<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.24.4</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>1283</ContextCount>
  <ElementCount>622</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>239</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>13</UnitCount>
  <MyReports>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0000001 - Document - Cover</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/Cover</Role>
      <ShortName>Cover</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>9952151 - Statement - Condensed Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/CondensedConsolidatedBalanceSheets</Role>
      <ShortName>Condensed Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>9952152 - Statement - Condensed Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/CondensedConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Condensed Consolidated Balance Sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>9952153 - Statement - Condensed Consolidated Statements of Operations (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/CondensedConsolidatedStatementsofOperationsUnaudited</Role>
      <ShortName>Condensed Consolidated Statements of Operations (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>9952154 - Statement - Condensed Consolidated Statements of Operations (Unaudited) (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/CondensedConsolidatedStatementsofOperationsUnauditedParenthetical</Role>
      <ShortName>Condensed Consolidated Statements of Operations (Unaudited) (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>9952155 - Statement - Condensed Consolidated Statements of Comprehensive (Loss) Income (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/CondensedConsolidatedStatementsofComprehensiveLossIncomeUnaudited</Role>
      <ShortName>Condensed Consolidated Statements of Comprehensive (Loss) Income (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>9952156 - Statement - Condensed Consolidated Statements of Equity (Deficit) (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/CondensedConsolidatedStatementsofEquityDeficitUnaudited</Role>
      <ShortName>Condensed Consolidated Statements of Equity (Deficit) (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>9952157 - Statement - Condensed Consolidated Statements of Equity (Deficit) (Unaudited) (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/CondensedConsolidatedStatementsofEquityDeficitUnauditedParenthetical</Role>
      <ShortName>Condensed Consolidated Statements of Equity (Deficit) (Unaudited) (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>9952158 - Statement - Condensed Consolidated Statements of Cash Flows (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited</Role>
      <ShortName>Condensed Consolidated Statements of Cash Flows (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>9952159 - Statement - Condensed Consolidated Statements of Cash Flows (Unaudited) (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/CondensedConsolidatedStatementsofCashFlowsUnauditedParenthetical</Role>
      <ShortName>Condensed Consolidated Statements of Cash Flows (Unaudited) (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>9952160 - Disclosure - ORGANIZATION AND NATURE OF BUSINESS OPERATIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/ORGANIZATIONANDNATUREOFBUSINESSOPERATIONS</Role>
      <ShortName>ORGANIZATION AND NATURE OF BUSINESS OPERATIONS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>9952161 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIES</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>9952162 - Disclosure - ACQUISITIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/ACQUISITIONS</Role>
      <ShortName>ACQUISITIONS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>9952163 - Disclosure - RESTRUCTURING CHARGE</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/RESTRUCTURINGCHARGE</Role>
      <ShortName>RESTRUCTURING CHARGE</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>9952164 - Disclosure - SECURITIES LENDING</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/SECURITIESLENDING</Role>
      <ShortName>SECURITIES LENDING</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>9952165 - Disclosure - ACCOUNTS RECEIVABLE</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/ACCOUNTSRECEIVABLE</Role>
      <ShortName>ACCOUNTS RECEIVABLE</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>9952166 - Disclosure - PREPAID EXPENSES AND OTHER ASSETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/PREPAIDEXPENSESANDOTHERASSETS</Role>
      <ShortName>PREPAID EXPENSES AND OTHER ASSETS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>9952167 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/GOODWILLANDOTHERINTANGIBLEASSETS</Role>
      <ShortName>GOODWILL AND OTHER INTANGIBLE ASSETS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>9952168 - Disclosure - NOTES PAYABLE</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://brileyfin.com/role/NOTESPAYABLE</Role>
      <ShortName>NOTES PAYABLE</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>9952169 - Disclosure - TERM LOANS AND REVOLVING CREDIT FACILITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/TERMLOANSANDREVOLVINGCREDITFACILITY</Role>
      <ShortName>TERM LOANS AND REVOLVING CREDIT FACILITY</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>9952170 - Disclosure - SENIOR NOTES PAYABLE</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://brileyfin.com/role/SENIORNOTESPAYABLE</Role>
      <ShortName>SENIOR NOTES PAYABLE</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>9952171 - Disclosure - ACCRUED EXPENSES AND OTHER LIABILITIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/ACCRUEDEXPENSESANDOTHERLIABILITIES</Role>
      <ShortName>ACCRUED EXPENSES AND OTHER LIABILITIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>9952172 - Disclosure - REVENUE FROM CONTRACTS WITH CUSTOMERS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERS</Role>
      <ShortName>REVENUE FROM CONTRACTS WITH CUSTOMERS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>9952173 - Disclosure - INCOME TAXES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/INCOMETAXES</Role>
      <ShortName>INCOME TAXES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>9952174 - Disclosure - EARNINGS PER SHARE</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/EARNINGSPERSHARE</Role>
      <ShortName>EARNINGS PER SHARE</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>9952175 - Disclosure - COMMITMENTS AND CONTINGENCIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/COMMITMENTSANDCONTINGENCIES</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>9952176 - Disclosure - SHARE-BASED PAYMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/SHAREBASEDPAYMENTS</Role>
      <ShortName>SHARE-BASED PAYMENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>9952177 - Disclosure - NET CAPITAL REQUIREMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/NETCAPITALREQUIREMENTS</Role>
      <ShortName>NET CAPITAL REQUIREMENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>9952178 - Disclosure - RELATED PARTY TRANSACTIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/RELATEDPARTYTRANSACTIONS</Role>
      <ShortName>RELATED PARTY TRANSACTIONS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>9952179 - Disclosure - BUSINESS SEGMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/BUSINESSSEGMENTS</Role>
      <ShortName>BUSINESS SEGMENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>9952180 - Disclosure - SUBSEQUENT EVENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/SUBSEQUENTEVENTS</Role>
      <ShortName>SUBSEQUENT EVENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>995410 - Disclosure - Pay vs Performance Disclosure</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/PvpDisclosure</Role>
      <ShortName>Pay vs Performance Disclosure</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>995445 - Disclosure - Insider Trading Arrangements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/InsiderTradingArrangements</Role>
      <ShortName>Insider Trading Arrangements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>9955511 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESPolicies</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>9955512 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESTables</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://brileyfin.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIES</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>9955513 - Disclosure - ACQUISITIONS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/ACQUISITIONSTables</Role>
      <ShortName>ACQUISITIONS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://brileyfin.com/role/ACQUISITIONS</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>9955514 - Disclosure - RESTRUCTURING CHARGE (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/RESTRUCTURINGCHARGETables</Role>
      <ShortName>RESTRUCTURING CHARGE (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://brileyfin.com/role/RESTRUCTURINGCHARGE</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>9955515 - Disclosure - SECURITIES LENDING (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/SECURITIESLENDINGTables</Role>
      <ShortName>SECURITIES LENDING (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://brileyfin.com/role/SECURITIESLENDING</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>9955516 - Disclosure - ACCOUNTS RECEIVABLE (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/ACCOUNTSRECEIVABLETables</Role>
      <ShortName>ACCOUNTS RECEIVABLE (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://brileyfin.com/role/ACCOUNTSRECEIVABLE</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>9955517 - Disclosure - PREPAID EXPENSES AND OTHER ASSETS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/PREPAIDEXPENSESANDOTHERASSETSTables</Role>
      <ShortName>PREPAID EXPENSES AND OTHER ASSETS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://brileyfin.com/role/PREPAIDEXPENSESANDOTHERASSETS</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>9955518 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/GOODWILLANDOTHERINTANGIBLEASSETSTables</Role>
      <ShortName>GOODWILL AND OTHER INTANGIBLE ASSETS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://brileyfin.com/role/GOODWILLANDOTHERINTANGIBLEASSETS</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>9955519 - Disclosure - SENIOR NOTES PAYABLE (Tables)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://brileyfin.com/role/SENIORNOTESPAYABLETables</Role>
      <ShortName>SENIOR NOTES PAYABLE (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://brileyfin.com/role/SENIORNOTESPAYABLE</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>9955520 - Disclosure - ACCRUED EXPENSES AND OTHER LIABILITIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/ACCRUEDEXPENSESANDOTHERLIABILITIESTables</Role>
      <ShortName>ACCRUED EXPENSES AND OTHER LIABILITIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://brileyfin.com/role/ACCRUEDEXPENSESANDOTHERLIABILITIES</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>9955521 - Disclosure - REVENUE FROM CONTRACTS WITH CUSTOMERS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERSTables</Role>
      <ShortName>REVENUE FROM CONTRACTS WITH CUSTOMERS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://brileyfin.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERS</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>9955522 - Disclosure - EARNINGS PER SHARE (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/EARNINGSPERSHARETables</Role>
      <ShortName>EARNINGS PER SHARE (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://brileyfin.com/role/EARNINGSPERSHARE</ParentRole>
      <Position>45</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>9955523 - Disclosure - BUSINESS SEGMENTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/BUSINESSSEGMENTSTables</Role>
      <ShortName>BUSINESS SEGMENTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://brileyfin.com/role/BUSINESSSEGMENTS</ParentRole>
      <Position>46</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>9955524 - Disclosure - ORGANIZATION AND NATURE OF BUSINESS OPERATIONS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/ORGANIZATIONANDNATUREOFBUSINESSOPERATIONSDetails</Role>
      <ShortName>ORGANIZATION AND NATURE OF BUSINESS OPERATIONS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://brileyfin.com/role/ORGANIZATIONANDNATUREOFBUSINESSOPERATIONS</ParentRole>
      <Position>47</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>9955525 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional information (A-H) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESAdditionalinformationAHDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional information (A-H) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>9955526 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional information (I-K) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESAdditionalinformationIKDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional information (I-K) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>9955527 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional information (L-P) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESAdditionalinformationLPDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional information (L-P) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>9955528 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of cash, cash equivalents and restricted cash (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESScheduleofcashcashequivalentsandrestrictedcashDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of cash, cash equivalents and restricted cash (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>9955529 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of securities and other investments owned and securities sold not yet purchased at fair value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESScheduleofsecuritiesandotherinvestmentsownedandsecuritiessoldnotyetpurchasedatfairvalueDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of securities and other investments owned and securities sold not yet purchased at fair value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>9955530 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of equity method investments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESScheduleofequitymethodinvestmentsDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of equity method investments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>9955531 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Equity securities without readily determinable fair value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESEquitysecuritieswithoutreadilydeterminablefairvalueDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Equity securities without readily determinable fair value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>9955532 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of financial assets and liabilities measured on recurring basis (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESScheduleoffinancialassetsandliabilitiesmeasuredonrecurringbasisDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of financial assets and liabilities measured on recurring basis (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>9955533 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of significant unobservable inputs of level 3 financial assets and liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESScheduleofsignificantunobservableinputsoflevel3financialassetsandliabilitiesDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of significant unobservable inputs of level 3 financial assets and liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>9955534 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of fair value measurement of level 3 financial assets and liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESScheduleoffairvaluemeasurementoflevel3financialassetsandliabilitiesDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of fair value measurement of level 3 financial assets and liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>9955535 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of financial assets measured on nonrecurring basis (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESScheduleoffinancialassetsmeasuredonnonrecurringbasisDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of financial assets measured on nonrecurring basis (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>9955536 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of investments in the VIE (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESScheduleofinvestmentsintheVIEDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of investments in the VIE (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>9955537 - Disclosure - ACQUISITIONS - Additional information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/ACQUISITIONSAdditionalinformationDetails</Role>
      <ShortName>ACQUISITIONS - Additional information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>9955538 - Disclosure - ACQUISITIONS - Schedule of recognized identified assets acquired and liabilities assumed (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/ACQUISITIONSScheduleofrecognizedidentifiedassetsacquiredandliabilitiesassumedDetails</Role>
      <ShortName>ACQUISITIONS - Schedule of recognized identified assets acquired and liabilities assumed (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>9955539 - Disclosure - ACQUISITIONS - Schedule of acquired indefinite-lived intangible assets by major class (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/ACQUISITIONSScheduleofacquiredindefinitelivedintangibleassetsbymajorclassDetails</Role>
      <ShortName>ACQUISITIONS - Schedule of acquired indefinite-lived intangible assets by major class (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>9955540 - Disclosure - ACQUISITIONS - Pro forma (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/ACQUISITIONSProformaDetails</Role>
      <ShortName>ACQUISITIONS - Pro forma (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>9955541 - Disclosure - RESTRUCTURING CHARGE - Additional information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/RESTRUCTURINGCHARGEAdditionalinformationDetails</Role>
      <ShortName>RESTRUCTURING CHARGE - Additional information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>9955542 - Disclosure - RESTRUCTURING CHARGE - Schedule of changes in accrued restructuring charge (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/RESTRUCTURINGCHARGEScheduleofchangesinaccruedrestructuringchargeDetails</Role>
      <ShortName>RESTRUCTURING CHARGE - Schedule of changes in accrued restructuring charge (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>65</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>9955543 - Disclosure - RESTRUCTURING CHARGE - Schedule of summarize the restructuring activities by reportable segment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/RESTRUCTURINGCHARGEScheduleofsummarizetherestructuringactivitiesbyreportablesegmentDetails</Role>
      <ShortName>RESTRUCTURING CHARGE - Schedule of summarize the restructuring activities by reportable segment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>9955544 - Disclosure - SECURITIES LENDING - Schedule of contractual gross and net securities borrowing and lending balances (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/SECURITIESLENDINGScheduleofcontractualgrossandnetsecuritiesborrowingandlendingbalancesDetails</Role>
      <ShortName>SECURITIES LENDING - Schedule of contractual gross and net securities borrowing and lending balances (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>9955545 - Disclosure - SECURITIES LENDING - Schedule of contract value of securities leading transaction by type of collateral (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/SECURITIESLENDINGScheduleofcontractvalueofsecuritiesleadingtransactionbytypeofcollateralDetails</Role>
      <ShortName>SECURITIES LENDING - Schedule of contract value of securities leading transaction by type of collateral (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>9955546 - Disclosure - ACCOUNTS RECEIVABLE - Schedule of components of accounts receivable, net (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/ACCOUNTSRECEIVABLEScheduleofcomponentsofaccountsreceivablenetDetails</Role>
      <ShortName>ACCOUNTS RECEIVABLE - Schedule of components of accounts receivable, net (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>69</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>9955547 - Disclosure - ACCOUNTS RECEIVABLE - Schedule of allowance for doubtful accounts (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/ACCOUNTSRECEIVABLEScheduleofallowancefordoubtfulaccountsDetails</Role>
      <ShortName>ACCOUNTS RECEIVABLE - Schedule of allowance for doubtful accounts (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>70</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>9955548 - Disclosure - PREPAID EXPENSES AND OTHER ASSETS - Schedule of prepaids and other assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/PREPAIDEXPENSESANDOTHERASSETSScheduleofprepaidsandotherassetsDetails</Role>
