Financial Instruments - Fair Value of Company's Financial Assets Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost	$ 26,656	$ 10,845
Available-for-sale securities, Gross Unrealized Gains	1
Available-for-sale securities, Estimated Fair Value	26,657	10,845
Less amounts classified as cash equivalents, Amortized Cost	(10,293)	(10,845)
Less amounts classified as cash equivalents, Estimated Fair Value	(10,293)	(10,845)
Amounts classified as marketable securities, Amortized Cost	16,363
Amounts classified as marketable securities, Gross Unrealized Gains	1
Amounts classified as marketable securities, Estimated Fair Value	16,364
Level 1 [Member] \| Money market funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost	3,495	10,845
Available-for-sale securities, Estimated Fair Value	3,495	$ 10,845
Level 1 [Member] \| U.S. Treasury securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost	1,594
Available-for-sale securities, Gross Unrealized Gains	1
Available-for-sale securities, Estimated Fair Value	1,595
Level 2 [Member] \| Repurchase agreements [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost	5,000
Available-for-sale securities, Estimated Fair Value	5,000
Level 2 [Member] \| U.S. corporate debt obligations [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost	5,155
Available-for-sale securities, Estimated Fair Value	5,155
Level 2 [Member] \| U.S. commercial paper [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost	11,412
Available-for-sale securities, Estimated Fair Value	$ 11,412

Marketable securities amortized cost.

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- Definition

Marketable securities gross unrealized gains.

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- 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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-Publisher FASB
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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).

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

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Amount of short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of investment in marketable security, classified as current.

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