<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.25.2</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>300</ContextCount>
  <ElementCount>277</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>76</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>9</UnitCount>
  <MyReports>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0000001 - Document - Cover</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/Cover</Role>
      <ShortName>Cover</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>9952151 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/CONDENSEDCONSOLIDATEDBALANCESHEETS</Role>
      <ShortName>CONDENSED CONSOLIDATED BALANCE SHEETS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="fat-20250629.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://fatbrands.com/role/CONDENSEDCONSOLIDATEDBALANCESHEETSParenthetical</Role>
      <ShortName>CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="fat-20250629.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://fatbrands.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFOPERATIONS</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>9952154 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' DEFICIT</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFCHANGESINSTOCKHOLDERSDEFICIT</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' DEFICIT</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="fat-20250629.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://fatbrands.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFCASHFLOWS</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>9952156 - Disclosure - ORGANIZATION AND RELATIONSHIPS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/ORGANIZATIONANDRELATIONSHIPS</Role>
      <ShortName>ORGANIZATION AND RELATIONSHIPS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>9952157 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIES</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>9952158 - Disclosure - REFRANCHISING</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/REFRANCHISING</Role>
      <ShortName>REFRANCHISING</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>9952159 - Disclosure - PROPERTY AND EQUIPMENT, NET</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/PROPERTYANDEQUIPMENTNET</Role>
      <ShortName>PROPERTY AND EQUIPMENT, NET</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>9952160 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS, NET</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/GOODWILLANDOTHERINTANGIBLEASSETSNET</Role>
      <ShortName>GOODWILL AND OTHER INTANGIBLE ASSETS, NET</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>9952161 - Disclosure - INCOME TAXES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/INCOMETAXES</Role>
      <ShortName>INCOME TAXES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>9952162 - Disclosure - LEASES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/LEASES</Role>
      <ShortName>LEASES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>9952163 - Disclosure - DEBT</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/DEBT</Role>
      <ShortName>DEBT</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>9952164 - Disclosure - REDEEMABLE PREFERRED STOCK</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/REDEEMABLEPREFERREDSTOCK</Role>
      <ShortName>REDEEMABLE PREFERRED STOCK</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>9952165 - Disclosure - SHARE-BASED COMPENSATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/SHAREBASEDCOMPENSATION</Role>
      <ShortName>SHARE-BASED COMPENSATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>9952166 - Disclosure - WARRANTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/WARRANTS</Role>
      <ShortName>WARRANTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>9952167 - Disclosure - COMMON STOCK</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/COMMONSTOCK</Role>
      <ShortName>COMMON STOCK</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>9952168 - Disclosure - COMMITMENTS AND CONTINGENCIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/COMMITMENTSANDCONTINGENCIES</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>9952169 - Disclosure - GEOGRAPHIC INFORMATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/GEOGRAPHICINFORMATION</Role>
      <ShortName>GEOGRAPHIC INFORMATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>9952170 - Disclosure - SEGMENT INFORMATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/SEGMENTINFORMATION</Role>
      <ShortName>SEGMENT INFORMATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>9952171 - Disclosure - NON-CONTROLLING INTEREST</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/NONCONTROLLINGINTEREST</Role>
      <ShortName>NON-CONTROLLING INTEREST</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.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>23</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.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>24</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>9955511 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESPolicies</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>9955512 - Disclosure - REFRANCHISING (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/REFRANCHISINGTables</Role>
      <ShortName>REFRANCHISING (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://fatbrands.com/role/REFRANCHISING</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>9955513 - Disclosure - PROPERTY AND EQUIPMENT, NET (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/PROPERTYANDEQUIPMENTNETTables</Role>
      <ShortName>PROPERTY AND EQUIPMENT, NET (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://fatbrands.com/role/PROPERTYANDEQUIPMENTNET</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>9955514 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS, NET (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/GOODWILLANDOTHERINTANGIBLEASSETSNETTables</Role>
