<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.26.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>147</ContextCount>
  <ElementCount>283</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>42</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>6</UnitCount>
  <MyReports>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>995200090 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>995200100 - Statement - Condensed Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/StatementCondensedConsolidatedBalanceSheets</Role>
      <ShortName>Condensed Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>995200105 - Statement - Condensed Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/StatementCondensedConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Condensed Consolidated Balance Sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>995200200 - Statement - Condensed Consolidated Statements of Operations and Comprehensive Loss</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/StatementCondensedConsolidatedStatementsOfOperationsAndComprehensiveLoss</Role>
      <ShortName>Condensed Consolidated Statements of Operations and Comprehensive Loss</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>995200300 - Statement - Condensed Consolidated Statements of Stockholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/StatementCondensedConsolidatedStatementsOfStockholdersEquity</Role>
      <ShortName>Condensed Consolidated Statements of Stockholders' Equity</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>995200400 - Statement - Condensed Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/StatementCondensedConsolidatedStatementsOfCashFlows</Role>
      <ShortName>Condensed Consolidated Statements of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>995210101 - Disclosure - Organization and Description of Business</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureOrganizationAndDescriptionOfBusiness</Role>
      <ShortName>Organization and Description of Business</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>995210201 - Disclosure - Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureSummaryOfSignificantAccountingPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>995210301 - Disclosure - Fixed Assets, Net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureFixedAssetsNet</Role>
      <ShortName>Fixed Assets, Net</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>995210401 - Disclosure - Patents and Other Intangible Assets, Net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosurePatentsAndOtherIntangibleAssetsNet</Role>
      <ShortName>Patents and Other Intangible Assets, Net</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>995210501 - Disclosure - Revenue, Contract Assets, and Contract Liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureRevenueContractAssetsAndContractLiabilities</Role>
      <ShortName>Revenue, Contract Assets, and Contract Liabilities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>995210601 - Disclosure - Deferred Costs</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureDeferredCosts</Role>
      <ShortName>Deferred Costs</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>995210701 - Disclosure - Product Warranties</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureProductWarranties</Role>
      <ShortName>Product Warranties</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>995210801 - Disclosure - Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureEquity</Role>
      <ShortName>Equity</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>995210901 - Disclosure - Net Loss per Common Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureNetLossPerCommonShare</Role>
      <ShortName>Net Loss per Common Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>995211001 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureCommitmentsAndContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>995211101 - Disclosure - Government Assistance</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureGovernmentAssistance</Role>
      <ShortName>Government Assistance</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>995211201 - Disclosure - Subsequent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureSubsequentEvents</Role>
      <ShortName>Subsequent Events</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>995410 - Disclosure - Pay vs Performance Disclosure</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/PvpDisclosure</Role>
      <ShortName>Pay vs Performance Disclosure</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.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>20</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>99920202 - Disclosure - Summary of Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureSummaryOfSignificantAccountingPoliciesPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://www.clearsigncombustion.com/role/DisclosureSummaryOfSignificantAccountingPolicies</ParentRole>
      <Position>21</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>99930303 - Disclosure - Fixed Assets, Net (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureFixedAssetsNetTables</Role>
      <ShortName>Fixed Assets, Net (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.clearsigncombustion.com/role/DisclosureFixedAssetsNet</ParentRole>
      <Position>22</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>99930403 - Disclosure - Patents and Other Intangible Assets, Net (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosurePatentsAndOtherIntangibleAssetsNetTables</Role>
      <ShortName>Patents and Other Intangible Assets, Net (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.clearsigncombustion.com/role/DisclosurePatentsAndOtherIntangibleAssetsNet</ParentRole>
