<XML>
<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.25.4</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>792</ContextCount>
  <ElementCount>597</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>213</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>4</UnitCount>
  <MyReports>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>000 - Document - Document And Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-document-and-entity-information</Role>
      <ShortName>Document And Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>001 - Statement - Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-consolidated-balance-sheets</Role>
      <ShortName>Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>002 - Statement - Consolidated Balance Sheets (Parentheticals)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-consolidated-balance-sheets-parentheticals</Role>
      <ShortName>Consolidated Balance Sheets (Parentheticals)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>003 - Statement - Consolidated Statements of Operations and Comprehensive Income (Loss)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-consolidated-statements-of-operations-and-comprehensive-income-loss</Role>
      <ShortName>Consolidated Statements of Operations and Comprehensive Income (Loss)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>004 - Statement - Consolidated Statements of Operations and Comprehensive Income (Loss) (Parentheticals)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-consolidated-statements-of-operations-and-comprehensive-income-loss-parentheticals</Role>
      <ShortName>Consolidated Statements of Operations and Comprehensive Income (Loss) (Parentheticals)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>005 - Statement - Consolidated Statements of Changes in Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-consolidated-statements-of-changes-in-equity</Role>
      <ShortName>Consolidated Statements of Changes in Equity</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>006 - Statement - Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-consolidated-statements-of-cash-flows-</Role>
      <ShortName>Consolidated Statements of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>995443 - Disclosure - Award Timing Disclosure</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/AwardTimingDisclosure</Role>
      <ShortName>Award Timing Disclosure</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.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>9</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>995447 - Disclosure - Insider Trading Policies and Procedures</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/InsiderTradingPoliciesProc</Role>
      <ShortName>Insider Trading Policies and Procedures</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>995550 - Disclosure - Cybersecurity Risk Management and Strategy Disclosure</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/cyd/role/CybersecurityRiskManagementAndStrategyDisclosure</Role>
      <ShortName>Cybersecurity Risk Management and Strategy Disclosure</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>995555 - Disclosure - Note 1 - Organization and Nature of Operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-1-organization-and-nature-of-operations</Role>
      <ShortName>Note 1 - Organization and Nature of Operations</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>995556 - Disclosure - Note 2 - Basis of Presentation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-2-basis-of-presentation</Role>
      <ShortName>Note 2 - Basis of Presentation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>995557 - Disclosure - Note 3 - Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-3-summary-of-significant-accounting-policies</Role>
      <ShortName>Note 3 - Summary of Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>995558 - Disclosure - Note 4 - Other Recent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-4-other-recent-events</Role>
      <ShortName>Note 4 - Other Recent Events</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>995559 - Disclosure - Note 5 - Investment Banking and New Issue and Net Trading</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-5-investment-banking-and-new-issue-and-net-trading</Role>
      <ShortName>Note 5 - Investment Banking and New Issue and Net Trading</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>995560 - Disclosure - Note 6 - Receivables From and Payables to Brokers, Dealers, and Clearing Agencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-6-receivables-from-and-payables-to-brokers-dealers-and-clearing-agencies</Role>
      <ShortName>Note 6 - Receivables From and Payables to Brokers, Dealers, and Clearing Agencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>995561 - Disclosure - Note 7 - Other Receivables</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-7-other-receivables</Role>
      <ShortName>Note 7 - Other Receivables</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>995562 - Disclosure - Note 8 - Financial Instruments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-8-financial-instruments</Role>
      <ShortName>Note 8 - Financial Instruments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>995563 - Disclosure - Note 9 - Fair Value Disclosures</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-9-fair-value-disclosures</Role>
      <ShortName>Note 9 - Fair Value Disclosures</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>995564 - Disclosure - Note 10 - Derivative Financial Instruments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-10-derivative-financial-instruments</Role>
      <ShortName>Note 10 - Derivative Financial Instruments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>995565 - Disclosure - Note 11 - Collateralized Securities Transactions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-11-collateralized-securities-transactions</Role>
      <ShortName>Note 11 - Collateralized Securities Transactions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>995566 - Disclosure - Note 12 - Investments in Equity Method Affiliates</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-12-investments-in-equity-method-affiliates</Role>
      <ShortName>Note 12 - Investments in Equity Method Affiliates</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>995567 - Disclosure - Note 13 - Goodwill</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-13-goodwill</Role>
      <ShortName>Note 13 - Goodwill</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>995568 - Disclosure - Note 14 - Leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-14-leases</Role>
      <ShortName>Note 14 - Leases</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>995569 - Disclosure - Note 15 - Other Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-15-other-assets</Role>
      <ShortName>Note 15 - Other Assets</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>995570 - Disclosure - Note 16 - Furniture, Equipment, and Leasehold Improvements, Net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-16-furniture-equipment-and-leasehold-improvements-net</Role>
