Investments - Summary of Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 1,041,003	$ 620,483
Amortized Cost	1,379,160
Gross Unrealized Gains	654	4,401
Gross Unrealized Losses	(2,319)	(60)
Estimated Fair Value	1,039,339	624,824
Cash and Cash Equivalents	1,377,495
Short-term investments	1,039,339	624,824
Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	6,814	2,679
Gross Unrealized Gains	21	73
Gross Unrealized Losses	(21)	0
Estimated Fair Value	6,814	2,752
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		19,994
Amortized Cost	189,958
Gross Unrealized Gains	6	0
Gross Unrealized Losses	(6)	0
Estimated Fair Value	9,994	19,994
Cash and Cash Equivalents	189,958
Corporate notes and bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		433,445
Amortized Cost	658,317
Gross Unrealized Gains	626	4,248
Gross Unrealized Losses	(1,341)	(41)
Estimated Fair Value	649,408	437,652
Cash and Cash Equivalents	657,602
U.S. Treasuries
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		74,914
Amortized Cost	307,634
Gross Unrealized Gains	0	26
Gross Unrealized Losses	(294)	(6)
Estimated Fair Value	157,342	74,934
Cash and Cash Equivalents	307,340
U.S. Government agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	216,437	89,451
Gross Unrealized Gains	1	54
Gross Unrealized Losses	(657)	(13)
Estimated Fair Value	215,781	89,492
Cash and Cash Equivalents
Debt Securities, Available-for-sale [Line Items]
Cash and Cash Equivalents	338,156	0
Cash and Cash Equivalents \| Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Cash and Cash Equivalents	0	0
Cash and Cash Equivalents \| Commercial paper
Debt Securities, Available-for-sale [Line Items]
Cash and Cash Equivalents	179,964	0
Cash and Cash Equivalents \| Corporate notes and bonds
Debt Securities, Available-for-sale [Line Items]
Cash and Cash Equivalents	8,194	0
Cash and Cash Equivalents \| U.S. Treasuries
Debt Securities, Available-for-sale [Line Items]
Cash and Cash Equivalents	149,998	0
Cash and Cash Equivalents \| U.S. Government agencies
Debt Securities, Available-for-sale [Line Items]
Cash and Cash Equivalents	0	0
Short-Term Investments
Debt Securities, Available-for-sale [Line Items]
Short-term investments	1,039,339	624,824
Short-Term Investments \| Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Short-term investments	6,814	2,752
Short-Term Investments \| Commercial paper
Debt Securities, Available-for-sale [Line Items]
Short-term investments	9,994	19,994
Short-Term Investments \| Corporate notes and bonds
Debt Securities, Available-for-sale [Line Items]
Short-term investments	649,408	437,652
Short-Term Investments \| U.S. Treasuries
Debt Securities, Available-for-sale [Line Items]
Short-term investments	157,342	74,934
Short-Term Investments \| U.S. Government agencies
Debt Securities, Available-for-sale [Line Items]
Short-term investments	$ 215,781	$ 89,492

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