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Subsequent Events - Additional Information (Detail) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017
Subsequent Event [Line Items] |  |  |  |
Operating income (loss) | $ 14,531 | $ 15,039 | $ 27,752 | $ 28,629
WisdomTree Japan [Member] |  |  |  |
Subsequent Event [Line Items] |  |  |  |
Operating income (loss) | $ (1,125) | $ (1,232) | $ (2,357) | $ (2,365)

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- Definition The net result for the period of deducting operating expenses from operating revenues. + References No definition available. + Details
Name: | us-gaap_OperatingIncomeLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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- Definition Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event. + References No definition available. + Details
Name: | us-gaap_SubsequentEventLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=wetf_WisdomTreeJapanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |