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

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- References

No definition available.

+ Details

Name:	us-gaap_AccountingPoliciesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

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- 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