Basis of Presentation and Summary of Significant Accounting Policies - Revenue by Source (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Total revenue	$ 64,835	$ 41,848	$ 204,660	$ 116,429
Royalties
Disaggregation of Revenue [Line Items]
Total revenue	15,648	9,005	31,376	22,751
Kyprolis
Disaggregation of Revenue [Line Items]
Total revenue	8,821	6,923	18,548	16,809
Evomela
Disaggregation of Revenue [Line Items]
Total revenue	2,665	1,802	7,191	4,577
Other
Disaggregation of Revenue [Line Items]
Total revenue	4,162	280	5,637	1,365
Captisol
Disaggregation of Revenue [Line Items]
Total revenue	35,093	23,389	128,875	68,966
Contract revenue
Disaggregation of Revenue [Line Items]
Total revenue	14,094	9,454	44,409	24,712
Service Revenue
Disaggregation of Revenue [Line Items]
Total revenue	4,828	7,341	17,650	15,280
License Fees
Disaggregation of Revenue [Line Items]
Total revenue	200	158	2,293	1,793
Milestone
Disaggregation of Revenue [Line Items]
Total revenue	7,419	960	19,436	4,766
Other
Disaggregation of Revenue [Line Items]
Total revenue	$ 1,647	$ 995	$ 5,030	$ 2,873