<?xml version="1.0" encoding="utf-8"?>
<xbrl
  xmlns="http://www.xbrl.org/2003/instance"
  xmlns:dei="http://xbrl.sec.gov/dei/2026"
  xmlns:ffd="http://xbrl.sec.gov/ffd/2026"
  xmlns:iso4217="http://www.xbrl.org/2003/iso4217"
  xmlns:link="http://www.xbrl.org/2003/linkbase"
  xmlns:xbrldi="http://xbrl.org/2006/xbrldi"
  xmlns:xlink="http://www.w3.org/1999/xlink"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <link:schemaRef
      xlink:href="https://xbrl.sec.gov/ffd/2026/ffd-2026.xsd"
      xlink:type="simple"/>
    <context id="rc">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000886128</identifier>
        </entity>
        <period>
            <startDate>2026-07-17</startDate>
            <endDate>2026-07-17</endDate>
        </period>
    </context>
    <context id="offrl_1">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000886128</identifier>
            <segment>
                <xbrldi:typedMember dimension="ffd:OfferingAxis">
                    <dei:lineNo>1</dei:lineNo>
                </xbrldi:typedMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-07-17</startDate>
            <endDate>2026-07-17</endDate>
        </period>
    </context>
    <unit id="USD">
        <measure>iso4217:USD</measure>
    </unit>
    <unit id="pure">
        <measure>pure</measure>
    </unit>
    <unit id="Shares">
        <measure>shares</measure>
    </unit>
    <ffd:FormTp contextRef="rc" id="ixv-345">S-3</ffd:FormTp>
    <ffd:SubmissnTp contextRef="rc" id="ixv-346">424B7</ffd:SubmissnTp>
    <ffd:FeeExhibitTp contextRef="rc" id="ixv-347">EX-FILING FEES</ffd:FeeExhibitTp>
    <ffd:RegnFileNb contextRef="rc" id="ixv-348">333-296607</ffd:RegnFileNb>
    <dei:EntityCentralIndexKey contextRef="rc" id="ixv-349">0000886128</dei:EntityCentralIndexKey>
    <dei:EntityRegistrantName contextRef="rc" id="ixv-350">FUELCELL ENERGY INC</dei:EntityRegistrantName>
    <ffd:OfferingTableNa contextRef="rc" id="hiddenrcOfferingTableNa" xsi:nil="true"/>
    <ffd:OffsetTableNa contextRef="rc" id="hiddenrcOffsetTableNa">N/A</ffd:OffsetTableNa>
    <ffd:CombinedProspectusTableNa contextRef="rc" id="hiddenrcCombinedProspectusTableNa">N/A</ffd:CombinedProspectusTableNa>
    <ffd:FormTp contextRef="rc" id="ixv-378">S-3</ffd:FormTp>
    <dei:EntityRegistrantName contextRef="rc" id="ixv-379">FUELCELL ENERGY INC</dei:EntityRegistrantName>
    <ffd:PrevslyPdFlg contextRef="offrl_1" id="ixv-380">false</ffd:PrevslyPdFlg>
    <ffd:OfferingSctyTp contextRef="offrl_1" id="ixv-381">Equity</ffd:OfferingSctyTp>
    <ffd:OfferingSctyTitl contextRef="offrl_1" id="ixv-382">Common Stock, par value $0.0001 per share</ffd:OfferingSctyTitl>
    <ffd:Rule457aFlg contextRef="offrl_1" id="ixv-383">true</ffd:Rule457aFlg>
    <ffd:AmtSctiesRegd
      contextRef="offrl_1"
      decimals="0"
      id="ixv-384"
      unitRef="Shares">12000000</ffd:AmtSctiesRegd>
    <ffd:MaxOfferingPricPerScty
      contextRef="offrl_1"
      decimals="2"
      id="ixv-385"
      unitRef="USD">18.28</ffd:MaxOfferingPricPerScty>
    <ffd:MaxAggtOfferingPric
      contextRef="offrl_1"
      decimals="2"
      id="ixv-386"
      unitRef="USD">219360000.00</ffd:MaxAggtOfferingPric>
    <ffd:FeeRate
      contextRef="offrl_1"
      decimals="7"
      id="ixv-387"
      unitRef="pure">0.0001381</ffd:FeeRate>
    <ffd:FeeAmt
      contextRef="offrl_1"
      decimals="2"
      id="ixv-388"
      unitRef="USD">30293.62</ffd:FeeAmt>
    <ffd:TtlOfferingAmt contextRef="rc" decimals="2" id="ixv-389" unitRef="USD">219360000.00</ffd:TtlOfferingAmt>
    <ffd:TtlFeeAmt contextRef="rc" decimals="2" id="ixv-390" unitRef="USD">30293.62</ffd:TtlFeeAmt>
    <ffd:TtlPrevslyPdAmt contextRef="rc" decimals="2" id="ixv-391" unitRef="USD">0.00</ffd:TtlPrevslyPdAmt>
    <ffd:TtlOffsetAmt contextRef="rc" decimals="2" id="ixv-392" unitRef="USD">0.00</ffd:TtlOffsetAmt>
    <ffd:NetFeeAmt contextRef="rc" decimals="2" id="ixv-393" unitRef="USD">30293.62</ffd:NetFeeAmt>
    <ffd:OfferingNote contextRef="offrl_1" id="ixv-394">Estimated solely to calculate the registration fee in accordance with Rule 457(c) of the Securities Act on the basis of the average of the high and low sales prices of the registrant's shares of common stock as reported by The Nasdaq Global Market on July 16, 2026. In accordance with Rules 456(b) and 457(r) under the Securities Act, the registrant initially deferred payment of all of the registration fee for registration statement No. 333-296607.</ffd:OfferingNote>
    <ffd:NrrtvMaxAggtOfferingPric contextRef="rc" decimals="2" id="ixv-395" unitRef="USD">219360000.00</ffd:NrrtvMaxAggtOfferingPric>
    <ffd:FnlPrspctsFlg contextRef="rc" id="ixv-396">true</ffd:FnlPrspctsFlg>
</xbrl>
