Investments - Summary of Fair Value of Available for Sale Investments (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule of Available-for-sale Securities [Line Items]
Investments, Amortized Cost	$ 6,759	$ 12,959
Investments, Gross Unrealized Gain		8
Investments, Fair Value	6,759	12,967
Corporate Notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments, Amortized Cost		5,489
Investments, Gross Unrealized Gain		2
Investments, Fair Value		5,491
Treasury Bills [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments, Amortized Cost	1,249
Investments, Fair Value	1,249
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments, Amortized Cost	1,999	7,470
Investments, Gross Unrealized Gain		6
Investments, Fair Value	1,999	$ 7,476
Agency Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments, Amortized Cost	3,511
Investments, Fair Value	$ 3,511

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).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563

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- Definition

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121558606&loc=SL82898722-210454

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121558606&loc=SL82898722-210454

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=121553693&loc=d3e26626-111562

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