SHARE-BASED COMPENSATION - Stock Options by Exercise Price (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2019 $ / shares shares
Options Outstanding
Number Outstanding (in shares) | shares	11,969
Options Exercisable
Number Exercisable (in shares) | shares	9,368
$1.46 - $1.57
Range of Exercise Prices
Low (in dollars per share)	$ 1.46
High (in dollars per share)	$ 1.57
Options Outstanding
Number Outstanding (in shares) | shares	1,987
Weighted Average Remaining Contract Life (Years)	6 years 4 months 24 days
Weighted Average Exercise Prices (in dollars per share)	$ 1.47
Options Exercisable
Number Exercisable (in shares) | shares	1,334
Weighted Average Exercise Price (in dollars per share)	$ 1.47
$1.72 - $2.78
Range of Exercise Prices
Low (in dollars per share)	1.72
High (in dollars per share)	$ 2.78
Options Outstanding
Number Outstanding (in shares) | shares	875
Weighted Average Remaining Contract Life (Years)	6 years 3 months 18 days
Weighted Average Exercise Prices (in dollars per share)	$ 2.50
Options Exercisable
Number Exercisable (in shares) | shares	761
Weighted Average Exercise Price (in dollars per share)	$ 2.55
$3.29 - $3.29
Range of Exercise Prices
Low (in dollars per share)	3.29
High (in dollars per share)	$ 3.29
Options Outstanding
Number Outstanding (in shares) | shares	2,988
Weighted Average Remaining Contract Life (Years)	7 years 2 months 12 days
Weighted Average Exercise Prices (in dollars per share)	$ 3.29
Options Exercisable
Number Exercisable (in shares) | shares	1,302
Weighted Average Exercise Price (in dollars per share)	$ 3.29
$3.41 - $7.09
Range of Exercise Prices
Low (in dollars per share)	3.41
High (in dollars per share)	$ 7.09
Options Outstanding
Number Outstanding (in shares) | shares	2,111
Weighted Average Remaining Contract Life (Years)	3 years 3 months 18 days
Weighted Average Exercise Prices (in dollars per share)	$ 5.86
Options Exercisable
Number Exercisable (in shares) | shares	2,078
Weighted Average Exercise Price (in dollars per share)	$ 5.86
$7.1 - $7.77
Range of Exercise Prices
Low (in dollars per share)	7.10
High (in dollars per share)	$ 7.77
Options Outstanding
Number Outstanding (in shares) | shares	1,924
Weighted Average Remaining Contract Life (Years)	5 years 2 months 12 days
Weighted Average Exercise Prices (in dollars per share)	$ 7.67
Options Exercisable
Number Exercisable (in shares) | shares	1,857
Weighted Average Exercise Price (in dollars per share)	$ 7.67
$7.88 - $9.74
Range of Exercise Prices
Low (in dollars per share)	7.88
High (in dollars per share)	$ 9.74
Options Outstanding
Number Outstanding (in shares) | shares	2,084
Weighted Average Remaining Contract Life (Years)	4 years 2 months 12 days
Weighted Average Exercise Prices (in dollars per share)	$ 8.90
Options Exercisable
Number Exercisable (in shares) | shares	2,036
Weighted Average Exercise Price (in dollars per share)	$ 8.91