Fair Value Measurements - Fair Value Inputs, Liabilities, Quantitative Information (Details) $ in Thousands	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration liabilities	$ 36,917	$ 48,088
Revenue-based royalty | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration liabilities	4,545	7,710
Revenue milestones | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration liabilities	46,305	66,114
Regulatory approval | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration liabilities	$ 4,900	$ 2,885
Discount rate | Revenue-based royalty | Minimum | Discounted Cash Flow | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable inputs, contingent liability	0.12	0.13
Discount rate | Revenue-based royalty | Maximum | Discounted Cash Flow | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable inputs, contingent liability	0.15	0.24
Discount rate | Revenue-based royalty | Weighted Average | Discounted Cash Flow | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable inputs, contingent liability	0.135
Discount rate | Revenue milestones | Minimum | Discounted Cash Flow | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable inputs, contingent liability	0.075	0.09
Discount rate | Revenue milestones | Maximum | Discounted Cash Flow | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable inputs, contingent liability	0.12	0.135
Discount rate | Revenue milestones | Weighted Average | Discounted Cash Flow | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable inputs, contingent liability	0.090
Discount rate | Regulatory approval | Discounted Cash Flow | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable inputs, contingent liability	0.01	0.024
Probability of milestone payment | Regulatory approval | Discounted Cash Flow | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable inputs, contingent liability	1	0.65