<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.22.0.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>353</ContextCount>
  <ElementCount>623</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>112</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>12</UnitCount>
  <MyReports>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>00090 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>00100 - Statement - CONSOLIDATED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/StatementConsolidatedBalanceSheets</Role>
      <ShortName>CONSOLIDATED BALANCE SHEETS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>00105 - Statement - CONSOLIDATED BALANCE SHEETS (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/StatementConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>CONSOLIDATED BALANCE SHEETS (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>00200 - Statement - CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/StatementConsolidatedStatementsOfComprehensiveIncome</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>00300 - Statement - CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/StatementConsolidatedStatementsOfChangesInShareholdersEquity</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>00400 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/StatementConsolidatedStatementsOfCashFlows</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF CASH FLOWS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>10101 - Disclosure - GENERAL INFORMATION, ORGANIZATION AND PRINCIPAL ACTIVITIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureGeneralInformationOrganizationAndPrincipalActivities</Role>
      <ShortName>GENERAL INFORMATION, ORGANIZATION AND PRINCIPAL ACTIVITIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>10201 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureSignificantAccountingPolicies</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>10301 - Disclosure - FINANCIAL ASSETS AND FINANCIAL LIABILITIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureFinancialAssetsAndFinancialLiabilities</Role>
      <ShortName>FINANCIAL ASSETS AND FINANCIAL LIABILITIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>10401 - Disclosure - SHORT-TERM INVESTMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureShortTermInvestments</Role>
      <ShortName>SHORT-TERM INVESTMENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>10501 - Disclosure - LEASE</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureLease</Role>
      <ShortName>LEASE</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>10601 - Disclosure - LOANS AND ADVANCES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureLoansAndAdvances</Role>
      <ShortName>LOANS AND ADVANCES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>10701 - Disclosure - PROPERTY AND EQUIPMENT, NET</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosurePropertyAndEquipmentNet</Role>
      <ShortName>PROPERTY AND EQUIPMENT, NET</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>10801 - Disclosure - INTANGIBLE ASSETS, NET</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureIntangibleAssetsNet</Role>
      <ShortName>INTANGIBLE ASSETS, NET</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>10901 - Disclosure - LONG-TERM INVESTMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureLongTermInvestments</Role>
      <ShortName>LONG-TERM INVESTMENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>11001 - Disclosure - OTHER ASSETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureOtherAssets</Role>
      <ShortName>OTHER ASSETS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>11101 - Disclosure - BORROWINGS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureBorrowings</Role>
      <ShortName>BORROWINGS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>11201 - Disclosure - ACCRUED EXPENSES AND OTHER LIABILITIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureAccruedExpensesAndOtherLiabilities</Role>
      <ShortName>ACCRUED EXPENSES AND OTHER LIABILITIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>11301 - Disclosure - ORDINARY SHARES AND TREASURY STOCK</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureOrdinarySharesAndTreasuryStock</Role>
      <ShortName>ORDINARY SHARES AND TREASURY STOCK</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>11401 - Disclosure - RESTRICTED NET ASSETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureRestrictedNetAssets</Role>
      <ShortName>RESTRICTED NET ASSETS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>11501 - Disclosure - REDEEMABLE CONVERTIBLE PREFERRED SHARES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureRedeemableConvertiblePreferredShares</Role>
      <ShortName>REDEEMABLE CONVERTIBLE PREFERRED SHARES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>11601 - Disclosure - SHARE-BASED COMPENSATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureShareBasedCompensation</Role>
      <ShortName>SHARE-BASED COMPENSATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>11701 - Disclosure - NET INCOME PER SHARE</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureNetIncomePerShare</Role>
      <ShortName>NET INCOME PER SHARE</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>11801 - Disclosure - COLLATERALIZED TRANSACTIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureCollateralizedTransactions</Role>
