Quarterly report pursuant to Section 13 or 15(d)

Investments in Marketable Debt Securities, Available for Sale - Schedule of Amortized Cost and Fair Value of Marketable Securities, Available-for-Sale, by Type of Security (Detail)

v3.21.2
Investments in Marketable Debt Securities, Available for Sale - Schedule of Amortized Cost and Fair Value of Marketable Securities, Available-for-Sale, by Type of Security (Detail) - USD ($)
$ in Thousands
Sep. 30, 2021
Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost $ 245,640 $ 203,329
Allowance for Credit Losses 0  
Fair Value 247,404 206,031
Short-term investments [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 116,852 158,148
Allowance for Credit Losses 0 0
Gross Unrealized Gains 50 116
Gross Unrealized Losses 0 (6)
Fair Value 116,902 158,258
Short-term investments [Member] | U.S. Treasuries [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 19,984 75,887
Allowance for Credit Losses 0 0
Gross Unrealized Gains 7 88
Gross Unrealized Losses 0 (5)
Fair Value 19,991 75,970
Short-term investments [Member] | U.S. Government Sponsored Entities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost   32,439
Allowance for Credit Losses   0
Gross Unrealized Gains   8
Gross Unrealized Losses   0
Fair Value 0 32,447
Short-term investments [Member] | Corporate debt [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 96,868 49,822
Allowance for Credit Losses 0 0
Gross Unrealized Gains 43 20
Gross Unrealized Losses 0 (1)
Fair Value 96,911 49,841
Long-term marketable securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 128,788 45,181
Allowance for Credit Losses 0 0
Gross Unrealized Gains 1,780 2,636
Gross Unrealized Losses (66) (44)
Fair Value 130,502 47,773
Long-term marketable securities [Member] | U.S. Treasuries [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 86,893 3,375
Allowance for Credit Losses 0 0
Gross Unrealized Gains 190 266
Gross Unrealized Losses (26) 0
Fair Value 87,057 3,641
Long-term marketable securities [Member] | U.S. Government Sponsored Entities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 797 1,114
Allowance for Credit Losses 0 0
Gross Unrealized Gains 27 38
Gross Unrealized Losses (2) 0
Fair Value 822 1,152
Long-term marketable securities [Member] | Corporate debt [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 33,845 34,183
Allowance for Credit Losses 0 0
Gross Unrealized Gains 1,422 2,137
Gross Unrealized Losses (33) (33)
Fair Value 35,234 36,287
Long-term marketable securities [Member] | Asset-backed Securities ("ABS") and Other [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 7,253 6,509
Allowance for Credit Losses 0 0
Gross Unrealized Gains 141 195
Gross Unrealized Losses (5) (11)
Fair Value $ 7,389 $ 6,693