This item represents the deferred credit for an incentive or inducement received by a lessee from a lessor, in order to motivate the lessee to enter the lease agreement, which incentive or inducement is to be recognized as a reduction of rental expense over the lease term.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Lease Incentive

-URI http://asc.fasb.org/extlink&oid=6516590

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 55

-Paragraph 3

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

-Topic 840

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-Section 25

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+ Details

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

- Definition

Amount of rent expense incurred for leased assets, including but not limited to, furniture and equipment, that is not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

+ References

No definition available.

+ Details

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

- Definition

Date which lease or group of leases is set to expire, in CCYY-MM-DD format.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

This item represents a receivable for an incentive or inducement contractually stipulated between parties to a lease whereby the lessor has committed to provide the entity (lessee) with a cash payment as inducement to enter the lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 25

-Paragraph 2

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Balance Type:	debit
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- Definition

Term of the lessee's leasing arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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

- Definition

Letters of credit decreased amount.

+ References

No definition available.

+ Details

Name:	wetf_LettersOfCreditDecreasedAmount
Namespace Prefix:	wetf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Operating Lease Agreement Date

+ References

No definition available.

+ Details

Name:	wetf_OperatingLeaseAgreementDate
Namespace Prefix:	wetf_
Data Type:	xbrli:gYearMonthItemType
Balance Type:	na
Period Type:	duration

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Commitments and Contingencies - Additional Information (Detail) ¥ in Thousands, £ in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jul. 31, 2015 GBP (£)	Jul. 31, 2015 USD ($)	May. 31, 2015 USD ($)	May. 31, 2015 JPY (¥)	Dec. 31, 2014 USD ($)	Aug. 31, 2013 USD ($)
Loss Contingencies [Line Items]
Operating leases expenses	$ 829	$ 768	$ 1,623	$ 1,594
Period in which U.S. office lease expires				Jan. 01, 2014
New lease agreement term				16 years
New lease agreement date				2013-08
Lease incentives received including for deferred rent period										$ 3,223
Leasehold improvement allowance	$ 509		509						$ 509	$ 3,223
Stand by letter of credit decreased			$ 1,384
Japan [Member]
Loss Contingencies [Line Items]
New lease agreement term			3 years
New lease agreement date			2015-05
Lease incentives received including for deferred rent period							$ 85	¥ 10,440
U.K. [Member]
Loss Contingencies [Line Items]
New lease agreement term			5 years
New lease agreement date			2015-07
U.K. [Member] \| Subsequent Events [Member]
Loss Contingencies [Line Items]
Lease incentives received including for deferred rent period					£ 26	$ 41