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Marketable Investments - Additional Information (Detail) $ in Millions | 12 Months Ended
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Dec. 31, 2018 USD ($)
Other Income, Net [Member] |
Schedule of Available-for-sale Securities [Line Items] |
Realized losses on sales of available-for-sale securities | $ 0.2

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- Definition Amount of realized loss on 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 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27357-111563 + Details
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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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- Details
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