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Investments - Details of Investments Carried at Cost (Detail) - USD ($) $ in Thousands | Dec. 31, 2019 | Dec. 27, 2019 | Dec. 31, 2018
--- | --- | --- | ---
Investment [Line Items] |  |  |
Investments | $ 11,192 |  | $ 28,080
Advisor Engine [Member] | Convertible Preferred Stock [Member] |  |  |
Investment [Line Items] |  |  |
Investments |  |  | 25,000
Thesys Group, Inc [Member] |  |  |
Investment [Line Items] |  |  |
Investments | 3,080 |  | $ 3,080
Securrency Inc [Member] | Convertible Preferred Stock [Member] |  |  |
Investment [Line Items] |  |  |
Investments | $ 8,112 | $ 8,112 |

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- Definition Amount, after adjustment, of cost-method investment. Adjustments include, but are not limited to, dividends received in excess of earnings after date of investment that are considered a return of investment and other than temporary impairments. + References No definition available. + Details
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- Definition Line items represent reporting 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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- Details
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