      <ShortName>Note 16 - Furniture, Equipment, and Leasehold Improvements, Net</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>995571 - Disclosure - Note 17 - Accounts Payable and Other Liabilities - Accounts Payable and Other Liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-17-accounts-payable-and-other-liabilities-accounts-payable-and-other-liabilities</Role>
      <ShortName>Note 17 - Accounts Payable and Other Liabilities - Accounts Payable and Other Liabilities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>995572 - Disclosure - Note 18 - Variable Interest Entities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-18-variable-interest-entities</Role>
      <ShortName>Note 18 - Variable Interest Entities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>995573 - Disclosure - Note 19 - Accrued Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-19-accrued-compensation</Role>
      <ShortName>Note 19 - Accrued Compensation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>995574 - Disclosure - Note 20 - Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-20-debt-</Role>
      <ShortName>Note 20 - Debt</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>995575 - Disclosure - Note 21 - Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-21-equity-</Role>
      <ShortName>Note 21 - Equity</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>995576 - Disclosure - Note 22 - Equity-based Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-22-equitybased-compensation</Role>
      <ShortName>Note 22 - Equity-based Compensation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>995577 - Disclosure - Note 23 - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-23-income-taxes-</Role>
      <ShortName>Note 23 - Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>995578 - Disclosure - Note 24 - Accumulated Other Comprehensive Income (Loss) ("AOCI")</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-24-accumulated-other-comprehensive-income-loss-aoci</Role>
      <ShortName>Note 24 - Accumulated Other Comprehensive Income (Loss) ("AOCI")</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>995579 - Disclosure - Note 25 - Net Capital Requirements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-25-net-capital-requirements</Role>
      <ShortName>Note 25 - Net Capital Requirements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>995580 - Disclosure - Note 26 - Earnings (Loss) Per Common Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-26-earnings-loss-per-common-share</Role>
      <ShortName>Note 26 - Earnings (Loss) Per Common Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>995581 - Disclosure - Note 27 - Reserve Requirements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-27-reserve-requirements-</Role>
      <ShortName>Note 27 - Reserve Requirements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>995582 - Disclosure - Note 28 - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-28-commitments-and-contingencies</Role>
      <ShortName>Note 28 - Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>995583 - Disclosure - Note 29 - Segment and Geographic Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-29-segment-and-geographic-information</Role>
      <ShortName>Note 29 - Segment and Geographic Information</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>995584 - Disclosure - Note 30 - Supplemental Cash Flow Disclosure</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-30-supplemental-cash-flow-disclosure-</Role>
      <ShortName>Note 30 - Supplemental Cash Flow Disclosure</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>995585 - Disclosure - Note 31 - Related Party Transactions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-31-related-party-transactions-</Role>
      <ShortName>Note 31 - Related Party Transactions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>995586 - Disclosure - Note 32 - Due From Due to Related Parties</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-32-due-from-due-to-related-parties</Role>
      <ShortName>Note 32 - Due From Due to Related Parties</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>995587 - Disclosure - Note 33 - Subsequent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-33-subsequent-events</Role>
      <ShortName>Note 33 - Subsequent Events</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>995588 - Disclosure - Schedule I</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-schedule-i-</Role>
      <ShortName>Schedule I</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>995589 - Disclosure - Note 4 - Other Recent Events (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-4-other-recent-events-tables</Role>
      <ShortName>Note 4 - Other Recent Events (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-4-other-recent-events</ParentRole>
      <Position>46</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>995590 - Disclosure - Note 5 - Investment Banking and New Issue and Net Trading (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-5-investment-banking-and-new-issue-and-net-trading-tables</Role>
      <ShortName>Note 5 - Investment Banking and New Issue and Net Trading (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-5-investment-banking-and-new-issue-and-net-trading</ParentRole>
      <Position>47</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>995591 - Disclosure - Note 6 - Receivables From and Payables to Brokers, Dealers, and Clearing Agencies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-6-receivables-from-and-payables-to-brokers-dealers-and-clearing-agencies-tables</Role>
      <ShortName>Note 6 - Receivables From and Payables to Brokers, Dealers, and Clearing Agencies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-6-receivables-from-and-payables-to-brokers-dealers-and-clearing-agencies</ParentRole>
      <Position>48</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>995592 - Disclosure - Note 7 - Other Receivables (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-7-other-receivables-tables</Role>
      <ShortName>Note 7 - Other Receivables (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-7-other-receivables</ParentRole>
      <Position>49</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>995593 - Disclosure - Note 8 - Financial Instruments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-8-financial-instruments-tables</Role>
      <ShortName>Note 8 - Financial Instruments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-8-financial-instruments</ParentRole>
      <Position>50</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>995594 - Disclosure - Note 9 - Fair Value Disclosures (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-9-fair-value-disclosures-tables</Role>
      <ShortName>Note 9 - Fair Value Disclosures (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-9-fair-value-disclosures</ParentRole>
      <Position>51</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>995595 - Disclosure - Note 10 - Derivative Financial Instruments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-10-derivative-financial-instruments-tables</Role>
      <ShortName>Note 10 - Derivative Financial Instruments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-10-derivative-financial-instruments</ParentRole>
