Available-for-Sale Marketable Securities - Schedule of Amortized Cost and Fair Values of Marketable Debt Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Investments Debt And Equity Securities [Abstract]
Amortized Cost of marketable debt securities, contractual maturity, less than one year	$ 149,031		$ 149,164
Amortized Cost of marketable debt securities, contractual maturity, One year to three years	56,748		70,570
Amortized Cost	205,779		219,734
Fair value of marketable debt securities, contractual maturities, less than one year	149,063		149,242
Fair value of marketable debt securities, contractual maturity, One year to three years	56,728		70,565
Total fair Value of marketable debt securities, contractual maturity	205,791		219,807
Proceeds from sale of available-for-sale marketable securities	8,029	$ 0
Realized gain (loss)	39
Interest receivable	$ 346		$ 311

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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Amount of realized gain (loss) 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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Carrying amount as of the balance sheet date of current interest earned but not received. Also called accrued interest or accrued interest receivable. For classified balance sheets, represents the current amount receivable, that is amounts expected to be collected within one year or the normal operating cycle, if longer.

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Amount of cash inflow from sale 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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