      <ShortName>GOODWILL AND OTHER INTANGIBLE ASSETS, NET (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://fatbrands.com/role/GOODWILLANDOTHERINTANGIBLEASSETSNET</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>9955515 - Disclosure - INCOME TAXES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/INCOMETAXESTables</Role>
      <ShortName>INCOME TAXES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://fatbrands.com/role/INCOMETAXES</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>9955516 - Disclosure - LEASES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/LEASESTables</Role>
      <ShortName>LEASES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://fatbrands.com/role/LEASES</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>9955517 - Disclosure - DEBT (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/DEBTTables</Role>
      <ShortName>DEBT (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://fatbrands.com/role/DEBT</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>9955518 - Disclosure - WARRANTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/WARRANTSTables</Role>
      <ShortName>WARRANTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://fatbrands.com/role/WARRANTS</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>9955519 - Disclosure - GEOGRAPHIC INFORMATION (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/GEOGRAPHICINFORMATIONTables</Role>
      <ShortName>GEOGRAPHIC INFORMATION (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://fatbrands.com/role/GEOGRAPHICINFORMATION</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>9955520 - Disclosure - ORGANIZATION AND RELATIONSHIPS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/ORGANIZATIONANDRELATIONSHIPSDetails</Role>
      <ShortName>ORGANIZATION AND RELATIONSHIPS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://fatbrands.com/role/ORGANIZATIONANDRELATIONSHIPS</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>9955521 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://fatbrands.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESPolicies</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>9955522 - Disclosure - REFRANCHISING - Schedule of Remaining Assets Classified as Held for Sale (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/REFRANCHISINGScheduleofRemainingAssetsClassifiedasHeldforSaleDetails</Role>
      <ShortName>REFRANCHISING - Schedule of Remaining Assets Classified as Held for Sale (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>9955523 - Disclosure - REFRANCHISING - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/REFRANCHISINGNarrativeDetails</Role>
      <ShortName>REFRANCHISING - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>9955524 - Disclosure - REFRANCHISING - Schedule of Operating Results of Refranchising Program (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/REFRANCHISINGScheduleofOperatingResultsofRefranchisingProgramDetails</Role>
      <ShortName>REFRANCHISING - Schedule of Operating Results of Refranchising Program (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>9955525 - Disclosure - PROPERTY AND EQUIPMENT, NET - Schedule of Carrying Value of Property and Equipment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/PROPERTYANDEQUIPMENTNETScheduleofCarryingValueofPropertyandEquipmentDetails</Role>
      <ShortName>PROPERTY AND EQUIPMENT, NET - Schedule of Carrying Value of Property and Equipment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>9955526 - Disclosure - PROPERTY AND EQUIPMENT, NET - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/PROPERTYANDEQUIPMENTNETNarrativeDetails</Role>
      <ShortName>PROPERTY AND EQUIPMENT, NET - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>9955527 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS, NET - Changes in Carrying Value of Goodwill and Other Intangible Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/GOODWILLANDOTHERINTANGIBLEASSETSNETChangesinCarryingValueofGoodwillandOtherIntangibleAssetsDetails</Role>
      <ShortName>GOODWILL AND OTHER INTANGIBLE ASSETS, NET - Changes in Carrying Value of Goodwill and Other Intangible Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>9955528 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS, NET - Gross Carrying Value and Accumulated Amortization (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/GOODWILLANDOTHERINTANGIBLEASSETSNETGrossCarryingValueandAccumulatedAmortizationDetails</Role>
      <ShortName>GOODWILL AND OTHER INTANGIBLE ASSETS, NET - Gross Carrying Value and Accumulated Amortization (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>9955529 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS, NET - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/GOODWILLANDOTHERINTANGIBLEASSETSNETNarrativeDetails</Role>
      <ShortName>GOODWILL AND OTHER INTANGIBLE ASSETS, NET - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>9955530 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS, NET - Expected Future Amortization (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/GOODWILLANDOTHERINTANGIBLEASSETSNETExpectedFutureAmortizationDetails</Role>
      <ShortName>GOODWILL AND OTHER INTANGIBLE ASSETS, NET - Expected Future Amortization (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>9955531 - Disclosure - INCOME TAXES - Schedule of Provision for Income Taxes (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/INCOMETAXESScheduleofProvisionforIncomeTaxesDetails</Role>
      <ShortName>INCOME TAXES - Schedule of Provision for Income Taxes (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>9955532 - Disclosure - INCOME TAXES - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/INCOMETAXESNarrativeDetails</Role>
      <ShortName>INCOME TAXES - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>9955533 - Disclosure - LEASES - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/LEASESNarrativeDetails</Role>
      <ShortName>LEASES - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>9955534 - Disclosure - LEASES - Schedule of Operating Lease Right of Use Assets and Operating Lease Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/LEASESScheduleofOperatingLeaseRightofUseAssetsandOperatingLeaseLiabilitiesDetails</Role>
      <ShortName>LEASES - Schedule of Operating Lease Right of Use Assets and Operating Lease Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>9955535 - Disclosure - LEASES - Schedule of Contractual Future Maturities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/LEASESScheduleofContractualFutureMaturitiesDetails</Role>
      <ShortName>LEASES - Schedule of Contractual Future Maturities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>9955536 - Disclosure - LEASES - Schedule of Supplemental Cash Flow Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/LEASESScheduleofSupplementalCashFlowInformationDetails</Role>
      <ShortName>LEASES - Schedule of Supplemental Cash Flow Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>9955537 - Disclosure - DEBT - Schedule of Long-Term Debt (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/DEBTScheduleofLongTermDebtDetails</Role>
      <ShortName>DEBT - Schedule of Long-Term Debt (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>9955538 - Disclosure - DEBT - Fazoli's/ Native Securitization (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/DEBTFazolisNativeSecuritizationDetails</Role>
      <ShortName>DEBT - Fazoli's/ Native Securitization (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>9955539 - Disclosure - DEBT - Retained Notes (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://fatbrands.com/role/DEBTRetainedNotesDetails</Role>
      <ShortName>DEBT - Retained Notes (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>9955540 - Disclosure - DEBT - Construction Loan Agreement (Twin Peaks) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/DEBTConstructionLoanAgreementTwinPeaksDetails</Role>
      <ShortName>DEBT - Construction Loan Agreement (Twin Peaks) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>9955541 - Disclosure - DEBT - Promissory Notes (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://fatbrands.com/role/DEBTPromissoryNotesDetails</Role>
      <ShortName>DEBT - Promissory Notes (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>9955542 - Disclosure - REDEEMABLE PREFERRED STOCK (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/REDEEMABLEPREFERREDSTOCKDetails</Role>
      <ShortName>REDEEMABLE PREFERRED STOCK (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://fatbrands.com/role/REDEEMABLEPREFERREDSTOCK</ParentRole>
      <Position>56</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>9955543 - Disclosure - SHARE-BASED COMPENSATION (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/SHAREBASEDCOMPENSATIONDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://fatbrands.com/role/SHAREBASEDCOMPENSATION</ParentRole>
      <Position>57</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>9955544 - Disclosure - WARRANTS - Warrant Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/WARRANTSWarrantActivityDetails</Role>
      <ShortName>WARRANTS - Warrant Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>9955545 - Disclosure - WARRANTS - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/WARRANTSNarrativeDetails</Role>
      <ShortName>WARRANTS - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>9955546 - Disclosure - COMMON STOCK (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/COMMONSTOCKDetails</Role>
      <ShortName>COMMON STOCK (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://fatbrands.com/role/COMMONSTOCK</ParentRole>
      <Position>60</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>9955547 - Disclosure - COMMITMENTS AND CONTINGENCIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/COMMITMENTSANDCONTINGENCIESDetails</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://fatbrands.com/role/COMMITMENTSANDCONTINGENCIES</ParentRole>
      <Position>61</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>9955548 - Disclosure - GEOGRAPHIC INFORMATION (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/GEOGRAPHICINFORMATIONDetails</Role>
      <ShortName>GEOGRAPHIC INFORMATION (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://fatbrands.com/role/GEOGRAPHICINFORMATIONTables</ParentRole>
      <Position>62</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>9955549 - Disclosure - SEGMENT INFORMATION (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/SEGMENTINFORMATIONDetails</Role>
      <ShortName>SEGMENT INFORMATION (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://fatbrands.com/role/SEGMENTINFORMATION</ParentRole>
      <Position>63</Position>
    </Report>
    <Report instance="fat-20250629.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>9955550 - Disclosure - NON-CONTROLLING INTEREST (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://fatbrands.com/role/NONCONTROLLINGINTERESTDetails</Role>
      <ShortName>NON-CONTROLLING INTEREST (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://fatbrands.com/role/NONCONTROLLINGINTEREST</ParentRole>
      <Position>64</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="fat-20250629.htm">fat-20250629.htm</File>
    <File>fat-20250629.xsd</File>
    <File>fat-20250629_cal.xml</File>
    <File>fat-20250629_def.xml</File>
    <File>fat-20250629_lab.xml</File>
    <File>fat-20250629_pre.xml</File>
  </InputFiles>
  <SupplementalFiles>
    <File>fat-20250629_g1.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy items="826">http://fasb.org/us-gaap/2025</BaseTaxonomy>
    <BaseTaxonomy items="37">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>