      <Position>52</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>995596 - Disclosure - Note 11 - Collateralized Securities Transactions (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-11-collateralized-securities-transactions-tables</Role>
      <ShortName>Note 11 - Collateralized Securities Transactions (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-11-collateralized-securities-transactions</ParentRole>
      <Position>53</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>995597 - Disclosure - Note 12 - Investments in Equity Method Affiliates (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-12-investments-in-equity-method-affiliates-tables</Role>
      <ShortName>Note 12 - Investments in Equity Method Affiliates (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-12-investments-in-equity-method-affiliates</ParentRole>
      <Position>54</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>995598 - Disclosure - Note 13 - Goodwill (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-13-goodwill-tables</Role>
      <ShortName>Note 13 - Goodwill (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-13-goodwill</ParentRole>
      <Position>55</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>995599 - Disclosure - Note 14 - Leases (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-14-leases-tables</Role>
      <ShortName>Note 14 - Leases (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-14-leases</ParentRole>
      <Position>56</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>995600 - Disclosure - Note 15 - Other Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-15-other-assets-tables</Role>
      <ShortName>Note 15 - Other Assets (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-15-other-assets</ParentRole>
      <Position>57</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>995601 - Disclosure - Note 16 - Furniture, Equipment, and Leasehold Improvements, Net (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-16-furniture-equipment-and-leasehold-improvements-net-tables</Role>
      <ShortName>Note 16 - Furniture, Equipment, and Leasehold Improvements, Net (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-16-furniture-equipment-and-leasehold-improvements-net</ParentRole>
      <Position>58</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>995602 - Disclosure - Note 17 - Accounts Payable and Other Liabilities - Accounts Payable and Other Liabilities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-17-accounts-payable-and-other-liabilities-accounts-payable-and-other-liabilities-tables</Role>
      <ShortName>Note 17 - Accounts Payable and Other Liabilities - Accounts Payable and Other Liabilities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-17-accounts-payable-and-other-liabilities-accounts-payable-and-other-liabilities</ParentRole>
      <Position>59</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>995603 - Disclosure - Note 18 - Variable Interest Entities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-18-variable-interest-entities-tables</Role>
      <ShortName>Note 18 - Variable Interest Entities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-18-variable-interest-entities</ParentRole>
      <Position>60</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>995604 - Disclosure - Note 19 - Accrued Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-19-accrued-compensation-tables</Role>
      <ShortName>Note 19 - Accrued Compensation (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-19-accrued-compensation</ParentRole>
      <Position>61</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>995605 - Disclosure - Note 20 - Debt (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-20-debt-tables</Role>
      <ShortName>Note 20 - Debt (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-20-debt-</ParentRole>
      <Position>62</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>995606 - Disclosure - Note 21 - Equity (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-21-equity-tables</Role>
      <ShortName>Note 21 - Equity (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-21-equity-</ParentRole>
      <Position>63</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>995607 - Disclosure - Note 22 - Equity-based Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-22-equitybased-compensation-tables</Role>
      <ShortName>Note 22 - Equity-based Compensation (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-22-equitybased-compensation</ParentRole>
      <Position>64</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>995608 - Disclosure - Note 23 - Income Taxes (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-23-income-taxes-tables</Role>
      <ShortName>Note 23 - Income Taxes (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-23-income-taxes-</ParentRole>
      <Position>65</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>995609 - Disclosure - Note 24 - Accumulated Other Comprehensive Income (Loss) ("AOCI") (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-24-accumulated-other-comprehensive-income-loss-aoci-tables</Role>
      <ShortName>Note 24 - Accumulated Other Comprehensive Income (Loss) ("AOCI") (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-24-accumulated-other-comprehensive-income-loss-aoci</ParentRole>
      <Position>66</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>995610 - Disclosure - Note 25 - Net Capital Requirements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-25-net-capital-requirements-tables</Role>
      <ShortName>Note 25 - Net Capital Requirements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-25-net-capital-requirements</ParentRole>
      <Position>67</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>995611 - Disclosure - Note 26 - Earnings (Loss) Per Common Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-26-earnings-loss-per-common-share-tables</Role>
      <ShortName>Note 26 - Earnings (Loss) Per Common Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-26-earnings-loss-per-common-share</ParentRole>
      <Position>68</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>995612 - Disclosure - Note 28 - Commitments and Contingencies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-28-commitments-and-contingencies-tables</Role>
      <ShortName>Note 28 - Commitments and Contingencies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-28-commitments-and-contingencies</ParentRole>
      <Position>69</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>995613 - Disclosure - Note 29 - Segment and Geographic Information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-29-segment-and-geographic-information-tables</Role>
      <ShortName>Note 29 - Segment and Geographic Information (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-29-segment-and-geographic-information</ParentRole>
      <Position>70</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>995614 - Disclosure - Note 31 - Related Party Transactions (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-31-related-party-transactions-tables</Role>
      <ShortName>Note 31 - Related Party Transactions (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-31-related-party-transactions-</ParentRole>
