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Investments - Summary of Gross Unrealized Losses and Fair Value of Available-For-Sale Investment Securities in Unrealized Loss Position (Detail) - USD ($)
$ in Thousands
Jun. 30, 2021
Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Estimated Fair Value $ 49,152 $ 169,353
Less Than 12 Months, Unrealized Losses (8) (43)
Total, Estimated Fair Value 49,152 169,353
Total, Unrealized Losses (8) (43)
US Treasury Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Estimated Fair Value 5,052 129,631
Less Than 12 Months, Unrealized Losses (1) (27)
Total, Estimated Fair Value 5,052 129,631
Total, Unrealized Losses (1) (27)
US Government Sponsored Enterprises Debt Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Estimated Fair Value 15,002 10,004
Less Than 12 Months, Unrealized Losses (1) (5)
Total, Estimated Fair Value 15,002 10,004
Total, Unrealized Losses (1) (5)
Commercial paper    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Estimated Fair Value 22,480 23,466
Less Than 12 Months, Unrealized Losses (3) (11)
Total, Estimated Fair Value 22,480 23,466
Total, Unrealized Losses (3) (11)
Municipal bonds    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Estimated Fair Value 6,618  
Less Than 12 Months, Unrealized Losses (3)  
Total, Estimated Fair Value 6,618  
Total, Unrealized Losses $ (3)  
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