Number of shares of equity interests issued or issuable to acquire entity.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)(4)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

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- Definition

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

+ References

No definition available.

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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.

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- 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

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- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any 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

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- 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

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- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

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- Definition

The cash outflow to acquire asset without physical form usually arising from contractual or other legal rights, excluding goodwill.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3213-108585

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- Definition

Committed senior secured debt financing in support of the ETFS pending acquisition.

+ References

No definition available.

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Balance Type:	credit
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- Definition

Common Stock Shares Issuable Upon Conversion Of Convertible Preferred Stock

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No definition available.

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- Definition

The anticipated cash consideration to be paid from cash on hand associated with a pending business acquisition.

+ References

No definition available.

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Namespace Prefix:	wetf_
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Balance Type:	debit
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- Definition

Organization Consolidation And Presentation Of Financial Statements [Line Items]

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Organizational and Description of Business - Additional Information (Detail) - USD ($)		12 Months Ended
	Nov. 13, 2017	Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Business acquisition, cash paid		$ 2,132,000
ETFS Pending Acquisition Business [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Business acquisition, cash paid	$ 253,000,000
Consideration to be paid from cash on hand	$ 53,000,000
Business acquisition, number of common shares that the preferred stock is convertible into	14,750,000
Debt instrument, interest rate		Credit facilities will accrue at a rate per annum of up to LIBOR plus 2.00% (commencing at LIBOR plus 1.75%) or up to ABR plus 1.00% (commencing at ABR plus 0.75%), subject to step-downs based on our ratio of debt to adjusted earnings before
ETFS Pending Acquisition Business [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Debt instrument, Variable rate basis		LIBOR
Debt instrument, interest rate	1.75%
ETFS Pending Acquisition Business [Member] \| Alternate Base Rate [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Debt instrument, Variable rate basis		ABR
Debt instrument, interest rate	0.75%
ETFS Pending Acquisition Business [Member] \| Maximum [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Debt instrument, interest rate	2.00%
ETFS Pending Acquisition Business [Member] \| Maximum [Member] \| Alternate Base Rate [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Debt instrument, interest rate	1.00%
ETFS Pending Acquisition Business [Member] \| Series A Non-Voting Convertible Preferred Stock [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Business acquisition, number of shares to be issued	14,750
ETFS Pending Acquisition Business [Member] \| Secured Debt [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Committed senior secured debt financing	$ 250,000,000
ETFS Pending Acquisition Business [Member] \| Revolving Credit Facility [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Revolving credit facility maximum borrowing capacity	$ 50,000,000
Commitment fee percentage	0.50%
ETFS Pending Acquisition Business [Member] \| Term Loan Facility [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Borrowing under term loan facility	$ 200,000,000
ETFS Pending Acquisition Business [Member] \| Common Stock [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Business acquisition, number of shares to be issued	15,250,000