<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.26.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>222</ContextCount>
  <ElementCount>367</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>85</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>6</UnitCount>
  <MyReports>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0000001 - Document - Cover</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/Cover</Role>
      <ShortName>Cover</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>9952151 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/CONDENSEDCONSOLIDATEDBALANCESHEETS</Role>
      <ShortName>CONDENSED CONSOLIDATED BALANCE SHEETS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>9952152 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/CONDENSEDCONSOLIDATEDBALANCESHEETSParenthetical</Role>
      <ShortName>CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>9952153 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFOPERATIONSANDCOMPREHENSIVELOSS</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>9952154 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS??? EQUITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFCHANGESINSTOCKHOLDERSEQUITY</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS??? EQUITY</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>9952155 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFCASHFLOWS</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>9952156 - Disclosure - Organization and Description of Business</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/OrganizationandDescriptionofBusiness</Role>
      <ShortName>Organization and Description of Business</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>9952157 - Disclosure - Basis of Presentation and Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/BasisofPresentationandSummaryofSignificantAccountingPolicies</Role>
      <ShortName>Basis of Presentation and Summary of Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>9952158 - Disclosure - Revenues</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/Revenues</Role>
      <ShortName>Revenues</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>9952159 - Disclosure - Marketable Securities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/MarketableSecurities</Role>
      <ShortName>Marketable Securities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>9952160 - Disclosure - Fair Value Measurements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/FairValueMeasurements</Role>
      <ShortName>Fair Value Measurements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>9952161 - Disclosure - Property and Equipment, Net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/PropertyandEquipmentNet</Role>
      <ShortName>Property and Equipment, Net</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>9952162 - Disclosure - Capitalized Internal-Use??Software, Net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/CapitalizedInternalUseSoftwareNet</Role>
      <ShortName>Capitalized Internal-Use??Software, Net</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>9952163 - Disclosure - Leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/Leases</Role>
      <ShortName>Leases</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>9952164 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/CommitmentsandContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>9952165 - Disclosure - Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/Debt</Role>
      <ShortName>Debt</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>9952166 - Disclosure - Stockholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/StockholdersEquity</Role>
      <ShortName>Stockholders' Equity</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>9952167 - Disclosure - Stock-Based Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/StockBasedCompensation</Role>
      <ShortName>Stock-Based Compensation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>9952168 - Disclosure - Net Loss per Share Attributable to Common Stockholders</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/NetLossperShareAttributabletoCommonStockholders</Role>
      <ShortName>Net Loss per Share Attributable to Common Stockholders</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>9952169 - Disclosure - Restructuring</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/Restructuring</Role>
      <ShortName>Restructuring</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>9952170 - Disclosure - Segment Reporting</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/SegmentReporting</Role>
      <ShortName>Segment Reporting</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.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>22</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>9955511 - Disclosure - Basis of Presentation and Summary of Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesPolicies</Role>
      <ShortName>Basis of Presentation and Summary of Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://www.backblaze.com/role/BasisofPresentationandSummaryofSignificantAccountingPolicies</ParentRole>
      <Position>23</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>9955512 - Disclosure - Basis of Presentation and Summary of Significant Accounting Policies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesTables</Role>
      <ShortName>Basis of Presentation and Summary of Significant Accounting Policies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.backblaze.com/role/BasisofPresentationandSummaryofSignificantAccountingPolicies</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>9955513 - Disclosure - Revenues (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/RevenuesTables</Role>
