Fair Value of Financial Instruments - Narrative (Details)		3 Months Ended		9 Months Ended
	Nov. 04, 2016	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)
Fair Value, Option, Quantitative Disclosures [Line Items]
Company acquired right to receive certain future milestone		$ 88,544,000	$ 85,776,000	$ 245,258,000	$ 257,991,000
Royalty percentage	0.50
Progenics Pharmaceuticals Inc
Fair Value, Option, Quantitative Disclosures [Line Items]
Royalty percentage				0.05
Progenics Pharmaceuticals Inc | Net Sales Targets For Azedra
Fair Value, Option, Quantitative Disclosures [Line Items]
Potential payments, high		70,000,000.0		$ 70,000,000.0
Progenics Pharmaceuticals Inc | 1095 commercialization milestone
Fair Value, Option, Quantitative Disclosures [Line Items]
Potential payments, high		$ 5,000,000.0		5,000,000.0
Royalty | Progenics Pharmaceuticals Inc
Fair Value, Option, Quantitative Disclosures [Line Items]
Company acquired right to receive certain future milestone				$ 5,000,000.0