      <Position>71</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>995615 - Disclosure - Note 32 - Due From Due to Related Parties (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-32-due-from-due-to-related-parties-tables</Role>
      <ShortName>Note 32 - Due From Due to Related Parties (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-32-due-from-due-to-related-parties</ParentRole>
      <Position>72</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>995616 - Disclosure - Schedule I (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-schedule-i-tables</Role>
      <ShortName>Schedule I (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-schedule-i-</ParentRole>
      <Position>73</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>995617 - Disclosure - Note 1 - Organization and Nature of Operations (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-1-organization-and-nature-of-operations-details-textual</Role>
      <ShortName>Note 1 - Organization and Nature of Operations (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-1-organization-and-nature-of-operations</ParentRole>
      <Position>74</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>995618 - Disclosure - Note 2 - Basis of Presentation (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-2-basis-of-presentation-details-textual</Role>
      <ShortName>Note 2 - Basis of Presentation (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-2-basis-of-presentation</ParentRole>
      <Position>75</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>995619 - Disclosure - Note 3 - Summary of Significant Accounting Policies (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-3-summary-of-significant-accounting-policies-details-textual</Role>
      <ShortName>Note 3 - Summary of Significant Accounting Policies (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>76</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>995620 - Disclosure - Note 4 - Other Recent Events (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-4-other-recent-events-details-textual</Role>
      <ShortName>Note 4 - Other Recent Events (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-4-other-recent-events-tables</ParentRole>
      <Position>77</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>995621 - Disclosure - Note 4 - Other Recent Events - SPAC Investment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-4-other-recent-events-spac-investment-details</Role>
      <ShortName>Note 4 - Other Recent Events - SPAC Investment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>78</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>995622 - Disclosure - Note 5 - Investment Banking and New Issue and Net Trading (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-5-investment-banking-and-new-issue-and-net-trading-details-textual</Role>
      <ShortName>Note 5 - Investment Banking and New Issue and Net Trading (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-5-investment-banking-and-new-issue-and-net-trading-tables</ParentRole>
      <Position>79</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>995623 - Disclosure - Note 5 - Investment Banking and New Issue and Net Trading - Investment Banking and New Issue (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-5-investment-banking-and-new-issue-and-net-trading-investment-banking-and-new-issue-details</Role>
      <ShortName>Note 5 - Investment Banking and New Issue and Net Trading - Investment Banking and New Issue (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>80</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>995624 - Disclosure - Note 5 - Investment Banking and New Issue and Net Trading - Net Trading (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-5-investment-banking-and-new-issue-and-net-trading-net-trading-details</Role>
      <ShortName>Note 5 - Investment Banking and New Issue and Net Trading - Net Trading (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-5-investment-banking-and-new-issue-and-net-trading-tables</ParentRole>
      <Position>81</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>995625 - Disclosure - Note 6 - Receivables from and Payables to Brokers, Dealers, and Clearing Agencies - Receivables from and Payables to from Brokers, Dealers and Clearing Agencies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-6-receivables-from-and-payables-to-brokers-dealers-and-clearing-agencies-receivables-from-and-payables-to-from-brokers-dealers-and-clearing-agencies-details</Role>
      <ShortName>Note 6 - Receivables from and Payables to Brokers, Dealers, and Clearing Agencies - Receivables from and Payables to from Brokers, Dealers and Clearing Agencies (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>82</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>995626 - Disclosure - Note 7 - Other Receivables (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-7-other-receivables-details-textual</Role>
      <ShortName>Note 7 - Other Receivables (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-7-other-receivables-tables</ParentRole>
      <Position>83</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>995627 - Disclosure - Note 7 - Other Receivables - Other Receivables (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-7-other-receivables-other-receivables-details</Role>
      <ShortName>Note 7 - Other Receivables - Other Receivables (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>84</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>995628 - Disclosure - Note 8 - Financial Instruments (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-8-financial-instruments-details-textual</Role>
      <ShortName>Note 8 - Financial Instruments (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-8-financial-instruments-tables</ParentRole>
      <Position>85</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>995629 - Disclosure - Note 8 - Financial Instruments - Investments - Trading (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-8-financial-instruments-investments-trading-details</Role>
      <ShortName>Note 8 - Financial Instruments - Investments - Trading (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>86</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R87.htm</HtmlFileName>
      <LongName>995630 - Disclosure - Note 8 - Financial Instruments - Financial Instruments Sold, Not Yet Purchased (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-8-financial-instruments-financial-instruments-sold-not-yet-purchased-details</Role>
      <ShortName>Note 8 - Financial Instruments - Financial Instruments Sold, Not Yet Purchased (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>87</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R88.htm</HtmlFileName>
      <LongName>995631 - Disclosure - Note 8 - Financial Instruments - Other Investments, at Fair Value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-8-financial-instruments-other-investments-at-fair-value-details</Role>
      <ShortName>Note 8 - Financial Instruments - Other Investments, at Fair Value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>88</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R89.htm</HtmlFileName>