      <ShortName>COLLATERALIZED TRANSACTIONS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>11901 - Disclosure - BROKERAGE COMMISSION AND HANDLING CHARGE INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureBrokerageCommissionAndHandlingChargeIncome</Role>
      <ShortName>BROKERAGE COMMISSION AND HANDLING CHARGE INCOME</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>12001 - Disclosure - INTEREST INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureInterestIncome</Role>
      <ShortName>INTEREST INCOME</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>12101 - Disclosure - OTHER INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureOtherIncome</Role>
      <ShortName>OTHER INCOME</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>12201 - Disclosure - BROKERAGE COMMISSION AND HANDLING CHARGE EXPENSES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureBrokerageCommissionAndHandlingChargeExpenses</Role>
      <ShortName>BROKERAGE COMMISSION AND HANDLING CHARGE EXPENSES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>12301 - Disclosure - INTEREST EXPENSES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureInterestExpenses</Role>
      <ShortName>INTEREST EXPENSES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>12401 - Disclosure - PROCESSING AND SERVICING COSTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureProcessingAndServicingCosts</Role>
      <ShortName>PROCESSING AND SERVICING COSTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>12501 - Disclosure - NON-INTEREST COST AND EXPENSES BY NATURE</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureNonInterestCostAndExpensesByNature</Role>
      <ShortName>NON-INTEREST COST AND EXPENSES BY NATURE</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>12601 - Disclosure - TAXATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureTaxation</Role>
      <ShortName>TAXATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>12701 - Disclosure - DEFINED CONTRIBUTION PLAN</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureDefinedContributionPlan</Role>
      <ShortName>DEFINED CONTRIBUTION PLAN</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>12801 - Disclosure - REGULATORY REQUIREMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureRegulatoryRequirements</Role>
      <ShortName>REGULATORY REQUIREMENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>12901 - Disclosure - COMMITMENTS AND CONTINGENCIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureCommitmentsAndContingencies</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>13001 - Disclosure - RELATED PARTY BALANCES AND TRANSACTIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureRelatedPartyBalancesAndTransactions</Role>
      <ShortName>RELATED PARTY BALANCES AND TRANSACTIONS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>13101 - Disclosure - SUBSEQUENT EVENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureSubsequentEvents</Role>
      <ShortName>SUBSEQUENT EVENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>20202 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureSignificantAccountingPoliciesPolicies</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>30103 - Disclosure - ORGANIZATION AND PRINCIPAL ACTIVITIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureOrganizationAndPrincipalActivitiesTables</Role>
      <ShortName>ORGANIZATION AND PRINCIPAL ACTIVITIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>30203 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureSignificantAccountingPoliciesTables</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureSignificantAccountingPolicies</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>30303 - Disclosure - FINANCIAL ASSETS AND FINANCIAL LIABILITIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureFinancialAssetsAndFinancialLiabilitiesTables</Role>
      <ShortName>FINANCIAL ASSETS AND FINANCIAL LIABILITIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureFinancialAssetsAndFinancialLiabilities</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>30403 - Disclosure - SHORT-TERM INVESTMENTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureShortTermInvestmentsTables</Role>
      <ShortName>SHORT-TERM INVESTMENTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureShortTermInvestments</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>30503 - Disclosure - LEASE (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureLeaseTables</Role>
      <ShortName>LEASE (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureLease</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>30603 - Disclosure - LOANS AND ADVANCES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureLoansAndAdvancesTables</Role>
      <ShortName>LOANS AND ADVANCES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureLoansAndAdvances</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>30703 - Disclosure - PROPERTY AND EQUIPMENT, NET (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosurePropertyAndEquipmentNetTables</Role>
      <ShortName>PROPERTY AND EQUIPMENT, NET (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosurePropertyAndEquipmentNet</ParentRole>
      <Position>45</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>30803 - Disclosure - INTANGIBLE ASSETS, NET (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureIntangibleAssetsNetTables</Role>
      <ShortName>INTANGIBLE ASSETS, NET (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureIntangibleAssetsNet</ParentRole>
