Basis of Presentation and Summary of Significant Accounting Policies - Revenue by Source (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Disaggregation of Revenue
Total revenues	$ 30,978	$ 43,979
Royalties
Disaggregation of Revenue
Total revenues	19,095	17,647
Revenue from intangible royalty assets
Disaggregation of Revenue
Total revenues	18,357	17,154
Kyprolis
Disaggregation of Revenue
Total revenues	6,632	6,228
Evomela
Disaggregation of Revenue
Total revenues	1,397	2,550
Teriparatide injection
Disaggregation of Revenue
Total revenues	2,041	3,500
Rylaze
Disaggregation of Revenue
Total revenues	2,952	2,609
Filspari
Disaggregation of Revenue
Total revenues	1,772	0
Vaxneuvance
Disaggregation of Revenue
Total revenues	1,387	638
Other
Disaggregation of Revenue
Total revenues	2,176	1,629
Income from financial royalty assets
Disaggregation of Revenue
Total revenues	738	493
Captisol
Disaggregation of Revenue
Total revenues	9,212	10,622
Contract revenue and other income
Disaggregation of Revenue
Total revenues	2,671	15,710
Milestone and other
Disaggregation of Revenue
Total revenues	727	15,710
Other income
Disaggregation of Revenue
Total revenues	$ 1,944	$ 0