Investments - Summary of Gross Unrealized Losses and Fair Value of Available-For-Sale Investment Securities in Unrealized Loss Position (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Estimated Fair Value	$ 290,997	$ 169,353
Less Than 12 Months, Unrealized Losses	213	43
Total, Estimated Fair Value	290,997	169,353
Total, Unrealized Losses	213	43
US Treasury Securities
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Estimated Fair Value	140,287	129,631
Less Than 12 Months, Unrealized Losses	100	27
Total, Estimated Fair Value	140,287	129,631
Total, Unrealized Losses	100	27
Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Estimated Fair Value		6,252
Total, Estimated Fair Value		6,252
Total, Unrealized Losses
Municipal Bonds
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Estimated Fair Value	26,006
Less Than 12 Months, Unrealized Losses	22
Total, Estimated Fair Value	26,006
Total, Unrealized Losses	22
US Government Sponsored Enterprises Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Estimated Fair Value	49,512	10,004
Less Than 12 Months, Unrealized Losses	38	5
Total, Estimated Fair Value	49,512	10,004
Total, Unrealized Losses	38	5
Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Estimated Fair Value	75,192	23,466
Less Than 12 Months, Unrealized Losses	53	11
Total, Estimated Fair Value	75,192	23,466
Total, Unrealized Losses	$ 53	$ 11