SHARE-BASED COMPENSATION - RSU Plan During Current Period (Details) - RSUs - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Changes in RSUs [Roll Forward]
RSUs outstanding beginning (in shares)	3,861
RSUs issued (in shares)	3,793	1,955	1,292
RSUs released (in shares)	(1,712)	(1,456)	(1,496)
RSUs forfeited (in shares)	(403)	(323)	(396)
RSUs outstanding ending (in shares)	5,539	3,861
RSU weighted average purchase price (in dollars per share)	$ 0
RSU weighted average remaining contractual terms	1 year 3 months 18 days
RSU aggregate intrinsic value	$ 13,572
RSU vested Number of Restricted Stock Units (in shares)	5,539
RSU vested and expected to vest weighted average purchase price (in dollars per share)	$ 0
RSU vested and expected to vest weighted average remaining contractual term	1 year 3 months 18 days
RSUs vested and expected to vest aggregate intrinsic value	$ 13,572
RSU Options Exercisable (in shares)	41
RSU options weighted average purchase price exercisable (in dollars per share)	$ 0
RSU options weighted average remaining recognition period	0 years
RSU exercisable aggregate intrinsic value.	$ 101
Weighted average remaining recognition period in years	2 years
Unamortized compensation expense	$ 17,352