Quarterly report pursuant to Section 13 or 15(d)

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

v3.21.2
Investments in Marketable Securities - Schedule of Amortized Cost and Fair Value of Marketable Securities, Available-for-Sale, by Type of Security (Detail) - USD ($)
$ in Thousands
Jun. 30, 2021
Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost $ 242,630 $ 203,329
Allowance for Credit Losses 0  
Fair Value 244,686 206,031
Short-term investments [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 147,142 158,148
Allowance for Credit Losses 0 0
Gross Unrealized Gains 31 116
Gross Unrealized Losses (1) (6)
Fair Value 147,172 158,258
Short-term investments [Member] | U.S. Treasuries [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 74,424 75,887
Allowance for Credit Losses 0 0
Gross Unrealized Gains 12 88
Gross Unrealized Losses 0 (5)
Fair Value 74,436 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   32,447
Short-term investments [Member] | Corporate debt [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 72,718 49,822
Allowance for Credit Losses 0 0
Gross Unrealized Gains 19 20
Gross Unrealized Losses (1) (1)
Fair Value 72,736 49,841
Long-term marketable securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 95,488 45,181
Allowance for Credit Losses 0 0
Gross Unrealized Gains 2,070 2,636
Gross Unrealized Losses (44) (44)
Fair Value 97,514 47,773
Long-term marketable securities [Member] | U.S. Treasuries [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 52,033 3,375
Allowance for Credit Losses 0 0
Gross Unrealized Gains 185 266
Gross Unrealized Losses (22) 0
Fair Value 52,196 3,641
Long-term marketable securities [Member] | U.S. Government Sponsored Entities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 888 1,114
Allowance for Credit Losses 0 0
Gross Unrealized Gains 27 38
Gross Unrealized Losses (2) 0
Fair Value 913 1,152
Long-term marketable securities [Member] | Corporate debt [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 35,998 34,183
Allowance for Credit Losses 0 0
Gross Unrealized Gains 1,669 2,137
Gross Unrealized Losses (18) (33)
Fair Value 37,649 36,287
Long-term marketable securities [Member] | Asset-backed Securities ("ABS") and Other [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 6,569 6,509
Allowance for Credit Losses 0 0
Gross Unrealized Gains 189 195
Gross Unrealized Losses (2) (11)
Fair Value $ 6,756 $ 6,693