3.26.1 html 204 283 1 false 76 0 false 6 false false R1.htm 0000001 - Document - Cover Sheet http://www.omnicomgroup.com/role/Cover Cover Cover 1 false false R2.htm 9952151 - Statement - Consolidated Balance Sheets Sheet http://www.omnicomgroup.com/role/ConsolidatedBalanceSheets Consolidated Balance Sheets Statements 2 false false R3.htm 9952152 - Statement - Consolidated Balance Sheets (Parenthetical) Sheet http://www.omnicomgroup.com/role/ConsolidatedBalanceSheetsParenthetical Consolidated Balance Sheets (Parenthetical) Statements 3 false false R4.htm 9952153 - Statement - Consolidated Statements of Income Sheet http://www.omnicomgroup.com/role/ConsolidatedStatementsofIncome Consolidated Statements of Income Statements 4 false false R5.htm 9952154 - Statement - Consolidated Statements of Comprehensive Income Sheet http://www.omnicomgroup.com/role/ConsolidatedStatementsofComprehensiveIncome Consolidated Statements of Comprehensive Income Statements 5 false false R6.htm 9952155 - Statement - Consolidated Statements of Equity Sheet http://www.omnicomgroup.com/role/ConsolidatedStatementsofEquity Consolidated Statements of Equity Statements 6 false false R7.htm 9952156 - Statement - Consolidated Statements of Cash Flows Sheet http://www.omnicomgroup.com/role/ConsolidatedStatementsofCashFlows Consolidated Statements of Cash Flows Statements 7 false false R8.htm 9952157 - Disclosure - Presentation of Financial Statements Sheet http://www.omnicomgroup.com/role/PresentationofFinancialStatements Presentation of Financial Statements Notes 8 false false R9.htm 9952158 - Disclosure - Revenue Sheet http://www.omnicomgroup.com/role/Revenue Revenue Notes 9 false false R10.htm 9952159 - Disclosure - Net Income per Share Sheet http://www.omnicomgroup.com/role/NetIncomeperShare Net Income per Share Notes 10 false false R11.htm 9952160 - Disclosure - Goodwill and Intangible Assets Sheet http://www.omnicomgroup.com/role/GoodwillandIntangibleAssets Goodwill and Intangible Assets Notes 11 false false R12.htm 9952161 - Disclosure - Business Combinations Sheet http://www.omnicomgroup.com/role/BusinessCombinations Business Combinations Notes 12 false false R13.htm 9952162 - Disclosure - Debt Sheet http://www.omnicomgroup.com/role/Debt Debt Notes 13 false false R14.htm 9952163 - Disclosure - Segment Reporting Sheet http://www.omnicomgroup.com/role/SegmentReporting Segment Reporting Notes 14 false false R15.htm 9952164 - Disclosure - Income Taxes Sheet http://www.omnicomgroup.com/role/IncomeTaxes Income Taxes Notes 15 false false R16.htm 9952165 - Disclosure - Pension and Other Postemployment Benefits Sheet http://www.omnicomgroup.com/role/PensionandOtherPostemploymentBenefits Pension and Other Postemployment Benefits Notes 16 false false R17.htm 9952166 - Disclosure - Severance and Repositioning Costs Sheet http://www.omnicomgroup.com/role/SeveranceandRepositioningCosts Severance and Repositioning Costs Notes 17 false false R18.htm 9952167 - Disclosure - Loss on Assets Held for Sale or Dispositions of Subsidiaries Sheet http://www.omnicomgroup.com/role/LossonAssetsHeldforSaleorDispositionsofSubsidiaries Loss on Assets Held for Sale or Dispositions of Subsidiaries Notes 18 false false R19.htm 9952168 - Disclosure - Supplemental Cash Flow Data Sheet http://www.omnicomgroup.com/role/SupplementalCashFlowData Supplemental Cash Flow Data Notes 19 false false R20.htm 9952169 - Disclosure - Commitments and Contingent Liabilities Sheet http://www.omnicomgroup.com/role/CommitmentsandContingentLiabilities Commitments and Contingent Liabilities Notes 20 false false R21.htm 9952170 - Disclosure - Accumulated Other Comprehensive Income (Loss) Sheet http://www.omnicomgroup.com/role/AccumulatedOtherComprehensiveIncomeLoss Accumulated Other Comprehensive Income (Loss) Notes 21 false false R22.htm 9952171 - Disclosure - Fair Value Sheet http://www.omnicomgroup.com/role/FairValue Fair Value Notes 22 false false R23.htm 9952172 - Disclosure - Accelerated Share Repurchase Sheet http://www.omnicomgroup.com/role/AcceleratedShareRepurchase Accelerated Share Repurchase Notes 23 false false R24.htm 9952173 - Disclosure - Subsequent Events Sheet http://www.omnicomgroup.com/role/SubsequentEvents Subsequent Events Notes 24 false false R25.htm 9955511 - Disclosure - Revenue (Tables) Sheet http://www.omnicomgroup.com/role/RevenueTables Revenue (Tables) Tables http://www.omnicomgroup.com/role/Revenue 25 false false R26.htm 9955512 - Disclosure - Net Income per Share (Tables) Sheet http://www.omnicomgroup.com/role/NetIncomeperShareTables Net Income per Share (Tables) Tables http://www.omnicomgroup.com/role/NetIncomeperShare 26 false false R27.htm 9955513 - Disclosure - Goodwill and Intangible Assets (Tables) Sheet http://www.omnicomgroup.com/role/GoodwillandIntangibleAssetsTables Goodwill and Intangible Assets (Tables) Tables http://www.omnicomgroup.com/role/GoodwillandIntangibleAssets 27 false false R28.htm 9955514 - Disclosure - Business Combinations (Tables) Sheet http://www.omnicomgroup.com/role/BusinessCombinationsTables Business Combinations (Tables) Tables http://www.omnicomgroup.com/role/BusinessCombinations 28 false false R29.htm 9955515 - Disclosure - Debt (Tables) Sheet http://www.omnicomgroup.com/role/DebtTables Debt (Tables) Tables http://www.omnicomgroup.com/role/Debt 29 false false R30.htm 9955516 - Disclosure - Segment Reporting (Tables) Sheet http://www.omnicomgroup.com/role/SegmentReportingTables Segment Reporting (Tables) Tables http://www.omnicomgroup.com/role/SegmentReporting 30 false false R31.htm 9955517 - Disclosure - Pension and Other Postemployment Benefits (Tables) Sheet http://www.omnicomgroup.com/role/PensionandOtherPostemploymentBenefitsTables Pension and Other Postemployment Benefits (Tables) Tables http://www.omnicomgroup.com/role/PensionandOtherPostemploymentBenefits 31 false false R32.htm 9955518 - Disclosure - Severance and Repositioning Costs (Tables) Sheet http://www.omnicomgroup.com/role/SeveranceandRepositioningCostsTables Severance and Repositioning Costs (Tables) Tables http://www.omnicomgroup.com/role/SeveranceandRepositioningCosts 32 false false R33.htm 9955519 - Disclosure - Loss on Assets Held for Sale or Dispositions of Subsidiaries (Tables) Sheet http://www.omnicomgroup.com/role/LossonAssetsHeldforSaleorDispositionsofSubsidiariesTables Loss on Assets Held for Sale or Dispositions of Subsidiaries (Tables) Tables http://www.omnicomgroup.com/role/LossonAssetsHeldforSaleorDispositionsofSubsidiaries 33 false false R34.htm 9955520 - Disclosure - Supplemental Cash Flow Data (Tables) Sheet http://www.omnicomgroup.com/role/SupplementalCashFlowDataTables Supplemental Cash Flow Data (Tables) Tables http://www.omnicomgroup.com/role/SupplementalCashFlowData 34 false false R35.htm 9955521 - Disclosure - Accumulated Other Comprehensive Income (Loss) (Tables) Sheet http://www.omnicomgroup.com/role/AccumulatedOtherComprehensiveIncomeLossTables Accumulated Other Comprehensive Income (Loss) (Tables) Tables http://www.omnicomgroup.com/role/AccumulatedOtherComprehensiveIncomeLoss 35 false false R36.htm 9955522 - Disclosure - Fair Value (Tables) Sheet http://www.omnicomgroup.com/role/FairValueTables Fair Value (Tables) Tables http://www.omnicomgroup.com/role/FairValue 36 false false R37.htm 9955524 - Disclosure - Presentation of Financial Statements (Details) Sheet http://www.omnicomgroup.com/role/PresentationofFinancialStatementsDetails Presentation of Financial Statements (Details) Details http://www.omnicomgroup.com/role/PresentationofFinancialStatements 37 false false R38.htm 9955525 - Disclosure - Revenue (Details) Sheet http://www.omnicomgroup.com/role/RevenueDetails Revenue (Details) Details http://www.omnicomgroup.com/role/RevenueTables 38 false false R39.htm 