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Variable Interest Entity - Summary of Information about Variable Interests (Parenthetical) (Detail) $ in Thousands | 12 Months Ended
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Dec. 31, 2019 USD ($)
Variable Interest Entity [Line Items] |
Impairment of AdvisorEngine Financial Interests | $ 30,138

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

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- Definition Impairment of AdvisorEngine financial interests + References No definition available. + Details
Name: | wetf_VariableInterestEntityNonconsolidatedCarryingAmountAssetsImpairment
Namespace Prefix: | wetf_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration