$MMC
MARSH & MCLENNAN COMPANIES, INC. Stock $mmc

$mmc Overview Financials Valuation SEC Filings Company Website

2024 Q1 Form 10-K Financial Statement

#000006270924000016 Filed on February 12, 2024

Income Statement

Concept	2024 Q1	2023 Q4	2023
Revenue	$6.473B	$5.554B	$22.74B
YoY Change	9.27%	10.59%	9.73%
Cost Of Revenue
YoY Change
Gross Profit
YoY Change
Gross Profit Margin
Selling, General & Admin	$3.470B	$3.268B	$13.10B
YoY Change	8.2%	7.57%	8.52%
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$189.0M	$443.0M	$713.0M
YoY Change	125.0%	-3.7%	-0.83%
% of Gross Profit
Operating Expenses	$4.506B	$4.451B	$17.45B
YoY Change	7.34%	2.51%	6.17%
Operating Profit	$1.925B		$5.282B
YoY Change	11.53%		23.41%
Interest Expense	-$121.0M	-$112.0M	-$495.0M
YoY Change	-188.97%	-9.68%	14.32%
% of Operating Profit	-6.29%		-9.37%
Other Income/Expense, Net	$67.00M	$57.00M	$239.0M
YoY Change	15.52%	0.0%	1.7%
Pretax Income	$1.871B	$1.048B	$5.026B
YoY Change	12.44%	70.96%	23.13%
Income Tax	$447.0M	$283.0M	$1.224B
% Of Pretax Income	23.89%	27.0%	24.35%
Net Earnings	$1.400B	$756.0M	$3.756B
YoY Change	13.36%	62.23%	23.15%
Net Earnings / Revenue	21.63%	13.61%	16.52%
Basic Earnings Per Share	$2.84		$7.60
Diluted Earnings Per Share	$2.82	$1.52	$7.53
COMMON SHARES
Basic Shares Outstanding	491.7M shares	493.1M shares	494.0M shares
Diluted Shares Outstanding	497.0M shares		499.0M shares

Balance Sheet

Concept	2024 Q1	2023 Q4	2023
SHORT-TERM ASSETS
Cash & Short-Term Investments	$1.452B	$3.358B	$3.358B
YoY Change	44.33%	132.87%	132.87%
Cash & Equivalents	$1.452B	$3.358B	$3.358B
Short-Term Investments
Other Short-Term Assets	$12.24B	$11.97B	$11.97B
YoY Change	770.08%	1091.24%	1091.24%
Inventory
Prepaid Expenses
Receivables	$7.605B	$6.418B	$6.418B
Other Receivables	$0.00	$0.00	$0.00
Total Short-Term Assets	$21.30B	$21.75B	$21.75B
YoY Change	133.72%	162.06%	162.06%
LONG-TERM ASSETS
Property, Plant & Equipment	$2.371B	$2.423B	$2.423B
YoY Change	173.47%	-0.41%	-0.41%
Goodwill	$17.31B	$17.23B
YoY Change	6.22%	6.03%
Intangibles
YoY Change
Long-Term Investments	$272.0M	$266.0M	$266.0M
YoY Change	27.1%	23.72%	23.72%
Other Assets	$3.685B	$3.998B	$3.998B
YoY Change	150.51%	1.63%	1.63%
Total Long-Term Assets	$26.27B	$26.28B	$26.28B
YoY Change	4.07%	4.48%	4.48%
TOTAL ASSETS
Total Short-Term Assets	$21.30B	$21.75B	$21.75B
Total Long-Term Assets	$26.27B	$26.28B	$26.28B
Total Assets	$47.57B	$48.03B	$48.03B
YoY Change	38.46%	43.57%	43.57%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$3.379B	$3.403B	$3.403B
YoY Change	-0.79%	3.81%	3.81%
Accrued Expenses	$1.849B	$3.658B	$3.658B
YoY Change	5.72%	7.43%	7.43%
Deferred Revenue
YoY Change
Short-Term Debt	$50.00M	$0.00	$0.00
YoY Change	-94.08%	-100.0%
Long-Term Debt Due	$1.119B	$1.619B	$1.619B
YoY Change	-11.68%	504.1%	504.1%
Total Short-Term Liabilities	$18.66B	$19.80B	$19.80B
YoY Change	135.78%	176.0%	176.0%
LONG-TERM LIABILITIES
Long-Term Debt	$12.30B	$11.84B	$11.84B
YoY Change	13.46%	5.5%	5.5%
Other Long-Term Liabilities	$3.990B	$4.021B	$4.021B
YoY Change	178.44%	-6.62%	-6.62%
Total Long-Term Liabilities	$16.29B	$15.87B	$15.87B
YoY Change	32.72%	2.14%	2.14%
TOTAL LIABILITIES
Total Short-Term Liabilities	$18.66B	$19.80B	$19.80B
Total Long-Term Liabilities	$16.29B	$15.87B	$15.87B
Total Liabilities	$35.15B	$35.66B	$35.66B
YoY Change	74.11%	57.06%	57.06%
SHAREHOLDERS EQUITY
Retained Earnings	$23.46B	$22.76B
YoY Change	11.97%	12.11%
Common Stock	$1.673B	$1.803B
YoY Change	2.95%	3.62%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$12.42B	$12.37B	$12.37B
YoY Change
Total Liabilities & Shareholders Equity	$47.57B	$48.03B	$48.03B
YoY Change	38.46%	43.57%	43.57%

Cashflow Statement

Concept	2024 Q1	2023 Q4	2023
OPERATING ACTIVITIES
Net Income	$1.400B	$756.0M	$3.756B
YoY Change	13.36%	62.23%	23.15%
Depreciation, Depletion And Amortization	$189.0M	$443.0M	$713.0M
YoY Change	125.0%	-3.7%	-0.83%
Cash From Operating Activities	-$781.0M	$1.783B	$4.258B
YoY Change	-4.64%	18.71%	22.89%
INVESTING ACTIVITIES
Capital Expenditures	$87.00M	$119.0M	$433.0M
YoY Change	3.57%	-215.53%	-192.13%
Acquisitions			-$976.0M
YoY Change			-270.63%
Other Investing Activities	-$281.0M	-$355.0M	-$984.0M
YoY Change	9266.67%	-7.55%	158.95%
Cash From Investing Activities	-$368.0M	-$474.0M	-$1.417B
YoY Change	0.0%	-2.67%	66.71%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net			-$1.099B
YoY Change			-45.65%
Debt Paid & Issued, Net	$1.004B		$266.0M
YoY Change	25000.0%		-27.12%
Cash From Financing Activities	135.0M	-2.334B	-1.119B
YoY Change	-82.54%	117.32%	6.98%
NET CHANGE
Cash From Operating Activities	-781.0M	1.783B	4.258B
Cash From Investing Activities	-368.0M	-474.0M	-1.417B
Cash From Financing Activities	135.0M	-2.334B	-1.119B
Net Change In Cash	-1.014B	-1.025B	1.722B
YoY Change	287.02%	1637.29%	9.75%
FREE CASH FLOW
Cash From Operating Activities	-$781.0M	$1.783B	$4.258B
Capital Expenditures	$87.00M	$119.0M	$433.0M
Free Cash Flow	-$868.0M	$1.664B	$3.825B
YoY Change	-3.88%	3.68%	-2.8%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2022	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	1950000000	usd
CY2021	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	1159000000	usd
CY2021	mmc	Proceeds From Issuance Of Commercial Paper With Maturity Greater Than90 Days ProceedsFromIssuanceOfCommercialPaperWithMaturityGreaterThan90Days	0	usd
CY2022	mmc	Repayments Of Commercial Paper With Maturity Greater Than90 Days RepaymentsOfCommercialPaperWithMaturityGreaterThan90Days	0	usd
CY2021	mmc	Repayments Of Commercial Paper With Maturity Greater Than90 Days RepaymentsOfCommercialPaperWithMaturityGreaterThan90Days	0	usd
CY2023	dei	Entity Central Index Key EntityCentralIndexKey	0000062709
CY2023	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2023
CY2023	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2023	dei	Amendment Flag AmendmentFlag	false
CY2023Q4	us-gaap	Revenue Remaining Performance Obligation Expected Timing Of Satisfaction Period1 RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1	P1Y
CY2023Q4	us-gaap	Revenue Remaining Performance Obligation Expected Timing Of Satisfaction Period1 RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1	P1Y
CY2023Q4	us-gaap	Revenue Remaining Performance Obligation Expected Timing Of Satisfaction Period1 RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1	P1Y
CY2023Q4	us-gaap	Revenue Remaining Performance Obligation Expected Timing Of Satisfaction Period1 RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1	P1Y
CY2023Q4	us-gaap	Revenue Remaining Performance Obligation Expected Timing Of Satisfaction Period1 RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1
CY2022	us-gaap	Disposal Group Not Discontinued Operation Gain Loss On Disposal Statement Of Income Extensible List DisposalGroupNotDiscontinuedOperationGainLossOnDisposalStatementOfIncomeExtensibleList	http://fasb.org/us-gaap/2023#RevenueFromContractWithCustomerIncludingAssessedTax
CY2023	dei	Document Annual Report DocumentAnnualReport	true
CY2023	dei	Document Period End Date DocumentPeriodEndDate	2023-12-31
CY2023	dei	Document Period End Date DocumentPeriodEndDate	2023-12-31
CY2023	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2023	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2023	dei	Document Transition Report DocumentTransitionReport	false
CY2023	dei	Entity File Number EntityFileNumber	1-5998
CY2023	dei	Entity Registrant Name EntityRegistrantName	Marsh & McLennan Companies, Inc.
CY2023	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	DE
CY2023	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	36-2668272
CY2023	dei	Entity Address Address Line1 EntityAddressAddressLine1	1166 Avenue of the Americas
CY2023	dei	Entity Address City Or Town EntityAddressCityOrTown	New York
CY2023	dei	Entity Address State Or Province EntityAddressStateOrProvince	NY
CY2023	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	10036
CY2023	dei	City Area Code CityAreaCode	212
CY2023	dei	Local Phone Number LocalPhoneNumber	345-5000
CY2023	dei	Security12b Title Security12bTitle	Common Stock, par value $1.00 per share
CY2023	dei	Trading Symbol TradingSymbol	MMC
CY2023	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
CY2023	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2023	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2023	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
CY2023	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2023	dei	Entity Small Business EntitySmallBusiness	false
CY2023	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
CY2023	dei	Entity Shell Company EntityShellCompany	false
CY2023	dei	Icfr Auditor Attestation Flag IcfrAuditorAttestationFlag	true
CY2023	dei	Document Fin Stmt Error Correction Flag DocumentFinStmtErrorCorrectionFlag	false
CY2023Q2	dei	Entity Public Float EntityPublicFloat	92849878606	usd
CY2024Q1	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	491656196	shares
CY2023	dei	Auditor Name AuditorName	Deloitte & Touche LLP
CY2023	dei	Auditor Location AuditorLocation	New York, New York
CY2023	dei	Auditor Firm AuditorFirmId	34
CY2023	us-gaap	Revenue From Contract With Customer Including Assessed Tax RevenueFromContractWithCustomerIncludingAssessedTax	22736000000	usd
CY2022	us-gaap	Revenue From Contract With Customer Including Assessed Tax RevenueFromContractWithCustomerIncludingAssessedTax	20720000000	usd
CY2021	us-gaap	Revenue From Contract With Customer Including Assessed Tax RevenueFromContractWithCustomerIncludingAssessedTax	19820000000	usd
CY2023	us-gaap	Labor And Related Expense LaborAndRelatedExpense	13099000000	usd
CY2022	us-gaap	Labor And Related Expense LaborAndRelatedExpense	12071000000	usd
CY2021	us-gaap	Labor And Related Expense LaborAndRelatedExpense	11425000000	usd
CY2023	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	4355000000	usd
CY2022	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	4369000000	usd
CY2021	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	4083000000	usd
CY2023	us-gaap	Operating Expenses OperatingExpenses	17454000000	usd
CY2022	us-gaap	Operating Expenses OperatingExpenses	16440000000	usd
CY2021	us-gaap	Operating Expenses OperatingExpenses	15508000000	usd
CY2023	us-gaap	Operating Income Loss OperatingIncomeLoss	5282000000	usd
CY2022	us-gaap	Operating Income Loss OperatingIncomeLoss	4280000000	usd
CY2021	us-gaap	Operating Income Loss OperatingIncomeLoss	4312000000	usd
CY2023	us-gaap	Defined Benefit Plan Other Costs DefinedBenefitPlanOtherCosts	-239000000	usd
CY2022	us-gaap	Defined Benefit Plan Other Costs DefinedBenefitPlanOtherCosts	-235000000	usd
CY2021	us-gaap	Defined Benefit Plan Other Costs DefinedBenefitPlanOtherCosts	-277000000	usd
CY2023	us-gaap	Investment Income Interest InvestmentIncomeInterest	78000000	usd
CY2022	us-gaap	Investment Income Interest InvestmentIncomeInterest	15000000	usd
CY2021	us-gaap	Investment Income Interest InvestmentIncomeInterest	2000000	usd
CY2023	us-gaap	Interest Expense InterestExpense	578000000	usd
CY2022	us-gaap	Interest Expense InterestExpense	469000000	usd
CY2021	us-gaap	Interest Expense InterestExpense	444000000	usd
CY2022	us-gaap	Gain Loss On Investments GainLossOnInvestments	21000000	usd
CY2021	us-gaap	Gain Loss On Investments GainLossOnInvestments	61000000	usd
CY2021	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	4208000000	usd
CY2023	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	46000000	usd
CY2023	us-gaap	Net Income Loss NetIncomeLoss	3756000000	usd
CY2022	us-gaap	Net Income Loss NetIncomeLoss	3050000000	usd
CY2023	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	7.60
CY2022	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	6.11
CY2021	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	6.20
CY2023	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	7.53
CY2022	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	6.04
CY2021	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	6.13
CY2023	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	494000000	shares
CY2022	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	499000000	shares
CY2021	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	507000000	shares
CY2023	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	499000000	shares
CY2022	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	505000000	shares
CY2021	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	513000000	shares
CY2023Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	492000000	shares
CY2022Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	495000000	shares
CY2021Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	504000000	shares
CY2023	us-gaap	Profit Loss ProfitLoss	3802000000	usd
CY2022	us-gaap	Profit Loss ProfitLoss	3087000000	usd
CY2021	us-gaap	Profit Loss ProfitLoss	3174000000	usd
CY2023	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Before Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentBeforeTax	389000000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Before Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentBeforeTax	-1198000000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Before Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentBeforeTax	-389000000	usd
CY2023	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	503000000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	-641000000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	-1229000000	usd
CY2023	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	-114000000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	-557000000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	840000000	usd
