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Significant Accounting Policies - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified | 12 Months Ended | 9 Months Ended
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Dec. 31, 2014 Segment Financial_Institution | Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2014
Related Party Transaction [Line Items] |  |  |  |
Cash and cash equivalents maturity period, maximum | 90 days |  |  |
Number of financial institutions | 1wetf_NumberOfFinancialInstitutions |  |  | 1wetf_NumberOfFinancialInstitutions
Accounts receivable related-party | $ 17,288us-gaap_AccountsReceivableRelatedParties | $ 14,791us-gaap_AccountsReceivableRelatedParties |  | $ 17,288us-gaap_AccountsReceivableRelatedParties
ETF advisory fee revenue | 182,816us-gaap_InvestmentAdvisoryFees | 148,594us-gaap_InvestmentAdvisoryFees | 84,024us-gaap_InvestmentAdvisoryFees |
Joint venture agreement date | Jan. 01, 2013 |  |  |
Marketing fees | 594us-gaap_MarketingExpense | 1,368us-gaap_MarketingExpense | 806us-gaap_MarketingExpense |
Number of operating segments | 1us-gaap_NumberOfOperatingSegments |  |  |
Boost Issuer PLC [Member] |  |  |  |
Related Party Transaction [Line Items] |  |  |  |
ETF advisory fee revenue |  |  |  | 829us-gaap_InvestmentAdvisoryFees / dei_LegalEntityAxis = wetf_BoostIssuerPlcMember
WisdomTree Trust [Member] |  |  |  |
Related Party Transaction [Line Items] |  |  |  |
ETF advisory fee revenue | $ 181,987us-gaap_InvestmentAdvisoryFees / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = wetf_WisdomtreeTrustMember | $ 148,594us-gaap_InvestmentAdvisoryFees / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = wetf_WisdomtreeTrustMember | $ 84,024us-gaap_InvestmentAdvisoryFees / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = wetf_WisdomtreeTrustMember |

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- Definition For an unclassified balance sheet, amount of receivables arising from transactions with related parties. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(k)(1)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39622-107864 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.(a),3) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39603-107864 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 3 -Subparagraph a -Article 5 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 08 -Paragraph k -Subparagraph 1 -Article 4 Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 3 -Article 7 + Details
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