<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.22.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>144</ContextCount>
  <ElementCount>390</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>49</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>6</UnitCount>
  <MyReports>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>000 - Document - Document And Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/DocumentAndEntityInformation</Role>
      <ShortName>Document And Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>001 - Statement - Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ConsolidatedBalanceSheet</Role>
      <ShortName>Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>002 - Statement - Consolidated Balance Sheets (Parentheticals)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ConsolidatedBalanceSheet_Parentheticals</Role>
      <ShortName>Consolidated Balance Sheets (Parentheticals)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>003 - Statement - Consolidated Statements of Operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ConsolidatedIncomeStatement</Role>
      <ShortName>Consolidated Statements of Operations</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>004 - Statement - Consolidated Statements of Comprehensive Loss</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ConsolidatedComprehensiveIncome</Role>
      <ShortName>Consolidated Statements of Comprehensive Loss</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>005 - Statement - Statements of Changes in Shareholders??? Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ShareholdersEquityType2or3</Role>
      <ShortName>Statements of Changes in Shareholders??? Equity</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.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://cyren.com/role/ConsolidatedCashFlow</Role>
      <ShortName>Consolidated Statements of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>007 - Disclosure - General</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/General</Role>
      <ShortName>General</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>008 - Disclosure - Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/SignificantAccountingPolicies</Role>
      <ShortName>Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>009 - Disclosure - Property and Equipment, Net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/PropertyandEquipmentNet</Role>
      <ShortName>Property and Equipment, Net</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>010 - Disclosure - Intangible Assets, Net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/IntangibleAssetsNet</Role>
      <ShortName>Intangible Assets, Net</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>011 - Disclosure - Goodwill</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/Goodwill</Role>
      <ShortName>Goodwill</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>012 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/CommitmentsandContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>013 - Disclosure - Leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/Leases</Role>
      <ShortName>Leases</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>014 - Disclosure - Shareholders??? Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ShareholdersEquity</Role>
      <ShortName>Shareholders??? Equity</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>015 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/IncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>016 - Disclosure - Segment and Geographic Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/SegmentandGeographicInformation</Role>
      <ShortName>Segment and Geographic Information</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>017 - Disclosure - Financial Expense, Net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/FinancialExpenseNet</Role>
      <ShortName>Financial Expense, Net</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>018 - Disclosure - Related Parties</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/RelatedParties</Role>
      <ShortName>Related Parties</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>019 - Disclosure - Subsequent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/SubsequentEvents</Role>
      <ShortName>Subsequent Events</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>020 - Disclosure - Accounting Policies, by Policy (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/AccountingPoliciesByPolicy</Role>
      <ShortName>Accounting Policies, by Policy (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://cyren.com/role/SignificantAccountingPolicies</ParentRole>
      <Position>21</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>021 - Disclosure - Significant Accounting Policies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/SignificantAccountingPoliciesTables</Role>
      <ShortName>Significant Accounting Policies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://cyren.com/role/SignificantAccountingPolicies</ParentRole>
      <Position>22</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>022 - Disclosure - Property and Equipment, Net (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/PropertyandEquipmentNetTables</Role>
      <ShortName>Property and Equipment, Net (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://cyren.com/role/PropertyandEquipmentNet</ParentRole>
      <Position>23</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>023 - Disclosure - Intangible Assets, Net (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/IntangibleAssetsNetTables</Role>
      <ShortName>Intangible Assets, Net (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://cyren.com/role/IntangibleAssetsNet</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>024 - Disclosure - Goodwill (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/GoodwillTables</Role>
      <ShortName>Goodwill (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://cyren.com/role/Goodwill</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>025 - Disclosure - Leases (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/LeasesTables</Role>
      <ShortName>Leases (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://cyren.com/role/Leases</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>026 - Disclosure - Shareholders??? Equity (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ShareholdersEquityTables</Role>
      <ShortName>Shareholders??? Equity (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://cyren.com/role/ShareholdersEquity</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>027 - Disclosure - Income Taxes (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/IncomeTaxesTables</Role>
      <ShortName>Income Taxes (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://cyren.com/role/IncomeTaxes</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>028 - Disclosure - Segment and Geographic Information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/SegmentandGeographicInformationTables</Role>
      <ShortName>Segment and Geographic Information (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://cyren.com/role/SegmentandGeographicInformation</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>029 - Disclosure - Financial Expense, Net (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/FinancialExpenseNetTables</Role>
      <ShortName>Financial Expense, Net (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://cyren.com/role/FinancialExpenseNet</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>030 - Disclosure - Related Parties (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/RelatedPartiesTables</Role>
      <ShortName>Related Parties (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://cyren.com/role/RelatedParties</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>031 - Disclosure - General (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/GeneralDetails</Role>
      <ShortName>General (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/General</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>032 - Disclosure - Significant Accounting Policies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/SignificantAccountingPoliciesDetails</Role>
      <ShortName>Significant Accounting Policies (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/SignificantAccountingPoliciesTables</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>033 - Disclosure - Significant Accounting Policies (Details) - Schedule of depreciation is calculated using the straight-line method over the estimated useful lives of the assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ScheduleofdepreciationiscalculatedusingthestraightlinemethodovertheestimatedusefullivesoftheassetsTable</Role>
      <ShortName>Significant Accounting Policies (Details) - Schedule of depreciation is calculated using the straight-line method over the estimated useful lives of the assets</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/SignificantAccountingPoliciesTables</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>034 - Disclosure - Significant Accounting Policies (Details) - Schedule of fair value for options granted</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ScheduleoffairvalueforoptionsgrantedTable</Role>
      <ShortName>Significant Accounting Policies (Details) - Schedule of fair value for options granted</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/SignificantAccountingPoliciesTables</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>035 - Disclosure - Property and Equipment, Net (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/PropertyandEquipmentNetDetails</Role>
      <ShortName>Property and Equipment, Net (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/PropertyandEquipmentNetTables</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>036 - Disclosure - Property and Equipment, Net (Details) - Schedule of property and equipment, net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ScheduleofpropertyandequipmentnetTable</Role>
      <ShortName>Property and Equipment, Net (Details) - Schedule of property and equipment, net</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/PropertyandEquipmentNetTables</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>037 - Disclosure - Intangible Assets, Net (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/IntangibleAssetsNetDetails</Role>
      <ShortName>Intangible Assets, Net (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/IntangibleAssetsNetTables</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>038 - Disclosure - Intangible Assets, Net (Details) - Schedule of definite-lived intangible assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ScheduleofdefinitelivedintangibleassetsTable</Role>
      <ShortName>Intangible Assets, Net (Details) - Schedule of definite-lived intangible assets</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/IntangibleAssetsNetTables</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>039 - Disclosure - Intangible Assets, Net (Details) - Schedule of weighted average remaining amortization period for the major classes of intangible assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ScheduleofweightedaverageremainingamortizationperiodforthemajorclassesofintangibleassetsTable</Role>
      <ShortName>Intangible Assets, Net (Details) - Schedule of weighted average remaining amortization period for the major classes of intangible assets</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/IntangibleAssetsNetTables</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>040 - Disclosure - Intangible Assets, Net (Details) - Schedule of estimated aggregate amortization expenses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ScheduleofestimatedaggregateamortizationexpensesTable</Role>
      <ShortName>Intangible Assets, Net (Details) - Schedule of estimated aggregate amortization expenses</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/IntangibleAssetsNetTables</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>041 - Disclosure - Goodwill (Details) - Schedule of changes in the carrying amount of goodwill</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ScheduleofchangesinthecarryingamountofgoodwillTable</Role>
      <ShortName>Goodwill (Details) - Schedule of changes in the carrying amount of goodwill</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/GoodwillTables</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>042 - Disclosure - Commitments and Contingencies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/CommitmentsandContingenciesDetails</Role>
      <ShortName>Commitments and Contingencies (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/CommitmentsandContingencies</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>043 - Disclosure - Leases (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/LeasesDetails</Role>
      <ShortName>Leases (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/LeasesTables</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>044 - Disclosure - Leases (Details) - Schedule of operating right-of-use assets and operating lease liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ScheduleofoperatingrightofuseassetsandoperatingleaseliabilitiesTable</Role>
      <ShortName>Leases (Details) - Schedule of operating right-of-use assets and operating lease liabilities</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/LeasesTables</ParentRole>
      <Position>45</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>045 - Disclosure - Leases (Details) - Schedule of minimum lease payments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ScheduleofminimumleasepaymentsTable</Role>
      <ShortName>Leases (Details) - Schedule of minimum lease payments</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/LeasesTables</ParentRole>
      <Position>46</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>046 - Disclosure - Leases (Details) - Schedule of weighted average remaining lease terms and discount rates for all of operating leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ScheduleofweightedaverageremainingleasetermsanddiscountratesforallofoperatingleasesTable</Role>
      <ShortName>Leases (Details) - Schedule of weighted average remaining lease terms and discount rates for all of operating leases</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/LeasesTables</ParentRole>
      <Position>47</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>047 - Disclosure - Shareholders??? Equity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ShareholdersEquityDetails</Role>
      <ShortName>Shareholders??? Equity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/ShareholdersEquityTables</ParentRole>
      <Position>48</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>048 - Disclosure - Shareholders??? Equity (Details) - Schedule of employees and directors' stock option activity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ScheduleofemployeesanddirectorsstockoptionactivityTable</Role>
      <ShortName>Shareholders??? Equity (Details) - Schedule of employees and directors' stock option activity</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/ShareholdersEquityTables</ParentRole>
      <Position>49</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>049 - Disclosure - Shareholders??? Equity (Details) - Schedule of employee and directors??? options outstanding</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ScheduleofemployeeanddirectorsoptionsoutstandingTable</Role>
      <ShortName>Shareholders??? Equity (Details) - Schedule of employee and directors??? options outstanding</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/ShareholdersEquityTables</ParentRole>
      <Position>50</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>050 - Disclosure - Shareholders??? Equity (Details) - Schedule of options to non-employees and non-directors</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ScheduleofoptionstononemployeesandnondirectorsTable</Role>
      <ShortName>Shareholders??? Equity (Details) - Schedule of options to non-employees and non-directors</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/ShareholdersEquityTables</ParentRole>
      <Position>51</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>051 - Disclosure - Shareholders??? Equity (Details) - Schedule of RSUs activity for employees, directors and non-employees</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ScheduleofRSUsactivityforemployeesdirectorsandnonemployeesTable</Role>
      <ShortName>Shareholders??? Equity (Details) - Schedule of RSUs activity for employees, directors and non-employees</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/ShareholdersEquityTables</ParentRole>
      <Position>52</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>052 - Disclosure - Shareholders??? Equity (Details) - Schedule of stock-based compensation expense</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ScheduleofstockbasedcompensationexpenseTable</Role>
      <ShortName>Shareholders??? Equity (Details) - Schedule of stock-based compensation expense</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/ShareholdersEquityTables</ParentRole>
      <Position>53</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>053 - Disclosure - Income Taxes (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/IncomeTaxesDetails</Role>
      <ShortName>Income Taxes (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/IncomeTaxesTables</ParentRole>
      <Position>54</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>054 - Disclosure - Income Taxes (Details) - Schedule of deferred taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ScheduleofdeferredtaxesTable</Role>
      <ShortName>Income Taxes (Details) - Schedule of deferred taxes</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/IncomeTaxesTables</ParentRole>
