Available-for-Sale Securities - Additional Information (Detail)	3 Months Ended
Mar. 31, 2019 USD ($) Security	Dec. 31, 2018 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Number of available-for-sale securities in unrealized loss positions for less than twelve months \| Security	12
Other-than-temporary declines in the value of any available-for-sale securities	$ 0
Maximum maturity of available-for-sale debt securities	1 year
Available-for-sale Securities [Member] \| Money Market Funds and Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents	$ 10,600,000	$ 17,200,000

Available for sale securities maximum maturity period.

No definition available.

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- Definition

Number of investment positions in available-for-sale investments in a continuous unrealized loss position for less than one year or normal operating cycle, if longer, for which an other-than-temporary impairment (OTTI) has not been recognized in the income statement.

+ References

No definition available.

+ Details

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- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.1)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

The amount by which the fair value of an investment in debt and equity securities categorized as Available-for-sale is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

+ References

No definition available.

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- Definition

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.

+ References

No definition available.

+ Details

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