Liabilities Related to the Sales of Future Royalties - Schedule of Liability Related to Potential Future Royalties (Detail) - USD ($) $ in Thousands	12 Months Ended				118 Months Ended
	Dec. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2021
Liability Related To Sale Of Future Royalties [Roll Forward]
Liabilities related to the sales of future royalties—beginning balance	$ 205,255				$ 0
Royalty monetization proceeds	0				274,000
Non-cash royalty revenue	(77,746)		$ (48,563)	$ (36,303)	(333,451)
Non-cash interest expense	47,313		30,267	$ 25,044	244,273
Payments to RPI	0				(10,000)
Loss on revaluation of liability related to the sale of future royalties	(23,522)				(23,522)
Liabilities related to the sales of future royalties – ending balance	198,344	$ 198,344	205,255		198,344
Less: unamortized transaction costs	(2,917)	(2,917)			(2,917)
Liabilities related to the sales of future royalties, net	195,427	195,427	200,340		195,427
2012 Purchase and Sale Agreement
Liability Related To Sale Of Future Royalties [Roll Forward]
Liabilities related to the sales of future royalties—beginning balance	65,880				0
Royalty monetization proceeds	0				124,000
Non-cash royalty revenue	(37,578)				(282,658)
Non-cash interest expense	26,458				223,418
Payments to RPI	0				(10,000)
Loss on revaluation of liability related to the sale of future royalties	(23,522)				(23,522)
Liabilities related to the sales of future royalties – ending balance	78,282	78,282	65,880		78,282
Less: unamortized transaction costs	0	0			0
Liabilities related to the sales of future royalties, net	78,282	78,282			78,282
2020 Purchase and Sale Agreement
Liability Related To Sale Of Future Royalties [Roll Forward]
Liabilities related to the sales of future royalties—beginning balance	139,375	0
Royalty monetization proceeds	0	150,000
Non-cash royalty revenue	(40,168)	(50,793)
Non-cash interest expense	20,855	20,855
Payments to RPI	0	0
Loss on revaluation of liability related to the sale of future royalties		0
Liabilities related to the sales of future royalties – ending balance	120,062	120,062	$ 139,375		120,062
Less: unamortized transaction costs	(2,917)	(2,917)			(2,917)
Liabilities related to the sales of future royalties, net	$ 117,145	$ 117,145			$ 117,145