      <Position>46</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>30903 - Disclosure - LONG-TERM INVESTMENTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureLongTermInvestmentsTables</Role>
      <ShortName>LONG-TERM INVESTMENTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureLongTermInvestments</ParentRole>
      <Position>47</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>31003 - Disclosure - OTHER ASSETS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureOtherAssetsTables</Role>
      <ShortName>OTHER ASSETS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureOtherAssets</ParentRole>
      <Position>48</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>31103 - Disclosure - BORROWINGS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureBorrowingsTables</Role>
      <ShortName>BORROWINGS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureBorrowings</ParentRole>
      <Position>49</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>31203 - Disclosure - ACCRUED EXPENSES AND OTHER LIABILITIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureAccruedExpensesAndOtherLiabilitiesTables</Role>
      <ShortName>ACCRUED EXPENSES AND OTHER LIABILITIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureAccruedExpensesAndOtherLiabilities</ParentRole>
      <Position>50</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>31603 - Disclosure - SHARE-BASED COMPENSATION (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureShareBasedCompensationTables</Role>
      <ShortName>SHARE-BASED COMPENSATION (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureShareBasedCompensation</ParentRole>
      <Position>51</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>31703 - Disclosure - NET INCOME PER SHARE (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureNetIncomePerShareTables</Role>
      <ShortName>NET INCOME PER SHARE (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureNetIncomePerShare</ParentRole>
      <Position>52</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>31803 - Disclosure - COLLATERALIZED TRANSACTIONS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureCollateralizedTransactionsTables</Role>
      <ShortName>COLLATERALIZED TRANSACTIONS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureCollateralizedTransactions</ParentRole>
      <Position>53</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>31903 - Disclosure - BROKERAGE COMMISSION AND HANDLING CHARGE INCOME (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureBrokerageCommissionAndHandlingChargeIncomeTables</Role>
      <ShortName>BROKERAGE COMMISSION AND HANDLING CHARGE INCOME (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureBrokerageCommissionAndHandlingChargeIncome</ParentRole>
      <Position>54</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>32003 - Disclosure - INTEREST INCOME (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureInterestIncomeTables</Role>
      <ShortName>INTEREST INCOME (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureInterestIncome</ParentRole>
      <Position>55</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>32103 - Disclosure - OTHER INCOME (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureOtherIncomeTables</Role>
      <ShortName>OTHER INCOME (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureOtherIncome</ParentRole>
      <Position>56</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>32203 - Disclosure - BROKERAGE COMMISSION AND HANDLING CHARGE EXPENSES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureBrokerageCommissionAndHandlingChargeExpensesTables</Role>
      <ShortName>BROKERAGE COMMISSION AND HANDLING CHARGE EXPENSES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureBrokerageCommissionAndHandlingChargeIncome</ParentRole>
      <Position>57</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>32303 - Disclosure - INTEREST EXPENSES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureInterestExpensesTables</Role>
      <ShortName>INTEREST EXPENSES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureInterestExpenses</ParentRole>
      <Position>58</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>32403 - Disclosure - PROCESSING AND SERVICING COSTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureProcessingAndServicingCostsTables</Role>
      <ShortName>PROCESSING AND SERVICING COSTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureProcessingAndServicingCosts</ParentRole>
      <Position>59</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>32503 - Disclosure - NON-INTEREST COST AND EXPENSES BY NATURE (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureNonInterestCostAndExpensesByNatureTables</Role>
      <ShortName>NON-INTEREST COST AND EXPENSES BY NATURE (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureNonInterestCostAndExpensesByNature</ParentRole>
      <Position>60</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>32603 - Disclosure - TAXATION (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureTaxationTables</Role>
      <ShortName>TAXATION (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureTaxation</ParentRole>
      <Position>61</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>32803 - Disclosure - REGULATORY REQUIREMENTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureRegulatoryRequirementsTables</Role>
      <ShortName>REGULATORY REQUIREMENTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureRegulatoryRequirements</ParentRole>
