{
 "documentInfo": {
  "documentType": "https://xbrl.org/2021/xbrl-json",
  "features": {
   "xbrl:canonicalValues": true
  },
  "namespaces": {
   "ifrs-full": "http://xbrl.ifrs.org/taxonomy/2020-03-16/ifrs-full",
   "iso4217": "http://www.xbrl.org/2003/iso4217",
   "johnsonmattheyplc": "http://johnsonmattheyplc.com/xbrl/2021",
   "scheme": "http://standards.iso.org/iso/17442",
   "xbrl": "https://xbrl.org/2021",
   "xbrli": "http://www.xbrl.org/2003/instance"
  },
  "taxonomy": [
   "http://johnsonmattheyplc.com/xbrl/2021/johnsonmattheyplc-2022-03-31.xsd"
  ]
 },
 "facts": {
  "fact-1": {
   "value": "Common customers and partnersAs our customers transition to net zero, new market opportunities are opening up for JM through existing customers. For instance, we have automotive customers in Clean Air today who are becoming Hydrogen Technologies customers for fuel cells. We are also building cross-business offers, such as our Catalyst Technologies and Hydrogen Technologies businesses working together to create an integrated value proposition for customers in blue and green hydrogen. Also, our presence in several net zero transition technologies, such as blue and green hydrogen, reduces our risk and ensures our position as a market leader, regardless of which technology becomes dominant at any given point in time. Shared technology capabilities We have common technology capabilities across all our businesses, with more than 5,000 patents granted and around 1,500 patent applications pending. With PGM chemistry expertise at our core, we can take advantage of our unique heritage at scale across engineering, design, synthesis and catalysis. Because of this, our people have shared core skills that we can invest in and grow since we use them across the whole of JM. This also gives us the opportunity to accelerate our product development thanks to our integrated position in the value chain.A shared PGM ecosystemOur PGM Services business is our backbone. That means we can ensure around 80% of the PGMs that are used in our products are refined within the group. This demonstrates the physical flow between our businesses and provides a strong foundation for the whole of JM. This integration give us and our customers many advantages, including superior insights and market edge from an integrated view of PGMs supply and demand, along with resilience in our metals supply and increased customer trust. We also have a unique position in the circular economy, given our internal refining skills. This is especially important to ensure we have a highly competitive integrated offer as we move through the next wave of emissions control legislation. We can also optimise supply and demand, which lowers exposure to PGMs price risk for both JM and our customers. And we deploy more efficient working capital, since our integrated position means we can be more flexible in the way that we source and supply metal.We will serve our global customer base through our four businesses: the current corbusiness of Clean Air, together with our growth businesses, Catalyst Technologies and Hydrogen Technologies, all built on our foundational PGM Services business, which supplies and enables the other businesses. These businesses are tightly  linked by three reinforcing synergies: common customers and partners, shared technology capabilities, and a shared PGM ecosystem that enables dependable supply and circularity.",
   "dimensions": {
    "concept": "ifrs-full:DescriptionOfNatureOfEntitysOperationsAndPrincipalActivities",
    "language": "en",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00"
   }
  },
  "fact-10": {
   "value": "16025000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Revenue",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-11": {
   "value": "15435000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Revenue",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-12": {
   "value": "14971000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CostOfSales",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-13": {
   "value": "14481000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CostOfSales",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-14": {
   "value": "1054000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:GrossProfit",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-15": {
   "value": "954000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:GrossProfit",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-16": {
   "value": "101000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DistributionCosts",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-17": {
   "value": "103000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DistributionCosts",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-18": {
   "value": "400000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdministrativeExpense",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-19": {
   "value": "377000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdministrativeExpense",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-20": {
   "value": "106000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:GainsLossesOnDisposalsOfInvestments",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-21": {
   "value": "-1000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:GainsLossesOnDisposalsOfInvestments",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-22": {
   "value": "6000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AmortisationExpense",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-23": {
   "value": "10000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AmortisationExpense",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-24": {
   "value": "42000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:GainsLossesOnLitigationSettlements",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-25": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:GainsLossesOnLitigationSettlements",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-26": {
   "value": "440000000",
   "decimals": -6,
   "dimensions": {
    "concept": "johnsonmattheyplc:MajorImpairmentAndRestructuringCharges",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-27": {
   "value": "154000000",
   "decimals": -6,
   "dimensions": {
    "concept": "johnsonmattheyplc:MajorImpairmentAndRestructuringCharges",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-28": {
   "value": "255000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProfitLossFromOperatingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-29": {
   "value": "309000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProfitLossFromOperatingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-30": {
   "value": "101000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:FinanceCosts",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-31": {
   "value": "158000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:FinanceCosts",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-32": {
   "value": "41000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:FinanceIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-33": {
   "value": "73000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:FinanceIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-34": {
   "value": "195000000",
   "decimals": -6,
   "dimensions": {
    "concept": "johnsonmattheyplc:ProfitBeforeTaxFromContinuingOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-35": {
   "value": "224000000",
   "decimals": -6,
   "dimensions": {
    "concept": "johnsonmattheyplc:ProfitBeforeTaxFromContinuingOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-36": {
   "value": "79000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncomeTaxExpenseContinuingOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-37": {
   "value": "30000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncomeTaxExpenseContinuingOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-38": {
   "value": "116000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProfitLossFromContinuingOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-39": {
   "value": "194000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProfitLossFromContinuingOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-40": {
   "value": "-217000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProfitLossFromDiscontinuedOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-41": {
   "value": "11000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProfitLossFromDiscontinuedOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-42": {
   "value": "-101000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProfitLoss",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-43": {