      <LongName>995632 - Disclosure - Note 9 - Fair Value Disclosures (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-9-fair-value-disclosures-details-textual</Role>
      <ShortName>Note 9 - Fair Value Disclosures (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-9-fair-value-disclosures-tables</ParentRole>
      <Position>89</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R90.htm</HtmlFileName>
      <LongName>995633 - Disclosure - Note 9 - Fair Value Disclosures - Fair Value Measurements on a Recurring Basis (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-9-fair-value-disclosures-fair-value-measurements-on-a-recurring-basis-details</Role>
      <ShortName>Note 9 - Fair Value Disclosures - Fair Value Measurements on a Recurring Basis (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>90</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R91.htm</HtmlFileName>
      <LongName>995634 - Disclosure - Note 9 - Fair Value Disclosures - Fair Value Measurements of Investments in Certain Entities That Calculate Net Asset Value per Share (or Its Equivalent) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-9-fair-value-disclosures-fair-value-measurements-of-investments-in-certain-entities-that-calculate-net-asset-value-per-share-or-its-equivalent-details</Role>
      <ShortName>Note 9 - Fair Value Disclosures - Fair Value Measurements of Investments in Certain Entities That Calculate Net Asset Value per Share (or Its Equivalent) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>91</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R92.htm</HtmlFileName>
      <LongName>995635 - Disclosure - Note 10 - Derivative Financial Instruments (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-10-derivative-financial-instruments-details-textual</Role>
      <ShortName>Note 10 - Derivative Financial Instruments (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-10-derivative-financial-instruments-tables</ParentRole>
      <Position>92</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R93.htm</HtmlFileName>
      <LongName>995636 - Disclosure - Note 10 - Derivative Financial Instruments - Balance Sheet Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-10-derivative-financial-instruments-balance-sheet-information-details</Role>
      <ShortName>Note 10 - Derivative Financial Instruments - Balance Sheet Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>93</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R94.htm</HtmlFileName>
      <LongName>995637 - Disclosure - Note 10 - Derivative Financial Instruments - Statement of Operations Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-10-derivative-financial-instruments-statement-of-operations-information-details</Role>
      <ShortName>Note 10 - Derivative Financial Instruments - Statement of Operations Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>94</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R95.htm</HtmlFileName>
      <LongName>995638 - Disclosure - Note 10 - Derivative Financial Instruments - Statement of Operations Information (Details) (Parentheticals)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-10-derivative-financial-instruments-statement-of-operations-information-details-parentheticals</Role>
      <ShortName>Note 10 - Derivative Financial Instruments - Statement of Operations Information (Details) (Parentheticals)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>95</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R96.htm</HtmlFileName>
      <LongName>995639 - Disclosure - Note 10 - Derivative Financial Instruments - Share Forward Arrangements (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-10-derivative-financial-instruments-share-forward-arrangements-details</Role>
      <ShortName>Note 10 - Derivative Financial Instruments - Share Forward Arrangements (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>96</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R97.htm</HtmlFileName>
      <LongName>995640 - Disclosure - Note 11 - Collateralized Securities Transactions (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-11-collateralized-securities-transactions-details-textual</Role>
      <ShortName>Note 11 - Collateralized Securities Transactions (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-11-collateralized-securities-transactions-tables</ParentRole>
      <Position>97</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R98.htm</HtmlFileName>
      <LongName>995641 - Disclosure - Note 11 - Collateralized Securities Transactions - Secured Borrowings (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-11-collateralized-securities-transactions-secured-borrowings-details</Role>
      <ShortName>Note 11 - Collateralized Securities Transactions - Secured Borrowings (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>98</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R99.htm</HtmlFileName>
      <LongName>995642 - Disclosure - Note 12 - Investments in Equity Method Affiliates (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-12-investments-in-equity-method-affiliates-details-textual</Role>
      <ShortName>Note 12 - Investments in Equity Method Affiliates (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-12-investments-in-equity-method-affiliates-tables</ParentRole>
      <Position>99</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R100.htm</HtmlFileName>
      <LongName>995643 - Disclosure - Note 12 - Investments in Equity Method Affiliates - Investments in Equity Method Affiliates (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-12-investments-in-equity-method-affiliates-investments-in-equity-method-affiliates-details</Role>
      <ShortName>Note 12 - Investments in Equity Method Affiliates - Investments in Equity Method Affiliates (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>100</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R101.htm</HtmlFileName>
      <LongName>995644 - Disclosure - Note 13 - Goodwill (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-13-goodwill-details-textual</Role>
      <ShortName>Note 13 - Goodwill (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-13-goodwill-tables</ParentRole>
      <Position>101</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R102.htm</HtmlFileName>
      <LongName>995645 - Disclosure - Note 13 - Goodwill - Goodwill (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-13-goodwill-goodwill-details</Role>
      <ShortName>Note 13 - Goodwill - Goodwill (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>102</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R103.htm</HtmlFileName>
      <LongName>995646 - Disclosure - Note 14 - Leases (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-14-leases-details-textual</Role>
      <ShortName>Note 14 - Leases (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-14-leases-tables</ParentRole>
      <Position>103</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R104.htm</HtmlFileName>
      <LongName>995647 - Disclosure - Note 14 - Leases - Future Maturity of Lease Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-14-leases-future-maturity-of-lease-liabilities-details</Role>
      <ShortName>Note 14 - Leases - Future Maturity of Lease Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>104</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R105.htm</HtmlFileName>
      <LongName>995648 - Disclosure - Note 15 - Other Assets - Other Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-15-other-assets-other-assets-details</Role>
      <ShortName>Note 15 - Other Assets - Other Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>105</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R106.htm</HtmlFileName>
      <LongName>995649 - Disclosure - Note 16 - Furniture, Equipment, and Leasehold Improvements, Net (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-16-furniture-equipment-and-leasehold-improvements-net-details-textual</Role>
      <ShortName>Note 16 - Furniture, Equipment, and Leasehold Improvements, Net (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-16-furniture-equipment-and-leasehold-improvements-net-tables</ParentRole>
      <Position>106</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R107.htm</HtmlFileName>
      <LongName>995650 - Disclosure - Note 16 - Furniture, Equipment, and Leasehold Improvements, Net - Furniture, Equipment, and Leasehold Improvements, Net (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-16-furniture-equipment-and-leasehold-improvements-net-furniture-equipment-and-leasehold-improvements-net-details</Role>
      <ShortName>Note 16 - Furniture, Equipment, and Leasehold Improvements, Net - Furniture, Equipment, and Leasehold Improvements, Net (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>107</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R108.htm</HtmlFileName>
      <LongName>995651 - Disclosure - Note 17 - Accounts Payable and Other Liabilities - Accounts Payable and Other Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-17-accounts-payable-and-other-liabilities-accounts-payable-and-other-liabilities-details</Role>
      <ShortName>Note 17 - Accounts Payable and Other Liabilities - Accounts Payable and Other Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-17-accounts-payable-and-other-liabilities-accounts-payable-and-other-liabilities-tables</ParentRole>
      <Position>108</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R109.htm</HtmlFileName>
      <LongName>995652 - Disclosure - Note 18 - Variable Interest Entities (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-18-variable-interest-entities-details-textual</Role>
      <ShortName>Note 18 - Variable Interest Entities (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-18-variable-interest-entities-tables</ParentRole>
      <Position>109</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R110.htm</HtmlFileName>
      <LongName>995653 - Disclosure - Note 18 - Variable Interest Entities - Consolidated VIEs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-18-variable-interest-entities-consolidated-vies-details</Role>
      <ShortName>Note 18 - Variable Interest Entities - Consolidated VIEs (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>110</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R111.htm</HtmlFileName>
      <LongName>995654 - Disclosure - Note 18 - Variable Interest Entities - Carrying Value of Variable Interests in Non-consolidated Variable Interest Entities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-18-variable-interest-entities-carrying-value-of-variable-interests-in-nonconsolidated-variable-interest-entities-details</Role>
      <ShortName>Note 18 - Variable Interest Entities - Carrying Value of Variable Interests in Non-consolidated Variable Interest Entities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>111</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R112.htm</HtmlFileName>
      <LongName>995655 - Disclosure - Note 19 - Accrued Compensation - Accrued Compensation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-19-accrued-compensation-accrued-compensation-details</Role>
      <ShortName>Note 19 - Accrued Compensation - Accrued Compensation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>112</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R113.htm</HtmlFileName>
      <LongName>995656 - Disclosure - Note 20 - Debt (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-20-debt-details-textual</Role>
      <ShortName>Note 20 - Debt (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-20-debt-tables</ParentRole>
      <Position>113</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R114.htm</HtmlFileName>
      <LongName>995657 - Disclosure - Note 20 - Debt - Detail of Debt (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-20-debt-detail-of-debt-details</Role>
      <ShortName>Note 20 - Debt - Detail of Debt (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>114</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R115.htm</HtmlFileName>
      <LongName>995658 - Disclosure - Note 20 - Debt - Interest Expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-20-debt-interest-expense-details</Role>
      <ShortName>Note 20 - Debt - Interest Expense (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>115</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R116.htm</HtmlFileName>
      <LongName>995659 - Disclosure - Note 21 - Equity (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-21-equity-details-textual</Role>
      <ShortName>Note 21 - Equity (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-21-equity-tables</ParentRole>
      <Position>116</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R117.htm</HtmlFileName>
      <LongName>995660 - Disclosure - Note 21 - Equity - Rollforward of Shares Outstanding (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-21-equity-rollforward-of-shares-outstanding-details</Role>
      <ShortName>Note 21 - Equity - Rollforward of Shares Outstanding (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>117</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R118.htm</HtmlFileName>
      <LongName>995661 - Disclosure - Note 21 - Equity - Rollforward of Units Outstanding (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-21-equity-rollforward-of-units-outstanding-details</Role>
      <ShortName>Note 21 - Equity - Rollforward of Units Outstanding (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>118</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R119.htm</HtmlFileName>
      <LongName>995662 - Disclosure - Note 21 - Equity - Schedule of Effects of Changes in Ownership Interest Subsidiary (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-21-equity-schedule-of-effects-of-changes-in-ownership-interest-subsidiary-details</Role>
      <ShortName>Note 21 - Equity - Schedule of Effects of Changes in Ownership Interest Subsidiary (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>119</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R120.htm</HtmlFileName>
      <LongName>995663 - Disclosure - Note 21 - Equity - Rollforward of Non-controlling Interests (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-21-equity-rollforward-of-noncontrolling-interests-details</Role>
      <ShortName>Note 21 - Equity - Rollforward of Non-controlling Interests (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>120</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R121.htm</HtmlFileName>