      <Position>62</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>33003 - Disclosure - RELATED PARTY BALANCES AND TRANSACTIONS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureRelatedPartyBalancesAndTransactionsTables</Role>
      <ShortName>RELATED PARTY BALANCES AND TRANSACTIONS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureRelatedPartyBalancesAndTransactions</ParentRole>
      <Position>63</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>40101 - Disclosure - GENERAL INFORMATION, ORGANIZATION AND PRINCIPAL ACTIVITIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureGeneralInformationOrganizationAndPrincipalActivitiesDetails</Role>
      <ShortName>GENERAL INFORMATION, ORGANIZATION AND PRINCIPAL ACTIVITIES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureGeneralInformationOrganizationAndPrincipalActivities</ParentRole>
      <Position>64</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>40201 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Exclusive Option Agreement (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureSignificantAccountingPoliciesExclusiveOptionAgreementDetails</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES - Exclusive Option Agreement (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>65</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>40202 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - VIE Companies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureSignificantAccountingPoliciesVieCompaniesDetails</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES - VIE Companies (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>40203 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Transactions between the VIE and other entities in the consolidated group (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureSignificantAccountingPoliciesTransactionsBetweenVieAndOtherEntitiesInConsolidatedGroupDetails</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES - Transactions between the VIE and other entities in the consolidated group (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>40204 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Convenience Translation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureSignificantAccountingPoliciesConvenienceTranslationDetails</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES - Convenience Translation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>40205 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Current Expected Credit Losses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureSignificantAccountingPoliciesCurrentExpectedCreditLossesDetails</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES - Current Expected Credit Losses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>69</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>40206 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Leases (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureSignificantAccountingPoliciesLeasesDetails</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES - Leases (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>70</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>40207 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Property and Equipment, net (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureSignificantAccountingPoliciesPropertyAndEquipmentNetDetails</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES - Property and Equipment, net (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>71</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>40208 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Intangible Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureSignificantAccountingPoliciesIntangibleAssetsDetails</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES - Intangible Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>72</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>40209 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Long-term investments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureSignificantAccountingPoliciesLongTermInvestmentsDetails</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES - Long-term investments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>73</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>40210 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Impairment of Long-lived Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureSignificantAccountingPoliciesImpairmentOfLongLivedAssetsDetails</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES - Impairment of Long-lived Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>74</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>40211 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Customer loyalty program (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureSignificantAccountingPoliciesCustomerLoyaltyProgramDetails</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES - Customer loyalty program (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>75</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>40212 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Share-Based Compensation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureSignificantAccountingPoliciesShareBasedCompensationDetails</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES - Share-Based Compensation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>76</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>40213 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Taxation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureSignificantAccountingPoliciesTaxationDetails</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES - Taxation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>77</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>40214 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Segment Reporting (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureSignificantAccountingPoliciesSegmentReportingDetails</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES - Segment Reporting (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>78</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>40215 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Significant Risks and Uncertainties (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureSignificantAccountingPoliciesSignificantRisksAndUncertaintiesDetails</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES - Significant Risks and Uncertainties (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>79</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>40301 - Disclosure - FINANCIAL ASSETS AND FINANCIAL LIABILITIES - Financial Assets and Liabilities Measured at value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureFinancialAssetsAndFinancialLiabilitiesFinancialAssetsAndLiabilitiesMeasuredAtValueDetails</Role>
      <ShortName>FINANCIAL ASSETS AND FINANCIAL LIABILITIES - Financial Assets and Liabilities Measured at value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>80</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>40302 - Disclosure - FINANCIAL ASSETS AND FINANCIAL LIABILITIES - Transfers Between Level 1 and Level 2 (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureFinancialAssetsAndFinancialLiabilitiesTransfersBetweenLevel1AndLevel2Details</Role>
      <ShortName>FINANCIAL ASSETS AND FINANCIAL LIABILITIES - Transfers Between Level 1 and Level 2 (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>81</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>40303 - Disclosure - FINANCIAL ASSETS AND FINANCIAL LIABILITIES - Financial Assets and Liabilities Not Measured at Fair Value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureFinancialAssetsAndFinancialLiabilitiesFinancialAssetsAndLiabilitiesNotMeasuredAtFairValueDetails</Role>
      <ShortName>FINANCIAL ASSETS AND FINANCIAL LIABILITIES - Financial Assets and Liabilities Not Measured at Fair Value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>82</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>40304 - Disclosure - FINANCIAL ASSETS AND FINANCIAL LIABILITIES - Netting of Financial Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureFinancialAssetsAndFinancialLiabilitiesNettingOfFinancialAssetsDetails</Role>
      <ShortName>FINANCIAL ASSETS AND FINANCIAL LIABILITIES - Netting of Financial Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>83</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>40305 - Disclosure - FINANCIAL ASSETS AND FINANCIAL LIABILITIES - Netting of Financial Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureFinancialAssetsAndFinancialLiabilitiesNettingOfFinancialLiabilitiesDetails</Role>
      <ShortName>FINANCIAL ASSETS AND FINANCIAL LIABILITIES - Netting of Financial Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>84</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>40401 - Disclosure - SHORT-TERM INVESTMENTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureShortTermInvestmentsDetails</Role>
      <ShortName>SHORT-TERM INVESTMENTS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureShortTermInvestmentsTables</ParentRole>
      <Position>85</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>40402 - Disclosure - SHORT-TERM INVESTMENTS - Additional information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureShortTermInvestmentsAdditionalInformationDetails</Role>
      <ShortName>SHORT-TERM INVESTMENTS - Additional information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>86</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R87.htm</HtmlFileName>
      <LongName>40501 - Disclosure - LEASE - Balances reported in the consolidated balance sheets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureLeaseBalancesReportedInConsolidatedBalanceSheetsDetails</Role>
      <ShortName>LEASE - Balances reported in the consolidated balance sheets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>87</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R88.htm</HtmlFileName>
      <LongName>40502 - Disclosure - LEASE - Operating lease cost reported in the consolidated statements (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureLeaseOperatingLeaseCostReportedInConsolidatedStatementsDetails</Role>
      <ShortName>LEASE - Operating lease cost reported in the consolidated statements (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>88</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R89.htm</HtmlFileName>
      <LongName>40503 - Disclosure - LEASE - Undiscounted cash flows of the Group's leases (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureLeaseUndiscountedCashFlowsOfGroupSLeasesDetails</Role>
      <ShortName>LEASE - Undiscounted cash flows of the Group's leases (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>89</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R90.htm</HtmlFileName>
      <LongName>40601 - Disclosure - LOANS AND ADVANCES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureLoansAndAdvancesDetails</Role>
      <ShortName>LOANS AND ADVANCES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureLoansAndAdvancesTables</ParentRole>
      <Position>90</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R91.htm</HtmlFileName>
      <LongName>40701 - Disclosure - PROPERTY AND EQUIPMENT, NET (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosurePropertyAndEquipmentNetDetails</Role>
      <ShortName>PROPERTY AND EQUIPMENT, NET (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosurePropertyAndEquipmentNetTables</ParentRole>
      <Position>91</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R92.htm</HtmlFileName>
      <LongName>40801 - Disclosure - INTANGIBLE ASSETS, NET (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureIntangibleAssetsNetDetails</Role>
      <ShortName>INTANGIBLE ASSETS, NET (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureIntangibleAssetsNetTables</ParentRole>
      <Position>92</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R93.htm</HtmlFileName>
      <LongName>40901 - Disclosure - LONG-TERM INVESTMENTS - equity method investments and equity investments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureLongTermInvestmentsEquityMethodInvestmentsAndEquityInvestmentsDetails</Role>
      <ShortName>LONG-TERM INVESTMENTS - equity method investments and equity investments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>93</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R94.htm</HtmlFileName>
      <LongName>40902 - Disclosure - LONG-TERM INVESTMENTS Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureLongTermInvestmentsAdditionalInformationDetails</Role>
      <ShortName>LONG-TERM INVESTMENTS Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>94</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R95.htm</HtmlFileName>
      <LongName>41001 - Disclosure - OTHER ASSETS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureOtherAssetsDetails</Role>
      <ShortName>OTHER ASSETS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureOtherAssetsTables</ParentRole>
      <Position>95</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R96.htm</HtmlFileName>
      <LongName>41101 - Disclosure - BORROWINGS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureBorrowingsDetails</Role>
      <ShortName>BORROWINGS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureBorrowingsTables</ParentRole>
      <Position>96</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R97.htm</HtmlFileName>
      <LongName>41102 - Disclosure - BORROWINGS - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureBorrowingsAdditionalInformationDetails</Role>
      <ShortName>BORROWINGS - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>97</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R98.htm</HtmlFileName>
      <LongName>41201 - Disclosure - ACCRUED EXPENSES AND OTHER LIABILITIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureAccruedExpensesAndOtherLiabilitiesDetails</Role>
      <ShortName>ACCRUED EXPENSES AND OTHER LIABILITIES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureAccruedExpensesAndOtherLiabilitiesTables</ParentRole>
      <Position>98</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R99.htm</HtmlFileName>
      <LongName>41301 - Disclosure - ORDINARY SHARES AND TREASURY STOCK (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureOrdinarySharesAndTreasuryStockDetails</Role>
      <ShortName>ORDINARY SHARES AND TREASURY STOCK (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureOrdinarySharesAndTreasuryStock</ParentRole>
      <Position>99</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R100.htm</HtmlFileName>
      <LongName>41401 - Disclosure - RESTRICTED NET ASSETS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureRestrictedNetAssetsDetails</Role>
      <ShortName>RESTRICTED NET ASSETS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureRestrictedNetAssets</ParentRole>
      <Position>100</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R101.htm</HtmlFileName>
      <LongName>41501 - Disclosure - REDEEMABLE CONVERTIBLE PREFERRED SHARES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureRedeemableConvertiblePreferredSharesDetails</Role>
      <ShortName>REDEEMABLE CONVERTIBLE PREFERRED SHARES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureRedeemableConvertiblePreferredShares</ParentRole>
      <Position>101</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R102.htm</HtmlFileName>
      <LongName>41601 - Disclosure - SHARE-BASED COMPENSATION - Share-based compensation expenses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureShareBasedCompensationShareBasedCompensationExpensesDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION - Share-based compensation expenses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>102</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R103.htm</HtmlFileName>
      <LongName>41602 - Disclosure - SHARE-BASED COMPENSATION - Share Options (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureShareBasedCompensationShareOptionsDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION - Share Options (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>103</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R104.htm</HtmlFileName>
      <LongName>41603 - Disclosure - SHARE-BASED COMPENSATION - Share Options Granted (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureShareBasedCompensationShareOptionsGrantedDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION - Share Options Granted (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>104</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R105.htm</HtmlFileName>
