Fair Value Measurements - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Current portion of contingent consideration	$ 8,800	$ 25,600
Business consideration liabilities	42,400	$ 63,800
Convertible Senior Notes, Excluding Over-Allotment Option Notes | Convertible notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of convertible notes	260,500
Brabant Pharma Limited
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Current portion of contingent consideration	8,800
Business consideration liabilities	$ 42,400