LIABILITY RELATED TO THE SALE OF FUTURE ROYALTIES (Details) - USD ($)	1 Months Ended	3 Months Ended
	Apr. 30, 2020	Mar. 31, 2021	Jan. 01, 2030	Dec. 31, 2020	Apr. 10, 2020
Liability Related To The Sale Of Future Royalties Line Items [Line Items]
Receivable related to the sale of future royalties		$ 500,000,000		$ 500,000,000
Liability related to the sale of future royalties, net of current portion		1,086,065,000		1,058,225,000
Blackstone Group Inc. | Collaborative Arrangement
Liability Related To The Sale Of Future Royalties Line Items [Line Items]
Collaborative arrangement, royalties and commercial milestones acquired by collaborator, percent					50.00%
Commercial milestones acquired by collaborator, percent					75.00%
Expected royalty interest payments		1,000,000,000.00
Consideration received	$ 500,000,000.0
Receivable related to the sale of future royalties		500,000,000.0
Liability related to the sale of future royalties, net of current portion		1,099,725,000		$ 1,071,541,000	$ 1,000,000,000.00
Interest rate					11.00%
Closing costs		(13,000,000.0)
Interest expense including amortization of closing costs		$ 28,184,000
Forecast | Blackstone Group Inc. | Collaborative Arrangement
Liability Related To The Sale Of Future Royalties Line Items [Line Items]
Collaborative arrangement, royalties and commercial milestones acquired by collaborator, percent			55.00%