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Schedule of Unrealized Loss on Available-for-Sale Investments (Detail) - USD ($) $ in Thousands | Sep. 30, 2023 | Dec. 31, 2022
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Debt Securities, Available-for-sale [Line Items] |  |
Available-for-sale investments with unrealized losses, Less than 12 months, Fair Value | $ 27,556 | $ 56,275
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss | 515 | 1,616
Available-for-sale investments with unrealized losses, 12 months or longer, Fair Value | 108,781 | 78,406
Available-for-sale investments with unrealized losses, 12 months or longer, Unrealized Loss | 9,027 | 9,148
Available-for-sale investments with unrealized losses, Fair Value, Total | 136,337 | 134,681
Available-for-sale investments with unrealized losses, Unrealized Loss, Total | 9,542 | 10,764
Asset-backed securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Available-for-sale investments with unrealized losses, Less than 12 months, Fair Value | 0 | 0
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss | 0 | 0
Available-for-sale investments with unrealized losses, 12 months or longer, Fair Value | 14,336 | 16,016
Available-for-sale investments with unrealized losses, 12 months or longer, Unrealized Loss | 2,708 | 2,889
Available-for-sale investments with unrealized losses, Fair Value, Total | 14,336 | 16,016
Available-for-sale investments with unrealized losses, Unrealized Loss, Total | 2,708 | 2,889
Corporate bonds and direct obligations of government agencies |  |
Debt Securities, Available-for-sale [Line Items] |  |
Available-for-sale investments with unrealized losses, Less than 12 months, Fair Value | 20,707 | 54,031
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss | 507 | 1,516
Available-for-sale investments with unrealized losses, 12 months or longer, Fair Value | 92,167 | 62,390
Available-for-sale investments with unrealized losses, 12 months or longer, Unrealized Loss | 6,251 | 6,259
Available-for-sale investments with unrealized losses, Fair Value, Total | 112,874 | 116,421
Available-for-sale investments with unrealized losses, Unrealized Loss, Total | 6,758 | 7,775
U.S. Treasury obligations |  |
Debt Securities, Available-for-sale [Line Items] |  |
Available-for-sale investments with unrealized losses, Less than 12 months, Fair Value | 6,849 | 2,244
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss | 8 | 100
Available-for-sale investments with unrealized losses, 12 months or longer, Fair Value | 2,278 | 0
Available-for-sale investments with unrealized losses, 12 months or longer, Unrealized Loss | 68 | 0
Available-for-sale investments with unrealized losses, Fair Value, Total | 9,127 | 2,244
Available-for-sale investments with unrealized losses, Unrealized Loss, Total | $ 76 | $ 100

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