      <ShortName>Revenues (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.backblaze.com/role/Revenues</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>9955514 - Disclosure - Marketable Securities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/MarketableSecuritiesTables</Role>
      <ShortName>Marketable Securities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.backblaze.com/role/MarketableSecurities</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>9955515 - Disclosure - Fair Value Measurements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/FairValueMeasurementsTables</Role>
      <ShortName>Fair Value Measurements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.backblaze.com/role/FairValueMeasurements</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>9955516 - Disclosure - Property and Equipment, Net (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/PropertyandEquipmentNetTables</Role>
      <ShortName>Property and Equipment, Net (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.backblaze.com/role/PropertyandEquipmentNet</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>9955517 - Disclosure - Capitalized Internal-Use??Software, Net (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/CapitalizedInternalUseSoftwareNetTables</Role>
      <ShortName>Capitalized Internal-Use??Software, Net (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.backblaze.com/role/CapitalizedInternalUseSoftwareNet</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>9955518 - Disclosure - Leases (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/LeasesTables</Role>
      <ShortName>Leases (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.backblaze.com/role/Leases</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>9955519 - Disclosure - Stock-Based Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/StockBasedCompensationTables</Role>
      <ShortName>Stock-Based Compensation (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.backblaze.com/role/StockBasedCompensation</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>9955520 - Disclosure - Net Loss per Share Attributable to Common Stockholders (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/NetLossperShareAttributabletoCommonStockholdersTables</Role>
      <ShortName>Net Loss per Share Attributable to Common Stockholders (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.backblaze.com/role/NetLossperShareAttributabletoCommonStockholders</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>9955521 - Disclosure - Restructuring (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/RestructuringTables</Role>
      <ShortName>Restructuring (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.backblaze.com/role/Restructuring</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>9955522 - Disclosure - Segment Reporting (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/SegmentReportingTables</Role>
      <ShortName>Segment Reporting (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.backblaze.com/role/SegmentReporting</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>9955523 - Disclosure - Basis of Presentation and Summary of Significant Accounting Policies - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesNarrativeDetails</Role>
      <ShortName>Basis of Presentation and Summary of Significant Accounting Policies - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.backblaze.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesTables</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>9955524 - Disclosure - Basis of Presentation and Summary of Significant Accounting Policies - Schedules of Concentration of Risk, by Risk Factor (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesSchedulesofConcentrationofRiskbyRiskFactorDetails</Role>
      <ShortName>Basis of Presentation and Summary of Significant Accounting Policies - Schedules of Concentration of Risk, by Risk Factor (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>9955525 - Disclosure - Revenues - Schedule of Disaggregation of Revenues (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/RevenuesScheduleofDisaggregationofRevenuesDetails</Role>
      <ShortName>Revenues - Schedule of Disaggregation of Revenues (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>9955526 - Disclosure - Revenues - Schedule of Revenue by Geographic Area (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/RevenuesScheduleofRevenuebyGeographicAreaDetails</Role>
      <ShortName>Revenues - Schedule of Revenue by Geographic Area (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>9955527 - Disclosure - Revenues - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/RevenuesNarrativeDetails</Role>
      <ShortName>Revenues - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>9955528 - Disclosure - Revenues - Schedule of Deferred Revenue (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/RevenuesScheduleofDeferredRevenueDetails</Role>
      <ShortName>Revenues - Schedule of Deferred Revenue (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>9955529 - Disclosure - Revenues - Schedule of Revenue, Remaining Performance Obligation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/RevenuesScheduleofRevenueRemainingPerformanceObligationDetails</Role>
      <ShortName>Revenues - Schedule of Revenue, Remaining Performance Obligation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>9955530 - Disclosure - Revenues - Schedule of Deferred Contract Costs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/RevenuesScheduleofDeferredContractCostsDetails</Role>
      <ShortName>Revenues - Schedule of Deferred Contract Costs (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>9955531 - Disclosure - Marketable Securities - Schedule of Fair Values and Gross Unrealized Gains and Losses on Investments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/MarketableSecuritiesScheduleofFairValuesandGrossUnrealizedGainsandLossesonInvestmentsDetails</Role>
      <ShortName>Marketable Securities - Schedule of Fair Values and Gross Unrealized Gains and Losses on Investments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>9955532 - Disclosure - Marketable Securities - Schedule of Scheduled Maturities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/MarketableSecuritiesScheduleofScheduledMaturitiesDetails</Role>
      <ShortName>Marketable Securities - Schedule of Scheduled Maturities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>9955533 - Disclosure - Marketable Securities - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/MarketableSecuritiesNarrativeDetails</Role>
      <ShortName>Marketable Securities - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>9955534 - Disclosure - Fair Value Measurements - Schedule of Held-To-Maturity Investments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/FairValueMeasurementsScheduleofHeldToMaturityInvestmentsDetails</Role>
      <ShortName>Fair Value Measurements - Schedule of Held-To-Maturity Investments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>9955535 - Disclosure - Fair Value Measurements - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/FairValueMeasurementsNarrativeDetails</Role>
      <ShortName>Fair Value Measurements - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>9955536 - Disclosure - Property and Equipment, Net - Schedule of Property and Equipment, Net (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/PropertyandEquipmentNetScheduleofPropertyandEquipmentNetDetails</Role>
      <ShortName>Property and Equipment, Net - Schedule of Property and Equipment, Net (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>9955537 - Disclosure - Property and Equipment, Net - Schedule of Long-Lived Assets by Geographic Areas (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/PropertyandEquipmentNetScheduleofLongLivedAssetsbyGeographicAreasDetails</Role>
      <ShortName>Property and Equipment, Net - Schedule of Long-Lived Assets by Geographic Areas (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>9955538 - Disclosure - Capitalized Internal-Use??Software, Net - Schedule of Capitalized Internal Use Software (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/CapitalizedInternalUseSoftwareNetScheduleofCapitalizedInternalUseSoftwareDetails</Role>
      <ShortName>Capitalized Internal-Use??Software, Net - Schedule of Capitalized Internal Use Software (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>9955539 - Disclosure - Capitalized Internal-Use??Software, Net - Schedule of Amortization Expense in Capitalized Internal Use Software (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/CapitalizedInternalUseSoftwareNetScheduleofAmortizationExpenseinCapitalizedInternalUseSoftwareDetails</Role>
      <ShortName>Capitalized Internal-Use??Software, Net - Schedule of Amortization Expense in Capitalized Internal Use Software (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>9955540 - Disclosure - Capitalized Internal-Use??Software, Net - Schedule of Future Amortization Expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/CapitalizedInternalUseSoftwareNetScheduleofFutureAmortizationExpenseDetails</Role>
      <ShortName>Capitalized Internal-Use??Software, Net - Schedule of Future Amortization Expense (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>9955541 - Disclosure - Leases - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/LeasesNarrativeDetails</Role>
      <ShortName>Leases - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>9955542 - Disclosure - Leases - Schedule Of Assets Acquired Through Finance Lease And Lease Financing Obligation Agreement (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/LeasesScheduleOfAssetsAcquiredThroughFinanceLeaseAndLeaseFinancingObligationAgreementDetails</Role>
      <ShortName>Leases - Schedule Of Assets Acquired Through Finance Lease And Lease Financing Obligation Agreement (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>9955543 - Disclosure - Leases - Schedule of Operating Lease Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/LeasesScheduleofOperatingLeaseInformationDetails</Role>
      <ShortName>Leases - Schedule of Operating Lease Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>9955544 - Disclosure - Leases - Schedule of Supplemental Cash Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/LeasesScheduleofSupplementalCashInformationDetails</Role>
      <ShortName>Leases - Schedule of Supplemental Cash Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>9955545 - Disclosure - Leases - Schedule of Future Minimum Commitments for Finance Leases and Lease Financing Obligations (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/LeasesScheduleofFutureMinimumCommitmentsforFinanceLeasesandLeaseFinancingObligationsDetails</Role>
      <ShortName>Leases - Schedule of Future Minimum Commitments for Finance Leases and Lease Financing Obligations (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>9955546 - Disclosure - Leases - Schedule of Future Minimum Obligations For Operating Leases And Non-Lease Components (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/LeasesScheduleofFutureMinimumObligationsForOperatingLeasesAndNonLeaseComponentsDetails</Role>
      <ShortName>Leases - Schedule of Future Minimum Obligations For Operating Leases And Non-Lease Components (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>9955547 - Disclosure - Commitments and Contingencies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/CommitmentsandContingenciesDetails</Role>
      <ShortName>Commitments and Contingencies (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.backblaze.com/role/CommitmentsandContingencies</ParentRole>
      <Position>59</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>9955548 - Disclosure - Debt (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/DebtDetails</Role>
      <ShortName>Debt (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.backblaze.com/role/Debt</ParentRole>
