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Marketable Securities - Schedule of Amortized Cost, Gross Unrealized Holding Losses and Fair Value of Available-for-Sale Debt Securities by Type of Security (Detail) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Available for sale securities:
Fair Value		$ 0
U.S. Government-Related Obligations [Member]
Available for sale securities:
Amortized Cost	$ 312,476,000
Gross Unrealized Holding Gains	122,000
Fair Value	$ 312,598,000

X

- Definition

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).

+ References

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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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Amount 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
-Name Accounting Standards Codification
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