CY2023	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	-133000000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	182000000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	305000000	usd
CY2023	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	19000000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-739000000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	535000000	usd
CY2023	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	3821000000	usd
CY2022	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	2348000000	usd
CY2021	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	3709000000	usd
CY2023	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	46000000	usd
CY2022	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	37000000	usd
CY2021	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	31000000	usd
CY2023	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	3775000000	usd
CY2022	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	2311000000	usd
CY2021	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	3678000000	usd
CY2023Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	3358000000	usd
CY2022Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	1442000000	usd
CY2023Q4	mmc	Cash And Investments Held In Fiduciary Capacity Current CashAndInvestmentsHeldInFiduciaryCapacityCurrent	10794000000	usd
CY2022Q4	mmc	Cash And Investments Held In Fiduciary Capacity Current CashAndInvestmentsHeldInFiduciaryCapacityCurrent	10660000000	usd
CY2023Q4	mmc	Accrued Feesand Other Revenue Receivable Gross Current AccruedFeesandOtherRevenueReceivableGrossCurrent	5806000000	usd
CY2022Q4	mmc	Accrued Feesand Other Revenue Receivable Gross Current AccruedFeesandOtherRevenueReceivableGrossCurrent	5293000000	usd
CY2023Q4	mmc	Advanced Premiumsand Claims Receivable Gross Current AdvancedPremiumsandClaimsReceivableGrossCurrent	103000000	usd
CY2022Q4	mmc	Advanced Premiumsand Claims Receivable Gross Current AdvancedPremiumsandClaimsReceivableGrossCurrent	103000000	usd
CY2023Q4	us-gaap	Other Receivables Gross Current OtherReceivablesGrossCurrent	660000000	usd
CY2022Q4	us-gaap	Other Receivables Gross Current OtherReceivablesGrossCurrent	616000000	usd
CY2023Q4	us-gaap	Accounts Receivable Gross Current AccountsReceivableGrossCurrent	6569000000	usd
CY2022Q4	us-gaap	Accounts Receivable Gross Current AccountsReceivableGrossCurrent	6012000000	usd
CY2023Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	151000000	usd
CY2022Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	160000000	usd
CY2023Q4	us-gaap	Receivables Net Current ReceivablesNetCurrent	6418000000	usd
CY2022Q4	us-gaap	Receivables Net Current ReceivablesNetCurrent	5852000000	usd
CY2023Q4	us-gaap	Other Assets Current OtherAssetsCurrent	1178000000	usd
CY2022Q4	us-gaap	Other Assets Current OtherAssetsCurrent	1005000000	usd
CY2023Q4	us-gaap	Assets Current AssetsCurrent	21748000000	usd
CY2022Q4	us-gaap	Assets Current AssetsCurrent	18959000000	usd
CY2023Q4	us-gaap	Goodwill Goodwill	17231000000	usd
CY2022Q4	us-gaap	Goodwill Goodwill	16251000000	usd
CY2023Q4	us-gaap	Other Intangible Assets Net OtherIntangibleAssetsNet	2630000000	usd
CY2022Q4	us-gaap	Other Intangible Assets Net OtherIntangibleAssetsNet	2537000000	usd
CY2023Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	882000000	usd
CY2022Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	871000000	usd
CY2023Q4	us-gaap	Defined Benefit Plan Assets For Plan Benefits Noncurrent DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent	2051000000	usd
CY2022Q4	us-gaap	Defined Benefit Plan Assets For Plan Benefits Noncurrent DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent	2127000000	usd
CY2023Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	1541000000	usd
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CY2023Q4	us-gaap	Deferred Income Tax Assets Net DeferredIncomeTaxAssetsNet	357000000	usd
CY2022Q4	us-gaap	Deferred Income Tax Assets Net DeferredIncomeTaxAssetsNet	358000000	usd
CY2023Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	1590000000	usd
CY2022Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	1449000000	usd
CY2023Q4	us-gaap	Assets Assets	48030000000	usd
CY2022Q4	us-gaap	Assets Assets	44114000000	usd
CY2023Q4	us-gaap	Debt Current DebtCurrent	1619000000	usd
CY2022Q4	us-gaap	Debt Current DebtCurrent	268000000	usd
CY2023Q4	us-gaap	Accounts Payable And Accrued Liabilities Current AccountsPayableAndAccruedLiabilitiesCurrent	3403000000	usd
CY2022Q4	us-gaap	Accounts Payable And Accrued Liabilities Current AccountsPayableAndAccruedLiabilitiesCurrent	3278000000	usd
CY2023Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	3346000000	usd
CY2022Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	3095000000	usd
CY2023Q4	us-gaap	Operating Lease Liability Current OperatingLeaseLiabilityCurrent	312000000	usd
CY2022Q4	us-gaap	Operating Lease Liability Current OperatingLeaseLiabilityCurrent	310000000	usd
CY2023Q4	us-gaap	Accrued Income Taxes Current AccruedIncomeTaxesCurrent	321000000	usd
CY2022Q4	us-gaap	Accrued Income Taxes Current AccruedIncomeTaxesCurrent	221000000	usd
CY2023Q4	mmc	Fiduciary Liabilities Current FiduciaryLiabilitiesCurrent	10794000000	usd
CY2022Q4	mmc	Fiduciary Liabilities Current FiduciaryLiabilitiesCurrent	10660000000	usd
CY2023Q4	us-gaap	Liabilities Current LiabilitiesCurrent	19795000000	usd
CY2022Q4	us-gaap	Liabilities Current LiabilitiesCurrent	17832000000	usd
CY2023Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	11844000000	usd
CY2022Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	11227000000	usd
CY2023Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	779000000	usd
CY2022Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	921000000	usd
CY2023Q4	us-gaap	Operating Lease Liability Noncurrent OperatingLeaseLiabilityNoncurrent	1661000000	usd
CY2022Q4	us-gaap	Operating Lease Liability Noncurrent OperatingLeaseLiabilityNoncurrent	1667000000	usd
CY2023Q4	mmc	Liability For Errors And Omissions LiabilityForErrorsAndOmissions	314000000	usd
CY2022Q4	mmc	Liability For Errors And Omissions LiabilityForErrorsAndOmissions	355000000	usd
CY2023Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	1267000000	usd
CY2022Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	1363000000	usd
CY2023Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies	0	usd
CY2022Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies	0	usd
CY2023Q4	us-gaap	Preferred Stock Par Or Stated Value Per Share PreferredStockParOrStatedValuePerShare	1
CY2022Q4	us-gaap	Preferred Stock Par Or Stated Value Per Share PreferredStockParOrStatedValuePerShare	1
CY2022Q4	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	6000000	shares
CY2023Q4	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	6000000	shares
CY2022Q4	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2023Q4	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2023Q4	us-gaap	Preferred Stock Value PreferredStockValue	0	usd
CY2022Q4	us-gaap	Preferred Stock Value PreferredStockValue	0	usd
CY2023Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	1
CY2022Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	1
CY2023Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	1600000000	shares
CY2022Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	1600000000	shares
CY2022Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	560641640	shares
CY2023Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	560641640	shares
CY2023Q4	us-gaap	Common Stock Value CommonStockValue	561000000	usd
CY2022Q4	us-gaap	Common Stock Value CommonStockValue	561000000	usd
CY2023Q4	us-gaap	Additional Paid In Capital Common Stock AdditionalPaidInCapitalCommonStock	1242000000	usd
CY2022Q4	us-gaap	Additional Paid In Capital Common Stock AdditionalPaidInCapitalCommonStock	1179000000	usd
CY2023Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	22759000000	usd
CY2022Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	20301000000	usd
CY2023Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-5295000000	usd
CY2022Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-5314000000	usd
CY2023Q4	us-gaap	Minority Interest MinorityInterest	179000000	usd
CY2022Q4	us-gaap	Minority Interest MinorityInterest	229000000	usd
CY2023Q4	mmc	Stockholders Equity Subtotal Before Treasury Stock StockholdersEquitySubtotalBeforeTreasuryStock	19446000000	usd
CY2022Q4	mmc	Stockholders Equity Subtotal Before Treasury Stock StockholdersEquitySubtotalBeforeTreasuryStock	16956000000	usd
CY2023Q4	us-gaap	Treasury Stock Common Shares TreasuryStockCommonShares	68635498	shares
CY2022Q4	us-gaap	Treasury Stock Common Shares TreasuryStockCommonShares	65855914	shares
CY2023Q4	us-gaap	Treasury Stock Common Value TreasuryStockCommonValue	7076000000	usd
CY2022Q4	us-gaap	Treasury Stock Common Value TreasuryStockCommonValue	6207000000	usd
CY2023Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	12370000000	usd
CY2022Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	10749000000	usd
CY2023Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	48030000000	usd
CY2022Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	44114000000	usd
CY2023	us-gaap	Profit Loss ProfitLoss	3802000000	usd
CY2022	us-gaap	Profit Loss ProfitLoss	3087000000	usd
CY2021	us-gaap	Profit Loss ProfitLoss	3174000000	usd
CY2023	us-gaap	Depreciation Depreciation	370000000	usd
CY2022	us-gaap	Depreciation Depreciation	381000000	usd
CY2021	us-gaap	Depreciation Depreciation	382000000	usd
CY2023	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	343000000	usd
CY2022	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	338000000	usd
CY2021	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	365000000	usd
CY2023	mmc	Leases Right Of Use Asset Amortization LeasesRightOfUseAssetAmortization	288000000	usd
CY2022	mmc	Leases Right Of Use Asset Amortization LeasesRightOfUseAssetAmortization	404000000	usd
CY2021	mmc	Leases Right Of Use Asset Amortization LeasesRightOfUseAssetAmortization	327000000	usd
CY2023	us-gaap	Business Combination Contingent Consideration Arrangements Change In Amount Of Contingent Consideration Liability1 BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1	-11000000	usd
CY2022	us-gaap	Business Combination Contingent Consideration Arrangements Change In Amount Of Contingent Consideration Liability1 BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1	11000000	usd
CY2021	us-gaap	Business Combination Contingent Consideration Arrangements Change In Amount Of Contingent Consideration Liability1 BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1	27000000	usd
CY2023	us-gaap	Deconsolidation Gain Or Loss Amount DeconsolidationGainOrLossAmount	0	usd
CY2022	us-gaap	Deconsolidation Gain Or Loss Amount DeconsolidationGainOrLossAmount	-39000000	usd
CY2021	us-gaap	Deconsolidation Gain Or Loss Amount DeconsolidationGainOrLossAmount	0	usd
CY2023	mmc	Consolidation Gain Loss Amount ConsolidationGainLossAmount	0	usd
CY2022	mmc	Consolidation Gain Loss Amount ConsolidationGainLossAmount	2000000	usd
CY2021	mmc	Consolidation Gain Loss Amount ConsolidationGainLossAmount	267000000	usd
CY2023	us-gaap	Gain Loss On Investments GainLossOnInvestments	5000000	usd
CY2022	us-gaap	Gain Loss On Investments GainLossOnInvestments	21000000	usd
CY2021	us-gaap	Gain Loss On Investments GainLossOnInvestments	61000000	usd
CY2023	us-gaap	Gain Loss On Sale Of Other Assets GainLossOnSaleOfOtherAssets	-16000000	usd
CY2022	us-gaap	Gain Loss On Sale Of Other Assets GainLossOnSaleOfOtherAssets	127000000	usd
CY2021	us-gaap	Gain Loss On Sale Of Other Assets GainLossOnSaleOfOtherAssets	33000000	usd
CY2023	us-gaap	Share Based Compensation ShareBasedCompensation	363000000	usd
CY2022	us-gaap	Share Based Compensation ShareBasedCompensation	367000000	usd
CY2021	us-gaap	Share Based Compensation ShareBasedCompensation	348000000	usd
CY2023	us-gaap	Increase Decrease In Receivables IncreaseDecreaseInReceivables	467000000	usd
CY2022	us-gaap	Increase Decrease In Receivables IncreaseDecreaseInReceivables	492000000	usd
CY2021	us-gaap	Increase Decrease In Receivables IncreaseDecreaseInReceivables	570000000	usd
CY2023	us-gaap	Increase Decrease In Other Noncurrent Assets IncreaseDecreaseInOtherNoncurrentAssets	154000000	usd
CY2022	us-gaap	Increase Decrease In Other Noncurrent Assets IncreaseDecreaseInOtherNoncurrentAssets	122000000	usd
CY2021	us-gaap	Increase Decrease In Other Noncurrent Assets IncreaseDecreaseInOtherNoncurrentAssets	354000000	usd
CY2023	us-gaap	Increase Decrease In Employee Related Liabilities IncreaseDecreaseInEmployeeRelatedLiabilities	195000000	usd
CY2022	us-gaap	Increase Decrease In Employee Related Liabilities IncreaseDecreaseInEmployeeRelatedLiabilities	171000000	usd
CY2021	us-gaap	Increase Decrease In Employee Related Liabilities IncreaseDecreaseInEmployeeRelatedLiabilities	574000000	usd
CY2023	us-gaap	Increase Decrease In Accrued Income Taxes Payable IncreaseDecreaseInAccruedIncomeTaxesPayable	105000000	usd
CY2022	us-gaap	Increase Decrease In Accrued Income Taxes Payable IncreaseDecreaseInAccruedIncomeTaxesPayable	-54000000	usd
CY2023	mmc	Pensionand Other Postretirement Benefit Contributions In Excessof Current Year Expense PensionandOtherPostretirementBenefitContributionsInExcessofCurrentYearExpense	335000000	usd
CY2022	mmc	Increase Decreasein Operating Lease Liabilities IncreaseDecreaseinOperatingLeaseLiabilities	-323000000	usd
CY2021	mmc	Increase Decreasein Operating Lease Liabilities IncreaseDecreaseinOperatingLeaseLiabilities	-349000000	usd
CY2021	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	3516000000	usd
CY2023	mmc	Proceeds From Issuance Of Commercial Paper With Maturity Greater Than90 Days ProceedsFromIssuanceOfCommercialPaperWithMaturityGreaterThan90Days	146000000	usd
CY2022	mmc	Proceeds From Issuance Of Commercial Paper With Maturity Greater Than90 Days ProceedsFromIssuanceOfCommercialPaperWithMaturityGreaterThan90Days	0	usd
CY2023	mmc	Repayments Of Commercial Paper With Maturity Greater Than90 Days RepaymentsOfCommercialPaperWithMaturityGreaterThan90Days	146000000	usd
CY2023	us-gaap	Proceeds From Issuance Of Debt ProceedsFromIssuanceOfDebt	2169000000	usd
CY2022	us-gaap	Proceeds From Issuance Of Debt ProceedsFromIssuanceOfDebt	984000000	usd
CY2021	us-gaap	Proceeds From Issuance Of Debt ProceedsFromIssuanceOfDebt	743000000	usd
CY2023	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	266000000	usd
CY2022	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	365000000	usd
CY2021	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	1016000000	usd
CY2023	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	139000000	usd
CY2022	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	7000000	usd
CY2021	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	0	usd
CY2023	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	148000000	usd
CY2022	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	198000000	usd
CY2021	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	101000000	usd
CY2023	us-gaap	Proceeds From Issuance Or Sale Of Equity ProceedsFromIssuanceOrSaleOfEquity	199000000	usd
CY2022	us-gaap	Proceeds From Issuance Or Sale Of Equity ProceedsFromIssuanceOrSaleOfEquity	126000000	usd
CY2021	us-gaap	Proceeds From Issuance Or Sale Of Equity ProceedsFromIssuanceOrSaleOfEquity	161000000	usd
CY2023	mmc	Payments For Acquisitions Deferred And Contingent Consideration PaymentsForAcquisitionsDeferredAndContingentConsideration	202000000	usd
CY2022	mmc	Payments For Acquisitions Deferred And Contingent Consideration PaymentsForAcquisitionsDeferredAndContingentConsideration	158000000	usd
CY2021	mmc	Payments For Acquisitions Deferred And Contingent Consideration PaymentsForAcquisitionsDeferredAndContingentConsideration	117000000	usd
CY2023	mmc	Receipts Of Contingent Consideration For Dispositions ReceiptsOfContingentConsiderationForDispositions	2000000	usd
CY2022	mmc	Receipts Of Contingent Consideration For Dispositions ReceiptsOfContingentConsiderationForDispositions	3000000	usd
CY2021	mmc	Receipts Of Contingent Consideration For Dispositions ReceiptsOfContingentConsiderationForDispositions	71000000	usd
CY2023	us-gaap	Payments Of Dividends Minority Interest PaymentsOfDividendsMinorityInterest	31000000	usd
CY2022	us-gaap	Payments Of Dividends Minority Interest PaymentsOfDividendsMinorityInterest	27000000	usd
CY2021	us-gaap	Payments Of Dividends Minority Interest PaymentsOfDividendsMinorityInterest	36000000	usd
CY2023	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	1298000000	usd
CY2022	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	1138000000	usd
CY2021	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	1026000000	usd
CY2023	mmc	Increase Decrease In Fiduciary Liabilities IncreaseDecreaseInFiduciaryLiabilities	-255000000	usd
CY2022	mmc	Increase Decrease In Fiduciary Liabilities IncreaseDecreaseInFiduciaryLiabilities	1684000000	usd
CY2021	mmc	Increase Decrease In Fiduciary Liabilities IncreaseDecreaseInFiduciaryLiabilities	1183000000	usd
CY2023	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-1119000000	usd
CY2022	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-1046000000	usd
CY2021	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-1297000000	usd
CY2023	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	416000000	usd
CY2022	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	470000000	usd
CY2021	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	406000000	usd
CY2023	us-gaap	Payments To Acquire Longterm Investments PaymentsToAcquireLongtermInvestments	57000000	usd
CY2022	us-gaap	Payments To Acquire Longterm Investments PaymentsToAcquireLongtermInvestments	22000000	usd
CY2021	us-gaap	Payments To Acquire Longterm Investments PaymentsToAcquireLongtermInvestments	28000000	usd
CY2023	us-gaap	Proceeds From Sale And Maturity Of Other Investments ProceedsFromSaleAndMaturityOfOtherInvestments	38000000	usd
CY2022	us-gaap	Proceeds From Sale And Maturity Of Other Investments ProceedsFromSaleAndMaturityOfOtherInvestments	86000000	usd
CY2021	us-gaap	Proceeds From Sale And Maturity Of Other Investments ProceedsFromSaleAndMaturityOfOtherInvestments	41000000	usd
CY2023	us-gaap	Proceeds From Divestiture Of Businesses Net Of Cash Divested ProceedsFromDivestitureOfBusinessesNetOfCashDivested	-17000000	usd
CY2022	us-gaap	Proceeds From Divestiture Of Businesses Net Of Cash Divested ProceedsFromDivestitureOfBusinessesNetOfCashDivested	119000000	usd
CY2021	us-gaap	Proceeds From Divestiture Of Businesses Net Of Cash Divested ProceedsFromDivestitureOfBusinessesNetOfCashDivested	84000000	usd
CY2023	mmc	Payment To Acquire Businesses Net Of Cash And Cash Held In A Fiduciary Capacity Acquired PaymentToAcquireBusinessesNetOfCashAndCashHeldInAFiduciaryCapacityAcquired	976000000	usd
CY2022	mmc	Payment To Acquire Businesses Net Of Cash And Cash Held In A Fiduciary Capacity Acquired PaymentToAcquireBusinessesNetOfCashAndCashHeldInAFiduciaryCapacityAcquired	572000000	usd
CY2021	mmc	Payment To Acquire Businesses Net Of Cash And Cash Held In A Fiduciary Capacity Acquired PaymentToAcquireBusinessesNetOfCashAndCashHeldInAFiduciaryCapacityAcquired	859000000	usd
CY2023	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-11000000	usd
CY2022	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-9000000	usd
CY2021	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-4000000	usd
CY2023	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-1417000000	usd
CY2022	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-850000000	usd
CY2021	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-1164000000	usd
CY2023	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	328000000	usd
CY2022	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	-841000000	usd
CY2021	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	-355000000	usd
CY2023	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	2050000000	usd
CY2022	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	728000000	usd
CY2021	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	700000000	usd
CY2022Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	12102000000	usd
CY2021Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	11374000000	usd
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	10674000000	usd
CY2023Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	14152000000	usd
CY2022Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	12102000000	usd
CY2021Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	11374000000	usd
CY2023Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	3358000000	usd
CY2022Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	1442000000	usd
CY2021Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	1752000000	usd
CY2023Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	10794000000	usd
CY2022Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	10660000000	usd
CY2021Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	9622000000	usd
CY2023Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	14152000000	usd
CY2022Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	12102000000	usd
CY2021Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	11374000000	usd
CY2023	mmc	Dividend Equivalents Per Share Cash Declared DividendEquivalentsPerShareCashDeclared	2.60
CY2022	mmc	Dividend Equivalents Per Share Cash Declared DividendEquivalentsPerShareCashDeclared	2.25
CY2021	mmc	Dividend Equivalents Per Share Cash Declared DividendEquivalentsPerShareCashDeclared	2.00
CY2023	mmc	Common Stock Dividends Per Share Cash Declared CommonStockDividendsPerShareCashDeclared	2.60
CY2022	mmc	Common Stock Dividends Per Share Cash Declared CommonStockDividendsPerShareCashDeclared	2.25
CY2021	mmc	Common Stock Dividends Per Share Cash Declared CommonStockDividendsPerShareCashDeclared	2.00
CY2023Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	12370000000	usd
CY2022Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	10749000000	usd
CY2021Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	11222000000	usd
CY2023	us-gaap	Number Of Operating Segments NumberOfOperatingSegments	2	segment
CY2023Q4	us-gaap	Restricted Cash And Cash Equivalents At Carrying Value RestrictedCashAndCashEquivalentsAtCarryingValue	486000000	usd
CY2022Q4	us-gaap	Restricted Cash And Cash Equivalents At Carrying Value RestrictedCashAndCashEquivalentsAtCarryingValue	348000000	usd
CY2023Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	2444000000	usd
CY2022Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	2402000000	usd
CY2023Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	1562000000	usd
CY2022Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	1531000000	usd
CY2023Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	882000000	usd
CY2022Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	871000000	usd
CY2023	us-gaap	Gain Loss On Investments GainLossOnInvestments	5000000	usd
CY2022	us-gaap	Gain Loss On Investments GainLossOnInvestments	21000000	usd
CY2021	us-gaap	Gain Loss On Investments GainLossOnInvestments	61000000	usd
CY2022Q4	us-gaap	Indefinite Lived Intangible Assets Excluding Goodwill IndefiniteLivedIntangibleAssetsExcludingGoodwill	0	usd
CY2023Q4	us-gaap	Indefinite Lived Intangible Assets Excluding Goodwill IndefiniteLivedIntangibleAssetsExcludingGoodwill	0	usd
CY2023Q4	us-gaap	Capitalized Computer Software Net CapitalizedComputerSoftwareNet	519000000	usd
CY2022Q4	us-gaap	Capitalized Computer Software Net CapitalizedComputerSoftwareNet	492000000	usd
CY2023Q4	us-gaap	Capitalized Computer Software Accumulated Amortization CapitalizedComputerSoftwareAccumulatedAmortization	2000000000	usd
CY2022Q4	us-gaap	Capitalized Computer Software Accumulated Amortization CapitalizedComputerSoftwareAccumulatedAmortization	1800000000	usd
CY2023Q4	mmc	Liability For Errors And Omissions Current And Noncurrent LiabilityForErrorsAndOmissionsCurrentAndNoncurrent	385000000	usd
CY2022Q4	mmc	Liability For Errors And Omissions Current And Noncurrent LiabilityForErrorsAndOmissionsCurrentAndNoncurrent	419000000	usd
CY2023	us-gaap	Profit Loss ProfitLoss	3802000000	usd
CY2022	us-gaap	Profit Loss ProfitLoss	3087000000	usd
CY2021	us-gaap	Profit Loss ProfitLoss	3174000000	usd
CY2023	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	46000000	usd
CY2022	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	37000000	usd
CY2021	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	31000000	usd
CY2023	us-gaap	Net Income Loss NetIncomeLoss	3756000000	usd
CY2022	us-gaap	Net Income Loss NetIncomeLoss	3050000000	usd
CY2021	us-gaap	Net Income Loss NetIncomeLoss	3143000000	usd
CY2023	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	494000000	shares
CY2022	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	499000000	shares
CY2021	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	507000000	shares
CY2023	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	5000000	shares
CY2022	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	6000000	shares
CY2021	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	6000000	shares
CY2023	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	499000000	shares
CY2022	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	505000000	shares
CY2021	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	513000000	shares
CY2023	mmc	Average Share Price Common Stock AverageSharePriceCommonStock	182.30
CY2022	mmc	Average Share Price Common Stock AverageSharePriceCommonStock	160.39
CY2021	mmc	Average Share Price Common Stock AverageSharePriceCommonStock	141.57
CY2023Q4	mmc	Uncollected Premiumsand Claims Netof Related Payables UncollectedPremiumsandClaimsNetofRelatedPayables	13800000000	usd
CY2022Q4	mmc	Uncollected Premiumsand Claims Netof Related Payables UncollectedPremiumsandClaimsNetofRelatedPayables	13000000000	usd
CY2022Q4	us-gaap	Assets Current AssetsCurrent	18959000000	usd
CY2022Q4	us-gaap	Assets Assets	44114000000	usd
CY2022Q4	us-gaap	Liabilities Current LiabilitiesCurrent	17832000000	usd
CY2023	us-gaap	Use Of Estimates UseOfEstimates	<div style="margin-top:5pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Estimates:</span><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> T</span><span style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">he preparation of the consolidated financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of assets and liabilities at the date of the financial statements, and the reported amounts of revenue and expense during the reporting period. </span></div><div style="margin-top:5pt"><span style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">On an ongoing basis, the Company evaluates its estimates, judgments and methodologies. The estimates are based on historical experience and on various other assumptions that the Company believes are reasonable. </span></div><div style="margin-top:5pt"><span style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Such matters include:</span></div><div style="margin-top:5pt;padding-left:36pt;text-indent:-18pt"><span style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">estimates of revenue;</span></div><div style="margin-top:5pt;padding-left:36pt;text-indent:-18pt"><span style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">impairment assessments and charges;</span></div><div style="margin-top:5pt;padding-left:36pt;text-indent:-18pt"><span style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">recoverability of long-lived assets;</span></div><div style="margin-top:5pt;padding-left:36pt;text-indent:-18pt"><span style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">liabilities for errors and omissions;</span></div><div style="margin-top:5pt;padding-left:36pt;text-indent:-18pt"><span style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">deferred tax assets, uncertain tax positions and income tax expense;</span></div><div style="margin-top:5pt;padding-left:36pt;text-indent:-18pt"><span style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">share-based and incentive compensation expense; </span></div><div style="margin-top:5pt;padding-left:36pt;text-indent:-18pt"><span style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">the allowance for current expected credit losses on receivables;</span></div><div style="margin-top:5pt;padding-left:36pt;text-indent:-18pt"><span style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">useful lives assigned to long-lived assets, and depreciation and amortization; and</span></div><div style="margin-top:5pt;padding-left:36pt;text-indent:-18pt"><span style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">fair value estimates of contingent consideration receivable or payable related to acquisitions or dispositions. </span></div><div style="margin-top:5pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The Company believes these estimates are reasonable based on information currently available at the time they are made. The Company also considered the potential impact of macroeconomic factors including from the multiple major wars, escalating conflict throughout the Middle East and rising tension in the South China Sea, slower GDP growth or recession, lower interest rates, capital markets volatility and inflation to its customer base in various industries and geographies. Insurance exposures subject to variable factors are subject to mid-term and end of term adjustments, as well as policy audits, which may reduce premiums and corresponding commissions. Estimates were updated based on internal and industry specific economic data. Actual results may differ from these estimates</span><span style="color:#000000;font-family:'Calibri',sans-serif;font-size:11pt;font-weight:400;line-height:120%">.</span></div>
CY2023	mmc	Revenue From Contract With Customer Threshold Percentage Of Total Revenue RevenueFromContractWithCustomerThresholdPercentageOfTotalRevenue	0.01
CY2023	mmc	Brokerage Revenue Number Of Annual Installments BrokerageRevenueNumberOfAnnualInstallments	4	installment
CY2023Q4	us-gaap	Contract With Customer Asset Gross ContractWithCustomerAssetGross	357000000	usd
CY2022Q4	us-gaap	Contract With Customer Asset Gross ContractWithCustomerAssetGross	335000000	usd
CY2021Q4	us-gaap	Contract With Customer Asset Gross ContractWithCustomerAssetGross	290000000	usd
CY2023Q4	us-gaap	Contract With Customer Liability ContractWithCustomerLiability	869000000	usd
CY2022Q4	us-gaap	Contract With Customer Liability ContractWithCustomerLiability	837000000	usd
CY2021Q4	us-gaap	Contract With Customer Liability ContractWithCustomerLiability	776000000	usd
CY2022Q4	us-gaap	Contract With Customer Asset Gross ContractWithCustomerAssetGross	335000000	usd
CY2021Q4	us-gaap	Contract With Customer Asset Gross ContractWithCustomerAssetGross	290000000	usd
CY2023	us-gaap	Contract With Customer Asset Cumulative Catch Up Adjustment To Revenue Change In Measure Of Progress ContractWithCustomerAssetCumulativeCatchUpAdjustmentToRevenueChangeInMeasureOfProgress	825000000	usd
CY2022	us-gaap	Contract With Customer Asset Cumulative Catch Up Adjustment To Revenue Change In Measure Of Progress ContractWithCustomerAssetCumulativeCatchUpAdjustmentToRevenueChangeInMeasureOfProgress	661000000	usd
CY2023	us-gaap	Contract With Customer Asset Reclassified To Receivable ContractWithCustomerAssetReclassifiedToReceivable	-805000000	usd
CY2022	us-gaap	Contract With Customer Asset Reclassified To Receivable ContractWithCustomerAssetReclassifiedToReceivable	-614000000	usd
CY2023	mmc	Contract With Customer Asset Effect Of Foreign Exchange Rate Changes ContractWithCustomerAssetEffectOfForeignExchangeRateChanges	2000000	usd
CY2022	mmc	Contract With Customer Asset Effect Of Foreign Exchange Rate Changes ContractWithCustomerAssetEffectOfForeignExchangeRateChanges	-2000000	usd
CY2023Q4	us-gaap	Contract With Customer Asset Gross ContractWithCustomerAssetGross	357000000	usd
CY2022Q4	us-gaap	Contract With Customer Asset Gross ContractWithCustomerAssetGross	335000000	usd
CY2022Q4	us-gaap	Contract With Customer Liability ContractWithCustomerLiability	837000000	usd
CY2021Q4	us-gaap	Contract With Customer Liability ContractWithCustomerLiability	776000000	usd
CY2023	mmc	Contractwith Customer Liability Increase Decreasefor Cash Receivedfor Performance Obligations Not Yet Fulfilled ContractwithCustomerLiabilityIncreaseDecreaseforCashReceivedforPerformanceObligationsNotYetFulfilled	822000000	usd
CY2022	mmc	Contractwith Customer Liability Increase Decreasefor Cash Receivedfor Performance Obligations Not Yet Fulfilled ContractwithCustomerLiabilityIncreaseDecreaseforCashReceivedforPerformanceObligationsNotYetFulfilled	726000000	usd
CY2023	us-gaap	Contract With Customer Liability Revenue Recognized ContractWithCustomerLiabilityRevenueRecognized	-799000000	usd
CY2022	us-gaap	Contract With Customer Liability Revenue Recognized ContractWithCustomerLiabilityRevenueRecognized	-640000000	usd
CY2023	mmc	Contract With Customer Liability Effect Of Foreign Exchange Rate Changes ContractWithCustomerLiabilityEffectOfForeignExchangeRateChanges	9000000	usd
CY2022	mmc	Contract With Customer Liability Effect Of Foreign Exchange Rate Changes ContractWithCustomerLiabilityEffectOfForeignExchangeRateChanges	-25000000	usd
CY2023Q4	us-gaap	Contract With Customer Liability ContractWithCustomerLiability	869000000	usd
CY2022Q4	us-gaap	Contract With Customer Liability ContractWithCustomerLiability	837000000	usd
CY2023	us-gaap	Contract With Customer Performance Obligation Satisfied In Previous Period ContractWithCustomerPerformanceObligationSatisfiedInPreviousPeriod	71000000	usd
CY2022	us-gaap	Contract With Customer Performance Obligation Satisfied In Previous Period ContractWithCustomerPerformanceObligationSatisfiedInPreviousPeriod	83000000	usd
CY2021	us-gaap	Contract With Customer Performance Obligation Satisfied In Previous Period ContractWithCustomerPerformanceObligationSatisfiedInPreviousPeriod	84000000	usd
CY2023	us-gaap	Capitalized Contract Cost Amortization CapitalizedContractCostAmortization	1800000000	usd
CY2022	us-gaap	Capitalized Contract Cost Amortization CapitalizedContractCostAmortization	1600000000	usd
CY2021	us-gaap	Capitalized Contract Cost Amortization CapitalizedContractCostAmortization	1500000000	usd
CY2023	mmc	Business Combination Consideration Transferred Assets Acquired BusinessCombinationConsiderationTransferredAssetsAcquired	1292000000	usd
CY2022	mmc	Business Combination Consideration Transferred Assets Acquired BusinessCombinationConsiderationTransferredAssetsAcquired	734000000	usd
CY2021	mmc	Business Combination Consideration Transferred Assets Acquired BusinessCombinationConsiderationTransferredAssetsAcquired	1697000000	usd
CY2023	mmc	Business Combination Consideration Transferred Deposits BusinessCombinationConsiderationTransferredDeposits	0	usd
CY2022	mmc	Business Combination Consideration Transferred Deposits BusinessCombinationConsiderationTransferredDeposits	24000000	usd
CY2021	mmc	Business Combination Consideration Transferred Deposits BusinessCombinationConsiderationTransferredDeposits	0	usd
CY2023	mmc	Business Combination Consideration Transferred Fiduciary Liabilities Assumed BusinessCombinationConsiderationTransferredFiduciaryLiabilitiesAssumed	93000000	usd
CY2022	mmc	Business Combination Consideration Transferred Fiduciary Liabilities Assumed BusinessCombinationConsiderationTransferredFiduciaryLiabilitiesAssumed	6000000	usd
CY2021	mmc	Business Combination Consideration Transferred Fiduciary Liabilities Assumed BusinessCombinationConsiderationTransferredFiduciaryLiabilitiesAssumed	18000000	usd
CY2023	us-gaap	Business Combination Consideration Transferred Liabilities Incurred BusinessCombinationConsiderationTransferredLiabilitiesIncurred	182000000	usd
CY2022	us-gaap	Business Combination Consideration Transferred Liabilities Incurred BusinessCombinationConsiderationTransferredLiabilitiesIncurred	49000000	usd
CY2021	us-gaap	Business Combination Consideration Transferred Liabilities Incurred BusinessCombinationConsiderationTransferredLiabilitiesIncurred	213000000	usd
CY2023	mmc	Business Combination Consideration Transferred Noncontrolling Interests Assumed BusinessCombinationConsiderationTransferredNoncontrollingInterestsAssumed	0	usd
CY2022	mmc	Business Combination Consideration Transferred Noncontrolling Interests Assumed BusinessCombinationConsiderationTransferredNoncontrollingInterestsAssumed	5000000	usd
CY2021	mmc	Business Combination Consideration Transferred Noncontrolling Interests Assumed BusinessCombinationConsiderationTransferredNoncontrollingInterestsAssumed	64000000	usd
CY2023	mmc	Business Combination Fair Value Of Previously Held Equity Method Investment BusinessCombinationFairValueOfPreviouslyHeldEquityMethodInvestment	0	usd
CY2022	mmc	Business Combination Fair Value Of Previously Held Equity Method Investment BusinessCombinationFairValueOfPreviouslyHeldEquityMethodInvestment	6000000	usd
CY2021	mmc	Business Combination Fair Value Of Previously Held Equity Method Investment BusinessCombinationFairValueOfPreviouslyHeldEquityMethodInvestment	390000000	usd
CY2023	mmc	Business Combination Contingentand Deferred Consideration BusinessCombinationContingentandDeferredConsideration	41000000	usd
CY2022	mmc	Business Combination Contingentand Deferred Consideration BusinessCombinationContingentandDeferredConsideration	120000000	usd
CY2021	mmc	Business Combination Contingentand Deferred Consideration BusinessCombinationContingentandDeferredConsideration	153000000	usd
CY2023	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	-976000000	usd
CY2022	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	-572000000	usd
CY2021	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	-859000000	usd
CY2023	us-gaap	Interest Paid Net InterestPaidNet	499000000	usd
CY2022	us-gaap	Interest Paid Net InterestPaidNet	431000000	usd
CY2021	us-gaap	Interest Paid Net InterestPaidNet	441000000	usd
CY2023	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	1119000000	usd
CY2022	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	1049000000	usd
CY2021	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	1069000000	usd
CY2023	mmc	Paymentof Contingent Consideration PaymentofContingentConsideration	41000000	usd
CY2022	mmc	Paymentof Contingent Consideration PaymentofContingentConsideration	38000000	usd
CY2021	mmc	Paymentof Contingent Consideration PaymentofContingentConsideration	49000000	usd
CY2023	mmc	Proceeds From Contingent Consideration Prior Period Dispositions ProceedsFromContingentConsiderationPriorPeriodDispositions	1000000	usd
CY2022	mmc	Proceeds From Contingent Consideration Prior Period Dispositions ProceedsFromContingentConsiderationPriorPeriodDispositions	0	usd
CY2021	mmc	Proceeds From Contingent Consideration Prior Period Dispositions ProceedsFromContingentConsiderationPriorPeriodDispositions	19000000	usd
CY2023	mmc	Fair Value Measurementwith Unobservable Inputs Reconciliation Recurring Basis Liability Gain Loss Includedin Earnings Net FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedinEarningsNet	-29000000	usd
CY2022	mmc	Fair Value Measurementwith Unobservable Inputs Reconciliation Recurring Basis Liability Gain Loss Includedin Earnings Net FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedinEarningsNet	-49000000	usd
CY2021	mmc	Fair Value Measurementwith Unobservable Inputs Reconciliation Recurring Basis Liability Gain Loss Includedin Earnings Net FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedinEarningsNet	-57000000	usd
CY2023	mmc	Adjustments And Payments Related To Contingent Consideration AdjustmentsAndPaymentsRelatedToContingentConsideration	11000000	usd
CY2022	mmc	Adjustments And Payments Related To Contingent Consideration AdjustmentsAndPaymentsRelatedToContingentConsideration	-11000000	usd
CY2021	mmc	Adjustments And Payments Related To Contingent Consideration AdjustmentsAndPaymentsRelatedToContingentConsideration	-27000000	usd
CY2023	mmc	Payments For Previous Acquisition Contingent Consideration PaymentsForPreviousAcquisitionContingentConsideration	135000000	usd
CY2022	mmc	Payments For Previous Acquisition Contingent Consideration PaymentsForPreviousAcquisitionContingentConsideration	32000000	usd
CY2021	mmc	Payments For Previous Acquisition Contingent Consideration PaymentsForPreviousAcquisitionContingentConsideration	28000000	usd
CY2023	mmc	Payments For Previous Acquisition Deferred Consideration PaymentsForPreviousAcquisitionDeferredConsideration	67000000	usd
CY2022	mmc	Payments For Previous Acquisition Deferred Consideration PaymentsForPreviousAcquisitionDeferredConsideration	126000000	usd
CY2021	mmc	Payments For Previous Acquisition Deferred Consideration PaymentsForPreviousAcquisitionDeferredConsideration	89000000	usd
CY2023	mmc	Payments For Previous Acquisition Deferredand Contingent Consideration PaymentsForPreviousAcquisitionDeferredandContingentConsideration	202000000	usd
CY2022	mmc	Payments For Previous Acquisition Deferredand Contingent Consideration PaymentsForPreviousAcquisitionDeferredandContingentConsideration	158000000	usd
CY2021	mmc	Payments For Previous Acquisition Deferredand Contingent Consideration PaymentsForPreviousAcquisitionDeferredandContingentConsideration	117000000	usd
CY2023	mmc	Proceeds From Previous Disposition Contingent Consideration ProceedsFromPreviousDispositionContingentConsideration	2000000	usd
CY2022	mmc	Proceeds From Previous Disposition Contingent Consideration ProceedsFromPreviousDispositionContingentConsideration	3000000	usd
CY2021	mmc	Proceeds From Previous Disposition Contingent Consideration ProceedsFromPreviousDispositionContingentConsideration	71000000	usd
CY2023	us-gaap	Stock Issued1 StockIssued1	310000000	usd
CY2022	us-gaap	Stock Issued1 StockIssued1	372000000	usd
CY2021	us-gaap	Stock Issued1 StockIssued1	228000000	usd
CY2023	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	363000000	usd
CY2022	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	367000000	usd
CY2021	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	348000000	usd
CY2022Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	160000000	usd
CY2021Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	166000000	usd
CY2020Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	142000000	usd
CY2023	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	17000000	usd
CY2022	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	17000000	usd
CY2021	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	46000000	usd
CY2023	mmc	Allowance For Doubtful Accounts Receivable Writeoffs Net Of Recoveries AllowanceForDoubtfulAccountsReceivableWriteoffsNetOfRecoveries	20000000	usd
CY2022	mmc	Allowance For Doubtful Accounts Receivable Writeoffs Net Of Recoveries AllowanceForDoubtfulAccountsReceivableWriteoffsNetOfRecoveries	17000000	usd
CY2021	mmc	Allowance For Doubtful Accounts Receivable Writeoffs Net Of Recoveries AllowanceForDoubtfulAccountsReceivableWriteoffsNetOfRecoveries	16000000	usd
CY2023	mmc	Allowance For Doubtful Accounts Receivable Effect Of Exchange Rate Changes And Other AllowanceForDoubtfulAccountsReceivableEffectOfExchangeRateChangesAndOther	-6000000	usd
CY2022	mmc	Allowance For Doubtful Accounts Receivable Effect Of Exchange Rate Changes And Other AllowanceForDoubtfulAccountsReceivableEffectOfExchangeRateChangesAndOther	-6000000	usd
CY2021	mmc	Allowance For Doubtful Accounts Receivable Effect Of Exchange Rate Changes And Other AllowanceForDoubtfulAccountsReceivableEffectOfExchangeRateChangesAndOther	-6000000	usd
CY2023Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	151000000	usd
CY2022Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	160000000	usd
CY2021Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	166000000	usd
CY2022	us-gaap	Litigation Settlement Expense LitigationSettlementExpense	30000000	usd
CY2023	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	5000000	usd
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CY2023	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	19000000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	-849000000	usd
CY2022	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	-110000000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-739000000	usd
CY2023	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	-114000000	usd
CY2023	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	-133000000	usd
CY2023	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	19000000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	-557000000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	182000000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-739000000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	840000000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	305000000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	535000000	usd
CY2023Q4	mmc	Accumulated Other Comprehensive Income Loss Foreign Currency Translation Adjustment Tax AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentTax	2000000	usd
CY2022Q4	mmc	Accumulated Other Comprehensive Income Loss Foreign Currency Translation Adjustment Tax AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentTax	-8000000	usd
CY2023Q4	mmc	Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Adjustment Tax AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansAdjustmentTax	1463000000	usd
CY2022Q4	mmc	Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Adjustment Tax AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansAdjustmentTax	1340000000	usd
CY2023	us-gaap	Business Combination Consideration Transferred1 BusinessCombinationConsiderationTransferred1	1200000000	usd
CY2023	us-gaap	Payments To Acquire Businesses Gross PaymentsToAcquireBusinessesGross	1100000000	usd
CY2023	mmc	Business Combination Contingentand Deferred Consideration BusinessCombinationContingentandDeferredConsideration	41000000	usd
CY2023	us-gaap	Finitelived Intangible Assets Acquired1 FinitelivedIntangibleAssetsAcquired1	427000000	usd
CY2023	us-gaap	Business Combination Pro Forma Information Revenue Of Acquiree Since Acquisition Date Actual BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual	152000000	usd
CY2023	us-gaap	Business Combination Pro Forma Information Earnings Or Loss Of Acquiree Since Acquisition Date Actual BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual	24000000	usd
CY2022	us-gaap	Business Combination Pro Forma Information Revenue Of Acquiree Since Acquisition Date Actual BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual	58000000	usd
CY2022	us-gaap	Business Combination Pro Forma Information Earnings Or Loss Of Acquiree Since Acquisition Date Actual BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual	-5000000	usd
CY2021	us-gaap	Business Combination Pro Forma Information Revenue Of Acquiree Since Acquisition Date Actual BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual	114000000	usd
CY2021	us-gaap	Business Combination Pro Forma Information Earnings Or Loss Of Acquiree Since Acquisition Date Actual BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual	3000000	usd
CY2023	us-gaap	Business Combination Acquisition Related Costs BusinessCombinationAcquisitionRelatedCosts	45000000	usd
CY2022	us-gaap	Business Combination Acquisition Related Costs BusinessCombinationAcquisitionRelatedCosts	29000000	usd
CY2023Q1	us-gaap	Proceeds From Divestiture Of Businesses Net Of Cash Divested ProceedsFromDivestitureOfBusinessesNetOfCashDivested	24000000	usd
CY2022	us-gaap	Business Combination Consideration Transferred1 BusinessCombinationConsiderationTransferred1	705000000	usd
CY2022	us-gaap	Payments To Acquire Businesses Gross PaymentsToAcquireBusinessesGross	579000000	usd
CY2022	mmc	Business Combination Contingentand Deferred Consideration BusinessCombinationContingentandDeferredConsideration	120000000	usd
CY2022	mmc	Business Combination Fair Value Of Previously Held Equity Method Investment BusinessCombinationFairValueOfPreviouslyHeldEquityMethodInvestment	6000000	usd
CY2022Q4	mmc	Cash And Cash Equivalents Held In A Fiduciary Capacity CashAndCashEquivalentsHeldInAFiduciaryCapacity	36000000	usd
CY2022Q1	us-gaap	Deconsolidation Gain Or Loss Amount DeconsolidationGainOrLossAmount	-39000000	usd
CY2023Q2	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	139000000	usd
CY2023	us-gaap	Business Acquisitions Pro Forma Revenue BusinessAcquisitionsProFormaRevenue	22904000000	usd
CY2022	us-gaap	Business Acquisitions Pro Forma Revenue BusinessAcquisitionsProFormaRevenue	21238000000	usd
CY2021	us-gaap	Business Acquisitions Pro Forma Revenue BusinessAcquisitionsProFormaRevenue	20220000000	usd
CY2023	us-gaap	Business Acquisitions Pro Forma Net Income Loss BusinessAcquisitionsProFormaNetIncomeLoss	3807000000	usd
CY2022	us-gaap	Business Acquisitions Pro Forma Net Income Loss BusinessAcquisitionsProFormaNetIncomeLoss	3058000000	usd
CY2021	us-gaap	Business Acquisitions Pro Forma Net Income Loss BusinessAcquisitionsProFormaNetIncomeLoss	3177000000	usd
CY2023	us-gaap	Business Acquisition Pro Forma Earnings Per Share Basic BusinessAcquisitionProFormaEarningsPerShareBasic	7.71
CY2022	us-gaap	Business Acquisition Pro Forma Earnings Per Share Basic BusinessAcquisitionProFormaEarningsPerShareBasic	6.12
CY2021	us-gaap	Business Acquisition Pro Forma Earnings Per Share Basic BusinessAcquisitionProFormaEarningsPerShareBasic	6.27
CY2023	us-gaap	Business Acquisition Pro Forma Earnings Per Share Diluted BusinessAcquisitionProFormaEarningsPerShareDiluted	7.63
CY2022	us-gaap	Business Acquisition Pro Forma Earnings Per Share Diluted BusinessAcquisitionProFormaEarningsPerShareDiluted	6.06
CY2021	us-gaap	Business Acquisition Pro Forma Earnings Per Share Diluted BusinessAcquisitionProFormaEarningsPerShareDiluted	6.20
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CY2023Q4	us-gaap	Indefinite Lived Intangible Assets Excluding Goodwill IndefiniteLivedIntangibleAssetsExcludingGoodwill	0	usd
CY2022Q4	us-gaap	Goodwill Goodwill	16251000000	usd
CY2021Q4	us-gaap	Goodwill Goodwill	16317000000	usd
CY2023	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	813000000	usd
CY2022	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	460000000	usd
CY2023	us-gaap	Goodwill Other Increase Decrease GoodwillOtherIncreaseDecrease	167000000	usd