      <Position>60</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>9955549 - Disclosure - Stockholders' Equity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/StockholdersEquityDetails</Role>
      <ShortName>Stockholders' Equity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.backblaze.com/role/StockholdersEquity</ParentRole>
      <Position>61</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>9955550 - Disclosure - Stock-Based Compensation - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/StockBasedCompensationNarrativeDetails</Role>
      <ShortName>Stock-Based Compensation - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>9955551 - Disclosure - Stock-Based Compensation - Schedule of Share-based Compensation Arrangements by Share-based Payment Award (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/StockBasedCompensationScheduleofSharebasedCompensationArrangementsbySharebasedPaymentAwardDetails</Role>
      <ShortName>Stock-Based Compensation - Schedule of Share-based Compensation Arrangements by Share-based Payment Award (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>9955552 - Disclosure - Stock-Based Compensation - Schedule of Stock Option Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/StockBasedCompensationScheduleofStockOptionActivityDetails</Role>
      <ShortName>Stock-Based Compensation - Schedule of Stock Option Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>9955553 - Disclosure - Stock-Based Compensation - Schedule of Share-based Payment Arrangement, Expensed and Capitalized, Amount (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/StockBasedCompensationScheduleofSharebasedPaymentArrangementExpensedandCapitalizedAmountDetails</Role>
      <ShortName>Stock-Based Compensation - Schedule of Share-based Payment Arrangement, Expensed and Capitalized, Amount (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>65</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>9955554 - Disclosure - Net Loss per Share Attributable to Common Stockholders - Schedule of Basic and Diluted Net Loss Per Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/NetLossperShareAttributabletoCommonStockholdersScheduleofBasicandDilutedNetLossPerShareDetails</Role>
      <ShortName>Net Loss per Share Attributable to Common Stockholders - Schedule of Basic and Diluted Net Loss Per Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>9955555 - Disclosure - Net Loss per Share Attributable to Common Stockholders - Schedule of Antidilutive Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/NetLossperShareAttributabletoCommonStockholdersScheduleofAntidilutiveSecuritiesDetails</Role>
      <ShortName>Net Loss per Share Attributable to Common Stockholders - Schedule of Antidilutive Securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>9955556 - Disclosure - Restructuring - Schedule of Restructuring Costs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/RestructuringScheduleofRestructuringCostsDetails</Role>
      <ShortName>Restructuring - Schedule of Restructuring Costs (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>9955557 - Disclosure - Restructuring - Schedule of Cumulative Restructuring Costs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/RestructuringScheduleofCumulativeRestructuringCostsDetails</Role>
      <ShortName>Restructuring - Schedule of Cumulative Restructuring Costs (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>69</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>9955558 - Disclosure - Restructuring - Schedule of Stock-Based Compensation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/RestructuringScheduleofStockBasedCompensationDetails</Role>
      <ShortName>Restructuring - Schedule of Stock-Based Compensation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>70</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>9955559 - Disclosure - Restructuring - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/RestructuringNarrativeDetails</Role>
      <ShortName>Restructuring - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>71</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>9955560 - Disclosure - Restructuring - Schedule of Restructuring Reserve Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/RestructuringScheduleofRestructuringReserveActivityDetails</Role>
      <ShortName>Restructuring - Schedule of Restructuring Reserve Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>72</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>9955561 - Disclosure - Segment Reporting - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/SegmentReportingNarrativeDetails</Role>
      <ShortName>Segment Reporting - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>73</Position>
    </Report>
    <Report instance="blze-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>9955562 - Disclosure - Segment Reporting - Schedule of Segment Reporting Information, by Segment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.backblaze.com/role/SegmentReportingScheduleofSegmentReportingInformationbySegmentDetails</Role>
      <ShortName>Segment Reporting - Schedule of Segment Reporting Information, by Segment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>74</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File doctype="10-Q" isDefinitelyFs="true" isUsgaap="true" original="blze-20260331.htm">blze-20260331.htm</File>
    <File>blze-20260331.xsd</File>
    <File>blze-20260331_cal.xml</File>
    <File>blze-20260331_def.xml</File>
    <File>blze-20260331_lab.xml</File>
    <File>blze-20260331_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="4">http://fasb.org/srt/2025</BaseTaxonomy>
    <BaseTaxonomy items="713">http://fasb.org/us-gaap/2025</BaseTaxonomy>
    <BaseTaxonomy items="30">http://xbrl.sec.gov/dei/2025</BaseTaxonomy>
    <BaseTaxonomy items="17">http://xbrl.sec.gov/ecd/2025</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