      <Position>55</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>055 - Disclosure - Income Taxes (Details) - Schedule of loss before tax benefit (expense)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ScheduleoflossbeforetaxbenefitexpenseTable</Role>
      <ShortName>Income Taxes (Details) - Schedule of loss before tax benefit (expense)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/IncomeTaxesTables</ParentRole>
      <Position>56</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>056 - Disclosure - Income Taxes (Details) - Schedule of tax benefit (expense)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ScheduleoftaxbenefitexpenseTable</Role>
      <ShortName>Income Taxes (Details) - Schedule of tax benefit (expense)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/IncomeTaxesTables</ParentRole>
      <Position>57</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>057 - Disclosure - Income Taxes (Details) - Schedule of unrecognized tax benefits related to uncertain tax positions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ScheduleofunrecognizedtaxbenefitsrelatedtouncertaintaxpositionsTable</Role>
      <ShortName>Income Taxes (Details) - Schedule of unrecognized tax benefits related to uncertain tax positions</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/IncomeTaxesTables</ParentRole>
      <Position>58</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>058 - Disclosure - Segment and Geographic Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/SegmentandGeographicInformationDetails</Role>
      <ShortName>Segment and Geographic Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/SegmentandGeographicInformationTables</ParentRole>
      <Position>59</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>059 - Disclosure - Segment and Geographic Information (Details) - Schedule of total revenue by solutions offered by geographic area</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ScheduleoftotalrevenuebysolutionsofferedbygeographicareaTable</Role>
      <ShortName>Segment and Geographic Information (Details) - Schedule of total revenue by solutions offered by geographic area</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/SegmentandGeographicInformationTables</ParentRole>
      <Position>60</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>060 - Disclosure - Segment and Geographic Information (Details) - Schedule of revenue generated by customer type</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ScheduleofrevenuegeneratedbycustomertypeTable</Role>
      <ShortName>Segment and Geographic Information (Details) - Schedule of revenue generated by customer type</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/SegmentandGeographicInformationTables</ParentRole>
      <Position>61</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>061 - Disclosure - Segment and Geographic Information (Details) - Schedule of long-lived tangible assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ScheduleoflonglivedtangibleassetsTable</Role>
      <ShortName>Segment and Geographic Information (Details) - Schedule of long-lived tangible assets</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/SegmentandGeographicInformationTables</ParentRole>
      <Position>62</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>062 - Disclosure - Financial Expense, Net (Details) - Schedule of financial expense, net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ScheduleoffinancialexpensenetTable</Role>
      <ShortName>Financial Expense, Net (Details) - Schedule of financial expense, net</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/FinancialExpenseNetTables</ParentRole>
      <Position>63</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>063 - Disclosure - Related Parties (Details) - Schedule of related party balances</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ScheduleofrelatedpartybalancesTable</Role>
      <ShortName>Related Parties (Details) - Schedule of related party balances</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/RelatedPartiesTables</ParentRole>
      <Position>64</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>064 - Disclosure - Related Parties (Details) - Schedule of related party transactions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/ScheduleofrelatedpartytransactionsTable</Role>
      <ShortName>Related Parties (Details) - Schedule of related party transactions</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/RelatedPartiesTables</ParentRole>
      <Position>65</Position>
    </Report>
    <Report instance="f10k2021_cyrenltd.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>065 - Disclosure - Subsequent Events (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cyren.com/role/SubsequentEventsDetails</Role>
      <ShortName>Subsequent Events (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://cyren.com/role/SubsequentEvents</ParentRole>
      <Position>66</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File doctype="10-K" original="f10k2021_cyrenltd.htm">f10k2021_cyrenltd.htm</File>
    <File>cyrn-20211231.xsd</File>
    <File>cyrn-20211231_cal.xml</File>
    <File>cyrn-20211231_def.xml</File>
    <File>cyrn-20211231_lab.xml</File>
    <File>cyrn-20211231_pre.xml</File>
    <File>f10k2021ex10-1_cyrenltd.htm</File>
    <File>f10k2021ex10-21_cyrenltd.htm</File>
    <File>f10k2021ex10-2_cyrenltd.htm</File>
    <File>f10k2021ex21_cyrenltd.htm</File>
    <File>f10k2021ex23-1_cyrenltd.htm</File>
    <File>f10k2021ex31-1_cyrenltd.htm</File>
    <File>f10k2021ex31-2_cyrenltd.htm</File>
    <File>f10k2021ex32-1_cyrenltd.htm</File>
    <File>f10k2021ex4-1_cyrenltd.htm</File>
  </InputFiles>
  <SupplementalFiles>
    <File>image_001.jpg</File>
    <File>image_002.jpg</File>
    <File>image_003.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy items="606">http://fasb.org/us-gaap/2021-01-31</BaseTaxonomy>
    <BaseTaxonomy items="37">http://xbrl.sec.gov/dei/2021q4</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