   "value": "205000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProfitLoss",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-44": {
   "value": "-0.526",
   "decimals": 3,
   "dimensions": {
    "concept": "ifrs-full:BasicEarningsLossPerShare",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP/xbrli:shares"
   }
  },
  "fact-45": {
   "value": "1.065",
   "decimals": 3,
   "dimensions": {
    "concept": "ifrs-full:BasicEarningsLossPerShare",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP/xbrli:shares"
   }
  },
  "fact-46": {
   "value": "-0.526",
   "decimals": 3,
   "dimensions": {
    "concept": "ifrs-full:DilutedEarningsLossPerShare",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP/xbrli:shares"
   }
  },
  "fact-47": {
   "value": "1.064",
   "decimals": 3,
   "dimensions": {
    "concept": "ifrs-full:DilutedEarningsLossPerShare",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP/xbrli:shares"
   }
  },
  "fact-48": {
   "value": "0.609",
   "decimals": 3,
   "dimensions": {
    "concept": "ifrs-full:BasicEarningsLossPerShareFromContinuingOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP/xbrli:shares"
   }
  },
  "fact-49": {
   "value": "1.009",
   "decimals": 3,
   "dimensions": {
    "concept": "ifrs-full:BasicEarningsLossPerShareFromContinuingOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP/xbrli:shares"
   }
  },
  "fact-50": {
   "value": "0.608",
   "decimals": 3,
   "dimensions": {
    "concept": "ifrs-full:DilutedEarningsLossPerShareFromContinuingOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP/xbrli:shares"
   }
  },
  "fact-51": {
   "value": "1.008",
   "decimals": 3,
   "dimensions": {
    "concept": "ifrs-full:DilutedEarningsLossPerShareFromContinuingOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP/xbrli:shares"
   }
  },
  "fact-52": {
   "value": "-101000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProfitLoss",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-53": {
   "value": "205000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProfitLoss",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-54": {
   "value": "177000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesOnRemeasurementsOfDefinedBenefitPlans",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-55": {
   "value": "-141000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesOnRemeasurementsOfDefinedBenefitPlans",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-56": {
   "value": "-5000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesFromInvestmentsInEquityInstruments",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-57": {
   "value": "5000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesFromInvestmentsInEquityInstruments",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-58": {
   "value": "35000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncomeTaxRelatingToComponentsOfOtherComprehensiveIncomeThatWillNotBeReclassifiedToProfitOrLoss",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-59": {
   "value": "-28000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncomeTaxRelatingToComponentsOfOtherComprehensiveIncomeThatWillNotBeReclassifiedToProfitOrLoss",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-60": {
   "value": "137000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeThatWillNotBeReclassifiedToProfitOrLossNetOfTax",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-61": {
   "value": "-108000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeThatWillNotBeReclassifiedToProfitOrLossNetOfTax",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-62": {
   "value": "75000000",
   "decimals": -6,
   "dimensions": {
    "concept": "johnsonmattheyplc:ExchangeDifferencesOnTranslationOfForeignOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-63": {
   "value": "-144000000",
   "decimals": -6,
   "dimensions": {
    "concept": "johnsonmattheyplc:ExchangeDifferencesOnTranslationOfForeignOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-64": {
   "value": "5000000",
   "decimals": -6,
   "dimensions": {
    "concept": "johnsonmattheyplc:ExchangeDifferencesOnTranslationOfDiscontinuedOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-65": {
   "value": "-18000000",
   "decimals": -6,
   "dimensions": {
    "concept": "johnsonmattheyplc:ExchangeDifferencesOnTranslationOfDiscontinuedOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-66": {
   "value": "-36000000",
   "decimals": -6,
   "dimensions": {
    "concept": "johnsonmattheyplc:AmountsChargedCreditedToHedgingReserve",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-67": {
   "value": "3000000",
   "decimals": -6,
   "dimensions": {
    "concept": "johnsonmattheyplc:AmountsChargedCreditedToHedgingReserve",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-68": {
   "value": "-2000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxHedgesOfNetInvestmentsInForeignOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-69": {
   "value": "12000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxHedgesOfNetInvestmentsInForeignOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-70": {
   "value": "-10000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncomeTaxRelatingToComponentsOfOtherComprehensiveIncomeThatWillBeReclassifiedToProfitOrLoss",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-71": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncomeTaxRelatingToComponentsOfOtherComprehensiveIncomeThatWillBeReclassifiedToProfitOrLoss",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-72": {
   "value": "52000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeThatWillBeReclassifiedToProfitOrLossNetOfTax",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-73": {
   "value": "-147000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeThatWillBeReclassifiedToProfitOrLossNetOfTax",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-74": {
   "value": "189000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-75": {
   "value": "-255000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-76": {
   "value": "88000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-77": {
   "value": "-50000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-78": {
   "value": "300000000",
   "decimals": -6,
   "dimensions": {
    "concept": "johnsonmattheyplc:ComprehensiveIncomeFromContinuingOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-79": {
   "value": "-43000000",
   "decimals": -6,
   "dimensions": {
    "concept": "johnsonmattheyplc:ComprehensiveIncomeFromContinuingOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-80": {
   "value": "-212000000",
   "decimals": -6,
   "dimensions": {
    "concept": "johnsonmattheyplc:ComprehensiveIncomeFromDiscontinuedOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-81": {
   "value": "-7000000",
   "decimals": -6,
   "dimensions": {
    "concept": "johnsonmattheyplc:ComprehensiveIncomeFromDiscontinuedOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-82": {
   "value": "88000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-83": {
   "value": "-50000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-3": {
   "value": "35000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncomeTaxRelatingToComponentsOfOtherComprehensiveIncomeThatWillNotBeReclassifiedToProfitOrLoss",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-2": {
   "value": "-28000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncomeTaxRelatingToComponentsOfOtherComprehensiveIncomeThatWillNotBeReclassifiedToProfitOrLoss",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-4": {
   "value": "-10000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncomeTaxRelatingToComponentsOfOtherComprehensiveIncomeThatWillBeReclassifiedToProfitOrLoss",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-84": {
   "value": "1238000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:PropertyPlantAndEquipment",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-85": {
   "value": "1424000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:PropertyPlantAndEquipment",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-86": {
   "value": "61000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:RightofuseAssets",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-87": {
   "value": "74000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:RightofuseAssets",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-88": {
   "value": "366000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Goodwill",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-89": {
   "value": "554000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Goodwill",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-90": {