CY2022	us-gaap	Goodwill Other Increase Decrease GoodwillOtherIncreaseDecrease	-526000000	usd
CY2023Q4	us-gaap	Goodwill Goodwill	17231000000	usd
CY2022Q4	us-gaap	Goodwill Goodwill	16251000000	usd
CY2023Q4	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	4728000000	usd
CY2023Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	2098000000	usd
CY2023Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	2630000000	usd
CY2022Q4	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	4353000000	usd
CY2022Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	1816000000	usd
CY2022Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	2537000000	usd
CY2023	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	343000000	usd
CY2022	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	338000000	usd
CY2021	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	365000000	usd
CY2023Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Next Twelve Months FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	351000000	usd
CY2023Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Two FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	309000000	usd
CY2023Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Three FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	287000000	usd
CY2023Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Four FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	278000000	usd
CY2023Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Five FiniteLivedIntangibleAssetsAmortizationExpenseYearFive	270000000	usd
CY2023Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense After Year Five FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive	1135000000	usd
CY2023Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	2630000000	usd
CY2023	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	1823000000	usd
CY2022	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	1468000000	usd
CY2021	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	1590000000	usd
CY2023	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	3203000000	usd
CY2022	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	2614000000	usd
CY2021	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	2618000000	usd
CY2023	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	5026000000	usd
CY2022	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	4082000000	usd
CY2021	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	4208000000	usd
CY2023	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	273000000	usd
CY2022	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	262000000	usd
CY2021	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	251000000	usd
CY2023	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	838000000	usd
CY2022	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	653000000	usd
CY2021	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	714000000	usd
CY2023	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	142000000	usd
CY2022	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	123000000	usd
CY2021	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	132000000	usd
CY2023	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	1253000000	usd
CY2022	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	1038000000	usd
CY2021	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	1097000000	usd
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CY2021	us-gaap	Deferred Foreign Income Tax Expense Benefit DeferredForeignIncomeTaxExpenseBenefit	-12000000	usd
CY2023	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	15000000	usd
CY2022	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	10000000	usd
CY2021	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	-11000000	usd
CY2023	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-29000000	usd
CY2022	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-43000000	usd
CY2021	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-63000000	usd
CY2023	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	1224000000	usd
CY2022	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	995000000	usd
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	1034000000	usd
CY2023Q4	mmc	Deferred Tax Assets Tax Deferred Expense Reservesand Accruals Netof Valuation Allowance DeferredTaxAssetsTaxDeferredExpenseReservesandAccrualsNetofValuationAllowance	679000000	usd
CY2022Q4	mmc	Deferred Tax Assets Tax Deferred Expense Reservesand Accruals Netof Valuation Allowance DeferredTaxAssetsTaxDeferredExpenseReservesandAccrualsNetofValuationAllowance	670000000	usd
CY2023Q4	mmc	Deferred Tax Assets Operating Loss Carryforwards Foreign Netof Valuation Allowance DeferredTaxAssetsOperatingLossCarryforwardsForeignNetofValuationAllowance	299000000	usd
CY2022Q4	mmc	Deferred Tax Assets Operating Loss Carryforwards Foreign Netof Valuation Allowance DeferredTaxAssetsOperatingLossCarryforwardsForeignNetofValuationAllowance	275000000	usd
CY2023Q4	mmc	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Pensions And Postretirement Benefits Netof Valuation Allowance DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPensionsAndPostretirementBenefitsNetofValuationAllowance	134000000	usd
CY2022Q4	mmc	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Pensions And Postretirement Benefits Netof Valuation Allowance DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPensionsAndPostretirementBenefitsNetofValuationAllowance	172000000	usd
CY2023Q4	mmc	Deferred Tax Assets Operating Loss Carryforwards Domestic Net Of Valuation Allowance DeferredTaxAssetsOperatingLossCarryforwardsDomesticNetOfValuationAllowance	297000000	usd
CY2022Q4	mmc	Deferred Tax Assets Operating Loss Carryforwards Domestic Net Of Valuation Allowance DeferredTaxAssetsOperatingLossCarryforwardsDomesticNetOfValuationAllowance	285000000	usd
CY2023Q4	mmc	Deferred Tax Assets Deferred Income Net Of Valuation Allowance DeferredTaxAssetsDeferredIncomeNetOfValuationAllowance	48000000	usd
CY2022Q4	mmc	Deferred Tax Assets Deferred Income Net Of Valuation Allowance DeferredTaxAssetsDeferredIncomeNetOfValuationAllowance	34000000	usd
CY2023Q4	mmc	Deferred Tax Assets Tax Deferred Expense Other Net Of Valuation Allowance DeferredTaxAssetsTaxDeferredExpenseOtherNetOfValuationAllowance	32000000	usd
CY2022Q4	mmc	Deferred Tax Assets Tax Deferred Expense Other Net Of Valuation Allowance DeferredTaxAssetsTaxDeferredExpenseOtherNetOfValuationAllowance	25000000	usd
CY2023Q4	mmc	Deferred Tax Assets Net Net Of Valuation Allowance DeferredTaxAssetsNetNetOfValuationAllowance	1489000000	usd
CY2022Q4	mmc	Deferred Tax Assets Net Net Of Valuation Allowance DeferredTaxAssetsNetNetOfValuationAllowance	1461000000	usd
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CY2023	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
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CY2021	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2023	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.026
CY2022	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.027
CY2021	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.023
CY2023	us-gaap	Effective Income Tax Rate Reconciliation Foreign Income Tax Rate Differential EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential	0.022
CY2022	us-gaap	Effective Income Tax Rate Reconciliation Foreign Income Tax Rate Differential EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential	0.008
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CY2023	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	0
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CY2021	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	0.026
CY2023	mmc	Effective Income Tax Rate Reconciliation Gain On Deconsolidation Of Business Percent EffectiveIncomeTaxRateReconciliationGainOnDeconsolidationOfBusinessPercent	0
CY2022	mmc	Effective Income Tax Rate Reconciliation Gain On Deconsolidation Of Business Percent EffectiveIncomeTaxRateReconciliationGainOnDeconsolidationOfBusinessPercent	0
CY2021	mmc	Effective Income Tax Rate Reconciliation Gain On Deconsolidation Of Business Percent EffectiveIncomeTaxRateReconciliationGainOnDeconsolidationOfBusinessPercent	-0.015
CY2023	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense Share Based Compensation Cost EffectiveIncomeTaxRateReconciliationNondeductibleExpenseShareBasedCompensationCost	-0.007
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CY2022	us-gaap	Effective Income Tax Rate Reconciliation Tax Contingencies EffectiveIncomeTaxRateReconciliationTaxContingencies	0.001
CY2021	us-gaap	Effective Income Tax Rate Reconciliation Tax Contingencies EffectiveIncomeTaxRateReconciliationTaxContingencies	0.001
CY2023	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0.007
CY2022	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0.006
CY2021	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0.007
CY2023	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.243
CY2022	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.244
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CY2023	mmc	Operating Loss Carryforwards Percentage Subjectto Expiration OperatingLossCarryforwardsPercentageSubjecttoExpiration	0.10
CY2023	mmc	Deferred Tax Assets Operating Loss Carryforwards Not Subject To Expiration Percentage DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpirationPercentage	0.90
CY2022Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	97000000	usd
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Files In Submission

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$MMC
MARSH & MCLENNAN COMPANIES, INC. Stock $mmc

2024 Q1 Form 10-K Financial Statement

#000006270924000016 Filed on February 12, 2024

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$MMC MARSH & MCLENNAN COMPANIES, INC. Stock $mmc

2024 Q1 Form 10-K Financial Statement

#000006270924000016 Filed on February 12, 2024

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$MMC
MARSH & MCLENNAN COMPANIES, INC. Stock $mmc