Securities Owned - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Trading gains and losses on securities owned	$ (272)	$ 324	$ (833)	$ 105

Unrealized profit and loss on trading securities held at the reporting date.

No definition available.

Name:	wetf_UnrealizedProfitAndLossOnTradingSecuritiesHeldAtTheReportingDate
Namespace Prefix:	wetf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration