Fair Value Measurements - Summary of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Fair Value, Recurring - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Cash Equivalents
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	$ 711,365	$ 90,224
Gross Unrealized Holding Gains	0	1
Gross Unrealized Holding Losses	0	(1)
Estimated Fair Value	711,365	90,224
Cash Equivalents | Money Market Funds | Level 1
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	708,413	48,359
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	0	0
Estimated Fair Value	708,413	48,359
Cash Equivalents | US Government and Agencies Securities | Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	2,400	40,727
Gross Unrealized Holding Gains	0	1
Gross Unrealized Holding Losses	0	(1)
Estimated Fair Value	2,400	40,727
Cash Equivalents | Corporate Debt Securities | Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	552	1,138
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	0	0
Estimated Fair Value	552	1,138
Short-term Marketable Securities
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	209,502	253,435
Gross Unrealized Holding Gains	56	30
Gross Unrealized Holding Losses	(8)	(7)
Estimated Fair Value	209,550	253,458
Short-term Marketable Securities | US Government and Agencies Securities | Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	193,058	244,637
Gross Unrealized Holding Gains	56	30
Gross Unrealized Holding Losses	(1)	(5)
Estimated Fair Value	193,113	244,662
Short-term Marketable Securities | Corporate Debt Securities | Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	16,444	8,798
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	(7)	(2)
Estimated Fair Value	16,437	8,796
Long-term Marketable Securities
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	21,619	33,724
Gross Unrealized Holding Gains	8	7
Gross Unrealized Holding Losses	0	0
Estimated Fair Value	21,627	33,731
Long-term Marketable Securities | US Government and Agencies Securities | Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	17,437	33,724
Gross Unrealized Holding Gains	7	7
Gross Unrealized Holding Losses	0	0
Estimated Fair Value	17,444	33,731
Long-term Marketable Securities | Corporate Debt Securities | Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	4,182
Gross Unrealized Holding Gains	1
Gross Unrealized Holding Losses	0
Estimated Fair Value	4,183
Financial Assets
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	942,486	377,383
Gross Unrealized Holding Gains	64	38
Gross Unrealized Holding Losses	(8)	(8)
Estimated Fair Value	942,542	377,413
Short-term Financial Liabilities | Success Payment Liabilities | Level 3
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	5,000
Gross Unrealized Holding Gains	0
Gross Unrealized Holding Losses	0
Estimated Fair Value	5,000
Long-term Financial Liabilities | Contingent Consideration | Level 3
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	133,294	121,901
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	0	0
Estimated Fair Value	133,294	121,901
Long-term Financial Liabilities | Success Payment Liabilities | Level 3
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	187,151	76,494
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	0	0
Estimated Fair Value	187,151	76,494
Financial Liabilities
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	325,445	198,395
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	0	0
Estimated Fair Value	$ 325,445	$ 198,395