9955526 - Disclosure - Net Income per Share (Details) Sheet http://www.omnicomgroup.com/role/NetIncomeperShareDetails Net Income per Share (Details) Details http://www.omnicomgroup.com/role/NetIncomeperShareTables 39 false false R40.htm 9955527 - Disclosure - Goodwill and Intangible Assets (Details) Sheet http://www.omnicomgroup.com/role/GoodwillandIntangibleAssetsDetails Goodwill and Intangible Assets (Details) Details http://www.omnicomgroup.com/role/GoodwillandIntangibleAssetsTables 40 false false R41.htm 9955528 - Disclosure - Business Combinations (Details) Sheet http://www.omnicomgroup.com/role/BusinessCombinationsDetails Business Combinations (Details) Details http://www.omnicomgroup.com/role/BusinessCombinationsTables 41 false false R42.htm 9955529 - Disclosure - Debt (Details) Sheet http://www.omnicomgroup.com/role/DebtDetails Debt (Details) Details http://www.omnicomgroup.com/role/DebtTables 42 false false R43.htm 9955530 - Disclosure - Segment Reporting (Details) Sheet http://www.omnicomgroup.com/role/SegmentReportingDetails Segment Reporting (Details) Details http://www.omnicomgroup.com/role/SegmentReportingTables 43 false false R44.htm 9955531 - Disclosure - Segment Reporting - Geographical (Details) Sheet http://www.omnicomgroup.com/role/SegmentReportingGeographicalDetails Segment Reporting - Geographical (Details) Details 44 false false R45.htm 9955532 - Disclosure - Income Taxes (Details) Sheet http://www.omnicomgroup.com/role/IncomeTaxesDetails Income Taxes (Details) Details http://www.omnicomgroup.com/role/IncomeTaxes 45 false false R46.htm 9955533 - Disclosure - Pension and Other Postemployment Benefits (Details) Sheet http://www.omnicomgroup.com/role/PensionandOtherPostemploymentBenefitsDetails Pension and Other Postemployment Benefits (Details) Details http://www.omnicomgroup.com/role/PensionandOtherPostemploymentBenefitsTables 46 false false R47.htm 9955534 - Disclosure - Severance and Repositioning Costs (Details) Sheet http://www.omnicomgroup.com/role/SeveranceandRepositioningCostsDetails Severance and Repositioning Costs (Details) Details http://www.omnicomgroup.com/role/SeveranceandRepositioningCostsTables 47 false false R48.htm 9955535 - Disclosure - Loss on Assets Held for Sale or Dispositions of Subsidiaries (Details) Sheet http://www.omnicomgroup.com/role/LossonAssetsHeldforSaleorDispositionsofSubsidiariesDetails Loss on Assets Held for Sale or Dispositions of Subsidiaries (Details) Details http://www.omnicomgroup.com/role/LossonAssetsHeldforSaleorDispositionsofSubsidiariesTables 48 false false R49.htm 9955536 - Disclosure - Supplemental Cash Flow Data (Details) Sheet http://www.omnicomgroup.com/role/SupplementalCashFlowDataDetails Supplemental Cash Flow Data (Details) Details http://www.omnicomgroup.com/role/SupplementalCashFlowDataTables 49 false false R50.htm 9955537 - Disclosure - Accumulated Other Comprehensive Income (Loss) (Details) Sheet http://www.omnicomgroup.com/role/AccumulatedOtherComprehensiveIncomeLossDetails Accumulated Other Comprehensive Income (Loss) (Details) Details http://www.omnicomgroup.com/role/AccumulatedOtherComprehensiveIncomeLossTables 50 false false R51.htm 9955538 - Disclosure - Fair Value (Details) Sheet http://www.omnicomgroup.com/role/FairValueDetails Fair Value (Details) Details http://www.omnicomgroup.com/role/FairValueTables 51 false false R52.htm 9955539 - Disclosure - Accelerated Share Repurchase (Details) Sheet http://www.omnicomgroup.com/role/AcceleratedShareRepurchaseDetails Accelerated Share Repurchase (Details) Details http://www.omnicomgroup.com/role/AcceleratedShareRepurchase 52 false false All Reports Book All Reports omc-20260331.htm omc-20260331.xsd omc-20260331_cal.xml omc-20260331_def.xml omc-20260331_lab.xml omc-20260331_pre.xml omc-20260331_g1.jpg http://fasb.org/srt/2026 http://fasb.org/us-gaap/2026 http://xbrl.sec.gov/dei/2026 true true