   "value": "267000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IntangibleAssetsOtherThanGoodwill",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-91": {
   "value": "359000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IntangibleAssetsOtherThanGoodwill",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-92": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:InvestmentsInSubsidiaries",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-93": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:InvestmentsInSubsidiaries",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-94": {
   "value": "2000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:InvestmentAccountedForUsingEquityMethod",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-95": {
   "value": "2000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:InvestmentAccountedForUsingEquityMethod",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-96": {
   "value": "45000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:NoncurrentFinancialAssetsAtFairValueThroughOtherComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-97": {
   "value": "53000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:NoncurrentFinancialAssetsAtFairValueThroughOtherComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-98": {
   "value": "42000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherNoncurrentReceivables",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-99": {
   "value": "50000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherNoncurrentReceivables",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-100": {
   "value": "11000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:NoncurrentDerivativeFinancialAssets",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-101": {
   "value": "20000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:NoncurrentDerivativeFinancialAssets",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-102": {
   "value": "98000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DeferredTaxAssets",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-103": {
   "value": "140000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DeferredTaxAssets",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-104": {
   "value": "352000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:NoncurrentRecognisedAssetsDefinedBenefitPlan",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-105": {
   "value": "194000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:NoncurrentRecognisedAssetsDefinedBenefitPlan",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-106": {
   "value": "2482000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:NoncurrentAssets",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-107": {
   "value": "2870000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:NoncurrentAssets",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-108": {
   "value": "1549000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Inventories",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-109": {
   "value": "1814000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Inventories",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-110": {
   "value": "18000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CurrentTaxAssets",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-111": {
   "value": "13000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CurrentTaxAssets",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-112": {
   "value": "1796000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:TradeAndOtherCurrentReceivables",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-113": {
   "value": "2422000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:TradeAndOtherCurrentReceivables",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-114": {
   "value": "391000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CashAndCashEquivalents",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-115": {
   "value": "581000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CashAndCashEquivalents",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-116": {
   "value": "1000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CurrentDerivativeFinancialAssets",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-117": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CurrentDerivativeFinancialAssets",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-118": {
   "value": "27000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherCurrentFinancialAssets",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-119": {
   "value": "44000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherCurrentFinancialAssets",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-120": {
   "value": "402000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:NoncurrentAssetsOrDisposalGroupsClassifiedAsHeldForSale",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-121": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:NoncurrentAssetsOrDisposalGroupsClassifiedAsHeldForSale",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-122": {
   "value": "4184000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CurrentAssets",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-123": {
   "value": "4874000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CurrentAssets",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-124": {
   "value": "6666000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Assets",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-125": {
   "value": "7744000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Assets",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-126": {
   "value": "2563000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:TradeAndOtherCurrentPayables",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-127": {
   "value": "3325000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:TradeAndOtherCurrentPayables",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-128": {
   "value": "10000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CurrentLeaseLiabilities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-129": {
   "value": "11000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CurrentLeaseLiabilities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-130": {
   "value": "97000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CurrentTaxLiabilities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-131": {
   "value": "147000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CurrentTaxLiabilities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-132": {
   "value": "37000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:BankOverdraftsClassifiedAsCashEquivalents",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-133": {
   "value": "36000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:BankOverdraftsClassifiedAsCashEquivalents",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-134": {
   "value": "265000000",
   "decimals": -6,
   "dimensions": {
    "concept": "johnsonmattheyplc:CurrentBorrowingsAndRelatedSwaps",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-135": {
   "value": "26000000",
   "decimals": -6,
   "dimensions": {
    "concept": "johnsonmattheyplc:CurrentBorrowingsAndRelatedSwaps",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-136": {
   "value": "44000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherCurrentFinancialLiabilities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-137": {
   "value": "18000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherCurrentFinancialLiabilities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-138": {
   "value": "56000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CurrentProvisions",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-139": {
   "value": "35000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CurrentProvisions",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-140": {
   "value": "80000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:LiabilitiesIncludedInDisposalGroupsClassifiedAsHeldForSale",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-141": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:LiabilitiesIncludedInDisposalGroupsClassifiedAsHeldForSale",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-142": {
   "value": "3152000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CurrentLiabilities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-143": {
   "value": "3598000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CurrentLiabilities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-144": {
   "value": "899000000",
   "decimals": -6,
   "dimensions": {
    "concept": "johnsonmattheyplc:NonCurrentBorrowingsAndRelatedSwaps",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-145": {
   "value": "1252000000",
   "decimals": -6,
   "dimensions": {
    "concept": "johnsonmattheyplc:NonCurrentBorrowingsAndRelatedSwaps",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-146": {
   "value": "40000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:NoncurrentLeaseLiabilities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-147": {
   "value": "51000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:NoncurrentLeaseLiabilities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-148": {
   "value": "18000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DeferredTaxLiabilities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-149": {
   "value": "28000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DeferredTaxLiabilities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-150": {
   "value": "2000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:NoncurrentDerivativeFinancialLiabilities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-151": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:NoncurrentDerivativeFinancialLiabilities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-152": {
   "value": "72000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:NoncurrentRecognisedLiabilitiesDefinedBenefitPlan",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-153": {
   "value": "98000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:NoncurrentRecognisedLiabilitiesDefinedBenefitPlan",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-154": {
   "value": "12000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherFinancialLiabilities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-155": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherFinancialLiabilities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-156": {
   "value": "28000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:NoncurrentProvisions",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-157": {
   "value": "27000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:NoncurrentProvisions",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-158": {
   "value": "2000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherNoncurrentPayables",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-159": {
   "value": "5000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherNoncurrentPayables",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-160": {
   "value": "1073000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:NoncurrentLiabilities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-161": {
   "value": "1461000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:NoncurrentLiabilities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-162": {
   "value": "4225000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Liabilities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-163": {
   "value": "5059000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Liabilities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-164": {
   "value": "2441000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:NetAssetsLiabilities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-165": {
   "value": "2685000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:NetAssetsLiabilities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-166": {
   "value": "218000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IssuedCapital",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-167": {
   "value": "221000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IssuedCapital",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-168": {
   "value": "148000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:SharePremium",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-169": {
   "value": "148000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:SharePremium",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-170": {
   "value": "-24000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ReserveOfSharebasedPayments",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-171": {
   "value": "-29000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ReserveOfSharebasedPayments",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-172": {
   "value": "50000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherReserves",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-173": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherReserves",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-174": {
   "value": "2049000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:RetainedEarnings",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-175": {
   "value": "2345000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:RetainedEarnings",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-176": {
   "value": "2441000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Equity",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-177": {
   "value": "2685000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Equity",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-178": {
   "value": "195000000",
   "decimals": -6,
   "dimensions": {
    "concept": "johnsonmattheyplc:ProfitBeforeTaxFromContinuingOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-179": {
   "value": "224000000",
   "decimals": -6,
   "dimensions": {
    "concept": "johnsonmattheyplc:ProfitBeforeTaxFromContinuingOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-180": {
   "value": "-239000000",
   "decimals": -6,
   "dimensions": {
    "concept": "johnsonmattheyplc:LossProfitBeforeTaxFromDiscontinuedOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-181": {
   "value": "14000000",
   "decimals": -6,
   "dimensions": {
    "concept": "johnsonmattheyplc:LossProfitBeforeTaxFromDiscontinuedOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-182": {
   "value": "106000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForGainLossOnDisposalOfInvestmentsInSubsidiariesJointVenturesAndAssociates",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-183": {
   "value": "-1000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForGainLossOnDisposalOfInvestmentsInSubsidiariesJointVenturesAndAssociates",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-184": {
   "value": "151000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForDepreciationExpense",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-185": {
   "value": "158000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForDepreciationExpense",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-186": {
   "value": "39000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForAmortisationExpense",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-187": {
   "value": "32000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForAmortisationExpense",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-188": {
   "value": "632000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLoss",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-189": {
   "value": "122000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLoss",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-190": {
   "value": "2000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForLossesGainsOnDisposalOfNoncurrentAssets",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-191": {
   "value": "4000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForLossesGainsOnDisposalOfNoncurrentAssets",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-192": {
   "value": "8000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForSharebasedPayments",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-193": {
   "value": "9000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForSharebasedPayments",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-194": {
   "value": "123000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForDecreaseIncreaseInInventories",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-195": {
   "value": "19000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForDecreaseIncreaseInInventories",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-196": {
   "value": "588000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForDecreaseIncreaseInTradeAndOtherReceivables",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-197": {
   "value": "-430000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForDecreaseIncreaseInTradeAndOtherReceivables",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-198": {
   "value": "-783000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForIncreaseDecreaseInTradeAndOtherPayables",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-199": {
   "value": "607000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForIncreaseDecreaseInTradeAndOtherPayables",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-200": {
   "value": "25000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForProvisions",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-201": {
   "value": "41000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForProvisions",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-202": {
   "value": "-2000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForIncreaseDecreaseInEmployeeBenefitLiabilities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-203": {
   "value": "-7000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForIncreaseDecreaseInEmployeeBenefitLiabilities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-204": {
   "value": "19000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForFairValueGainsLosses",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-205": {
   "value": "-45000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForFairValueGainsLosses",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-206": {
   "value": "-60000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForFinanceIncomeCost",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-207": {
   "value": "-85000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:AdjustmentsForFinanceIncomeCost",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-208": {
   "value": "107000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncomeTaxesPaidRefundClassifiedAsOperatingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-209": {
   "value": "65000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncomeTaxesPaidRefundClassifiedAsOperatingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-210": {
   "value": "605000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CashFlowsFromUsedInOperatingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-211": {
   "value": "769000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CashFlowsFromUsedInOperatingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-212": {
   "value": "32000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:InterestReceivedClassifiedAsInvestingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-213": {
   "value": "66000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:InterestReceivedClassifiedAsInvestingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-214": {
   "value": "358000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:PurchaseOfPropertyPlantAndEquipmentClassifiedAsInvestingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-215": {
   "value": "304000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:PurchaseOfPropertyPlantAndEquipmentClassifiedAsInvestingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-216": {
   "value": "95000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:PurchaseOfIntangibleAssetsClassifiedAsInvestingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-217": {
   "value": "77000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:PurchaseOfIntangibleAssetsClassifiedAsInvestingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-218": {
   "value": "1000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProceedsFromOtherLongtermAssetsClassifiedAsInvestingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-219": {
   "value": "5000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProceedsFromOtherLongtermAssetsClassifiedAsInvestingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-220": {
   "value": "160000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CashFlowsFromLosingControlOfSubsidiariesOrOtherBusinessesClassifiedAsInvestingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-221": {
   "value": "19000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CashFlowsFromLosingControlOfSubsidiariesOrOtherBusinessesClassifiedAsInvestingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-222": {
   "value": "-260000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CashFlowsFromUsedInInvestingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-223": {
   "value": "-291000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CashFlowsFromUsedInInvestingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-224": {
   "value": "155000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:PaymentsToAcquireOrRedeemEntitysShares",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-225": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:PaymentsToAcquireOrRedeemEntitysShares",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-226": {
   "value": "9000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProceedsFromBorrowingsClassifiedAsFinancingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-227": {
   "value": "368000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProceedsFromBorrowingsClassifiedAsFinancingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-228": {
   "value": "140000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:RepaymentsOfBorrowingsClassifiedAsFinancingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-229": {
   "value": "298000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:RepaymentsOfBorrowingsClassifiedAsFinancingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-230": {
   "value": "139000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DividendsPaidToEquityHoldersOfParentClassifiedAsFinancingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-231": {
   "value": "99000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DividendsPaidToEquityHoldersOfParentClassifiedAsFinancingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-232": {
   "value": "111000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:InterestPaidClassifiedAsFinancingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-233": {
   "value": "159000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:InterestPaidClassifiedAsFinancingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-234": {
   "value": "14000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:PaymentsOfLeaseLiabilitiesClassifiedAsFinancingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-235": {
   "value": "14000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:PaymentsOfLeaseLiabilitiesClassifiedAsFinancingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-236": {
   "value": "-550000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CashFlowsFromUsedInFinancingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-237": {
   "value": "-202000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CashFlowsFromUsedInFinancingActivities",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-238": {
   "value": "-205000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncreaseDecreaseInCashAndCashEquivalentsBeforeEffectOfExchangeRateChanges",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-239": {
   "value": "276000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncreaseDecreaseInCashAndCashEquivalentsBeforeEffectOfExchangeRateChanges",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-240": {
   "value": "6000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:EffectOfExchangeRateChangesOnCashAndCashEquivalents",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-241": {
   "value": "-4000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:EffectOfExchangeRateChangesOnCashAndCashEquivalents",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-242": {
   "value": "545000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CashAndCashEquivalentsIfDifferentFromStatementOfFinancialPosition",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-243": {
   "value": "273000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CashAndCashEquivalentsIfDifferentFromStatementOfFinancialPosition",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-244": {
   "value": "346000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CashAndCashEquivalentsIfDifferentFromStatementOfFinancialPosition",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-245": {
   "value": "545000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CashAndCashEquivalentsIfDifferentFromStatementOfFinancialPosition",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-246": {
   "value": "254000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Cash",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-247": {
   "value": "119000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Cash",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-248": {
   "value": "137000000",
   "decimals": -6,
   "dimensions": {
    "concept": "johnsonmattheyplc:MoneyMarketFunds",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-249": {
   "value": "462000000",
   "decimals": -6,
   "dimensions": {
    "concept": "johnsonmattheyplc:MoneyMarketFunds",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-250": {
   "value": "37000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:BankOverdraftsClassifiedAsCashEquivalents",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-251": {
   "value": "36000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:BankOverdraftsClassifiedAsCashEquivalents",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-252": {
   "value": "-8000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CashAndCashEquivalentsClassifiedAsPartOfDisposalGroupHeldForSale",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-253": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CashAndCashEquivalentsClassifiedAsPartOfDisposalGroupHeldForSale",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-254": {
   "value": "346000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CashAndCashEquivalentsIfDifferentFromStatementOfFinancialPosition",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-255": {
   "value": "545000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:CashAndCashEquivalentsIfDifferentFromStatementOfFinancialPosition",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-256": {
   "value": "221000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Equity",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-257": {
   "value": "148000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Equity",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-258": {
   "value": "-32000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Equity",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-259": {
   "value": "142000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Equity",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-260": {
   "value": "2345000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Equity",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-261": {
   "value": "2824000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Equity",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-262": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProfitLoss",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-263": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProfitLoss",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-264": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProfitLoss",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-265": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProfitLoss",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-266": {
   "value": "205000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProfitLoss",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-267": {
   "value": "205000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProfitLoss",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-268": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesOnRemeasurementsOfDefinedBenefitPlans",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-269": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesOnRemeasurementsOfDefinedBenefitPlans",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-270": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesOnRemeasurementsOfDefinedBenefitPlans",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-271": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesOnRemeasurementsOfDefinedBenefitPlans",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-272": {
   "value": "-141000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesOnRemeasurementsOfDefinedBenefitPlans",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-273": {
   "value": "-141000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesOnRemeasurementsOfDefinedBenefitPlans",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-274": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesFromInvestmentsInEquityInstruments",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-275": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesFromInvestmentsInEquityInstruments",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-276": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesFromInvestmentsInEquityInstruments",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-277": {
   "value": "5000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesFromInvestmentsInEquityInstruments",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-278": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesFromInvestmentsInEquityInstruments",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-279": {
   "value": "5000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesFromInvestmentsInEquityInstruments",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-280": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxExchangeDifferencesOnTranslation",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-281": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxExchangeDifferencesOnTranslation",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-282": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxExchangeDifferencesOnTranslation",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-283": {
   "value": "-162000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxExchangeDifferencesOnTranslation",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-284": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxExchangeDifferencesOnTranslation",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-285": {
   "value": "-162000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxExchangeDifferencesOnTranslation",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-286": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxCashFlowHedges",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-287": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxCashFlowHedges",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-288": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxCashFlowHedges",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-289": {
   "value": "3000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxCashFlowHedges",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-290": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxCashFlowHedges",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-291": {
   "value": "3000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxCashFlowHedges",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-292": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxHedgesOfNetInvestmentsInForeignOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-293": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxHedgesOfNetInvestmentsInForeignOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-294": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxHedgesOfNetInvestmentsInForeignOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-295": {
   "value": "12000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxHedgesOfNetInvestmentsInForeignOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-296": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxHedgesOfNetInvestmentsInForeignOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-297": {
   "value": "12000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxHedgesOfNetInvestmentsInForeignOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-298": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncomeTaxRelatingToComponentsOfOtherComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-299": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncomeTaxRelatingToComponentsOfOtherComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-300": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncomeTaxRelatingToComponentsOfOtherComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-301": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncomeTaxRelatingToComponentsOfOtherComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-302": {
   "value": "-28000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncomeTaxRelatingToComponentsOfOtherComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-303": {
   "value": "-28000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncomeTaxRelatingToComponentsOfOtherComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-304": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-305": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-306": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-307": {
   "value": "-142000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-308": {
   "value": "92000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-309": {
   "value": "-50000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-310": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DividendsPaid",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-311": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DividendsPaid",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-312": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DividendsPaid",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-313": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DividendsPaid",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-314": {
   "value": "99000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DividendsPaid",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-315": {
   "value": "99000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DividendsPaid",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-316": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncreaseDecreaseThroughSharebasedPaymentTransactions",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-317": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncreaseDecreaseThroughSharebasedPaymentTransactions",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-318": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncreaseDecreaseThroughSharebasedPaymentTransactions",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-319": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncreaseDecreaseThroughSharebasedPaymentTransactions",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-320": {
   "value": "16000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncreaseDecreaseThroughSharebasedPaymentTransactions",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-321": {
   "value": "16000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncreaseDecreaseThroughSharebasedPaymentTransactions",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-322": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ShareIssueRelatedCost",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-323": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ShareIssueRelatedCost",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-324": {
   "value": "-3000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ShareIssueRelatedCost",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-325": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ShareIssueRelatedCost",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-326": {
   "value": "10000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ShareIssueRelatedCost",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-327": {
   "value": "7000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ShareIssueRelatedCost",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-328": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DecreaseIncreaseThroughTaxOnSharebasedPaymentTransactions",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-329": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DecreaseIncreaseThroughTaxOnSharebasedPaymentTransactions",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-330": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DecreaseIncreaseThroughTaxOnSharebasedPaymentTransactions",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-331": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DecreaseIncreaseThroughTaxOnSharebasedPaymentTransactions",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-332": {
   "value": "-1000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DecreaseIncreaseThroughTaxOnSharebasedPaymentTransactions",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-333": {
   "value": "-1000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DecreaseIncreaseThroughTaxOnSharebasedPaymentTransactions",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2020-04-01T00:00:00/2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-334": {
   "value": "221000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Equity",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-335": {
   "value": "148000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Equity",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-336": {
   "value": "-29000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Equity",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-337": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Equity",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-338": {
   "value": "2345000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Equity",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-339": {
   "value": "2685000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Equity",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-340": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProfitLoss",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-341": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProfitLoss",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-342": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProfitLoss",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-343": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProfitLoss",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-344": {
   "value": "-101000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProfitLoss",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-345": {
   "value": "-101000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ProfitLoss",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-346": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesOnRemeasurementsOfDefinedBenefitPlans",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-347": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesOnRemeasurementsOfDefinedBenefitPlans",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-348": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesOnRemeasurementsOfDefinedBenefitPlans",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-349": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesOnRemeasurementsOfDefinedBenefitPlans",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-350": {
   "value": "177000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesOnRemeasurementsOfDefinedBenefitPlans",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-351": {
   "value": "177000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesOnRemeasurementsOfDefinedBenefitPlans",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-352": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesFromInvestmentsInEquityInstruments",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-353": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesFromInvestmentsInEquityInstruments",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-354": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesFromInvestmentsInEquityInstruments",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-355": {
   "value": "-5000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesFromInvestmentsInEquityInstruments",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-356": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesFromInvestmentsInEquityInstruments",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-357": {
   "value": "-5000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesFromInvestmentsInEquityInstruments",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-358": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxExchangeDifferencesOnTranslation",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-359": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxExchangeDifferencesOnTranslation",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-360": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxExchangeDifferencesOnTranslation",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-361": {
   "value": "80000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxExchangeDifferencesOnTranslation",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-362": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxExchangeDifferencesOnTranslation",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-363": {
   "value": "80000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxExchangeDifferencesOnTranslation",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-364": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxCashFlowHedges",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-365": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxCashFlowHedges",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-366": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxCashFlowHedges",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-367": {
