XML 62 R45.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Significant Accounting Policies - Additional Information (Detail) | 3 Months Ended
--- | ---
Mar. 31, 2018
Accounting Policies [Abstract] |
Cash and cash equivalents maturity period, maximum | 90 days

X
- References No definition available. + Details
Name: | us-gaap_AccountingPoliciesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Cash and cash equivalents criteria maturity period. + References No definition available. + Details
Name: | wetf_CashAndCashEquivalentsCriteriaMaturityPeriod
Namespace Prefix: | wetf_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration