Cash Equivalents, Restricted Cash and Investments - Amortized Cost and Fair Value of Cash Equivalents and Investments (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 345,802	$ 354,813
Gross Unrealized Gains	0	7
Gross Unrealized Losses	(2,310)	(490)
Available-for-sale Securities	343,492	354,330
Money Market Fund [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	41,722	41,960
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Available-for-sale Securities	41,722	41,960
U.S. Treasury Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	97,758	40,397
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(958)	(160)
Available-for-sale Securities	96,800	40,237
Non US Government Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	24,616
Gross Unrealized Gains	0
Gross Unrealized Losses	(248)
Available-for-sale Securities	24,368
Commercial Paper [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	77,750	111,868
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Available-for-sale Securities	77,750	111,868
Asset-backed Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	19,517	39,988
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(213)	(62)
Available-for-sale Securities	19,304	39,926
Corporate Debt Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	84,439	103,779
Gross Unrealized Gains	0	7
Gross Unrealized Losses	(891)	(212)
Available-for-sale Securities	$ 83,548	103,574
Government-Sponsored Agencies [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost		16,821
Gross Unrealized Gains		0
Gross Unrealized Losses		(56)
Available-for-sale Securities		$ 16,765

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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