Available-for-Sale Debt Securities by Original Contractual Maturity (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Investments Debt And Equity Securities [Abstract]
One year or less, amortized cost	$ 77,745	$ 64,857
Greater than one year and less than five years, amortized cost	10,145	37,672
Amortized Cost	87,890	102,529
One year or less, fair value	77,869	65,117
Greater than one year and less than five years, fair value	10,202	38,086
Total available-for-sale securities fair value	$ 88,071	$ 103,203

Amortized cost of 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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