Cash, Cash Equivalents, Restricted Cash and Marketable Securities - Summary of Cash, Cash Equivalents and Marketable Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	$ 200,444	$ 150,983
Unrealized Gains	278	84
Unrealized Losses	(14)	(12)
Estimated Fair Value	200,708	151,055
Cash and Cash Equivalents
Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	60,485	39,884
Unrealized Gains	1
Unrealized Losses	(1)
Estimated Fair Value	60,485	39,884
Marketable Securities Available-for-Sale
Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	139,959	111,099
Unrealized Gains	277	84
Unrealized Losses	(13)	(12)
Estimated Fair Value	140,223	111,171
Cash \| Cash and Cash Equivalents
Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	7,735	4,038
Estimated Fair Value	7,735	4,038
Money Market Funds \| Cash and Cash Equivalents
Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	24,187	27,854
Estimated Fair Value	24,187	27,854
U.S. Treasuries \| Cash and Cash Equivalents
Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	5,999
Estimated Fair Value	5,999
U.S. Treasuries \| Marketable Securities Available-for-Sale
Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	16,159	6,511
Unrealized Gains	64	6
Estimated Fair Value	16,223	6,517
Corporate Debt Securities \| Cash and Cash Equivalents
Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	22,564	7,992
Unrealized Gains	1
Unrealized Losses	(1)
Estimated Fair Value	22,564	7,992
Corporate Debt Securities \| Marketable Securities Available-for-Sale
Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	69,539	53,353
Unrealized Gains	62	28
Unrealized Losses	(6)
Estimated Fair Value	69,595	53,381
U.S. Government Agency Securities \| Marketable Securities Available-for-Sale
Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	54,261	51,235
Unrealized Gains	151	50
Unrealized Losses	(7)	(12)
Estimated Fair Value	$ 54,405	$ 51,273

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

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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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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