      <ShortName>PREPAID EXPENSES AND OTHER ASSETS - Schedule of prepaids and other assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>71</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>9955549 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS - Additional information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/GOODWILLANDOTHERINTANGIBLEASSETSAdditionalinformationDetails</Role>
      <ShortName>GOODWILL AND OTHER INTANGIBLE ASSETS - Additional information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>72</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>9955550 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS - Schedule of carrying amount of goodwill (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/GOODWILLANDOTHERINTANGIBLEASSETSScheduleofcarryingamountofgoodwillDetails</Role>
      <ShortName>GOODWILL AND OTHER INTANGIBLE ASSETS - Schedule of carrying amount of goodwill (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>73</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>9955551 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS - Schedule of intangible assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/GOODWILLANDOTHERINTANGIBLEASSETSScheduleofintangibleassetsDetails</Role>
      <ShortName>GOODWILL AND OTHER INTANGIBLE ASSETS - Schedule of intangible assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>74</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>9955552 - Disclosure - NOTES PAYABLE (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://brileyfin.com/role/NOTESPAYABLEDetails</Role>
      <ShortName>NOTES PAYABLE (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://brileyfin.com/role/NOTESPAYABLE</ParentRole>
      <Position>75</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>9955553 - Disclosure - TERM LOANS AND REVOLVING CREDIT FACILITY - Part 1 (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/TERMLOANSANDREVOLVINGCREDITFACILITYPart1Details</Role>
      <ShortName>TERM LOANS AND REVOLVING CREDIT FACILITY - Part 1 (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://brileyfin.com/role/TERMLOANSANDREVOLVINGCREDITFACILITY</ParentRole>
      <Position>76</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>9955554 - Disclosure - TERM LOANS AND REVOLVING CREDIT FACILITY - Part 2 (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/TERMLOANSANDREVOLVINGCREDITFACILITYPart2Details</Role>
      <ShortName>TERM LOANS AND REVOLVING CREDIT FACILITY - Part 2 (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://brileyfin.com/role/TERMLOANSANDREVOLVINGCREDITFACILITY</ParentRole>
      <Position>77</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>9955555 - Disclosure - TERM LOANS AND REVOLVING CREDIT FACILITY - Part 3 (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/TERMLOANSANDREVOLVINGCREDITFACILITYPart3Details</Role>
      <ShortName>TERM LOANS AND REVOLVING CREDIT FACILITY - Part 3 (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://brileyfin.com/role/TERMLOANSANDREVOLVINGCREDITFACILITY</ParentRole>
      <Position>78</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>9955556 - Disclosure - SENIOR NOTES PAYABLE - Schedule of senior notes payable, net (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://brileyfin.com/role/SENIORNOTESPAYABLEScheduleofseniornotespayablenetDetails</Role>
      <ShortName>SENIOR NOTES PAYABLE - Schedule of senior notes payable, net (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>79</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>9955557 - Disclosure - SENIOR NOTES PAYABLE - Additional information (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://brileyfin.com/role/SENIORNOTESPAYABLEAdditionalinformationDetails</Role>
      <ShortName>SENIOR NOTES PAYABLE - Additional information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>80</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>9955558 - Disclosure - ACCRUED EXPENSES AND OTHER LIABILITIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/ACCRUEDEXPENSESANDOTHERLIABILITIESDetails</Role>
      <ShortName>ACCRUED EXPENSES AND OTHER LIABILITIES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://brileyfin.com/role/ACCRUEDEXPENSESANDOTHERLIABILITIESTables</ParentRole>
      <Position>81</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>9955559 - Disclosure - REVENUE FROM CONTRACTS WITH CUSTOMERS - Additional information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERSAdditionalinformationDetails</Role>
      <ShortName>REVENUE FROM CONTRACTS WITH CUSTOMERS - Additional information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>82</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>9955560 - Disclosure - REVENUE FROM CONTRACTS WITH CUSTOMERS - Schedule of revenues from contracts with customers (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERSScheduleofrevenuesfromcontractswithcustomersDetails</Role>
      <ShortName>REVENUE FROM CONTRACTS WITH CUSTOMERS - Schedule of revenues from contracts with customers (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>83</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>9955561 - Disclosure - INCOME TAXES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/INCOMETAXESDetails</Role>
      <ShortName>INCOME TAXES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://brileyfin.com/role/INCOMETAXES</ParentRole>
