<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.26.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>108</ContextCount>
  <ElementCount>227</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>46</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>8</UnitCount>
  <MyReports>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0000001 - Document - Cover</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/Cover</Role>
      <ShortName>Cover</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="frmi-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.fermiamerica.com/role/CondensedConsolidatedBalanceSheets</Role>
      <ShortName>Condensed Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="frmi-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.fermiamerica.com/role/CondensedConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Condensed Consolidated Balance Sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>9952153 - Statement - Condensed Consolidated Statements of Operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/CondensedConsolidatedStatementsofOperations</Role>
      <ShortName>Condensed Consolidated Statements of Operations</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>9952154 - Statement - Condensed Consolidated Statements of Stockholders???/Members??? Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/CondensedConsolidatedStatementsofStockholdersMembersEquity</Role>
      <ShortName>Condensed Consolidated Statements of Stockholders???/Members??? Equity</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="frmi-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.fermiamerica.com/role/CondensedConsolidatedStatementsofCashFlows</Role>
      <ShortName>Condensed Consolidated Statements of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="frmi-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.fermiamerica.com/role/OrganizationandDescriptionofBusiness</Role>
      <ShortName>Organization and Description of Business</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>9952157 - Disclosure - Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/SignificantAccountingPolicies</Role>
      <ShortName>Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>9952158 - Disclosure - Net Loss Per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/NetLossPerShare</Role>
      <ShortName>Net Loss Per Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>9952159 - Disclosure - Property, Plant, and Equipment</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/PropertyPlantandEquipment</Role>
      <ShortName>Property, Plant, and Equipment</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>9952160 - Disclosure - Debt, net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/Debtnet</Role>
      <ShortName>Debt, net</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>9952161 - Disclosure - Leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/Leases</Role>
      <ShortName>Leases</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>9952162 - Disclosure - Share-Based Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/ShareBasedCompensation</Role>
      <ShortName>Share-Based Compensation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>9952163 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/CommitmentsandContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>9952164 - Disclosure - Subsequent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/SubsequentEvents</Role>
      <ShortName>Subsequent Events</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.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>16</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>9955511 - Disclosure - Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/SignificantAccountingPoliciesPolicies</Role>
      <ShortName>Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://www.fermiamerica.com/role/SignificantAccountingPolicies</ParentRole>
      <Position>17</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>9955512 - Disclosure - Significant Accounting Policies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/SignificantAccountingPoliciesTables</Role>
      <ShortName>Significant Accounting Policies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.fermiamerica.com/role/SignificantAccountingPolicies</ParentRole>
      <Position>18</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>9955513 - Disclosure - Net Loss Per Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/NetLossPerShareTables</Role>
      <ShortName>Net Loss Per Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.fermiamerica.com/role/NetLossPerShare</ParentRole>
      <Position>19</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>9955514 - Disclosure - Property, Plant, and Equipment (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/PropertyPlantandEquipmentTables</Role>
      <ShortName>Property, Plant, and Equipment (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.fermiamerica.com/role/PropertyPlantandEquipment</ParentRole>
      <Position>20</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>9955515 - Disclosure - Debt, net (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/DebtnetTables</Role>
      <ShortName>Debt, net (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.fermiamerica.com/role/Debtnet</ParentRole>
      <Position>21</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>9955516 - Disclosure - Leases (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/LeasesTables</Role>
      <ShortName>Leases (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.fermiamerica.com/role/Leases</ParentRole>
      <Position>22</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>9955517 - Disclosure - Share-Based Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/ShareBasedCompensationTables</Role>
      <ShortName>Share-Based Compensation (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.fermiamerica.com/role/ShareBasedCompensation</ParentRole>
      <Position>23</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>9955518 - Disclosure - Commitments and Contingencies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/CommitmentsandContingenciesTables</Role>
