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

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