Available-for-Sale Debt Securities by Original Contractual Maturity (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Investments Debt And Equity Securities [Abstract]
One year or less, amortized cost	$ 64,857	$ 43,822
Greater than one year and less than five years, amortized cost	37,672	15,656
Amortized Cost	102,529	59,478
One year or less, fair value	65,117	43,907
Greater than one year and less than five years, fair value	38,086	15,685
Total available-for-sale securities fair value	$ 103,203	$ 59,592

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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