Investments - Summary of Fair Value of Available-for-Sale Investments by Type of Security (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Schedule Of Held To Maturity Securities [Line Items]
Amortized Cost	$ 679,042	$ 230,351
Unrealized Losses	(1,088)
Unrealized Gains		64
Fair Value	677,954	230,415
Investments with a maturity of one year or less [Member]
Schedule Of Held To Maturity Securities [Line Items]
Amortized Cost	298,301	50,993
Unrealized Losses	(366)
Unrealized Gains		26
Fair Value	297,935	51,019
Investments with a maturity of one to two years [Member]
Schedule Of Held To Maturity Securities [Line Items]
Amortized Cost	380,741	179,358
Unrealized Losses	(722)
Unrealized Gains		38
Fair Value	380,019	179,396
U.S treasury bills [Member] | Investments with a maturity of one year or less [Member]
Schedule Of Held To Maturity Securities [Line Items]
Amortized Cost	189,406	29,997
Unrealized Losses	(228)
Unrealized Gains		21
Fair Value	189,178	30,018
U.S treasury bills [Member] | Investments with a maturity of one to two years [Member]
Schedule Of Held To Maturity Securities [Line Items]
Amortized Cost	280,743	3,008
Unrealized Losses	(535)
Fair Value	280,208	3,008
U.S agency securities [Member] | Investments with a maturity of one year or less [Member]
Schedule Of Held To Maturity Securities [Line Items]
Amortized Cost	108,895	20,996
Unrealized Losses	(138)
Unrealized Gains		5
Fair Value	108,757	21,001
U.S agency securities [Member] | Investments with a maturity of one to two years [Member]
Schedule Of Held To Maturity Securities [Line Items]
Amortized Cost	99,998	176,350
Unrealized Losses	(187)
Unrealized Gains		38
Fair Value	$ 99,811	$ 176,388