Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

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

- Definition

Description of the interest rate as being fixed or variable, and, if variable, identification of the index or rate on which the interest rate is based and the number of points or percentage added to that index or rate to set the rate, and other pertinent information, such as frequency of rate resets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3255-108585

+ Details

Name:	us-gaap_ProceedsFromIssuanceOfLongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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

- Definition

Debt Instrument Fee Percentage

+ References

No definition available.

+ Details

Name:	wetf_DebtInstrumentFeePercentage
Namespace Prefix:	wetf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_BusinessAcquisitionAxis=wetf_AcquisitionOfEtfsBusinessMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=wetf_TermLoanFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Subsequent Events - Senior Secured Debt Financing - Additional Information (Detail) - Acquisition of ETFS Business [Member] - USD ($)		3 Months Ended
	Apr. 11, 2018	Mar. 31, 2018
Term Loan Facility [Member]
Subsequent Event [Line Items]
Debt instrument, interest rate		Interest on the Term Loan accrues at a rate per annum equal to LIBOR, plus up to 2.00% (commencing at LIBOR, plus 1.75%)
Debt instrument, variable rate basis		LIBOR
Revolving Credit Facility [Member]
Subsequent Event [Line Items]
Debt instrument, interest rate		Revolver accrues at a rate per annum equal to LIBOR, plus up to 1.50% (commencing at LIBOR, plus 1.25%)
Revolving credit facility maximum borrowing capacity	$ 50,000,000
Subsequent Event [Member] \| Term Loan Facility [Member]
Subsequent Event [Line Items]
Proceeds from term loan	$ 200,000,000
Subsequent Event [Member] \| Term Loan Facility [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Subsequent Event [Line Items]
Debt instrument, interest rate	1.75%
Subsequent Event [Member] \| Term Loan Facility [Member] \| Maximum [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Subsequent Event [Line Items]
Debt instrument, interest rate	2.00%
Subsequent Event [Member] \| Revolving Credit Facility [Member]
Subsequent Event [Line Items]
Revolving credit facility maximum borrowing capacity	$ 50,000,000
Debt instrument, facility fee rate	0.50%
Subsequent Event [Member] \| Revolving Credit Facility [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Subsequent Event [Line Items]
Debt instrument, interest rate	1.25%
Subsequent Event [Member] \| Revolving Credit Facility [Member] \| Maximum [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Subsequent Event [Line Items]
Debt instrument, interest rate	1.50%