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v3.20.2

Fair Value Measurements - Additional Information (Detail) | 9 Months Ended
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Sep. 30, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
Liquid investments, original maturities | 90 days

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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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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Cash equivalents maturity period. + References No definition available. + Details
Name: | wetf_CashEquivalentsMaturityPeriod
Namespace Prefix: | wetf_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration