<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.22.0.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>829</ContextCount>
  <ElementCount>743</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>192</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>15</UnitCount>
  <MyReports>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>00090 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>00100 - Statement - GROUP INCOME STATEMENT</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/StatementGroupIncomeStatement</Role>
      <ShortName>GROUP INCOME STATEMENT</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>00200 - Statement - GROUP STATEMENT OF COMPREHENSIVE INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/StatementGroupStatementOfComprehensiveIncome</Role>
      <ShortName>GROUP STATEMENT OF COMPREHENSIVE INCOME</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>00300 - Statement - GROUP BALANCE SHEET</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/StatementGroupBalanceSheet</Role>
      <ShortName>GROUP BALANCE SHEET</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>00400 - Statement - GROUP CASH FLOW STATEMENT</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/StatementGroupCashFlowStatement</Role>
      <ShortName>GROUP CASH FLOW STATEMENT</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>00500 - Statement - GROUP STATEMENT OF CHANGES IN EQUITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/StatementGroupStatementOfChangesInEquity</Role>
      <ShortName>GROUP STATEMENT OF CHANGES IN EQUITY</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>00505 - Statement - GROUP STATEMENT OF CHANGES IN EQUITY (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/StatementGroupStatementOfChangesInEquityParenthetical</Role>
      <ShortName>GROUP STATEMENT OF CHANGES IN EQUITY (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>10101 - Disclosure - BASIS OF PREPARATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureBasisOfPreparation</Role>
      <ShortName>BASIS OF PREPARATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>10201 - Disclosure - BUSINESS SEGMENT INFORMATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureBusinessSegmentInformation</Role>
      <ShortName>BUSINESS SEGMENT INFORMATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>10301 - Disclosure - OPERATING PROFIT</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureOperatingProfit</Role>
      <ShortName>OPERATING PROFIT</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>10401 - Disclosure - INTEREST AND OTHER FINANCE COSTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureInterestAndOtherFinanceCosts</Role>
      <ShortName>INTEREST AND OTHER FINANCE COSTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>10501 - Disclosure - TAXATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureTaxation</Role>
      <ShortName>TAXATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>10601 - Disclosure - EARNINGS PER ORDINARY SHARE</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureEarningsPerOrdinaryShare</Role>
      <ShortName>EARNINGS PER ORDINARY SHARE</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>10701 - Disclosure - PROPERTY, PLANT AND EQUIPMENT</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosurePropertyPlantAndEquipment</Role>
      <ShortName>PROPERTY, PLANT AND EQUIPMENT</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>10801 - Disclosure - GOODWILL</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureGoodwill</Role>
      <ShortName>GOODWILL</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>10901 - Disclosure - INTANGIBLE ASSETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureIntangibleAssets</Role>
      <ShortName>INTANGIBLE ASSETS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>11001 - Disclosure - INVESTMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureInvestments</Role>
      <ShortName>INVESTMENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>11101 - Disclosure - INVESTMENTS IN ASSOCIATES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureInvestmentsInAssociates</Role>
      <ShortName>INVESTMENTS IN ASSOCIATES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>11201 - Disclosure - INVENTORIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureInventories</Role>
      <ShortName>INVENTORIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>11301 - Disclosure - TRADE AND OTHER RECEIVABLES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureTradeAndOtherReceivables</Role>
      <ShortName>TRADE AND OTHER RECEIVABLES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>11401 - Disclosure - TRADE AND OTHER PAYABLES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureTradeAndOtherPayables</Role>
      <ShortName>TRADE AND OTHER PAYABLES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>11501 - Disclosure - CASH AND BORROWINGS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureCashAndBorrowings</Role>
      <ShortName>CASH AND BORROWINGS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>11601 - Disclosure - FINANCIAL INSTRUMENTS AND RISK MANAGEMENT</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureFinancialInstrumentsAndRiskManagement</Role>
      <ShortName>FINANCIAL INSTRUMENTS AND RISK MANAGEMENT</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>11701 - Disclosure - PROVISIONS AND CONTINGENCIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureProvisionsAndContingencies</Role>
      <ShortName>PROVISIONS AND CONTINGENCIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>11801 - Disclosure - RETIREMENT BENEFIT OBLIGATIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureRetirementBenefitObligations</Role>
      <ShortName>RETIREMENT BENEFIT OBLIGATIONS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>11901 - Disclosure - EQUITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureEquity</Role>
      <ShortName>EQUITY</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>12001 - Disclosure - CASH FLOW STATEMENT</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureCashFlowStatement</Role>
      <ShortName>CASH FLOW STATEMENT</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>12101 - Disclosure - ACQUISITIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureAcquisitions</Role>
      <ShortName>ACQUISITIONS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>12201 - Disclosure - OTHER NOTES TO THE ACCOUNTS</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureOtherNotesToAccounts</Role>
      <ShortName>OTHER NOTES TO THE ACCOUNTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>12301 - Disclosure - POST BALANCE SHEET EVENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosurePostBalanceSheetEvents</Role>
      <ShortName>POST BALANCE SHEET EVENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>20102 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureSignificantAccountingPoliciesPolicies</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>30103 - Disclosure - BASIS OF PREPARATION (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureBasisOfPreparationTables</Role>
      <ShortName>BASIS OF PREPARATION (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureBasisOfPreparation</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>30203 - Disclosure - BUSINESS SEGMENT INFORMATION (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureBusinessSegmentInformationTables</Role>
      <ShortName>BUSINESS SEGMENT INFORMATION (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureBusinessSegmentInformation</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>30303 - Disclosure - OPERATING PROFIT (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureOperatingProfitTables</Role>
      <ShortName>OPERATING PROFIT (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureOperatingProfit</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>30403 - Disclosure - INTEREST AND OTHER FINANCE COSTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureInterestAndOtherFinanceCostsTables</Role>
      <ShortName>INTEREST AND OTHER FINANCE COSTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureInterestAndOtherFinanceCosts</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>30503 - Disclosure - TAXATION (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureTaxationTables</Role>
      <ShortName>TAXATION (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureTaxation</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>30603 - Disclosure - EARNINGS PER ORDINARY SHARE (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureEarningsPerOrdinaryShareTables</Role>
      <ShortName>EARNINGS PER ORDINARY SHARE (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureEarningsPerOrdinaryShare</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>30703 - Disclosure - PROPERTY, PLANT AND EQUIPMENT (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosurePropertyPlantAndEquipmentTables</Role>
      <ShortName>PROPERTY, PLANT AND EQUIPMENT (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosurePropertyPlantAndEquipment</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>30803 - Disclosure - GOODWILL (Table)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureGoodwillTable</Role>
      <ShortName>GOODWILL (Table)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureGoodwill</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>30903 - Disclosure - INTANGIBLE ASSETS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureIntangibleAssetsTables</Role>
      <ShortName>INTANGIBLE ASSETS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureIntangibleAssets</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>31003 - Disclosure - INVESTMENTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureInvestmentsTables</Role>
      <ShortName>INVESTMENTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureInvestments</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>31103 - Disclosure - INVESTMENTS IN ASSOCIATES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureInvestmentsInAssociatesTables</Role>
      <ShortName>INVESTMENTS IN ASSOCIATES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureInvestmentsInAssociates</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>31203 - Disclosure - INVENTORIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureInventoriesTables</Role>
      <ShortName>INVENTORIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureInventories</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>31303 - Disclosure - TRADE AND OTHER RECEIVABLES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureTradeAndOtherReceivablesTables</Role>
      <ShortName>TRADE AND OTHER RECEIVABLES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureTradeAndOtherReceivables</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>31403 - Disclosure - TRADE AND OTHER PAYABLES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureTradeAndOtherPayablesTables</Role>
      <ShortName>TRADE AND OTHER PAYABLES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureTradeAndOtherPayables</ParentRole>
      <Position>45</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>31503 - Disclosure - CASH AND BORROWINGS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureCashAndBorrowingsTables</Role>
      <ShortName>CASH AND BORROWINGS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureCashAndBorrowings</ParentRole>
      <Position>46</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>31603 - Disclosure - FINANCIAL INSTRUMENTS AND RISK MANAGEMENT (Table)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureFinancialInstrumentsAndRiskManagementTable</Role>
      <ShortName>FINANCIAL INSTRUMENTS AND RISK MANAGEMENT (Table)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureFinancialInstrumentsAndRiskManagement</ParentRole>
      <Position>47</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>31703 - Disclosure - PROVISIONS AND CONTINGENCIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureProvisionsAndContingenciesTables</Role>
      <ShortName>PROVISIONS AND CONTINGENCIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureProvisionsAndContingencies</ParentRole>
      <Position>48</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>31803 - Disclosure - RETIREMENT BENEFIT OBLIGATIONS (Table)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureRetirementBenefitObligationsTable</Role>
      <ShortName>RETIREMENT BENEFIT OBLIGATIONS (Table)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureRetirementBenefitObligations</ParentRole>
      <Position>49</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>31903 - Disclosure - EQUITY (Table)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureEquityTable</Role>
      <ShortName>EQUITY (Table)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureEquity</ParentRole>
      <Position>50</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>32003 - Disclosure - CASH FLOW STATEMENT (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureCashFlowStatementTables</Role>
      <ShortName>CASH FLOW STATEMENT (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureCashFlowStatement</ParentRole>
      <Position>51</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>32103 - Disclosure - ACQUISITIONS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureAcquisitionsTables</Role>
      <ShortName>ACQUISITIONS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureAcquisitions</ParentRole>
      <Position>52</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>32203 - Disclosure - OTHER NOTES TO THE ACCOUNTS (Tables)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureOtherNotesToAccountsTables</Role>
      <ShortName>OTHER NOTES TO THE ACCOUNTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureOtherNotesToAccounts</ParentRole>
      <Position>53</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>40101 - Disclosure - BASIS OF PREPARATION (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureBasisOfPreparationDetails</Role>
      <ShortName>BASIS OF PREPARATION (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureBasisOfPreparationTables</ParentRole>
      <Position>54</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>40201 - Disclosure - BUSINESS SEGMENT INFORMATION (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureBusinessSegmentInformationDetails</Role>
      <ShortName>BUSINESS SEGMENT INFORMATION (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureBusinessSegmentInformationTables</ParentRole>
      <Position>55</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>40202 - Disclosure - BUSINESS SEGMENT INFORMATION - Trading and operating profit by business segment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureBusinessSegmentInformationTradingAndOperatingProfitByBusinessSegmentDetails</Role>
      <ShortName>BUSINESS SEGMENT INFORMATION - Trading and operating profit by business segment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>40203 - Disclosure - BUSINESS SEGMENT INFORMATION - Assets and liabilities by business segment and geography (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureBusinessSegmentInformationAssetsAndLiabilitiesByBusinessSegmentAndGeographyDetails</Role>
      <ShortName>BUSINESS SEGMENT INFORMATION - Assets and liabilities by business segment and geography (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>40301 - Disclosure - OPERATING PROFIT (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureOperatingProfitDetails</Role>
      <ShortName>OPERATING PROFIT (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureOperatingProfitTables</ParentRole>
      <Position>58</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>40302 - Disclosure - OPERATING PROFIT - Information about the nature and cost of services (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureOperatingProfitInformationAboutNatureAndCostOfServicesDetails</Role>
      <ShortName>OPERATING PROFIT - Information about the nature and cost of services (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>40401 - Disclosure - INTEREST AND OTHER FINANCE COSTS - Interest Income/(expense) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureInterestAndOtherFinanceCostsInterestIncomeExpenseDetails</Role>
      <ShortName>INTEREST AND OTHER FINANCE COSTS - Interest Income/(expense) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>40402 - Disclosure - INTEREST AND OTHER FINANCE COSTS - Other Finance Costs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureInterestAndOtherFinanceCostsOtherFinanceCostsDetails</Role>
      <ShortName>INTEREST AND OTHER FINANCE COSTS - Other Finance Costs (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>40501 - Disclosure - TAXATION - Taxation attributable to the Group (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureTaxationTaxationAttributableToGroupDetails</Role>
      <ShortName>TAXATION - Taxation attributable to the Group (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>40502 - Disclosure - TAXATION - Factors affecting future tax charges (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureTaxationFactorsAffectingFutureTaxChargesDetails</Role>
      <ShortName>TAXATION - Factors affecting future tax charges (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>40503 - Disclosure - TAXATION - Deferred taxation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureTaxationDeferredTaxationDetails</Role>
      <ShortName>TAXATION - Deferred taxation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>40601 - Disclosure - EARNINGS PER ORDINARY SHARE - Calculation of basic, diluted and adjusted earnings per share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureEarningsPerOrdinaryShareCalculationOfBasicDilutedAndAdjustedEarningsPerShareDetails</Role>
      <ShortName>EARNINGS PER ORDINARY SHARE - Calculation of basic, diluted and adjusted earnings per share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>65</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>40602 - Disclosure - EARNINGS PER ORDINARY SHARE - Earnings per ordinary share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureEarningsPerOrdinaryShareEarningsPerOrdinaryShareDetails</Role>
      <ShortName>EARNINGS PER ORDINARY SHARE - Earnings per ordinary share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>40701 - Disclosure - PROPERTY, PLANT AND EQUIPMENT (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosurePropertyPlantAndEquipmentDetails</Role>
      <ShortName>PROPERTY, PLANT AND EQUIPMENT (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosurePropertyPlantAndEquipmentTables</ParentRole>
      <Position>67</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>40801 - Disclosure - GOODWILL (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureGoodwillDetails</Role>
      <ShortName>GOODWILL (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureGoodwillTable</ParentRole>
      <Position>68</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>40901 - Disclosure - INTANGIBLE ASSETS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureIntangibleAssetsDetails</Role>
      <ShortName>INTANGIBLE ASSETS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureIntangibleAssetsTables</ParentRole>
      <Position>69</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>41001 - Disclosure - INVESTMENTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureInvestmentsDetails</Role>
      <ShortName>INVESTMENTS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureInvestmentsTables</ParentRole>
      <Position>70</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>41101 - Disclosure - INVESTMENTS IN ASSOCIATES - Amounts recognised in the balance sheet and income statement (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureInvestmentsInAssociatesAmountsRecognisedInBalanceSheetAndIncomeStatementDetails</Role>
      <ShortName>INVESTMENTS IN ASSOCIATES - Amounts recognised in the balance sheet and income statement (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>71</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>41102 - Disclosure - INVESTMENTS IN ASSOCIATES - Summarised statement of comprehensive income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureInvestmentsInAssociatesSummarisedStatementOfComprehensiveIncomeDetails</Role>
      <ShortName>INVESTMENTS IN ASSOCIATES - Summarised statement of comprehensive income (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>72</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>41103 - Disclosure - INVESTMENTS IN ASSOCIATES - Summarised balance sheet (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureInvestmentsInAssociatesSummarisedBalanceSheetDetails</Role>
      <ShortName>INVESTMENTS IN ASSOCIATES - Summarised balance sheet (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>73</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>41201 - Disclosure - INVENTORIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureInventoriesDetails</Role>
      <ShortName>INVENTORIES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureInventoriesTables</ParentRole>
      <Position>74</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>41301 - Disclosure - TRADE AND OTHER RECEIVABLES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureTradeAndOtherReceivablesDetails</Role>
      <ShortName>TRADE AND OTHER RECEIVABLES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureTradeAndOtherReceivablesTables</ParentRole>
      <Position>75</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>41302 - Disclosure - TRADE AND OTHER RECEIVABLES - Trade receivables past due (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureTradeAndOtherReceivablesTradeReceivablesPastDueDetails</Role>
      <ShortName>TRADE AND OTHER RECEIVABLES - Trade receivables past due (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>76</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>41303 - Disclosure - TRADE AND OTHER RECEIVABLES - Movements in the provision for bad and doubtful debts (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureTradeAndOtherReceivablesMovementsInProvisionForBadAndDoubtfulDebtsDetails</Role>
      <ShortName>TRADE AND OTHER RECEIVABLES - Movements in the provision for bad and doubtful debts (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>77</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>41304 - Disclosure - TRADE AND OTHER RECEIVABLES - Trade receivables denominated in major currencies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureTradeAndOtherReceivablesTradeReceivablesDenominatedInMajorCurrenciesDetails</Role>
      <ShortName>TRADE AND OTHER RECEIVABLES - Trade receivables denominated in major currencies (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>78</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>41401 - Disclosure - TRADE AND OTHER PAYABLES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureTradeAndOtherPayablesDetails</Role>
      <ShortName>TRADE AND OTHER PAYABLES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureTradeAndOtherPayablesTables</ParentRole>
      <Position>79</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>41501 - Disclosure - CASH AND BORROWINGS - Net debt (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureCashAndBorrowingsNetDebtDetails</Role>
      <ShortName>CASH AND BORROWINGS - Net debt (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>80</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>41502 - Disclosure - CASH AND BORROWINGS - Borrowings are repayable (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureCashAndBorrowingsBorrowingsAreRepayableDetails</Role>
      <ShortName>CASH AND BORROWINGS - Borrowings are repayable (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>81</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>41503 - Disclosure - CASH AND BORROWINGS - Liquidity risk exposures (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureCashAndBorrowingsLiquidityRiskExposuresDetails</Role>
      <ShortName>CASH AND BORROWINGS - Liquidity risk exposures (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>82</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>41504 - Disclosure - CASH AND BORROWINGS - Year end financial liabilities by contractual maturity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureCashAndBorrowingsYearEndFinancialLiabilitiesByContractualMaturityDetails</Role>
      <ShortName>CASH AND BORROWINGS - Year end financial liabilities by contractual maturity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>83</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>41505 - Disclosure - CASH AND BORROWINGS - Liquidity and capital resources (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureCashAndBorrowingsLiquidityAndCapitalResourcesDetails</Role>
      <ShortName>CASH AND BORROWINGS - Liquidity and capital resources (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>84</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>41601 - Disclosure - FINANCIAL INSTRUMENTS AND RISK MANAGEMENT - Foreign Exchange Exposures (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureFinancialInstrumentsAndRiskManagementForeignExchangeExposuresDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS AND RISK MANAGEMENT - Foreign Exchange Exposures (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>85</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>41602 - Disclosure - FINANCIAL INSTRUMENTS AND RISK MANAGEMENT - Interest Rate Exposures (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureFinancialInstrumentsAndRiskManagementInterestRateExposuresDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS AND RISK MANAGEMENT - Interest Rate Exposures (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>86</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R87.htm</HtmlFileName>
      <LongName>41603 - Disclosure - FINANCIAL INSTRUMENTS AND RISK MANAGEMENT - Credit Risk Exposures (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureFinancialInstrumentsAndRiskManagementCreditRiskExposuresDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS AND RISK MANAGEMENT - Credit Risk Exposures (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>87</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R88.htm</HtmlFileName>
      <LongName>41604 - Disclosure - FINANCIAL INSTRUMENTS AND RISK MANAGEMENT - Hedge (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureFinancialInstrumentsAndRiskManagementHedgeDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS AND RISK MANAGEMENT - Hedge (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureFinancialInstrumentsAndRiskManagementTable</ParentRole>
      <Position>88</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R89.htm</HtmlFileName>
      <LongName>41605 - Disclosure - FINANCIAL INSTRUMENTS AND RISK MANAGEMENT - Net investment hedge (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureFinancialInstrumentsAndRiskManagementNetInvestmentHedgeDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS AND RISK MANAGEMENT - Net investment hedge (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>89</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R90.htm</HtmlFileName>
      <LongName>41606 - Disclosure - FINANCIAL INSTRUMENTS AND RISK MANAGEMENT - Interest Bearing Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureFinancialInstrumentsAndRiskManagementInterestBearingLiabilitiesDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS AND RISK MANAGEMENT - Interest Bearing Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>90</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R91.htm</HtmlFileName>
      <LongName>41607 - Disclosure - FINANCIAL INSTRUMENTS AND RISK MANAGEMENT - Interest Bearing Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureFinancialInstrumentsAndRiskManagementInterestBearingAssetsDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS AND RISK MANAGEMENT - Interest Bearing Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>91</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R92.htm</HtmlFileName>
      <LongName>41608 - Disclosure - FINANCIAL INSTRUMENTS AND RISK MANAGEMENT - Fair Value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureFinancialInstrumentsAndRiskManagementFairValueDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS AND RISK MANAGEMENT - Fair Value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>92</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R93.htm</HtmlFileName>
      <LongName>41609 - Disclosure - FINANCIAL INSTRUMENTS AND RISK MANAGEMENT - Movement of financial instruments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureFinancialInstrumentsAndRiskManagementMovementOfFinancialInstrumentsDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS AND RISK MANAGEMENT - Movement of financial instruments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>93</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R94.htm</HtmlFileName>
      <LongName>41701 - Disclosure - PROVISIONS AND CONTINGENCIES - Changes in provisions (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureProvisionsAndContingenciesChangesInProvisionsDetails</Role>
      <ShortName>PROVISIONS AND CONTINGENCIES - Changes in provisions (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>94</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R95.htm</HtmlFileName>
      <LongName>41702 - Disclosure - PROVISIONS AND CONTINGENCIES - Current and non-current provisions (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureProvisionsAndContingenciesCurrentAndNonCurrentProvisionsDetails</Role>
      <ShortName>PROVISIONS AND CONTINGENCIES - Current and non-current provisions (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>95</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R96.htm</HtmlFileName>
      <LongName>41704 - Disclosure - PROVISIONS AND CONTINGENCIES - Legal proceedings (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureProvisionsAndContingenciesLegalProceedingsDetails</Role>
      <ShortName>PROVISIONS AND CONTINGENCIES - Legal proceedings (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>96</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R97.htm</HtmlFileName>
      <LongName>41801 - Disclosure - RETIREMENT BENEFIT OBLIGATIONS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureRetirementBenefitObligationsDetails</Role>
      <ShortName>RETIREMENT BENEFIT OBLIGATIONS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureRetirementBenefitObligationsTable</ParentRole>
      <Position>97</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R98.htm</HtmlFileName>
      <LongName>41802 - Disclosure - RETIREMENT BENEFIT OBLIGATIONS - Reconciliation of benefit obligations and pension assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureRetirementBenefitObligationsReconciliationOfBenefitObligationsAndPensionAssetsDetails</Role>
      <ShortName>RETIREMENT BENEFIT OBLIGATIONS - Reconciliation of benefit obligations and pension assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>98</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R99.htm</HtmlFileName>
      <LongName>41803 - Disclosure - RETIREMENT BENEFIT OBLIGATIONS - Plan assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureRetirementBenefitObligationsPlanAssetsDetails</Role>
      <ShortName>RETIREMENT BENEFIT OBLIGATIONS - Plan assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>99</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R100.htm</HtmlFileName>
      <LongName>41804 - Disclosure - RETIREMENT BENEFIT OBLIGATIONS - Principal actuarial assumptions (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureRetirementBenefitObligationsPrincipalActuarialAssumptionsDetails</Role>
      <ShortName>RETIREMENT BENEFIT OBLIGATIONS - Principal actuarial assumptions (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>100</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R101.htm</HtmlFileName>
      <LongName>41805 - Disclosure - RETIREMENT BENEFIT OBLIGATIONS - Sensitivity analysis (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureRetirementBenefitObligationsSensitivityAnalysisDetails</Role>
      <ShortName>RETIREMENT BENEFIT OBLIGATIONS - Sensitivity analysis (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>101</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R102.htm</HtmlFileName>
      <LongName>41901 - Disclosure - EQUITY - Share Capital (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureEquityShareCapitalDetails</Role>
      <ShortName>EQUITY - Share Capital (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>102</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R103.htm</HtmlFileName>
      <LongName>41902 - Disclosure - EQUITY - Equity Components (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureEquityEquityComponentsDetails</Role>
      <ShortName>EQUITY - Equity Components (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>103</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R104.htm</HtmlFileName>
      <LongName>41903 - Disclosure - EQUITY - Shares Buy-back (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureEquitySharesBuyBackDetails</Role>
      <ShortName>EQUITY - Shares Buy-back (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>104</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R105.htm</HtmlFileName>
      <LongName>41904 - Disclosure - EQUITY - Treasury Shares (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureEquityTreasurySharesDetails</Role>
      <ShortName>EQUITY - Treasury Shares (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>105</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R106.htm</HtmlFileName>
      <LongName>41905 - Disclosure - EQUITY - Dividends (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureEquityDividendsDetails</Role>
      <ShortName>EQUITY - Dividends (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>106</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R107.htm</HtmlFileName>
      <LongName>42001 - Disclosure - CASH FLOW STATEMENT - Analysis of net debt (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureCashFlowStatementAnalysisOfNetDebtDetails</Role>
      <ShortName>CASH FLOW STATEMENT - Analysis of net debt (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>107</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R108.htm</HtmlFileName>
      <LongName>42002 - Disclosure - CASH FLOW STATEMENT - Reconciliation of net cash flow to movement in net debt (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureCashFlowStatementReconciliationOfNetCashFlowToMovementInNetDebtDetails</Role>
      <ShortName>CASH FLOW STATEMENT - Reconciliation of net cash flow to movement in net debt (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>108</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R109.htm</HtmlFileName>
      <LongName>42003 - Disclosure - CASH FLOW STATEMENT - Cash and cash equivalents (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureCashFlowStatementCashAndCashEquivalentsDetails</Role>
      <ShortName>CASH FLOW STATEMENT - Cash and cash equivalents (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>109</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R110.htm</HtmlFileName>
      <LongName>42004 - Disclosure - CASH FLOW STATEMENT - Cash outflows (inflows) arising from financing activities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureCashFlowStatementCashOutflowsInflowsArisingFromFinancingActivitiesDetails</Role>
      <ShortName>CASH FLOW STATEMENT - Cash outflows (inflows) arising from financing activities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>110</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R111.htm</HtmlFileName>
      <LongName>42101 - Disclosure - ACQUISITIONS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureAcquisitionsDetails</Role>
      <ShortName>ACQUISITIONS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosureAcquisitionsTables</ParentRole>
      <Position>111</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R112.htm</HtmlFileName>
      <LongName>42201 - Disclosure - OTHER NOTES TO THE ACCOUNTS - Stock Options Outstanding (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureOtherNotesToAccountsStockOptionsOutstandingDetails</Role>
      <ShortName>OTHER NOTES TO THE ACCOUNTS - Stock Options Outstanding (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>112</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R113.htm</HtmlFileName>
      <LongName>42202 - Disclosure - OTHER NOTES TO THE ACCOUNTS - Related Party Transactions (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosureOtherNotesToAccountsRelatedPartyTransactionsDetails</Role>
      <ShortName>OTHER NOTES TO THE ACCOUNTS - Related Party Transactions (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>113</Position>
    </Report>
    <Report instance="snn-20211231x20f.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R114.htm</HtmlFileName>
      <LongName>42301 - Disclosure - POST BALANCE SHEET EVENTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.smith-nephew.com/role/DisclosurePostBalanceSheetEventsDetails</Role>
      <ShortName>POST BALANCE SHEET EVENTS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.smith-nephew.com/role/DisclosurePostBalanceSheetEvents</ParentRole>
      <Position>114</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File doctype="20-F" original="snn-20211231x20f.htm">snn-20211231x20f.htm</File>
    <File>snn-20211231.xsd</File>
    <File>snn-20211231_cal.xml</File>
    <File>snn-20211231_def.xml</File>
    <File>snn-20211231_lab.xml</File>
    <File>snn-20211231_pre.xml</File>
    <File>snn-20211231xex1.htm</File>
    <File>snn-20211231xex12da.htm</File>
    <File>snn-20211231xex12db.htm</File>
    <File>snn-20211231xex13da.htm</File>
    <File>snn-20211231xex15d1.htm</File>
    <File>snn-20211231xex2dd.htm</File>
    <File>snn-20211231xex4dcxxxii.htm</File>
    <File>snn-20211231xex4dcxxxiii.htm</File>
    <File>snn-20211231xex4dcxxxiv.htm</File>
    <File>snn-20211231xex4dcxxxv.htm</File>
    <File>snn-20211231xex8.htm</File>
  </InputFiles>
  <SupplementalFiles>
    <File>snn-20211231x20f008.jpg</File>
    <File>snn-20211231x20f011.jpg</File>
    <File>snn-20211231x20f013.jpg</File>
    <File>snn-20211231x20f020.jpg</File>
    <File>snn-20211231x20f031.jpg</File>
    <File>snn-20211231x20f037.jpg</File>
    <File>snn-20211231x20f038.jpg</File>
    <File>snn-20211231x20f042.jpg</File>
    <File>snn-20211231x20f050.jpg</File>
    <File>snn-20211231x20f053.jpg</File>
    <File>snn-20211231x20f055.jpg</File>
    <File>snn-20211231x20f058.jpg</File>
    <File>snn-20211231x20f060.jpg</File>
    <File>snn-20211231x20f061.jpg</File>
    <File>snn-20211231x20f062.jpg</File>
    <File>snn-20211231x20f063.jpg</File>
    <File>snn-20211231x20f067.jpg</File>
    <File>snn-20211231x20f071.jpg</File>
    <File>snn-20211231x20f075.jpg</File>
    <File>snn-20211231x20f076.gif</File>
    <File>snn-20211231x20f078.jpg</File>
    <File>snn-20211231x20f083.jpg</File>
    <File>snn-20211231x20f085.jpg</File>
    <File>snn-20211231x20f094.jpg</File>
    <File>snn-20211231x20f096.jpg</File>
    <File>snn-20211231x20f099.jpg</File>
    <File>snn-20211231x20f103.jpg</File>
    <File>snn-20211231x20f106.jpg</File>
    <File>snn-20211231x20f109.jpg</File>
    <File>snn-20211231x20f112.jpg</File>
    <File>snn-20211231x20f116.jpg</File>
    <File>snn-20211231x20f121.jpg</File>
    <File>snn-20211231x20f127.jpg</File>
    <File>snn-20211231x20f131.jpg</File>
    <File>snn-20211231x20f133.jpg</File>
    <File>snn-20211231x20f136.jpg</File>
    <File>snn-20211231x20f138.jpg</File>
    <File>snn-20211231x20f146.jpg</File>
    <File>snn-20211231x20f149.jpg</File>
    <File>snn-20211231x20f153.jpg</File>
    <File>snn-20211231x20f160.jpg</File>
