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Securities Owned - Additional Information (Detail) - USD ($) $ in Thousands | 3 Months Ended
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Mar. 31, 2021 | Mar. 31, 2020
Trading losses on securities owned | $ 561 | $ 196

X
- Definition Unrealized profit and loss on trading securities held at the reporting date. + References No definition available. + Details
Name: | wetf_UnrealizedProfitAndLossOnTradingSecuritiesHeldAtTheReportingDate
Namespace Prefix: | wetf_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration