XML 45 R30.htm IDEA: XBRL DOCUMENT
v3.4.0.3

Investments and Fair Value Measurements - Schedule of Investments (Detail) - USD ($) $ in Thousands | Mar. 31, 2016 | Dec. 31, 2015
--- | --- | ---
Schedule of Held-to-maturity Securities [Line Items] |  |
Held-to-Maturity debt instruments | $ 22,581 | $ 23,689
Federal Agency [Member] |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Held-to-Maturity debt instruments | $ 22,581 | $ 23,689

X
- Definition Amount before other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity. + References No definition available. + Details
Name: | us-gaap_HeldToMaturitySecuritiesAmortizedCostBeforeOtherThanTemporaryImpairment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- 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. + Details
Name: | us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_DebtSecurityAxis=wetf_FederalAgencyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |