<?xml version="1.0" encoding="utf-8"?>
<xbrl
  xmlns="http://www.xbrl.org/2003/instance"
  xmlns:dei="http://xbrl.sec.gov/dei/2025"
  xmlns:imcr="http://immunocore.com./20260506"
  xmlns:link="http://www.xbrl.org/2003/linkbase"
  xmlns:us-gaap="http://fasb.org/us-gaap/2025"
  xmlns:xbrldi="http://xbrl.org/2006/xbrldi"
  xmlns:xlink="http://www.w3.org/1999/xlink">
    <link:schemaRef xlink:href="imcr-20260506.xsd" xlink:type="simple"/>
    <context id="c20260506to20260506">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001671927</identifier>
        </entity>
        <period>
            <startDate>2026-05-06</startDate>
            <endDate>2026-05-06</endDate>
        </period>
    </context>
    <context id="c20260506to20260506_StatementClassOfStockAxis_AmericanDepositarySharesEachRepresentingOneOrdinaryShareNominalValue0002PerShareMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001671927</identifier>
            <segment>
                <xbrldi:explicitMember dimension="us-gaap:StatementClassOfStockAxis">imcr:AmericanDepositarySharesEachRepresentingOneOrdinaryShareNominalValue0002PerShareMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-05-06</startDate>
            <endDate>2026-05-06</endDate>
        </period>
    </context>
    <context id="c20260506to20260506_StatementClassOfStockAxis_OrdinaryShareNominalValue0002PerShareMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001671927</identifier>
            <segment>
                <xbrldi:explicitMember dimension="us-gaap:StatementClassOfStockAxis">imcr:OrdinaryShareNominalValue0002PerShareMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-05-06</startDate>
            <endDate>2026-05-06</endDate>
        </period>
    </context>
    <dei:AmendmentFlag
      contextRef="c20260506to20260506"
      id="Fact_2cc70f96db4e482e9e90162defae3189">false</dei:AmendmentFlag>
    <dei:EntityCentralIndexKey
      contextRef="c20260506to20260506"
      id="Fact_c1d5a8a3811c4f388c257cb684fcb451">0001671927</dei:EntityCentralIndexKey>
    <dei:EntityIncorporationStateCountryCode
      contextRef="c20260506to20260506"
      id="Fact_6085d964371a4ea89e74e450904b8fdf">X0</dei:EntityIncorporationStateCountryCode>
    <dei:EntityTaxIdentificationNumber
      contextRef="c20260506to20260506"
      id="Fact_3adb3d27c19e494baa0b56dfb855f9df">00-0000000</dei:EntityTaxIdentificationNumber>
    <dei:Security12bTitle
      contextRef="c20260506to20260506_StatementClassOfStockAxis_AmericanDepositarySharesEachRepresentingOneOrdinaryShareNominalValue0002PerShareMember"
      id="Fact_ea59d1fb6854440b8eb17adc629f2634">American Depositary Shares, each representing one ordinary share, nominal value 0.002 per share</dei:Security12bTitle>
    <dei:Security12bTitle
      contextRef="c20260506to20260506_StatementClassOfStockAxis_OrdinaryShareNominalValue0002PerShareMember"
      id="Fact_252c124e630d4c7d889c77925d1f11ea">Ordinary share, nominal value 0.002 per share*</dei:Security12bTitle>
    <dei:SecurityExchangeName
      contextRef="c20260506to20260506_StatementClassOfStockAxis_OrdinaryShareNominalValue0002PerShareMember"
      id="Fact_d865f5bc2fcd4bfab3ec46ac8665955f">NASDAQ</dei:SecurityExchangeName>
    <dei:SecurityExchangeName
      contextRef="c20260506to20260506_StatementClassOfStockAxis_AmericanDepositarySharesEachRepresentingOneOrdinaryShareNominalValue0002PerShareMember"
      id="Fact_11bbcb8d1de246fdb50ceb4977517d7d">NASDAQ</dei:SecurityExchangeName>
    <dei:DocumentType
      contextRef="c20260506to20260506"
      id="Fact_3df46f41e2db4e2194d40f71d5fdde96">8-K</dei:DocumentType>
    <dei:DocumentPeriodEndDate
      contextRef="c20260506to20260506"
      id="Fact_226ca3ddfb944dde8fc0e48858ed27fa">2026-05-06</dei:DocumentPeriodEndDate>
    <dei:EntityRegistrantName
      contextRef="c20260506to20260506"
      id="Fact_d90b2592c8824aa59b19d7a38442a854">Immunocore Holdings plc</dei:EntityRegistrantName>
    <dei:EntityFileNumber
      contextRef="c20260506to20260506"
      id="Fact_8a8258c1526442d9a8efb1cafe40d1d7">001-39992</dei:EntityFileNumber>
    <dei:EntityAddressAddressLine1
      contextRef="c20260506to20260506"
      id="Fact_1182fa82ffb844caab04a525ebfded4b">92 Park Drive</dei:EntityAddressAddressLine1>
    <dei:EntityAddressAddressLine2
      contextRef="c20260506to20260506"
      id="Fact_7b30d3eb37a0433c96b48916a9d95966">Milton Park Abingdon</dei:EntityAddressAddressLine2>
    <dei:EntityAddressCityOrTown
      contextRef="c20260506to20260506"
      id="Fact_35a3d595610c4a94b06fcdb027828299">Oxfordshire</dei:EntityAddressCityOrTown>
    <dei:EntityAddressCountry
      contextRef="c20260506to20260506"
      id="Fact_daaa54dd9fcc46ef96b5cd10f8579601">GB</dei:EntityAddressCountry>
    <dei:EntityAddressPostalZipCode
      contextRef="c20260506to20260506"
      id="Fact_5ed35a3a3a084af78a941b8eba7fdea8">OX14 4RY</dei:EntityAddressPostalZipCode>
    <dei:CityAreaCode
      contextRef="c20260506to20260506"
      id="Fact_61ee93397e6e4906bb02a560f8250ee0">44</dei:CityAreaCode>
    <dei:LocalPhoneNumber
      contextRef="c20260506to20260506"
      id="Fact_7fccd52805474499b03db6bdd97705cd">1235 438600</dei:LocalPhoneNumber>
    <dei:WrittenCommunications
      contextRef="c20260506to20260506"
      id="Fact_d7decea395a147e7bde362e13bde3d0a">false</dei:WrittenCommunications>
    <dei:SolicitingMaterial
      contextRef="c20260506to20260506"
      id="Fact_9f792add0e9f4f2183052d7af7ec92c9">false</dei:SolicitingMaterial>
    <dei:PreCommencementTenderOffer
      contextRef="c20260506to20260506"
      id="Fact_eff0e222b24947f9894a9e62567c2e53">false</dei:PreCommencementTenderOffer>
    <dei:PreCommencementIssuerTenderOffer
      contextRef="c20260506to20260506"
      id="Fact_f8cb435ead0f452dbbfc54455362aed7">false</dei:PreCommencementIssuerTenderOffer>
    <dei:TradingSymbol
      contextRef="c20260506to20260506_StatementClassOfStockAxis_AmericanDepositarySharesEachRepresentingOneOrdinaryShareNominalValue0002PerShareMember"
      id="Fact_cde31734922140178fbc0a7c46a18558">IMCR</dei:TradingSymbol>
    <dei:TradingSymbol
      contextRef="c20260506to20260506_StatementClassOfStockAxis_OrdinaryShareNominalValue0002PerShareMember"
      id="Fact_f923d58da11c4ab58cd2816e9307b0f1">*</dei:TradingSymbol>
    <dei:EntityEmergingGrowthCompany
      contextRef="c20260506to20260506"
      id="Fact_34ff76f3919e4bc2909978d438df10fc">false</dei:EntityEmergingGrowthCompany>
</xbrl>