      <ShortName>Commitments and Contingencies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.fermiamerica.com/role/CommitmentsandContingencies</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>9955519 - Disclosure - Organization and Description of Business (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/OrganizationandDescriptionofBusinessDetails</Role>
      <ShortName>Organization and Description of Business (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.fermiamerica.com/role/OrganizationandDescriptionofBusiness</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>9955520 - Disclosure - Significant Accounting Policies - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/SignificantAccountingPoliciesNarrativeDetails</Role>
      <ShortName>Significant Accounting Policies - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>9955521 - Disclosure - Significant Accounting Policies - Schedule of Supplemental Cash Flow Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/SignificantAccountingPoliciesScheduleofSupplementalCashFlowInformationDetails</Role>
      <ShortName>Significant Accounting Policies - Schedule of Supplemental Cash Flow Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>9955522 - Disclosure - Net Loss Per Share - Schedule of Net Loss Per Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/NetLossPerShareScheduleofNetLossPerShareDetails</Role>
      <ShortName>Net Loss Per Share - Schedule of Net Loss Per Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>9955523 - Disclosure - Net Loss Per Share - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/NetLossPerShareNarrativeDetails</Role>
      <ShortName>Net Loss Per Share - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>9955524 - Disclosure - Property, Plant, and Equipment - Schedule of Property, Plant, and Equipment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/PropertyPlantandEquipmentScheduleofPropertyPlantandEquipmentDetails</Role>
      <ShortName>Property, Plant, and Equipment - Schedule of Property, Plant, and Equipment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>9955525 - Disclosure - Property, Plant, and Equipment - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/PropertyPlantandEquipmentNarrativeDetails</Role>
      <ShortName>Property, Plant, and Equipment - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>9955526 - Disclosure - Debt, net - Schedule of Debt (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/DebtnetScheduleofDebtDetails</Role>
      <ShortName>Debt, net - Schedule of Debt (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>9955527 - Disclosure - Debt, net - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/DebtnetNarrativeDetails</Role>
      <ShortName>Debt, net - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>9955528 - Disclosure - Leases - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/LeasesNarrativeDetails</Role>
      <ShortName>Leases - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>9955529 - Disclosure - Leases - Schedule of Operating Lease Costs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/LeasesScheduleofOperatingLeaseCostsDetails</Role>
      <ShortName>Leases - Schedule of Operating Lease Costs (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>9955530 - Disclosure - Leases - Supplemental Information Related to Operating Leases (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/LeasesSupplementalInformationRelatedtoOperatingLeasesDetails</Role>
      <ShortName>Leases - Supplemental Information Related to Operating Leases (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>9955531 - Disclosure - Leases - Schedule of Future Minimum Lease Payments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/LeasesScheduleofFutureMinimumLeasePaymentsDetails</Role>
      <ShortName>Leases - Schedule of Future Minimum Lease Payments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>9955532 - Disclosure - Leases - Schedule of Lease Term and Discount Rate for Operating Leases (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/LeasesScheduleofLeaseTermandDiscountRateforOperatingLeasesDetails</Role>
      <ShortName>Leases - Schedule of Lease Term and Discount Rate for Operating Leases (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>9955533 - Disclosure - Share-Based Compensation - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/ShareBasedCompensationNarrativeDetails</Role>
      <ShortName>Share-Based Compensation - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>9955534 - Disclosure - Share-Based Compensation - Schedule of Share-Based Compensation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/ShareBasedCompensationScheduleofShareBasedCompensationDetails</Role>
      <ShortName>Share-Based Compensation - Schedule of Share-Based Compensation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>9955535 - Disclosure - Commitments and Contingencies - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/CommitmentsandContingenciesNarrativeDetails</Role>
      <ShortName>Commitments and Contingencies - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>9955536 - Disclosure - Commitments and Contingencies - Unconditional Purchase Obligations Maturity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/CommitmentsandContingenciesUnconditionalPurchaseObligationsMaturityDetails</Role>
      <ShortName>Commitments and Contingencies - Unconditional Purchase Obligations Maturity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="frmi-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>9955537 - Disclosure - Subsequent Events (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fermiamerica.com/role/SubsequentEventsDetails</Role>
      <ShortName>Subsequent Events (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.fermiamerica.com/role/SubsequentEvents</ParentRole>
      <Position>43</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="frmi-20260331.htm">frmi-20260331.htm</File>
    <File>frmi-20260331.xsd</File>
    <File>frmi-20260331_cal.xml</File>
    <File>frmi-20260331_def.xml</File>
    <File>frmi-20260331_lab.xml</File>
    <File>frmi-20260331_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="343">http://fasb.org/us-gaap/2025</BaseTaxonomy>
    <BaseTaxonomy items="33">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>
