercise price, Vested and expected to vest (in dollars per share) | $ / shares	7.85
Weighted average exercise price, Exercisable (in dollars per share) | $ / shares	$ 8.21
Weighted average remaining contractual life, Vested and expected to vest	4 years 9 months 18 days
Weighted average remaining contractual life, Exercisable	4 years 2 months 26 days
Aggregate intrinsic value, Outstanding | $	$ 431	$ 2,628
Aggregate intrinsic value, Vested and expected to vest | $	431
Aggregate intrinsic value, Exercisable | $	$ 161