      <Position>84</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>9955562 - Disclosure - EARNINGS PER SHARE - Additional information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/EARNINGSPERSHAREAdditionalinformationDetails</Role>
      <ShortName>EARNINGS PER SHARE - Additional information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>85</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>9955563 - Disclosure - EARNINGS PER SHARE - Schedule of basic and diluted earnings per share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/EARNINGSPERSHAREScheduleofbasicanddilutedearningspershareDetails</Role>
      <ShortName>EARNINGS PER SHARE - Schedule of basic and diluted earnings per share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>86</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R87.htm</HtmlFileName>
      <LongName>9955564 - Disclosure - COMMITMENTS AND CONTINGENCIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/COMMITMENTSANDCONTINGENCIESDetails</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://brileyfin.com/role/COMMITMENTSANDCONTINGENCIES</ParentRole>
      <Position>87</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R88.htm</HtmlFileName>
      <LongName>9955565 - Disclosure - SHARE-BASED PAYMENTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/SHAREBASEDPAYMENTSDetails</Role>
      <ShortName>SHARE-BASED PAYMENTS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://brileyfin.com/role/SHAREBASEDPAYMENTS</ParentRole>
      <Position>88</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R89.htm</HtmlFileName>
      <LongName>9955566 - Disclosure - NET CAPITAL REQUIREMENTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/NETCAPITALREQUIREMENTSDetails</Role>
      <ShortName>NET CAPITAL REQUIREMENTS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://brileyfin.com/role/NETCAPITALREQUIREMENTS</ParentRole>
      <Position>89</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R90.htm</HtmlFileName>
      <LongName>9955567 - Disclosure - RELATED PARTY TRANSACTIONS - Narrative Part 1 (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/RELATEDPARTYTRANSACTIONSNarrativePart1Details</Role>
      <ShortName>RELATED PARTY TRANSACTIONS - Narrative Part 1 (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>90</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R91.htm</HtmlFileName>
      <LongName>9955568 - Disclosure - RELATED PARTY TRANSACTIONS - Narrative Part 2 (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/RELATEDPARTYTRANSACTIONSNarrativePart2Details</Role>
      <ShortName>RELATED PARTY TRANSACTIONS - Narrative Part 2 (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>91</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R92.htm</HtmlFileName>
      <LongName>9955569 - Disclosure - BUSINESS SEGMENTS - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/BUSINESSSEGMENTSNarrativeDetails</Role>
      <ShortName>BUSINESS SEGMENTS - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>92</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R93.htm</HtmlFileName>
      <LongName>9955570 - Disclosure - BUSINESS SEGMENTS - Schedule of reportable segments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/BUSINESSSEGMENTSScheduleofreportablesegmentsDetails</Role>
      <ShortName>BUSINESS SEGMENTS - Schedule of reportable segments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>93</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R94.htm</HtmlFileName>
      <LongName>9955571 - Disclosure - BUSINESS SEGMENTS - Schedule of revenues by geographical area (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/BUSINESSSEGMENTSScheduleofrevenuesbygeographicalareaDetails</Role>
      <ShortName>BUSINESS SEGMENTS - Schedule of revenues by geographical area (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>94</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R95.htm</HtmlFileName>
      <LongName>9955572 - Disclosure - BUSINESS SEGMENTS - Long-lived assets by geographic areas (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/BUSINESSSEGMENTSLonglivedassetsbygeographicareasDetails</Role>
      <ShortName>BUSINESS SEGMENTS - Long-lived assets by geographic areas (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>95</Position>
    </Report>
    <Report instance="rily-20240630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R96.htm</HtmlFileName>
      <LongName>9955573 - Disclosure - SUBSEQUENT EVENTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://brileyfin.com/role/SUBSEQUENTEVENTSDetails</Role>
      <ShortName>SUBSEQUENT EVENTS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://brileyfin.com/role/SUBSEQUENTEVENTS</ParentRole>
      <Position>96</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="10-Q" isDefinitelyFs="true" isUsgaap="true" original="rily-20240630.htm">rily-20240630.htm</File>
    <File>rily-20240630.xsd</File>
    <File>rily-20240630_cal.xml</File>
    <File>rily-20240630_def.xml</File>
    <File>rily-20240630_lab.xml</File>
    <File>rily-20240630_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="17">http://fasb.org/srt/2024</BaseTaxonomy>
    <BaseTaxonomy items="2777">http://fasb.org/us-gaap/2024</BaseTaxonomy>
    <BaseTaxonomy items="54">http://xbrl.sec.gov/dei/2024</BaseTaxonomy>
    <BaseTaxonomy items="4">http://xbrl.sec.gov/ecd/2024</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
