Fair Value of Financial Instruments - Summary of Composition of Short and Long Term Investments (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 996,638	$ 903,277
Unrealized Gains	11	532
Unrealized Losses	(792)	(39)
Aggregate Fair Value	995,857	903,770
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	25,245	12,233
Aggregate Fair Value	25,245	12,233
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	250,443	115,983
Unrealized Gains	9	427
Unrealized Losses	(606)	(39)
Aggregate Fair Value	249,846	116,371
U.S. Government Agency Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	22,504
Unrealized Losses	(38)
Aggregate Fair Value	22,466
US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	698,446	774,667
Unrealized Gains	2	105
Unrealized Losses	(148)	0
Aggregate Fair Value	$ 698,300	774,772
Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		394
Unrealized Gains		0
Unrealized Losses		0
Aggregate Fair Value		$ 394

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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