   "value": "-36000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxCashFlowHedges",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-368": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxCashFlowHedges",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-369": {
   "value": "-36000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxCashFlowHedges",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-370": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxHedgesOfNetInvestmentsInForeignOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-371": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxHedgesOfNetInvestmentsInForeignOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-372": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxHedgesOfNetInvestmentsInForeignOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-373": {
   "value": "-2000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxHedgesOfNetInvestmentsInForeignOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-374": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxHedgesOfNetInvestmentsInForeignOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-375": {
   "value": "-2000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:OtherComprehensiveIncomeNetOfTaxHedgesOfNetInvestmentsInForeignOperations",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-376": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncomeTaxRelatingToComponentsOfOtherComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-377": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncomeTaxRelatingToComponentsOfOtherComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-378": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncomeTaxRelatingToComponentsOfOtherComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-379": {
   "value": "-10000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncomeTaxRelatingToComponentsOfOtherComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-380": {
   "value": "35000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncomeTaxRelatingToComponentsOfOtherComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-381": {
   "value": "25000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncomeTaxRelatingToComponentsOfOtherComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-382": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-383": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-384": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-385": {
   "value": "47000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-386": {
   "value": "41000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-387": {
   "value": "88000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ComprehensiveIncome",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-388": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DividendsPaid",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-389": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DividendsPaid",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-390": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DividendsPaid",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-391": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DividendsPaid",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-392": {
   "value": "139000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DividendsPaid",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-393": {
   "value": "139000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:DividendsPaid",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-394": {
   "value": "3000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:PurchaseOfTreasuryShares",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-395": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:PurchaseOfTreasuryShares",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-396": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:PurchaseOfTreasuryShares",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-397": {
   "value": "-3000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:PurchaseOfTreasuryShares",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-398": {
   "value": "200000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:PurchaseOfTreasuryShares",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-399": {
   "value": "200000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:PurchaseOfTreasuryShares",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-400": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncreaseDecreaseThroughSharebasedPaymentTransactions",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-401": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncreaseDecreaseThroughSharebasedPaymentTransactions",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-402": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncreaseDecreaseThroughSharebasedPaymentTransactions",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-403": {
   "value": "0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncreaseDecreaseThroughSharebasedPaymentTransactions",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-404": {
   "value": "15000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncreaseDecreaseThroughSharebasedPaymentTransactions",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-405": {
   "value": "15000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:IncreaseDecreaseThroughSharebasedPaymentTransactions",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-406": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ShareIssueRelatedCost",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-407": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ShareIssueRelatedCost",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-408": {
   "value": "-5000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ShareIssueRelatedCost",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-409": {
   "value": "-0",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ShareIssueRelatedCost",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-410": {
   "value": "13000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ShareIssueRelatedCost",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-411": {
   "value": "8000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:ShareIssueRelatedCost",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-412": {
   "value": "218000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Equity",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:IssuedCapitalMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-413": {
   "value": "148000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Equity",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:SharePremiumMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-414": {
   "value": "-24000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Equity",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "johnsonmattheyplc:SharesHeldInESOTMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-415": {
   "value": "50000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Equity",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:OtherReservesMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-416": {
   "value": "2049000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Equity",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "ifrs-full:ComponentsOfEquityAxis": "ifrs-full:RetainedEarningsMember",
    "unit": "iso4217:GBP"
   }
  },
  "fact-417": {
   "value": "2441000000",
   "decimals": -6,
   "dimensions": {
    "concept": "ifrs-full:Equity",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2022-04-01T00:00:00",
    "unit": "iso4217:GBP"
   }
  },
  "fact-5": {
   "value": "Johnson Matthey plc",
   "dimensions": {
    "concept": "ifrs-full:NameOfReportingEntityOrOtherMeansOfIdentification",
    "language": "en",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00"
   }
  },
  "fact-6": {
   "value": "public company limited by shares",
   "dimensions": {
    "concept": "ifrs-full:LegalFormOfEntity",
    "language": "en",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00"
   }
  },
  "fact-7": {
   "value": "England",
   "dimensions": {
    "concept": "ifrs-full:DomicileOfEntity",
    "language": "en",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00"
   }
  },
  "fact-8": {
   "value": "5th Floor 25 Farringdon Street London EC4A 4AB",
   "dimensions": {
    "concept": "ifrs-full:AddressOfRegisteredOfficeOfEntity",
    "language": "en",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00"
   }
  },
  "fact-9": {
   "value": "England and Wales",
   "dimensions": {
    "concept": "ifrs-full:CountryOfIncorporation",
    "language": "en",
    "entity": "scheme:2138001AVBSD1HSC6Z10",
    "period": "2021-04-01T00:00:00/2022-04-01T00:00:00"
   }
  }
 }
}