      <Position>23</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>99930603 - Disclosure - Deferred Costs (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureDeferredCostsTables</Role>
      <ShortName>Deferred Costs (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.clearsigncombustion.com/role/DisclosureDeferredCosts</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>99930703 - Disclosure - Product Warranties (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureProductWarrantiesTables</Role>
      <ShortName>Product Warranties (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.clearsigncombustion.com/role/DisclosureProductWarranties</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>99930803 - Disclosure - Equity (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureEquityTables</Role>
      <ShortName>Equity (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.clearsigncombustion.com/role/DisclosureEquity</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>99930903 - Disclosure - Net Loss per Common Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureNetLossPerCommonShareTables</Role>
      <ShortName>Net Loss per Common Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.clearsigncombustion.com/role/DisclosureNetLossPerCommonShare</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>99940101 - Disclosure - Organization and Description of Business - Business Segments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureOrganizationAndDescriptionOfBusinessBusinessSegmentsDetails</Role>
      <ShortName>Organization and Description of Business - Business Segments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>99940201 - Disclosure - Summary of Significant Accounting Policies - Reverse Stock Split (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureSummaryOfSignificantAccountingPoliciesReverseStockSplitDetails</Role>
      <ShortName>Summary of Significant Accounting Policies - Reverse Stock Split (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>99940202 - Disclosure - Summary of Significant Accounting Policies - Research and Development (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureSummaryOfSignificantAccountingPoliciesResearchAndDevelopmentDetails</Role>
      <ShortName>Summary of Significant Accounting Policies - Research and Development (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>99940203 - Disclosure - Summary of Significant Accounting Policies - Foreign Operations (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureSummaryOfSignificantAccountingPoliciesForeignOperationsDetails</Role>
      <ShortName>Summary of Significant Accounting Policies - Foreign Operations (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>99940301 - Disclosure - Fixed Assets, Net - Summary (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureFixedAssetsNetSummaryDetails</Role>
      <ShortName>Fixed Assets, Net - Summary (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>99940302 - Disclosure - Fixed Assets, Net - Leases (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureFixedAssetsNetLeasesDetails</Role>
      <ShortName>Fixed Assets, Net - Leases (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>99940303 - Disclosure - Fixed Assets, Net - Leases - Supplemental balance sheet and cash flow information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureFixedAssetsNetLeasesSupplementalBalanceSheetAndCashFlowInformationDetails</Role>
      <ShortName>Fixed Assets, Net - Leases - Supplemental balance sheet and cash flow information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>99940304 - Disclosure - Fixed Assets, Net - Minimum future lease payments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureFixedAssetsNetMinimumFutureLeasePaymentsDetails</Role>
      <ShortName>Fixed Assets, Net - Minimum future lease payments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>99940401 - Disclosure - Patents and Other Intangible Assets, Net - Summary (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosurePatentsAndOtherIntangibleAssetsNetSummaryDetails</Role>
      <ShortName>Patents and Other Intangible Assets, Net - Summary (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.clearsigncombustion.com/role/DisclosurePatentsAndOtherIntangibleAssetsNetTables</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>99940402 - Disclosure - Patents and Other Intangible Assets, Net - Future amortization expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosurePatentsAndOtherIntangibleAssetsNetFutureAmortizationExpenseDetails</Role>
      <ShortName>Patents and Other Intangible Assets, Net - Future amortization expense (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>99940403 - Disclosure - Patents and Other Intangible Assets, Net - Additional information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosurePatentsAndOtherIntangibleAssetsNetAdditionalInformationDetails</Role>
      <ShortName>Patents and Other Intangible Assets, Net - Additional information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>99940501 - Disclosure - Revenue, Contract Assets, and Contract Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureRevenueContractAssetsAndContractLiabilitiesDetails</Role>
      <ShortName>Revenue, Contract Assets, and Contract Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.clearsigncombustion.com/role/DisclosureRevenueContractAssetsAndContractLiabilities</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>99940601 - Disclosure - Deferred Costs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureDeferredCostsDetails</Role>
      <ShortName>Deferred Costs (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.clearsigncombustion.com/role/DisclosureDeferredCostsTables</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>99940701 - Disclosure - Product Warranties (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureProductWarrantiesDetails</Role>
      <ShortName>Product Warranties (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.clearsigncombustion.com/role/DisclosureProductWarrantiesTables</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>99940801 - Disclosure - Equity - Common Stock and Preferred Stock (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureEquityCommonStockAndPreferredStockDetails</Role>
      <ShortName>Equity - Common Stock and Preferred Stock (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>99940802 - Disclosure - Equity - Warrants &amp; Pre-Funded Warrants (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureEquityWarrantsPreFundedWarrantsDetails</Role>
      <ShortName>Equity - Warrants &amp; Pre-Funded Warrants (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>99940803 - Disclosure - Equity - Equity Incentive Plan (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureEquityEquityIncentivePlanDetails</Role>
      <ShortName>Equity - Equity Incentive Plan (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>99940804 - Disclosure - Equity - Weighted-average assumptions utilized in the calculation of the fair market value of stock options granted (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureEquityWeightedAverageAssumptionsUtilizedInCalculationOfFairMarketValueOfStockOptionsGrantedDetails</Role>
      <ShortName>Equity - Weighted-average assumptions utilized in the calculation of the fair market value of stock options granted (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>99940805 - Disclosure - Equity - Equity Incentive Plan Options and Inducement Options (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureEquityEquityIncentivePlanOptionsAndInducementOptionsDetails</Role>
      <ShortName>Equity - Equity Incentive Plan Options and Inducement Options (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>99940806 - Disclosure - Equity - Inducement Options (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureEquityInducementOptionsDetails</Role>
      <ShortName>Equity - Inducement Options (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>99940807 - Disclosure - Equity - Restricted Stock Units (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureEquityRestrictedStockUnitsDetails</Role>
      <ShortName>Equity - Restricted Stock Units (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>99940808 - Disclosure - Equity - Restricted Stock Units Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureEquityRestrictedStockUnitsActivityDetails</Role>
      <ShortName>Equity - Restricted Stock Units Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>99940809 - Disclosure - Equity - Restricted Stock Units - Compensation Expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureEquityRestrictedStockUnitsCompensationExpenseDetails</Role>
      <ShortName>Equity - Restricted Stock Units - Compensation Expense (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>99940810 - Disclosure - Equity - Stock Awards (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureEquityStockAwardsDetails</Role>
      <ShortName>Equity - Stock Awards (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>99940811 - Disclosure - Equity - Consultant Stock Plan (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureEquityConsultantStockPlanDetails</Role>
      <ShortName>Equity - Consultant Stock Plan (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>99940901 - Disclosure - Net Loss per Common Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureNetLossPerCommonShareDetails</Role>
      <ShortName>Net Loss per Common Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.clearsigncombustion.com/role/DisclosureNetLossPerCommonShareTables</ParentRole>
      <Position>53</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>99941001 - Disclosure - Commitments and Contingencies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureCommitmentsAndContingenciesDetails</Role>
      <ShortName>Commitments and Contingencies (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.clearsigncombustion.com/role/DisclosureCommitmentsAndContingencies</ParentRole>
      <Position>54</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>99941101 - Disclosure - Government Assistance (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureGovernmentAssistanceDetails</Role>
      <ShortName>Government Assistance (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.clearsigncombustion.com/role/DisclosureGovernmentAssistance</ParentRole>
      <Position>55</Position>
    </Report>
    <Report instance="clir-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>99941201 - Disclosure - Subsequent Events (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.clearsigncombustion.com/role/DisclosureSubsequentEventsDetails</Role>
      <ShortName>Subsequent Events (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.clearsigncombustion.com/role/DisclosureSubsequentEvents</ParentRole>
      <Position>56</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>clir-20260630.xsd</File>
    <File>clir-20260630_cal.xml</File>
    <File>clir-20260630_def.xml</File>
    <File>clir-20260630_lab.xml</File>
    <File>clir-20260630_pre.xml</File>
    <File doctype="10-Q" isDefinitelyFs="true" isUsgaap="true" original="clir-20260630x10q.htm">clir-20260630x10q.htm</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="502">http://fasb.org/us-gaap/2025</BaseTaxonomy>
    <BaseTaxonomy items="30">http://xbrl.sec.gov/dei/2025</BaseTaxonomy>
    <BaseTaxonomy items="4">http://xbrl.sec.gov/ecd/2025</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
