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Related Party Transactions - Additional Information (Detail) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2021 | Dec. 31, 2020
Related Party Transaction [Line Items] |  |
Losses related to certain WisdomTree ETFs | $ 384 | $ 290
WisdomTree ETF [Member] |  |
Related Party Transaction [Line Items] |  |
Investment | $ 23,626 | $ 23,932

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