SHARE-BASED COMPENSATION - Restricted Stock Units (Details) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended
	Sep. 30, 2021 USD ($) plan $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of equity compensation plans | plan	2
Weighted Average Remaining Contractual Term (Years)
Weighted average remaining contractual terms, vested and deferred	10 months 24 days
RSUs
Number of Restricted Stock Units
Beginning of period balance (in shares)	5,539
Number of RSUs granted (in shares)	801
Number of RSUs released (in shares)	(1,437)
Number of RSUs forfeited (in shares)	(187)
End of period balance (in shares)	4,716
RSUs vested and expected to vest (in shares)	4,716
RSUs exercisable (vested and deferred) (in shares)	5
Weighted average remaining recognition period in years	1 year 6 months
Unamortized compensation expense | $	$ 13,163
Weighted Average Purchase Price
Options weighted average purchase price (in dollars per shares) | $ / shares	$ 0
Vested and expected to vest weighted average purchase price (in dollars per shares) | $ / shares	0
Other than options weighted average purchase price exercisable, (in dollars per shares) | $ / shares	$ 0
Weighted Average Remaining Contractual Term (Years)
Weighted average remaining contractual terms	1 year 1 month 6 days
Weighted average remaining contractual terms, vested and expected	1 year 1 month 6 days
Weighted average remaining contractual terms, vested and deferred	0 years
Intrinsic Value
Aggregate intrinsic value of restricted stock units | $	$ 24,158
Aggregate intrinsic vested and expected to vest | $	24,158
Aggregate intrinsic (vested and deferred) | $	$ 26