      <LongName>995664 - Disclosure - Note 22 - Equity-based Compensation (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-22-equitybased-compensation-details-textual</Role>
      <ShortName>Note 22 - Equity-based Compensation (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-22-equitybased-compensation-tables</ParentRole>
      <Position>121</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R122.htm</HtmlFileName>
      <LongName>995665 - Disclosure - Note 22 - Equity-based Compensation - Equity-based Compensation Included in Compensation and Benefits (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-22-equitybased-compensation-equitybased-compensation-included-in-compensation-and-benefits-details</Role>
      <ShortName>Note 22 - Equity-based Compensation - Equity-based Compensation Included in Compensation and Benefits (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>122</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R123.htm</HtmlFileName>
      <LongName>995666 - Disclosure - Note 22 - Equity-based Compensation - Detail of Equity-based Compensation by Plan (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-22-equitybased-compensation-detail-of-equitybased-compensation-by-plan-details</Role>
      <ShortName>Note 22 - Equity-based Compensation - Detail of Equity-based Compensation by Plan (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>123</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R124.htm</HtmlFileName>
      <LongName>995667 - Disclosure - Note 22 - Equity-based Compensation - Restricted Stock (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-22-equitybased-compensation-restricted-stock-details</Role>
      <ShortName>Note 22 - Equity-based Compensation - Restricted Stock (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>124</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R125.htm</HtmlFileName>
      <LongName>995668 - Disclosure - Note 22 - Equity-based Compensation - Performance Based Vesting (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-22-equitybased-compensation-performance-based-vesting-details</Role>
      <ShortName>Note 22 - Equity-based Compensation - Performance Based Vesting (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>125</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R126.htm</HtmlFileName>
      <LongName>995669 - Disclosure - Note 23 - Income Taxes (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-23-income-taxes-details-textual</Role>
      <ShortName>Note 23 - Income Taxes (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-23-income-taxes-tables</ParentRole>
      <Position>126</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R127.htm</HtmlFileName>
      <LongName>995670 - Disclosure - Note 23 - Income Taxes - Income Tax Expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-23-income-taxes-income-tax-expense-details</Role>
      <ShortName>Note 23 - Income Taxes - Income Tax Expense (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>127</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R128.htm</HtmlFileName>
      <LongName>995671 - Disclosure - Note 23 - Income Taxes - Income (Loss) Before Income Taxes (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-23-income-taxes-income-loss-before-income-taxes-details</Role>
      <ShortName>Note 23 - Income Taxes - Income (Loss) Before Income Taxes (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>128</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R129.htm</HtmlFileName>
      <LongName>995672 - Disclosure - Note 23 - Income Taxes - Income Tax Rate Reconciliation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-23-income-taxes-income-tax-rate-reconciliation-details</Role>
      <ShortName>Note 23 - Income Taxes - Income Tax Rate Reconciliation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>129</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R130.htm</HtmlFileName>
      <LongName>995673 - Disclosure - Note 23 - Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-23-income-taxes-schedule-of-deferred-tax-assets-and-liabilities-details</Role>
      <ShortName>Note 23 - Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>130</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R131.htm</HtmlFileName>
      <LongName>995674 - Disclosure - Note 23 - Income Taxes - Tax Payments Made and Refunds Received (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-23-income-taxes-tax-payments-made-and-refunds-received-details</Role>
      <ShortName>Note 23 - Income Taxes - Tax Payments Made and Refunds Received (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>131</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R132.htm</HtmlFileName>
      <LongName>995675 - Disclosure - Note 24 - Accumulated Other Comprehensive Income (Loss) ("AOCI") - Accumulated Other Comprehensive Income (Loss) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-24-accumulated-other-comprehensive-income-loss-aoci-accumulated-other-comprehensive-income-loss-details</Role>
      <ShortName>Note 24 - Accumulated Other Comprehensive Income (Loss) ("AOCI") - Accumulated Other Comprehensive Income (Loss) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-24-accumulated-other-comprehensive-income-loss-aoci-tables</ParentRole>
      <Position>132</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R133.htm</HtmlFileName>
      <LongName>995676 - Disclosure - Note 25 - Net Capital Requirements - Statutory Net Capital Requirements (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-25-net-capital-requirements-statutory-net-capital-requirements-details</Role>
      <ShortName>Note 25 - Net Capital Requirements - Statutory Net Capital Requirements (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>133</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R134.htm</HtmlFileName>
      <LongName>995677 - Disclosure - Note 26 - Earnings (Loss) Per Common Share (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-26-earnings-loss-per-common-share-details-textual</Role>
      <ShortName>Note 26 - Earnings (Loss) Per Common Share (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-26-earnings-loss-per-common-share-tables</ParentRole>
      <Position>134</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R135.htm</HtmlFileName>
      <LongName>995678 - Disclosure - Note 26 - Earnings (Loss) Per Common Share - Earnings (Loss) Per Common Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-26-earnings-loss-per-common-share-earnings-loss-per-common-share-details</Role>
      <ShortName>Note 26 - Earnings (Loss) Per Common Share - Earnings (Loss) Per Common Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-26-earnings-loss-per-common-share-tables</ParentRole>
      <Position>135</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R136.htm</HtmlFileName>
      <LongName>995679 - Disclosure - Note 26 - Earnings (Loss) Per Common Share - Schedule of Anti-Dilutive Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-26-earnings-loss-per-common-share-schedule-of-antidilutive-securities-details</Role>
      <ShortName>Note 26 - Earnings (Loss) Per Common Share - Schedule of Anti-Dilutive Securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-26-earnings-loss-per-common-share-tables</ParentRole>