    <File>snn-20211231x20f162.jpg</File>
    <File>snn-20211231x20f165.jpg</File>
    <File>snn-20211231x20f170.jpg</File>
    <File>snn-20211231x20f171.jpg</File>
    <File>snn-20211231x20f176.jpg</File>
    <File>snn-20211231x20f180.jpg</File>
    <File>snn-20211231x20f181.jpg</File>
    <File>snn-20211231x20f184.jpg</File>
    <File>snn-20211231x20f190.jpg</File>
    <File>snn-20211231x20f191.jpg</File>
    <File>snn-20211231x20f194.jpg</File>
    <File>snn-20211231x20f200.jpg</File>
    <File>snn-20211231x20f201.jpg</File>
    <File>snn-20211231x20f204.jpg</File>
    <File>snn-20211231x20f210.jpg</File>
    <File>snn-20211231x20f212.jpg</File>
    <File>snn-20211231x20f219.jpg</File>
    <File>snn-20211231x20f222.jpg</File>
    <File>snn-20211231x20f224.jpg</File>
    <File>snn-20211231x20f225.gif</File>
    <File>snn-20211231x20f226.gif</File>
    <File>snn-20211231x20f227.gif</File>
    <File>snn-20211231x20f228.gif</File>
    <File>snn-20211231x20f229.gif</File>
    <File>snn-20211231x20f237.jpg</File>
    <File>snn-20211231x20f244.jpg</File>
    <File>snn-20211231x20f246.jpg</File>
    <File>snn-20211231x20f248.jpg</File>
    <File>snn-20211231x20f249.gif</File>
    <File>snn-20211231x20f250.jpg</File>
    <File>snn-20211231x20f256.jpg</File>
    <File>snn-20211231x20f257.jpg</File>
    <File>snn-20211231x20f258.jpg</File>
    <File>snn-20211231x20f271.jpg</File>
    <File>snn-20211231x20f272.gif</File>
    <File>snn-20211231x20f273.gif</File>
    <File>snn-20211231x20f274.gif</File>
    <File>snn-20211231x20f275.gif</File>
    <File>snn-20211231x20f276.gif</File>
    <File>snn-20211231x20f277.jpg</File>
    <File>snn-20211231x20f279.gif</File>
    <File>snn-20211231x20f281.gif</File>
    <File>snn-20211231x20f282.gif</File>
    <File>snn-20211231x20f285.gif</File>
    <File>snn-20211231x20f287.gif</File>
    <File>snn-20211231x20f291.gif</File>
    <File>snn-20211231x20f293.gif</File>
    <File>snn-20211231x20f295.gif</File>
    <File>snn-20211231x20f299.jpg</File>
    <File>snn-20211231x20f306.gif</File>
    <File>snn-20211231x20f309.jpg</File>
    <File>snn-20211231x20f311.jpg</File>
    <File>snn-20211231x20f314.jpg</File>
    <File>snn-20211231x20f315.gif</File>
    <File>snn-20211231x20f316.jpg</File>
    <File>snn-20211231x20f317.jpg</File>
    <File>snn-20211231x20f318.jpg</File>
    <File>snn-20211231x20f319.jpg</File>
    <File>snn-20211231x20f320.gif</File>
    <File>snn-20211231x20f321.jpg</File>
    <File>snn-20211231x20f322.gif</File>
    <File>snn-20211231x20f323.gif</File>
    <File>snn-20211231x20f324.jpg</File>
    <File>snn-20211231x20f325.jpg</File>
    <File>snn-20211231x20f326.jpg</File>
    <File>snn-20211231x20f327.jpg</File>
    <File>snn-20211231x20f328.jpg</File>
    <File>snn-20211231x20f329.jpg</File>
    <File>snn-20211231x20f330.jpg</File>
    <File>snn-20211231x20f331.jpg</File>
    <File>snn-20211231x20f332.jpg</File>
    <File>snn-20211231x20f333.jpg</File>
    <File>snn-20211231x20f334.jpg</File>
    <File>snn-20211231x20f335.jpg</File>
    <File>snn-20211231x20f336.jpg</File>
    <File>snn-20211231x20f337.jpg</File>
    <File>snn-20211231x20f338.gif</File>
    <File>snn-20211231x20f340.gif</File>
    <File>snn-20211231x20f341.jpg</File>
    <File>snn-20211231x20f342.jpg</File>
    <File>snn-20211231x20f343.jpg</File>
    <File>snn-20211231x20f344.jpg</File>
    <File>snn-20211231x20f347.jpg</File>
    <File>snn-20211231x20f348.jpg</File>
    <File>snn-20211231x20f351.jpg</File>
    <File>snn-20211231x20f352.jpg</File>
    <File>snn-20211231x20f354.jpg</File>
    <File>snn-20211231x20f355.jpg</File>
    <File>snn-20211231x20f356.jpg</File>
    <File>snn-20211231x20f357.jpg</File>
    <File>snn-20211231x20f358.jpg</File>
    <File>snn-20211231x20f359.jpg</File>
    <File>snn-20211231x20f360.jpg</File>
    <File>snn-20211231x20f361.jpg</File>
    <File>snn-20211231x20f362.jpg</File>
    <File>snn-20211231x20f363.jpg</File>
    <File>snn-20211231x20f364.jpg</File>
    <File>snn-20211231x20f367.jpg</File>
    <File>snn-20211231x20f368.jpg</File>
    <File>snn-20211231x20f369.jpg</File>
    <File>snn-20211231x20f370.jpg</File>
    <File>snn-20211231x20f373.jpg</File>
    <File>snn-20211231x20f377.jpg</File>
    <File>snn-20211231x20f380.jpg</File>
    <File>snn-20211231x20f385.jpg</File>
    <File>snn-20211231x20f386.gif</File>
    <File>snn-20211231x20f387.gif</File>
    <File>snn-20211231x20f390.jpg</File>
    <File>snn-20211231x20f391.jpg</File>
    <File>snn-20211231x20f392.gif</File>
    <File>snn-20211231x20f395.jpg</File>
    <File>snn-20211231x20f397.jpg</File>
    <File>snn-20211231x20f399.jpg</File>
    <File>snn-20211231x20f401.jpg</File>
    <File>snn-20211231x20f402.jpg</File>
    <File>snn-20211231x20f404.jpg</File>
    <File>snn-20211231x20f406.jpg</File>
    <File>snn-20211231x20f407.gif</File>
    <File>snn-20211231x20f409.jpg</File>
    <File>snn-20211231x20f411.jpg</File>
    <File>snn-20211231x20f412.gif</File>
    <File>snn-20211231x20f414.jpg</File>
    <File>snn-20211231x20f415.jpg</File>
    <File>snn-20211231x20f416.jpg</File>
    <File>snn-20211231x20f417.jpg</File>
    <File>snn-20211231x20f420.jpg</File>
    <File>snn-20211231x20f421.jpg</File>
    <File>snn-20211231x20f422.jpg</File>
    <File>snn-20211231x20f423.jpg</File>
    <File>snn-20211231x20f424.jpg</File>
    <File>snn-20211231x20f426.jpg</File>
    <File>snn-20211231x20f427.jpg</File>
    <File>snn-20211231x20f428.jpg</File>
    <File>snn-20211231x20f431.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy items="1976">http://xbrl.ifrs.org/taxonomy/2021-03-24/ifrs-full</BaseTaxonomy>
    <BaseTaxonomy items="46">http://xbrl.sec.gov/dei/2021q4</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
