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Balance Sheet Components - Summary of Amortized Cost, Gross Unrealized Holding Gains or Losses, and Fair Value of Available-for-Sale Investments (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 354,431	$ 8,272
Gross Unrealized Holding Gains	153	119
Gross Unrealized Holding Losses	(73)	(3)
Fair Value	354,511	8,388
Corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	127,005
Gross Unrealized Holding Gains	35
Gross Unrealized Holding Losses	(46)
Fair Value	126,994
Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	95,402
Gross Unrealized Holding Gains	0
Gross Unrealized Holding Losses	0
Fair Value	95,402
U.S. government bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	73,119
Gross Unrealized Holding Gains	5
Gross Unrealized Holding Losses	(16)
Fair Value	73,108
Agency bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	23,399
Gross Unrealized Holding Gains	4
Gross Unrealized Holding Losses	(4)
Fair Value	23,399
Asset-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	27,261
Gross Unrealized Holding Gains	2
Gross Unrealized Holding Losses	(7)
Fair Value	27,256
Foreign government bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	8,127
Gross Unrealized Holding Gains	0
Gross Unrealized Holding Losses	0
Fair Value	8,127
Bond and mutual funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		8,147
Gross Unrealized Holding Gains		0
Gross Unrealized Holding Losses		(3)
Fair Value		8,144
Equity investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	118	125
Gross Unrealized Holding Gains	107	119
Gross Unrealized Holding Losses	0	0
Fair Value	$ 225	$ 244

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+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

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