      <Position>136</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R137.htm</HtmlFileName>
      <LongName>995680 - Disclosure - Note 28 - Commitments and Contingencies (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-28-commitments-and-contingencies-details-textual</Role>
      <ShortName>Note 28 - Commitments and Contingencies (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-28-commitments-and-contingencies-tables</ParentRole>
      <Position>137</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R138.htm</HtmlFileName>
      <LongName>995681 - Disclosure - Note 28 - Comments and Contingencies - Future Lease Commitments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-28-comments-and-contingencies-future-lease-commitments-details</Role>
      <ShortName>Note 28 - Comments and Contingencies - Future Lease Commitments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>138</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R139.htm</HtmlFileName>
      <LongName>995682 - Disclosure - Note 29 - Segment and Geographic Information (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-29-segment-and-geographic-information-details-textual</Role>
      <ShortName>Note 29 - Segment and Geographic Information (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-29-segment-and-geographic-information-tables</ParentRole>
      <Position>139</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R140.htm</HtmlFileName>
      <LongName>995683 - Disclosure - Note 29 - Segment and Geographic Information - Statements of Operations Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-29-segment-and-geographic-information-statements-of-operations-information-details</Role>
      <ShortName>Note 29 - Segment and Geographic Information - Statements of Operations Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>140</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R141.htm</HtmlFileName>
      <LongName>995684 - Disclosure - Note 29 - Segment and Geographic Information - Balance Sheet Data (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-29-segment-and-geographic-information-balance-sheet-data-details</Role>
      <ShortName>Note 29 - Segment and Geographic Information - Balance Sheet Data (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>141</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R142.htm</HtmlFileName>
      <LongName>995685 - Disclosure - Note 29 - Segment and Geographic Information - Geographic Data (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-29-segment-and-geographic-information-geographic-data-details</Role>
      <ShortName>Note 29 - Segment and Geographic Information - Geographic Data (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>142</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R143.htm</HtmlFileName>
      <LongName>995686 - Disclosure - Note 30 - Supplemental Cash Flow Disclosure (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-30-supplemental-cash-flow-disclosure-details-textual</Role>
      <ShortName>Note 30 - Supplemental Cash Flow Disclosure (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-30-supplemental-cash-flow-disclosure-</ParentRole>
      <Position>143</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R144.htm</HtmlFileName>
      <LongName>995687 - Disclosure - Note 31 - Related Party Transactions (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-31-related-party-transactions-details-textual</Role>
      <ShortName>Note 31 - Related Party Transactions (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-31-related-party-transactions-tables</ParentRole>
      <Position>144</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R145.htm</HtmlFileName>
      <LongName>995688 - Disclosure - Note 31 - Related Party Transactions - Routine Transactions Recognized in the Statements of Operations (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-31-related-party-transactions-routine-transactions-recognized-in-the-statements-of-operations-details</Role>
      <ShortName>Note 31 - Related Party Transactions - Routine Transactions Recognized in the Statements of Operations (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>145</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R146.htm</HtmlFileName>
      <LongName>995689 - Disclosure - Note 32 - Due From Due To Related Parties - Due From Due To Related Parties (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-32-due-from-due-to-related-parties-due-from-due-to-related-parties-details</Role>
      <ShortName>Note 32 - Due From Due To Related Parties - Due From Due To Related Parties (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>146</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R147.htm</HtmlFileName>
      <LongName>995690 - Disclosure - Note 33 - Subsequent Events (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-note-33-subsequent-events-details-textual</Role>
      <ShortName>Note 33 - Subsequent Events (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cohencpa.com/20251231/role/statement-note-33-subsequent-events</ParentRole>
      <Position>147</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R148.htm</HtmlFileName>
      <LongName>995691 - Disclosure - Schedule I - Condensed Financial Information of Registrant (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-schedule-i-condensed-financial-information-of-registrant-details</Role>
      <ShortName>Schedule I - Condensed Financial Information of Registrant (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>148</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R149.htm</HtmlFileName>
      <LongName>995692 - Disclosure - Schedule I - Condensed Statements of Operations (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-schedule-i-condensed-statements-of-operations-details</Role>
      <ShortName>Schedule I - Condensed Statements of Operations (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>149</Position>
    </Report>
    <Report instance="cohn20251231_10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R150.htm</HtmlFileName>
      <LongName>995693 - Disclosure - Schedule I - Statements of Cash Flows (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cohencpa.com/20251231/role/statement-schedule-i-statements-of-cash-flows-details</Role>
      <ShortName>Schedule I - Statements of Cash Flows (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>150</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>cohn-20251231.xsd</File>
    <File>cohn-20251231_cal.xml</File>
    <File>cohn-20251231_def.xml</File>
    <File>cohn-20251231_lab.xml</File>
    <File>cohn-20251231_pre.xml</File>
    <File doctype="10-K" isDefinitelyFs="true" isUsgaap="true" original="cohn20251231_10k.htm">cohn20251231_10k.htm</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="28">http://fasb.org/srt/2025</BaseTaxonomy>
    <BaseTaxonomy items="2060">http://fasb.org/us-gaap/2025</BaseTaxonomy>
    <BaseTaxonomy items="13">http://xbrl.sec.gov/cyd/2025</BaseTaxonomy>
    <BaseTaxonomy items="38">http://xbrl.sec.gov/dei/2025</BaseTaxonomy>
    <BaseTaxonomy items="7">http://xbrl.sec.gov/ecd/2025</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
</XML>