      <LongName>41604 - Disclosure - SHARE-BASED COMPENSATION - Fair value of options granted and compensation expenses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureShareBasedCompensationFairValueOfOptionsGrantedAndCompensationExpensesDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION - Fair value of options granted and compensation expenses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>105</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R106.htm</HtmlFileName>
      <LongName>41605 - Disclosure - SHARE-BASED COMPENSATION - Restricted Shares Plan (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureShareBasedCompensationRestrictedSharesPlanDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION - Restricted Shares Plan (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>106</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R107.htm</HtmlFileName>
      <LongName>41701 - Disclosure - NET INCOME PER SHARE (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureNetIncomePerShareDetails</Role>
      <ShortName>NET INCOME PER SHARE (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureNetIncomePerShareTables</ParentRole>
      <Position>107</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R108.htm</HtmlFileName>
      <LongName>41702 - Disclosure - NET INCOME PER SHARE - Computation of earnings per share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureNetIncomePerShareComputationOfEarningsPerShareDetails</Role>
      <ShortName>NET INCOME PER SHARE - Computation of earnings per share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>108</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R109.htm</HtmlFileName>
      <LongName>41703 - Disclosure - NET INCOME PER SHARE - Antidilutive securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureNetIncomePerShareAntidilutiveSecuritiesDetails</Role>
      <ShortName>NET INCOME PER SHARE - Antidilutive securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>109</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R110.htm</HtmlFileName>
      <LongName>41801 - Disclosure - COLLATERALIZED TRANSACTIONS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureCollateralizedTransactionsDetails</Role>
      <ShortName>COLLATERALIZED TRANSACTIONS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureCollateralizedTransactionsTables</ParentRole>
      <Position>110</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R111.htm</HtmlFileName>
      <LongName>41901 - Disclosure - BROKERAGE COMMISSION AND HANDLING CHARGE INCOME (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureBrokerageCommissionAndHandlingChargeIncomeDetails</Role>
      <ShortName>BROKERAGE COMMISSION AND HANDLING CHARGE INCOME (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureBrokerageCommissionAndHandlingChargeIncomeTables</ParentRole>
      <Position>111</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R112.htm</HtmlFileName>
      <LongName>42001 - Disclosure - INTEREST INCOME (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureInterestIncomeDetails</Role>
      <ShortName>INTEREST INCOME (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureInterestIncomeTables</ParentRole>
      <Position>112</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R113.htm</HtmlFileName>
      <LongName>42101 - Disclosure - OTHER INCOME (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureOtherIncomeDetails</Role>
      <ShortName>OTHER INCOME (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureOtherIncomeTables</ParentRole>
      <Position>113</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R114.htm</HtmlFileName>
      <LongName>42201 - Disclosure - BROKERAGE COMMISSION AND HANDLING CHARGE EXPENSES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureBrokerageCommissionAndHandlingChargeExpensesDetails</Role>
      <ShortName>BROKERAGE COMMISSION AND HANDLING CHARGE EXPENSES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureBrokerageCommissionAndHandlingChargeIncomeTables</ParentRole>
      <Position>114</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R115.htm</HtmlFileName>
      <LongName>42301 - Disclosure - INTEREST EXPENSES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureInterestExpensesDetails</Role>
      <ShortName>INTEREST EXPENSES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureInterestExpensesTables</ParentRole>
      <Position>115</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R116.htm</HtmlFileName>
      <LongName>42401 - Disclosure - PROCESSING AND SERVICING COSTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureProcessingAndServicingCostsDetails</Role>
      <ShortName>PROCESSING AND SERVICING COSTS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureProcessingAndServicingCostsTables</ParentRole>
      <Position>116</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R117.htm</HtmlFileName>
      <LongName>42501 - Disclosure - NON-INTEREST COST AND EXPENSES BY NATURE (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureNonInterestCostAndExpensesByNatureDetails</Role>
      <ShortName>NON-INTEREST COST AND EXPENSES BY NATURE (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureNonInterestCostAndExpensesByNatureTables</ParentRole>
      <Position>117</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R118.htm</HtmlFileName>
