Fair Value Measurements - Fair Value Inputs, Liabilities, Quantitative Information (Details) - Fair Value, Inputs, Level 3 $ in Thousands	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Revenue-based royalty
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration liabilities	$ 4,047	$ 4,545
Revenue milestones
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration liabilities	46,807	46,305
Regulatory approval
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration liabilities	$ 4,900	$ 4,900
Discount rate | Revenue-based royalty | Minimum | Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable inputs, contingent liability	0.12	0.12
Discount rate | Revenue-based royalty | Maximum | Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable inputs, contingent liability	0.16	0.15
Discount rate | Revenue-based royalty | Weighted Average | Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable inputs, contingent liability	0.154	0.135
Discount rate | Revenue milestones | Minimum | Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable inputs, contingent liability	0.10	0.075
Discount rate | Revenue milestones | Maximum | Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable inputs, contingent liability	0.14	0.12
Discount rate | Revenue milestones | Weighted Average | Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable inputs, contingent liability	0.104	0.090
Discount rate | Regulatory approval | Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable inputs, contingent liability	0.01	0.01
Probability of milestone payment | Regulatory approval | Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable inputs, contingent liability	1	1