Fair Value Measurements and Marketable Debt Securities - Summary of Marketable Debt Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 6,499	$ 24,489
Gross Unrealized Gains		2
Gross Unrealized Losses		(1)
Fair Value	6,499	24,490
U.S. Government Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost		2,005
Fair Value		2,005
Commercial Paper [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	6,499	22,484
Gross Unrealized Gains		2
Gross Unrealized Losses		(1)
Fair Value	$ 6,499	$ 22,485

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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-Publisher FASB
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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as current.

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