      <LongName>42601 - Disclosure - TAXATION - Income Tax - Applicable Tax Rates (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureTaxationIncomeTaxApplicableTaxRatesDetails</Role>
      <ShortName>TAXATION - Income Tax - Applicable Tax Rates (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>118</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R119.htm</HtmlFileName>
      <LongName>42602 - Disclosure - TAXATION - Composition of income tax expenses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureTaxationCompositionOfIncomeTaxExpensesDetails</Role>
      <ShortName>TAXATION - Composition of income tax expenses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>119</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R120.htm</HtmlFileName>
      <LongName>42603 - Disclosure - TAXATION - Tax Reconciliation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureTaxationTaxReconciliationDetails</Role>
      <ShortName>TAXATION - Tax Reconciliation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>120</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R121.htm</HtmlFileName>
      <LongName>42604 - Disclosure - TAXATION - Components of the deferred tax assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureTaxationComponentsOfDeferredTaxAssetsDetails</Role>
      <ShortName>TAXATION - Components of the deferred tax assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>121</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R122.htm</HtmlFileName>
      <LongName>42605 - Disclosure - TAXATION - Movement of Valuation Allowance (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureTaxationMovementOfValuationAllowanceDetails</Role>
      <ShortName>TAXATION - Movement of Valuation Allowance (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>122</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R123.htm</HtmlFileName>
      <LongName>42606 - Disclosure - TAXATION - Net operating loss carry forwards (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureTaxationNetOperatingLossCarryForwardsDetails</Role>
      <ShortName>TAXATION - Net operating loss carry forwards (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>123</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R124.htm</HtmlFileName>
      <LongName>42701 - Disclosure - DEFINED CONTRIBUTION PLAN (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureDefinedContributionPlanDetails</Role>
      <ShortName>DEFINED CONTRIBUTION PLAN (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureDefinedContributionPlan</ParentRole>
      <Position>124</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R125.htm</HtmlFileName>
      <LongName>42801 - Disclosure - REGULATORY REQUIREMENTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureRegulatoryRequirementsDetails</Role>
      <ShortName>REGULATORY REQUIREMENTS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureRegulatoryRequirementsTables</ParentRole>
      <Position>125</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R126.htm</HtmlFileName>
      <LongName>42901 - Disclosure - COMMITMENTS AND CONTINGENCIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureCommitmentsAndContingenciesDetails</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureCommitmentsAndContingencies</ParentRole>
      <Position>126</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R127.htm</HtmlFileName>
      <LongName>43001 - Disclosure - RELATED PARTY BALANCES AND TRANSACTIONS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureRelatedPartyBalancesAndTransactionsDetails</Role>
      <ShortName>RELATED PARTY BALANCES AND TRANSACTIONS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.futuholdings.com/role/DisclosureRelatedPartyBalancesAndTransactionsTables</ParentRole>
      <Position>127</Position>
    </Report>
    <Report instance="futu-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R128.htm</HtmlFileName>
      <LongName>43002 - Disclosure - RELATED PARTY BALANCES AND TRANSACTIONS - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.futuholdings.com/role/DisclosureRelatedPartyBalancesAndTransactionsAdditionalInformationDetails</Role>
      <ShortName>RELATED PARTY BALANCES AND TRANSACTIONS - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>128</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File doctype="20-F" original="futu-20211231x20f.htm">futu-20211231x20f.htm</File>
    <File>futu-20211231.xsd</File>
    <File>futu-20211231_cal.xml</File>
    <File>futu-20211231_def.xml</File>
    <File>futu-20211231_lab.xml</File>
    <File>futu-20211231_pre.xml</File>
    <File>futu-20211231xex12d1.htm</File>
    <File>futu-20211231xex12d2.htm</File>
    <File>futu-20211231xex13d1.htm</File>
    <File>futu-20211231xex13d2.htm</File>
    <File>futu-20211231xex15d1.htm</File>
    <File>futu-20211231xex15d2.htm</File>
    <File>futu-20211231xex15d3.htm</File>
    <File>futu-20211231xex4d5.htm</File>
    <File>futu-20211231xex4d6.htm</File>
    <File>futu-20211231xex4d7.htm</File>
    <File>futu-20211231xex4d8.htm</File>
    <File>futu-20211231xex4d9.htm</File>
    <File>futu-20211231xex8d1.htm</File>
  </InputFiles>
  <SupplementalFiles>
    <File>futu-20211231x20f009.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy items="19">http://fasb.org/srt/2021-01-31</BaseTaxonomy>
    <BaseTaxonomy items="1171">http://fasb.org/us-gaap/2021-01-31</BaseTaxonomy>
    <BaseTaxonomy items="48">http://xbrl.sec.gov/dei/2021q4</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
