REVENUE - Commercialization Agreement Revenue, net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenues	$ 25,472	$ 34,565	$ 77,686	$ 76,099
Royalty
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenues				13,100
Commercialization agreement, net
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenues	$ 0	$ 0	$ 0	11,258
Contract asset, amortization				$ 1,800