Significant Accounting Policies - Additional Information (Detail)	6 Months Ended
Jun. 30, 2018
Accounting Policies [Abstract]
Cash and cash equivalents maturity period, maximum	90 days

Cash and cash equivalents criteria maturity period.

No definition available.

Name:	wetf_CashAndCashEquivalentsCriteriaMaturityPeriod
Namespace Prefix:	wetf_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration