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

$mmc Overview Financials Valuation SEC Filings Company Website

2024 Q4 Form 10-Q Financial Statement

#000006270924000092 Filed on October 17, 2024

Income Statement

Concept	2024 Q4	2024 Q3
Revenue		$5.697B
YoY Change		5.85%
Cost Of Revenue
YoY Change
Gross Profit
YoY Change
Gross Profit Margin
Selling, General & Admin		$3.442B
YoY Change		4.72%
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization		$359.0M
YoY Change		99.44%
% of Gross Profit
Operating Expenses		$4.589B
YoY Change		4.63%
Operating Profit		$1.108B
YoY Change		11.24%
Interest Expense		-$141.0M
YoY Change		-197.24%
% of Operating Profit		-12.73%
Other Income/Expense, Net		$68.00M
YoY Change		9.68%
Pretax Income		$1.035B
YoY Change		11.29%
Income Tax		$283.0M
% Of Pretax Income		27.34%
Net Earnings		$747.0M
YoY Change		2.33%
Net Earnings / Revenue		13.11%
Basic Earnings Per Share		$1.52
Diluted Earnings Per Share		$1.51
COMMON SHARES
Basic Shares Outstanding	491.1M shares	491.8M shares
Diluted Shares Outstanding		496.0M shares

Balance Sheet

Concept	2024 Q4	2024 Q3
SHORT-TERM ASSETS
Cash & Short-Term Investments		$1.798B
YoY Change		-87.79%
Cash & Equivalents	$2.398B	$1.798B
Short-Term Investments
Other Short-Term Assets	$1.287B	$1.143B
YoY Change	-89.25%	10.97%
Inventory
Prepaid Expenses
Receivables		$7.422B
Other Receivables		$0.00
Total Short-Term Assets	$22.12B	$22.29B
YoY Change	1.7%	0.03%
LONG-TERM ASSETS
Property, Plant & Equipment	$859.0M	$884.0M
YoY Change	-64.55%	2.91%
Goodwill	$23.31B	$18.24B
YoY Change	35.26%	9.49%
Intangibles
YoY Change
Long-Term Investments	$257.0M	$275.0M
YoY Change	-3.38%	5.77%
Other Assets	$1.730B	$1.626B
YoY Change	-56.73%	6.14%
Total Long-Term Assets	$34.36B	$27.58B
YoY Change	30.75%	7.22%
TOTAL ASSETS
Total Short-Term Assets	$22.12B	$22.29B
Total Long-Term Assets	$34.36B	$27.58B
Total Assets	$56.48B	$49.86B
YoY Change	17.6%	3.88%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable		$3.099B
YoY Change		-1.4%
Accrued Expenses		$3.098B
YoY Change		5.55%
Deferred Revenue
YoY Change
Short-Term Debt		$0.00
YoY Change
Long-Term Debt Due	$519.0M	$518.0M
YoY Change	-67.94%	-72.27%
Total Short-Term Liabilities	$19.52B	$19.60B
YoY Change	-1.4%	-4.86%
LONG-TERM LIABILITIES
Long-Term Debt	$19.43B	$12.33B
YoY Change	64.03%	4.66%
Other Long-Term Liabilities	$1.265B	$1.396B
YoY Change	-68.54%	13.87%
Total Long-Term Liabilities	$20.69B	$13.73B
YoY Change	30.43%	5.53%
TOTAL LIABILITIES
Total Short-Term Liabilities	$19.52B	$19.60B
Total Long-Term Liabilities	$20.69B	$13.73B
Total Liabilities	$40.21B	$33.33B
YoY Change	12.76%	-0.84%
SHAREHOLDERS EQUITY
Retained Earnings	$25.31B	$24.52B
YoY Change	11.19%	11.42%
Common Stock	$1.931B	$1.850B
YoY Change	7.1%	8.12%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity		$13.88B
YoY Change
Total Liabilities & Shareholders Equity	$56.48B	$49.86B
YoY Change	17.6%	3.88%

Cashflow Statement

Concept	2024 Q4	2024 Q3
OPERATING ACTIVITIES
Net Income		$747.0M
YoY Change		2.33%
Depreciation, Depletion And Amortization		$359.0M
YoY Change		99.44%
Cash From Operating Activities		$1.912B
YoY Change		5.64%
INVESTING ACTIVITIES
Capital Expenditures		$73.00M
YoY Change		-34.82%
Acquisitions
YoY Change
Other Investing Activities		-$320.0M
YoY Change		-3.03%
Cash From Investing Activities		-$393.0M
YoY Change		-11.09%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities		-1.436B
YoY Change		-245.34%
NET CHANGE
Cash From Operating Activities		1.912B
Cash From Investing Activities		-393.0M
Cash From Financing Activities		-1.436B
Net Change In Cash		83.00M
YoY Change		-96.48%
FREE CASH FLOW
Cash From Operating Activities		$1.912B
Capital Expenditures		$73.00M
Free Cash Flow		$1.839B
YoY Change		8.3%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
	dei	Entity Address City Or Town EntityAddressCityOrTown	New York
	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	10036
	dei	City Area Code CityAreaCode	212
	dei	Local Phone Number LocalPhoneNumber	345-5000
	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
	dei	Entity Small Business EntitySmallBusiness	false
	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
	dei	Entity Shell Company EntityShellCompany	false
CY2024Q4	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	491121531	shares
CY2024Q3	us-gaap	Labor And Related Expense LaborAndRelatedExpense	3442000000	usd
CY2023Q3	us-gaap	Labor And Related Expense LaborAndRelatedExpense	3287000000	usd
	us-gaap	Labor And Related Expense LaborAndRelatedExpense	10366000000	usd
	us-gaap	Labor And Related Expense LaborAndRelatedExpense	9831000000	usd
CY2024Q3	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	1147000000	usd
CY2023Q3	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	1099000000	usd
	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	3350000000	usd
CY2023Q3	us-gaap	Defined Benefit Plan Other Costs DefinedBenefitPlanOtherCosts	-62000000	usd
	us-gaap	Defined Benefit Plan Other Costs DefinedBenefitPlanOtherCosts	-201000000	usd
	us-gaap	Defined Benefit Plan Other Costs DefinedBenefitPlanOtherCosts	-180000000	usd
CY2024Q3	us-gaap	Investment Income Interest InvestmentIncomeInterest	12000000	usd
CY2023Q3	us-gaap	Investment Income Interest InvestmentIncomeInterest	16000000	usd
	us-gaap	Investment Income Interest InvestmentIncomeInterest	61000000	usd
	us-gaap	Investment Income Interest InvestmentIncomeInterest	40000000	usd
	dei	Document Quarterly Report DocumentQuarterlyReport	true
	dei	Entity Address State Or Province EntityAddressStateOrProvince	NY
	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	3172000000	usd
CY2024Q3	us-gaap	Operating Expenses OperatingExpenses	4589000000	usd
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	1155000000	usd
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	941000000	usd
CY2024Q3	us-gaap	Profit Loss ProfitLoss	752000000	usd
CY2023Q3	us-gaap	Profit Loss ProfitLoss	738000000	usd
	us-gaap	Profit Loss ProfitLoss	3316000000	usd
	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	44000000	usd
	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	37000000	usd
CY2024Q3	us-gaap	Net Income Loss NetIncomeLoss	747000000	usd
CY2023Q3	us-gaap	Net Income Loss NetIncomeLoss	730000000	usd
	us-gaap	Net Income Loss NetIncomeLoss	3272000000	usd
CY2024Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.52
CY2023Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.48
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	6.65
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	6.07
CY2024Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.51
CY2023Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.47
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	6.59
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	6.01
CY2024Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	492000000	shares
CY2023Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	494000000	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	492000000	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	494000000	shares
CY2024Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	496000000	shares
CY2023Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	499000000	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	496000000	shares
CY2024Q3	us-gaap	Gain Loss On Investments GainLossOnInvestments	1000000	usd
	us-gaap	Gain Loss On Investments GainLossOnInvestments	3000000	usd
	us-gaap	Gain Loss On Investments GainLossOnInvestments	6000000	usd
CY2024Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	1035000000	usd
CY2023Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	930000000	usd
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	4471000000	usd
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	3978000000	usd
CY2024Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	283000000	usd
CY2023Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	192000000	usd
	us-gaap	Profit Loss ProfitLoss	3037000000	usd
CY2024Q3	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	5000000	usd
CY2023Q3	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	8000000	usd
CY2023Q4	us-gaap	Accounts Receivable Gross Current AccountsReceivableGrossCurrent	6569000000	usd
CY2024Q3	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	165000000	usd
CY2023Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	151000000	usd
CY2024Q3	us-gaap	Receivables Net Current ReceivablesNetCurrent	7422000000	usd
CY2023Q4	us-gaap	Receivables Net Current ReceivablesNetCurrent	6418000000	usd
CY2024Q3	us-gaap	Other Assets Current OtherAssetsCurrent	1143000000	usd
CY2023Q4	us-gaap	Other Assets Current OtherAssetsCurrent	1178000000	usd
CY2024Q3	us-gaap	Assets Current AssetsCurrent	22286000000	usd
CY2023Q4	us-gaap	Assets Current AssetsCurrent	21748000000	usd
CY2024Q3	us-gaap	Goodwill Goodwill	18235000000	usd
CY2023Q4	us-gaap	Goodwill Goodwill	17231000000	usd
CY2024Q3	us-gaap	Other Intangible Assets Net OtherIntangibleAssetsNet	2720000000	usd
CY2023Q4	us-gaap	Other Intangible Assets Net OtherIntangibleAssetsNet	2630000000	usd
CY2024Q3	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	1638000000	usd
CY2023Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	1562000000	usd
	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	37000000	usd
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	3577000000	usd
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	2854000000	usd
CY2024Q3	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	1798000000	usd
CY2023Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	3358000000	usd
CY2024Q3	mmc	Accrued Feesand Other Revenue Receivable Gross Current AccruedFeesandOtherRevenueReceivableGrossCurrent	6783000000	usd
CY2023Q4	mmc	Accrued Feesand Other Revenue Receivable Gross Current AccruedFeesandOtherRevenueReceivableGrossCurrent	5806000000	usd
CY2024Q3	mmc	Advanced Premiumsand Claims Receivable Gross Current AdvancedPremiumsandClaimsReceivableGrossCurrent	102000000	usd
CY2023Q4	mmc	Advanced Premiumsand Claims Receivable Gross Current AdvancedPremiumsandClaimsReceivableGrossCurrent	103000000	usd
CY2024Q3	us-gaap	Other Receivables Gross Current OtherReceivablesGrossCurrent	702000000	usd
CY2023Q4	us-gaap	Other Receivables Gross Current OtherReceivablesGrossCurrent	660000000	usd
CY2024Q3	us-gaap	Accounts Receivable Gross Current AccountsReceivableGrossCurrent	7587000000	usd
CY2024Q3	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	1487000000	usd
CY2023Q4	us-gaap	Deferred Income Tax Assets Net DeferredIncomeTaxAssetsNet	357000000	usd
CY2024Q3	us-gaap	Defined Benefit Plan Assets For Plan Benefits Noncurrent DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent	2384000000	usd
CY2023Q4	us-gaap	Defined Benefit Plan Assets For Plan Benefits Noncurrent DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent	2051000000	usd
CY2024Q3	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	1626000000	usd
CY2024Q3	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	2785000000	usd
CY2023Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	3346000000	usd
CY2024Q3	us-gaap	Operating Lease Liability Current OperatingLeaseLiabilityCurrent	313000000	usd
CY2023Q4	us-gaap	Operating Lease Liability Current OperatingLeaseLiabilityCurrent	312000000	usd
CY2024Q3	us-gaap	Assets Assets	49864000000	usd
CY2023Q4	us-gaap	Debt Current DebtCurrent	1619000000	usd
CY2024Q3	us-gaap	Accounts Payable And Accrued Liabilities Current AccountsPayableAndAccruedLiabilitiesCurrent	3099000000	usd
CY2023Q4	us-gaap	Accounts Payable And Accrued Liabilities Current AccountsPayableAndAccruedLiabilitiesCurrent	3403000000	usd
CY2024Q3	us-gaap	Accrued Income Taxes Current AccruedIncomeTaxesCurrent	565000000	usd
CY2023Q4	us-gaap	Accrued Income Taxes Current AccruedIncomeTaxesCurrent	321000000	usd
	us-gaap	Gain Loss On Sale Of Other Assets GainLossOnSaleOfOtherAssets	18000000	usd
	us-gaap	Gain Loss On Sale Of Other Assets GainLossOnSaleOfOtherAssets	-18000000	usd
	us-gaap	Share Based Compensation ShareBasedCompensation	283000000	usd
	us-gaap	Share Based Compensation ShareBasedCompensation	273000000	usd
	us-gaap	Increase Decrease In Receivables IncreaseDecreaseInReceivables	821000000	usd
	us-gaap	Increase Decrease In Receivables IncreaseDecreaseInReceivables	670000000	usd
	us-gaap	Increase Decrease In Other Noncurrent Assets IncreaseDecreaseInOtherNoncurrentAssets	45000000	usd
	us-gaap	Increase Decrease In Other Noncurrent Assets IncreaseDecreaseInOtherNoncurrentAssets	98000000	usd
	us-gaap	Increase Decrease In Employee Related Liabilities IncreaseDecreaseInEmployeeRelatedLiabilities	-582000000	usd
	us-gaap	Increase Decrease In Employee Related Liabilities IncreaseDecreaseInEmployeeRelatedLiabilities	-458000000	usd
	us-gaap	Increase Decrease In Accrued Income Taxes Payable IncreaseDecreaseInAccruedIncomeTaxesPayable	233000000	usd
	us-gaap	Increase Decrease In Accrued Income Taxes Payable IncreaseDecreaseInAccruedIncomeTaxesPayable	242000000	usd
	mmc	Pensionand Other Postretirement Benefit Contributions In Excessof Current Year Expense PensionandOtherPostretirementBenefitContributionsInExcessofCurrentYearExpense	262000000	usd
	mmc	Pensionand Other Postretirement Benefit Contributions In Excessof Current Year Expense PensionandOtherPostretirementBenefitContributionsInExcessofCurrentYearExpense	246000000	usd
	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-103000000	usd
	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	900000000	usd
	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	900000000	usd
	us-gaap	Proceeds From Issuance Of Debt ProceedsFromIssuanceOfDebt	988000000	usd
	us-gaap	Proceeds From Issuance Of Debt ProceedsFromIssuanceOfDebt	2170000000	usd
	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	1613000000	usd
	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	12000000	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
CY2023Q3	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	11586000000	usd
	mmc	Common Stock Dividends Per Share Cash Declared CommonStockDividendsPerShareCashDeclared	3.05
	mmc	Common Stock Dividends Per Share Cash Declared CommonStockDividendsPerShareCashDeclared	2.60
	us-gaap	Gain Loss On Investments GainLossOnInvestments	6000000	usd
	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.258
	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.237
CY2024Q3	us-gaap	Effective Income Tax Rate Reconciliation Share Based Compensation Excess Tax Benefit Percent EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitPercent	-0.003
CY2024Q3	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	122000000	usd
	us-gaap	Restructuring Charges RestructuringCharges	140000000	usd
	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2024
	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	Q3
	dei	Amendment Flag AmendmentFlag	false
	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
	us-gaap	Net Income Loss NetIncomeLoss	3000000000	usd
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	499000000	shares
CY2023Q3	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	493000000	shares
CY2024Q3	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	491000000	shares
CY2024Q3	us-gaap	Profit Loss ProfitLoss	752000000	usd
CY2023Q3	us-gaap	Profit Loss ProfitLoss	738000000	usd
	us-gaap	Profit Loss ProfitLoss	3316000000	usd
	us-gaap	Profit Loss ProfitLoss	3037000000	usd
CY2024Q3	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Before Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentBeforeTax	661000000	usd
	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Before Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentBeforeTax	389000000	usd
	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Before Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentBeforeTax	-131000000	usd
CY2024Q3	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	173000000	usd
CY2023Q3	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	-107000000	usd
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	105000000	usd
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	13000000	usd
CY2024Q3	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	488000000	usd
CY2023Q3	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	-366000000	usd
	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	284000000	usd
	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	-144000000	usd
CY2023Q3	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	39000000	usd
	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	-21000000	usd
CY2024Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	537000000	usd
CY2023Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-405000000	usd
CY2024Q3	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	1289000000	usd
CY2023Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	882000000	usd
CY2023Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	1541000000	usd
CY2024Q3	us-gaap	Deferred Income Tax Assets Net DeferredIncomeTaxAssetsNet	242000000	usd
CY2023Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	1590000000	usd
CY2023Q4	us-gaap	Assets Assets	48030000000	usd
CY2023Q3	us-gaap	Gain Loss On Investments GainLossOnInvestments	1000000	usd
CY2023Q3	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	493000000	shares
CY2023Q3	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Before Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentBeforeTax	-473000000	usd
CY2024Q3	us-gaap	Dividends Payable Current DividendsPayableCurrent	401000000	usd
CY2023Q4	us-gaap	Dividends Payable Current DividendsPayableCurrent	0	usd
CY2024Q3	mmc	Fiduciary Liabilities Current FiduciaryLiabilitiesCurrent	11923000000	usd
CY2023Q4	us-gaap	Liabilities Current LiabilitiesCurrent	19795000000	usd
CY2024Q3	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	12330000000	usd
CY2023Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	11844000000	usd
CY2024Q3	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	704000000	usd
CY2023Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	779000000	usd
CY2024Q3	us-gaap	Operating Lease Liability Noncurrent OperatingLeaseLiabilityNoncurrent	1618000000	usd
CY2023Q4	us-gaap	Operating Lease Liability Noncurrent OperatingLeaseLiabilityNoncurrent	1661000000	usd
CY2023Q4	mmc	Liability For Errors And Omissions LiabilityForErrorsAndOmissions	314000000	usd
CY2024Q3	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	1396000000	usd
CY2023Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	1267000000	usd
CY2024Q3	us-gaap	Commitments And Contingencies CommitmentsAndContingencies	0	usd
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CY2024Q3	us-gaap	Preferred Stock Par Or Stated Value Per Share PreferredStockParOrStatedValuePerShare	1
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	us-gaap	Profit Loss ProfitLoss	3316000000	usd
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	us-gaap	Interest Expense Nonoperating InterestExpenseNonoperating	469000000	usd
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CY2024Q3	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	884000000	usd
	dei	Document Transition Report DocumentTransitionReport	false
	dei	Entity Registrant Name EntityRegistrantName	Marsh & McLennan Companies, Inc.
	dei	Entity Address Address Line1 EntityAddressAddressLine1	1166 Avenue of the Americas
CY2024Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	1108000000	usd
	dei	Entity Central Index Key EntityCentralIndexKey	0000062709
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	dei	Entity File Number EntityFileNumber	1-5998
	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	DE
	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	36-2668272
	dei	Security12b Title Security12bTitle	Common Stock, par value $1.00 per share
	dei	Trading Symbol TradingSymbol	MMC
	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
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CY2024Q3	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	13882000000	usd
CY2023Q3	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	11586000000	usd
CY2024Q3	mmc	Common Stock Dividends Per Share Cash Declared CommonStockDividendsPerShareCashDeclared	1.63
CY2023Q3	mmc	Common Stock Dividends Per Share Cash Declared CommonStockDividendsPerShareCashDeclared	1.42
	us-gaap	Nature Of Operations NatureOfOperations	Nature of Operations <div style="margin-top:5pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Marsh & McLennan Companies, Inc., and its consolidated subsidiaries (the "Company"), a global professional services firm, is organized based on the different services that it offers. Under this structure, the Company’s two business segments are Risk and Insurance Services and Consulting.</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 Risk and Insurance Services segment ("RIS") includes risk management activities (risk advice, risk transfer, and risk control and mitigation solutions) as well as insurance and reinsurance broking and services for businesses, public entities, insurance companies, associations, professional services organizations, and private clients. The Company conducts business in this segment through Marsh and Guy Carpenter. Marsh provides data-driven risk advisory services and insurance solutions to commercial and consumer clients. Guy Carpenter develops advanced risk, reinsurance and capital strategies that help clients grow profitably and pursue emerging opportunities.</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 Consulting segment includes health, wealth and career advice, solutions and products, and specialized management, strategic, economic and brand consulting services. The Company conducts business in this segment through Mercer and Oliver Wyman Group. Mercer delivers advice and technology-driven solutions that help organizations redefine the future of work, reshape retirement and investment outcomes, and unlock health and well-being for a changing workforce. Oliver Wyman Group serves as a critical strategic, economic and brand advisor to private sector and governmental clients.</span></div>
	us-gaap	Number Of Operating Segments NumberOfOperatingSegments	2	segment
CY2024Q3	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	13882000000	usd
CY2023Q3	mmc	Common Stock Dividends Per Share Cash Declared CommonStockDividendsPerShareCashDeclared	1.42
	us-gaap	Nature Of Operations NatureOfOperations	Nature of Operations <div style="margin-top:5pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Marsh & McLennan Companies, Inc., and its consolidated subsidiaries (the "Company"), a global professional services firm, is organized based on the different services that it offers. Under this structure, the Company’s two business segments are Risk and Insurance Services and Consulting.</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 Risk and Insurance Services segment ("RIS") includes risk management activities (risk advice, risk transfer, and risk control and mitigation solutions) as well as insurance and reinsurance broking and services for businesses, public entities, insurance companies, associations, professional services organizations, and private clients. The Company conducts business in this segment through Marsh and Guy Carpenter. Marsh provides data-driven risk advisory services and insurance solutions to commercial and consumer clients. Guy Carpenter develops advanced risk, reinsurance and capital strategies that help clients grow profitably and pursue emerging opportunities.</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 Consulting segment includes health, wealth and career advice, solutions and products, and specialized management, strategic, economic and brand consulting services. The Company conducts business in this segment through Mercer and Oliver Wyman Group. Mercer delivers advice and technology-driven solutions that help organizations redefine the future of work, reshape retirement and investment outcomes, and unlock health and well-being for a changing workforce. Oliver Wyman Group serves as a critical strategic, economic and brand advisor to private sector and governmental clients.</span></div>
	us-gaap	Number Of Operating Segments NumberOfOperatingSegments	2	segment
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	us-gaap	Effective Income Tax Rate Reconciliation Share Based Compensation Excess Tax Benefit Percent EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitPercent	-0.013
	us-gaap	Effective Income Tax Rate Reconciliation Share Based Compensation Excess Tax Benefit Percent EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitPercent	-0.012
CY2023Q3	us-gaap	Effective Income Tax Rate Reconciliation Share Based Compensation Excess Tax Benefit Percent EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitPercent	-0.010
CY2023Q3	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	48000000	usd
CY2023Q3	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	-0.048
	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	-0.011
CY2023Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	124000000	usd
CY2024Q3	us-gaap	Decrease In Unrecognized Tax Benefits Is Reasonably Possible DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible	66000000	usd
CY2024Q3	us-gaap	Restricted Cash Current RestrictedCashCurrent	507000000	usd
CY2023Q4	us-gaap	Restricted Cash Current RestrictedCashCurrent	486000000	usd
	mmc	Equity Method Investment Lag Period EquityMethodInvestmentLagPeriod	P3M
CY2024Q3	us-gaap	Gain Loss On Investments GainLossOnInvestments	1000000	usd
	us-gaap	Gain Loss On Investments GainLossOnInvestments	3000000	usd
CY2024Q3	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.273
CY2023Q3	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.206
	us-gaap	Effective Income Tax Rate Reconciliation Share Based Compensation Excess Tax Benefit Percent EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitPercent	-0.013
	us-gaap	Effective Income Tax Rate Reconciliation Share Based Compensation Excess Tax Benefit Percent EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitPercent	-0.012
CY2023Q3	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	48000000	usd
CY2023Q3	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	-0.048
	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	-0.011
CY2023Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	124000000	usd
CY2024Q3	us-gaap	Decrease In Unrecognized Tax Benefits Is Reasonably Possible DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible	66000000	usd
	mmc	Revenue From Contract With Customer Threshold Percentage Of Total Revenue RevenueFromContractWithCustomerThresholdPercentageOfTotalRevenue	0.01
CY2024Q3	us-gaap	Contract With Customer Asset Net ContractWithCustomerAssetNet	433000000	usd
CY2023Q4	us-gaap	Contract With Customer Asset Net ContractWithCustomerAssetNet	357000000	usd
CY2024Q3	us-gaap	Contract With Customer Liability ContractWithCustomerLiability	864000000	usd
CY2023Q4	us-gaap	Contract With Customer Liability ContractWithCustomerLiability	869000000	usd
CY2024Q3	us-gaap	Contract With Customer Liability Revenue Recognized ContractWithCustomerLiabilityRevenueRecognized	149000000	usd
	us-gaap	Contract With Customer Liability Revenue Recognized ContractWithCustomerLiabilityRevenueRecognized	730000000	usd
CY2023Q3	us-gaap	Contract With Customer Liability Revenue Recognized ContractWithCustomerLiabilityRevenueRecognized	187000000	usd
	us-gaap	Contract With Customer Liability Revenue Recognized ContractWithCustomerLiabilityRevenueRecognized	698000000	usd
CY2024Q3	us-gaap	Contract With Customer Performance Obligation Satisfied In Previous Period ContractWithCustomerPerformanceObligationSatisfiedInPreviousPeriod	18000000	usd
	us-gaap	Contract With Customer Performance Obligation Satisfied In Previous Period ContractWithCustomerPerformanceObligationSatisfiedInPreviousPeriod	61000000	usd
CY2023Q3	us-gaap	Contract With Customer Performance Obligation Satisfied In Previous Period ContractWithCustomerPerformanceObligationSatisfiedInPreviousPeriod	20000000	usd
	us-gaap	Contract With Customer Performance Obligation Satisfied In Previous Period ContractWithCustomerPerformanceObligationSatisfiedInPreviousPeriod	64000000	usd
CY2024Q3	us-gaap	Contract With Customer Asset Net ContractWithCustomerAssetNet	433000000	usd
CY2023Q4	us-gaap	Contract With Customer Asset Net ContractWithCustomerAssetNet	357000000	usd
CY2024Q3	us-gaap	Contract With Customer Liability ContractWithCustomerLiability	864000000	usd
CY2023Q4	us-gaap	Contract With Customer Liability ContractWithCustomerLiability	869000000	usd
CY2024Q3	us-gaap	Contract With Customer Liability Revenue Recognized ContractWithCustomerLiabilityRevenueRecognized	149000000	usd
	us-gaap	Contract With Customer Liability Revenue Recognized ContractWithCustomerLiabilityRevenueRecognized	730000000	usd
CY2023Q3	us-gaap	Contract With Customer Liability Revenue Recognized ContractWithCustomerLiabilityRevenueRecognized	187000000	usd
CY2024Q3	us-gaap	Contract With Customer Performance Obligation Satisfied In Previous Period ContractWithCustomerPerformanceObligationSatisfiedInPreviousPeriod	18000000	usd
CY2023Q3	us-gaap	Contract With Customer Performance Obligation Satisfied In Previous Period ContractWithCustomerPerformanceObligationSatisfiedInPreviousPeriod	20000000	usd
CY2024Q3	mmc	Uncollected Premiumsand Claims Netof Related Payables UncollectedPremiumsandClaimsNetofRelatedPayables	15600000000	usd
CY2023Q4	mmc	Uncollected Premiumsand Claims Netof Related Payables UncollectedPremiumsandClaimsNetofRelatedPayables	13800000000	usd
CY2024Q3	mmc	Uncollected Premiumsand Claims Netof Related Payables UncollectedPremiumsandClaimsNetofRelatedPayables	15600000000	usd
CY2024Q3	us-gaap	Profit Loss ProfitLoss	752000000	usd
CY2023Q3	us-gaap	Profit Loss ProfitLoss	738000000	usd
	us-gaap	Profit Loss ProfitLoss	3316000000	usd
	us-gaap	Profit Loss ProfitLoss	3037000000	usd
CY2024Q3	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	5000000	usd
CY2023Q3	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	8000000	usd
	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	44000000	usd
	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	37000000	usd
CY2024Q3	us-gaap	Net Income Loss NetIncomeLoss	747000000	usd
CY2023Q3	us-gaap	Net Income Loss NetIncomeLoss	730000000	usd
	us-gaap	Net Income Loss NetIncomeLoss	3272000000	usd
	us-gaap	Net Income Loss NetIncomeLoss	3000000000	usd
CY2024Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	492000000	shares
CY2023Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	494000000	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	492000000	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	494000000	shares
CY2024Q3	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	4000000	shares
CY2023Q3	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	5000000	shares
	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	4000000	shares
CY2024Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	496000000	shares
CY2023Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	499000000	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	496000000	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	499000000	shares
CY2024Q3	mmc	Average Share Price Common Stock AverageSharePriceCommonStock	222.13
CY2023Q3	mmc	Average Share Price Common Stock AverageSharePriceCommonStock	191.66
	mmc	Average Share Price Common Stock AverageSharePriceCommonStock	209.06
	mmc	Average Share Price Common Stock AverageSharePriceCommonStock	178.64
	mmc	Business Combination Consideration Transferred Assets Acquired BusinessCombinationConsiderationTransferredAssetsAcquired	1310000000	usd
	mmc	Business Combination Consideration Transferred Assets Acquired BusinessCombinationConsiderationTransferredAssetsAcquired	760000000	usd
	mmc	Business Combination Consideration Transferred Fiduciary Liabilities Assumed BusinessCombinationConsiderationTransferredFiduciaryLiabilitiesAssumed	8000000	usd
	mmc	Business Combination Consideration Transferred Fiduciary Liabilities Assumed BusinessCombinationConsiderationTransferredFiduciaryLiabilitiesAssumed	14000000	usd
	mmc	Business Combination Consideration Transferred Liabilities Assumed BusinessCombinationConsiderationTransferredLiabilitiesAssumed	84000000	usd
CY2024Q3	us-gaap	Profit Loss ProfitLoss	752000000	usd
CY2023Q3	us-gaap	Profit Loss ProfitLoss	738000000	usd
	us-gaap	Profit Loss ProfitLoss	3316000000	usd
	us-gaap	Profit Loss ProfitLoss	3037000000	usd
CY2024Q3	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	5000000	usd
CY2023Q3	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	8000000	usd
	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	44000000	usd
	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	37000000	usd
CY2024Q3	us-gaap	Net Income Loss NetIncomeLoss	747000000	usd
CY2023Q3	us-gaap	Net Income Loss NetIncomeLoss	730000000	usd
	us-gaap	Net Income Loss NetIncomeLoss	3272000000	usd
CY2024Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	492000000	shares
CY2023Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	494000000	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	492000000	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	494000000	shares
	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	4000000	shares
	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	5000000	shares
CY2024Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	496000000	shares
CY2023Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	499000000	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	496000000	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	499000000	shares
CY2024Q3	mmc	Average Share Price Common Stock AverageSharePriceCommonStock	222.13
CY2023Q3	mmc	Average Share Price Common Stock AverageSharePriceCommonStock	191.66
	mmc	Average Share Price Common Stock AverageSharePriceCommonStock	209.06
	mmc	Average Share Price Common Stock AverageSharePriceCommonStock	178.64
	mmc	Business Combination Consideration Transferred Assets Acquired BusinessCombinationConsiderationTransferredAssetsAcquired	1310000000	usd
	mmc	Business Combination Consideration Transferred Assets Acquired BusinessCombinationConsiderationTransferredAssetsAcquired	760000000	usd
	mmc	Business Combination Consideration Transferred Fiduciary Liabilities Assumed BusinessCombinationConsiderationTransferredFiduciaryLiabilitiesAssumed	8000000	usd
	mmc	Business Combination Consideration Transferred Fiduciary Liabilities Assumed BusinessCombinationConsiderationTransferredFiduciaryLiabilitiesAssumed	14000000	usd
	mmc	Business Combination Consideration Transferred Liabilities Assumed BusinessCombinationConsiderationTransferredLiabilitiesAssumed	84000000	usd
	mmc	Business Combination Consideration Transferred Liabilities Assumed BusinessCombinationConsiderationTransferredLiabilitiesAssumed	98000000	usd
	mmc	Business Combination Consideration Contingent And Deferred Purchase Consideration BusinessCombinationConsiderationContingentAndDeferredPurchaseConsideration	176000000	usd
	mmc	Business Combination Consideration Contingent And Deferred Purchase Consideration BusinessCombinationConsiderationContingentAndDeferredPurchaseConsideration	29000000	usd
	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	1042000000	usd
	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	619000000	usd
	us-gaap	Interest Paid Net InterestPaidNet	538000000	usd
	us-gaap	Interest Paid Net InterestPaidNet	427000000	usd
	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	922000000	usd
	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	699000000	usd
	mmc	Paymentof Contingent Consideration PaymentofContingentConsideration	90000000	usd
	mmc	Paymentof Contingent Consideration PaymentofContingentConsideration	41000000	usd
	mmc	Proceeds From Contingent Consideration Prior Period Dispositions ProceedsFromContingentConsiderationPriorPeriodDispositions	0	usd
	mmc	Business Combination Consideration Transferred Liabilities Assumed BusinessCombinationConsiderationTransferredLiabilitiesAssumed	98000000	usd
	mmc	Business Combination Consideration Contingent And Deferred Purchase Consideration BusinessCombinationConsiderationContingentAndDeferredPurchaseConsideration	176000000	usd
	mmc	Business Combination Consideration Contingent And Deferred Purchase Consideration BusinessCombinationConsiderationContingentAndDeferredPurchaseConsideration	29000000	usd
	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	1042000000	usd
	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	619000000	usd
	us-gaap	Interest Paid Net InterestPaidNet	538000000	usd
	us-gaap	Interest Paid Net InterestPaidNet	427000000	usd
	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	922000000	usd
	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	699000000	usd
	mmc	Paymentof Contingent Consideration PaymentofContingentConsideration	90000000	usd
	mmc	Paymentof Contingent Consideration PaymentofContingentConsideration	41000000	usd
	mmc	Proceeds From Contingent Consideration Prior Period Dispositions ProceedsFromContingentConsiderationPriorPeriodDispositions	0	usd
	mmc	Proceeds From Contingent Consideration Prior Period Dispositions ProceedsFromContingentConsiderationPriorPeriodDispositions	1000000	usd
	mmc	Fair Value Measurementwith Unobservable Inputs Reconciliation Recurring Basis Liability Gain Loss Includedin Earnings Net FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedinEarningsNet	-21000000	usd
	mmc	Fair Value Measurementwith Unobservable Inputs Reconciliation Recurring Basis Liability Gain Loss Includedin Earnings Net FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedinEarningsNet	-21000000	usd
	mmc	Adjustments And Payments Related To Contingent Consideration AdjustmentsAndPaymentsRelatedToContingentConsideration	69000000	usd
	mmc	Adjustments And Payments Related To Contingent Consideration AdjustmentsAndPaymentsRelatedToContingentConsideration	19000000	usd
	mmc	Payments For Previous Acquisition Contingent Consideration PaymentsForPreviousAcquisitionContingentConsideration	73000000	usd
	mmc	Payments For Previous Acquisition Contingent Consideration PaymentsForPreviousAcquisitionContingentConsideration	135000000	usd
	mmc	Payments For Previous Acquisition Deferred Consideration PaymentsForPreviousAcquisitionDeferredConsideration	18000000	usd
	mmc	Payments For Previous Acquisition Deferred Consideration PaymentsForPreviousAcquisitionDeferredConsideration	52000000	usd
	mmc	Payments For Previous Acquisition Deferredand Contingent Consideration PaymentsForPreviousAcquisitionDeferredandContingentConsideration	91000000	usd
	mmc	Payments For Previous Acquisition Deferredand Contingent Consideration PaymentsForPreviousAcquisitionDeferredandContingentConsideration	187000000	usd
	mmc	Proceeds From Previous Disposition Contingent Consideration ProceedsFromPreviousDispositionContingentConsideration	1000000	usd
	mmc	Proceeds From Previous Disposition Contingent Consideration ProceedsFromPreviousDispositionContingentConsideration	2000000	usd
	us-gaap	Stock Issued1 StockIssued1	328000000	usd
	us-gaap	Stock Issued1 StockIssued1	304000000	usd
CY2024Q3	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	90000000	usd
	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	283000000	usd
CY2023Q3	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	82000000	usd
	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	273000000	usd
CY2024Q3	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	488000000	usd
CY2024Q3	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	-49000000	usd
CY2024Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	537000000	usd
CY2023Q3	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	-366000000	usd
CY2023Q3	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	39000000	usd
CY2023Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-405000000	usd
	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	284000000	usd
	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	-21000000	usd
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	305000000	usd
	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	-144000000	usd
	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	2000000	usd
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-146000000	usd
	us-gaap	Business Combination Consideration Transferred1 BusinessCombinationConsiderationTransferred1	1300000000	usd
	us-gaap	Payments To Acquire Businesses Gross PaymentsToAcquireBusinessesGross	1100000000	usd
	mmc	Business Combination Contingent And Deferred Consideration BusinessCombinationContingentAndDeferredConsideration	176000000	usd
	mmc	Payments For Previous Acquisition Deferred Consideration PaymentsForPreviousAcquisitionDeferredConsideration	18000000	usd
	mmc	Proceeds From Contingent Consideration Prior Period Dispositions ProceedsFromContingentConsiderationPriorPeriodDispositions	1000000	usd
	mmc	Fair Value Measurementwith Unobservable Inputs Reconciliation Recurring Basis Liability Gain Loss Includedin Earnings Net FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedinEarningsNet	-21000000	usd
	mmc	Adjustments And Payments Related To Contingent Consideration AdjustmentsAndPaymentsRelatedToContingentConsideration	69000000	usd
	mmc	Adjustments And Payments Related To Contingent Consideration AdjustmentsAndPaymentsRelatedToContingentConsideration	19000000	usd
	mmc	Payments For Previous Acquisition Contingent Consideration PaymentsForPreviousAcquisitionContingentConsideration	73000000	usd
	mmc	Payments For Previous Acquisition Contingent Consideration PaymentsForPreviousAcquisitionContingentConsideration	135000000	usd
	mmc	Payments For Previous Acquisition Deferred Consideration PaymentsForPreviousAcquisitionDeferredConsideration	18000000	usd
	mmc	Payments For Previous Acquisition Deferred Consideration PaymentsForPreviousAcquisitionDeferredConsideration	52000000	usd
	mmc	Payments For Previous Acquisition Deferredand Contingent Consideration PaymentsForPreviousAcquisitionDeferredandContingentConsideration	91000000	usd
	mmc	Payments For Previous Acquisition Deferredand Contingent Consideration PaymentsForPreviousAcquisitionDeferredandContingentConsideration	187000000	usd
	mmc	Proceeds From Previous Disposition Contingent Consideration ProceedsFromPreviousDispositionContingentConsideration	1000000	usd
	mmc	Proceeds From Previous Disposition Contingent Consideration ProceedsFromPreviousDispositionContingentConsideration	2000000	usd
	us-gaap	Stock Issued1 StockIssued1	328000000	usd
	us-gaap	Stock Issued1 StockIssued1	304000000	usd
CY2024Q3	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	90000000	usd
	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	283000000	usd
CY2023Q3	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	82000000	usd
	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	273000000	usd
CY2024Q3	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	488000000	usd
CY2024Q3	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	-49000000	usd
CY2023Q3	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	-366000000	usd
CY2023Q3	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	39000000	usd
CY2023Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-405000000	usd
	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	284000000	usd
	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	-21000000	usd
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	305000000	usd
	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	-144000000	usd
	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	2000000	usd
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-146000000	usd
	us-gaap	Business Combination Consideration Transferred1 BusinessCombinationConsiderationTransferred1	1300000000	usd
	us-gaap	Payments To Acquire Businesses Gross PaymentsToAcquireBusinessesGross	1100000000	usd
	mmc	Business Combination Contingent And Deferred Consideration BusinessCombinationContingentAndDeferredConsideration	176000000	usd
	mmc	Payments For Previous Acquisition Deferred Consideration PaymentsForPreviousAcquisitionDeferredConsideration	18000000	usd
	us-gaap	Finitelived Intangible Assets Acquired1 FinitelivedIntangibleAssetsAcquired1	371000000	usd
	us-gaap	Business Combination Consideration Transferred1 BusinessCombinationConsiderationTransferred1	711000000	usd
	us-gaap	Payments To Acquire Businesses Gross PaymentsToAcquireBusinessesGross	682000000	usd
	mmc	Business Combination Contingent And Deferred Consideration BusinessCombinationContingentAndDeferredConsideration	29000000	usd
CY2023Q1	mmc	Contingent Consideration Fiduciary Cash And Cash Equivalents Held ContingentConsiderationFiduciaryCashAndCashEquivalentsHeld	20000000	usd
CY2023Q2	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	139000000	usd
CY2024Q3	us-gaap	Business Acquisitions Pro Forma Revenue BusinessAcquisitionsProFormaRevenue	5707000000	usd
CY2023Q3	us-gaap	Business Acquisitions Pro Forma Revenue BusinessAcquisitionsProFormaRevenue	5494000000	usd
	us-gaap	Business Acquisitions Pro Forma Revenue BusinessAcquisitionsProFormaRevenue	18535000000	usd
	us-gaap	Business Acquisitions Pro Forma Revenue BusinessAcquisitionsProFormaRevenue	17621000000	usd
CY2024Q3	us-gaap	Business Acquisitions Pro Forma Net Income Loss BusinessAcquisitionsProFormaNetIncomeLoss	755000000	usd
CY2023Q3	us-gaap	Business Acquisitions Pro Forma Net Income Loss BusinessAcquisitionsProFormaNetIncomeLoss	749000000	usd
	us-gaap	Business Acquisitions Pro Forma Net Income Loss BusinessAcquisitionsProFormaNetIncomeLoss	3309000000	usd
	us-gaap	Business Acquisitions Pro Forma Net Income Loss BusinessAcquisitionsProFormaNetIncomeLoss	3065000000	usd
CY2024Q3	us-gaap	Business Acquisition Pro Forma Income Loss From Continuing Operations Before Changes In Accounting And Extraordinary Items Net Of Tax Per Share Basic BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareBasic	1.54
CY2023Q3	us-gaap	Business Acquisition Pro Forma Income Loss From Continuing Operations Before Changes In Accounting And Extraordinary Items Net Of Tax Per Share Basic BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareBasic	1.52
	us-gaap	Business Acquisition Pro Forma Income Loss From Continuing Operations Before Changes In Accounting And Extraordinary Items Net Of Tax Per Share Basic BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareBasic	6.73
	us-gaap	Business Acquisition Pro Forma Income Loss From Continuing Operations Before Changes In Accounting And Extraordinary Items Net Of Tax Per Share Basic BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareBasic	6.20
CY2024Q3	us-gaap	Business Acquisition Pro Forma Income Loss From Continuing Operations Before Changes In Accounting And Extraordinary Items Net Of Tax Per Share Diluted BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareDiluted	1.52
CY2023Q3	us-gaap	Business Acquisition Pro Forma Income Loss From Continuing Operations Before Changes In Accounting And Extraordinary Items Net Of Tax Per Share Diluted BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareDiluted	1.50
	us-gaap	Business Acquisition Pro Forma Income Loss From Continuing Operations Before Changes In Accounting And Extraordinary Items Net Of Tax Per Share Diluted BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareDiluted	6.67
	us-gaap	Business Acquisition Pro Forma Income Loss From Continuing Operations Before Changes In Accounting And Extraordinary Items Net Of Tax Per Share Diluted BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareDiluted	6.14
	us-gaap	Finitelived Intangible Assets Acquired1 FinitelivedIntangibleAssetsAcquired1	371000000	usd
	us-gaap	Business Combination Consideration Transferred1 BusinessCombinationConsiderationTransferred1	711000000	usd
	us-gaap	Payments To Acquire Businesses Gross PaymentsToAcquireBusinessesGross	682000000	usd
	mmc	Business Combination Contingent And Deferred Consideration BusinessCombinationContingentAndDeferredConsideration	29000000	usd
CY2023Q1	mmc	Contingent Consideration Fiduciary Cash And Cash Equivalents Held ContingentConsiderationFiduciaryCashAndCashEquivalentsHeld	20000000	usd
CY2023Q2	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	139000000	usd
CY2024Q3	us-gaap	Business Acquisitions Pro Forma Revenue BusinessAcquisitionsProFormaRevenue	5707000000	usd
	us-gaap	Business Acquisitions Pro Forma Revenue BusinessAcquisitionsProFormaRevenue	17621000000	usd
CY2024Q3	us-gaap	Business Acquisitions Pro Forma Net Income Loss BusinessAcquisitionsProFormaNetIncomeLoss	755000000	usd
CY2023Q3	us-gaap	Business Acquisitions Pro Forma Net Income Loss BusinessAcquisitionsProFormaNetIncomeLoss	749000000	usd
	us-gaap	Business Acquisitions Pro Forma Net Income Loss BusinessAcquisitionsProFormaNetIncomeLoss	3065000000	usd
CY2024Q3	us-gaap	Business Acquisition Pro Forma Income Loss From Continuing Operations Before Changes In Accounting And Extraordinary Items Net Of Tax Per Share Basic BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareBasic	1.54
CY2023Q3	us-gaap	Business Acquisition Pro Forma Income Loss From Continuing Operations Before Changes In Accounting And Extraordinary Items Net Of Tax Per Share Basic BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareBasic	1.52
	us-gaap	Business Acquisition Pro Forma Income Loss From Continuing Operations Before Changes In Accounting And Extraordinary Items Net Of Tax Per Share Basic BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareBasic	6.73
	us-gaap	Business Acquisition Pro Forma Income Loss From Continuing Operations Before Changes In Accounting And Extraordinary Items Net Of Tax Per Share Basic BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareBasic	6.20
CY2024Q3	us-gaap	Business Acquisition Pro Forma Income Loss From Continuing Operations Before Changes In Accounting And Extraordinary Items Net Of Tax Per Share Diluted BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareDiluted	1.52
CY2023Q3	us-gaap	Business Acquisition Pro Forma Income Loss From Continuing Operations Before Changes In Accounting And Extraordinary Items Net Of Tax Per Share Diluted BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareDiluted	1.50
	us-gaap	Business Acquisition Pro Forma Income Loss From Continuing Operations Before Changes In Accounting And Extraordinary Items Net Of Tax Per Share Diluted BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareDiluted	6.67
	us-gaap	Business Acquisition Pro Forma Income Loss From Continuing Operations Before Changes In Accounting And Extraordinary Items Net Of Tax Per Share Diluted BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareDiluted	6.14
CY2024Q3	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	0	usd
CY2024Q3	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	Goodwill Goodwill	17231000000	usd
CY2022Q4	us-gaap	Goodwill Goodwill	16251000000	usd
	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	826000000	usd
	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	480000000	usd
CY2024Q3	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	0	usd
CY2024Q3	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	Goodwill Goodwill	17231000000	usd
CY2022Q4	us-gaap	Goodwill Goodwill	16251000000	usd
	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	826000000	usd
	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	480000000	usd
	us-gaap	Goodwill Other Increase Decrease GoodwillOtherIncreaseDecrease	178000000	usd
	us-gaap	Goodwill Other Increase Decrease GoodwillOtherIncreaseDecrease	-76000000	usd
CY2024Q3	us-gaap	Goodwill Goodwill	18235000000	usd
CY2023Q3	us-gaap	Goodwill Goodwill	16655000000	usd
CY2024Q3	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	5000000000	usd
CY2024Q3	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	2280000000	usd
CY2024Q3	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	2720000000	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
CY2024Q3	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	90000000	usd
	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	269000000	usd
CY2023Q3	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	85000000	usd
	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	257000000	usd
CY2024Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Remainder Of Fiscal Year FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear	91000000	usd
CY2024Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Next Twelve Months FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	337000000	usd
CY2024Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Two FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	317000000	usd
CY2024Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Three FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	308000000	usd
CY2024Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Four FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	285000000	usd
CY2024Q3	mmc	Finite Lived Intangible Asset Expected Amortizationafter Year Four FiniteLivedIntangibleAssetExpectedAmortizationafterYearFour	1382000000	usd
CY2024Q3	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	2720000000	usd
	us-gaap	Goodwill Other Increase Decrease GoodwillOtherIncreaseDecrease	178000000	usd
	us-gaap	Goodwill Other Increase Decrease GoodwillOtherIncreaseDecrease	-76000000	usd
CY2024Q3	us-gaap	Goodwill Goodwill	18235000000	usd
CY2023Q3	us-gaap	Goodwill Goodwill	16655000000	usd
CY2024Q3	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	5000000000	usd
CY2024Q3	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	2280000000	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
CY2024Q3	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	90000000	usd
	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	269000000	usd
CY2023Q3	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	85000000	usd
	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	257000000	usd
CY2024Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Remainder Of Fiscal Year FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear	91000000	usd
CY2024Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Next Twelve Months FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	337000000	usd
CY2024Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Two FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	317000000	usd
CY2024Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Three FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	308000000	usd
CY2024Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Four FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	285000000	usd
CY2024Q3	mmc	Finite Lived Intangible Asset Expected Amortizationafter Year Four FiniteLivedIntangibleAssetExpectedAmortizationafterYearFour	1382000000	usd
CY2024Q3	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	2720000000	usd
CY2024Q3	us-gaap	Equity Method Investments EquityMethodInvestments	275000000	usd
CY2023Q4	us-gaap	Equity Method Investments EquityMethodInvestments	266000000	usd
CY2024Q3	us-gaap	Equity Securities Fv Ni EquitySecuritiesFvNi	19000000	usd
CY2024Q3	us-gaap	Equity Method Investments EquityMethodInvestments	275000000	usd
CY2023Q4	us-gaap	Equity Method Investments EquityMethodInvestments	266000000	usd
CY2024Q3	us-gaap	Equity Securities Fv Ni EquitySecuritiesFvNi	19000000	usd
CY2023Q4	us-gaap	Equity Securities Fv Ni EquitySecuritiesFvNi	16000000	usd
CY2024Q3	us-gaap	Equity Securities Without Readily Determinable Fair Value Amount EquitySecuritiesWithoutReadilyDeterminableFairValueAmount	21000000	usd
CY2023Q4	us-gaap	Equity Securities Without Readily Determinable Fair Value Amount EquitySecuritiesWithoutReadilyDeterminableFairValueAmount	20000000	usd
	mmc	Net Investment Hedge Threshold Percentageofthe Equity Balance NetInvestmentHedgeThresholdPercentageoftheEquityBalance	0.80
	us-gaap	Other Comprehensive Income Foreign Currency Transaction And Translation Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossBeforeReclassificationAndTax	8000000	usd
CY2024Q3	us-gaap	Operating Lease Impairment Loss OperatingLeaseImpairmentLoss	7000000	usd
	us-gaap	Operating Lease Impairment Loss OperatingLeaseImpairmentLoss	9000000	usd
CY2023Q3	us-gaap	Operating Lease Impairment Loss OperatingLeaseImpairmentLoss	6000000	usd
	us-gaap	Operating Lease Impairment Loss OperatingLeaseImpairmentLoss	19000000	usd
CY2024Q3	us-gaap	Operating Lease Cost OperatingLeaseCost	84000000	usd
CY2023Q3	us-gaap	Operating Lease Cost OperatingLeaseCost	82000000	usd
	us-gaap	Operating Lease Cost OperatingLeaseCost	247000000	usd
	us-gaap	Operating Lease Cost OperatingLeaseCost	243000000	usd
CY2024Q3	us-gaap	Short Term Lease Cost ShortTermLeaseCost	1000000	usd
CY2023Q3	us-gaap	Short Term Lease Cost ShortTermLeaseCost	1000000	usd
	us-gaap	Short Term Lease Cost ShortTermLeaseCost	4000000	usd
	us-gaap	Short Term Lease Cost ShortTermLeaseCost	4000000	usd
CY2024Q3	us-gaap	Variable Lease Cost VariableLeaseCost	31000000	usd
CY2023Q3	us-gaap	Variable Lease Cost VariableLeaseCost	31000000	usd
	us-gaap	Variable Lease Cost VariableLeaseCost	85000000	usd
	us-gaap	Variable Lease Cost VariableLeaseCost	94000000	usd
CY2024Q3	us-gaap	Sublease Income SubleaseIncome	2000000	usd
CY2023Q3	us-gaap	Sublease Income SubleaseIncome	2000000	usd
	us-gaap	Sublease Income SubleaseIncome	10000000	usd
	us-gaap	Sublease Income SubleaseIncome	8000000	usd
CY2023Q4	us-gaap	Equity Securities Fv Ni EquitySecuritiesFvNi	16000000	usd
CY2024Q3	us-gaap	Equity Securities Without Readily Determinable Fair Value Amount EquitySecuritiesWithoutReadilyDeterminableFairValueAmount	21000000	usd
CY2023Q4	us-gaap	Equity Securities Without Readily Determinable Fair Value Amount EquitySecuritiesWithoutReadilyDeterminableFairValueAmount	20000000	usd
	mmc	Net Investment Hedge Threshold Percentageofthe Equity Balance NetInvestmentHedgeThresholdPercentageoftheEquityBalance	0.80
	us-gaap	Other Comprehensive Income Foreign Currency Transaction And Translation Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossBeforeReclassificationAndTax	8000000	usd
CY2024Q3	us-gaap	Operating Lease Impairment Loss OperatingLeaseImpairmentLoss	7000000	usd
	us-gaap	Operating Lease Impairment Loss OperatingLeaseImpairmentLoss	9000000	usd
CY2023Q3	us-gaap	Operating Lease Impairment Loss OperatingLeaseImpairmentLoss	6000000	usd
	us-gaap	Operating Lease Impairment Loss OperatingLeaseImpairmentLoss	19000000	usd
CY2024Q3	us-gaap	Operating Lease Cost OperatingLeaseCost	84000000	usd
CY2023Q3	us-gaap	Operating Lease Cost OperatingLeaseCost	82000000	usd
	us-gaap	Operating Lease Cost OperatingLeaseCost	247000000	usd
	us-gaap	Operating Lease Cost OperatingLeaseCost	243000000	usd
CY2024Q3	us-gaap	Short Term Lease Cost ShortTermLeaseCost	1000000	usd
CY2023Q3	us-gaap	Short Term Lease Cost ShortTermLeaseCost	1000000	usd
	us-gaap	Short Term Lease Cost ShortTermLeaseCost	4000000	usd
	us-gaap	Short Term Lease Cost ShortTermLeaseCost	4000000	usd
CY2024Q3	us-gaap	Variable Lease Cost VariableLeaseCost	31000000	usd
CY2023Q3	us-gaap	Variable Lease Cost VariableLeaseCost	31000000	usd
	us-gaap	Variable Lease Cost VariableLeaseCost	85000000	usd
	us-gaap	Variable Lease Cost VariableLeaseCost	94000000	usd
CY2024Q3	us-gaap	Sublease Income SubleaseIncome	2000000	usd
CY2023Q3	us-gaap	Sublease Income SubleaseIncome	2000000	usd
	us-gaap	Sublease Income SubleaseIncome	10000000	usd
	us-gaap	Sublease Income SubleaseIncome	8000000	usd
CY2024Q3	us-gaap	Lease Cost LeaseCost	114000000	usd
	us-gaap	Lease Cost LeaseCost	326000000	usd
	us-gaap	Lease Cost LeaseCost	333000000	usd
	us-gaap	Operating Lease Payments OperatingLeasePayments	278000000	usd
	us-gaap	Operating Lease Payments OperatingLeasePayments	284000000	usd
	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	135000000	usd
	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	177000000	usd
CY2024Q3	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P7Y9M18D
CY2023Q3	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P8Y1M6D
CY2024Q3	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0364
CY2023Q3	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0328
CY2024Q3	us-gaap	Lease Cost LeaseCost	114000000	usd
CY2023Q3	us-gaap	Lease Cost LeaseCost	112000000	usd
	us-gaap	Lease Cost LeaseCost	326000000	usd
	us-gaap	Lease Cost LeaseCost	333000000	usd
	us-gaap	Operating Lease Payments OperatingLeasePayments	278000000	usd
	us-gaap	Operating Lease Payments OperatingLeasePayments	284000000	usd
	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	135000000	usd
	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	177000000	usd
CY2024Q3	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P7Y9M18D
CY2023Q3	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P8Y1M6D
CY2023Q3	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0328
CY2024Q3	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	371000000	usd
CY2024Q3	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	343000000	usd
CY2024Q3	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	305000000	usd
CY2024Q3	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	229000000	usd
CY2024Q3	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	183000000	usd
CY2024Q3	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	678000000	usd
CY2024Q3	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	2204000000	usd
CY2024Q3	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	273000000	usd
CY2024Q3	us-gaap	Operating Lease Liability OperatingLeaseLiability	1931000000	usd
CY2024Q3	us-gaap	Operating Lease Liability Current OperatingLeaseLiabilityCurrent	313000000	usd
CY2024Q3	us-gaap	Operating Lease Liability Noncurrent OperatingLeaseLiabilityNoncurrent	1618000000	usd
CY2024Q3	us-gaap	Operating Lease Liability OperatingLeaseLiability	1931000000	usd
CY2024Q3	us-gaap	Unrecorded Unconditional Purchase Obligation Balance Sheet Amount UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount	0	usd
CY2024Q3	us-gaap	Long Term Debt Current LongTermDebtCurrent	518000000	usd
CY2023Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	1619000000	usd
CY2024Q3	us-gaap	Debt Current DebtCurrent	518000000	usd
CY2023Q4	us-gaap	Debt Current DebtCurrent	1619000000	usd
CY2024Q3	us-gaap	Long Term Debt LongTermDebt	12848000000	usd
CY2023Q4	us-gaap	Long Term Debt LongTermDebt	13463000000	usd
CY2024Q3	us-gaap	Lessee Operating Lease Liability Payments Remainder Of Fiscal Year LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear	95000000	usd
CY2024Q3	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	371000000	usd
CY2024Q3	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	343000000	usd
CY2024Q3	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	305000000	usd
CY2024Q3	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	229000000	usd
CY2024Q3	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	183000000	usd
CY2024Q3	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	678000000	usd
CY2024Q3	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	2204000000	usd
CY2024Q3	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	273000000	usd
CY2024Q3	us-gaap	Operating Lease Liability OperatingLeaseLiability	1931000000	usd
CY2024Q3	us-gaap	Operating Lease Liability Current OperatingLeaseLiabilityCurrent	313000000	usd
CY2024Q3	us-gaap	Operating Lease Liability Noncurrent OperatingLeaseLiabilityNoncurrent	1618000000	usd
CY2024Q3	us-gaap	Operating Lease Liability OperatingLeaseLiability	1931000000	usd
CY2024Q3	us-gaap	Unrecorded Unconditional Purchase Obligation Balance Sheet Amount UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount	0	usd
CY2024Q3	us-gaap	Long Term Debt Current LongTermDebtCurrent	518000000	usd
CY2023Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	1619000000	usd
CY2024Q3	us-gaap	Debt Current DebtCurrent	518000000	usd
CY2023Q4	us-gaap	Debt Current DebtCurrent	1619000000	usd
CY2024Q3	us-gaap	Long Term Debt LongTermDebt	12848000000	usd
CY2023Q4	us-gaap	Long Term Debt LongTermDebt	13463000000	usd
CY2024Q3	us-gaap	Long Term Debt Current LongTermDebtCurrent	518000000	usd
CY2023Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	1619000000	usd
CY2024Q3	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	12330000000	usd
CY2023Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	11844000000	usd
CY2024Q3	us-gaap	Commercial Paper CommercialPaper	0	usd
CY2023Q4	us-gaap	Commercial Paper CommercialPaper	0	usd
CY2024Q3	us-gaap	Long Term Debt Current LongTermDebtCurrent	518000000	usd
CY2023Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	1619000000	usd
CY2024Q3	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	12330000000	usd
CY2023Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	11844000000	usd
CY2024Q3	us-gaap	Commercial Paper CommercialPaper	0	usd
CY2023Q4	us-gaap	Commercial Paper CommercialPaper	0	usd
CY2024Q3	us-gaap	Restructuring And Related Cost Expected Cost1 RestructuringAndRelatedCostExpectedCost1	650000000	usd
CY2024Q3	us-gaap	Restructuring And Related Cost Cost Incurred To Date1 RestructuringAndRelatedCostCostIncurredToDate1	540000000	usd
CY2024Q3	us-gaap	Restructuring Charges RestructuringCharges	54000000	usd
	us-gaap	Restructuring Charges RestructuringCharges	140000000	usd
CY2023Q3	us-gaap	Restructuring Charges RestructuringCharges	52000000	usd
	us-gaap	Restructuring Charges RestructuringCharges	170000000	usd
CY2024Q3	us-gaap	Restructuring Charges RestructuringCharges	54000000	usd
CY2023Q3	us-gaap	Restructuring Charges RestructuringCharges	52000000	usd
	us-gaap	Restructuring Charges RestructuringCharges	140000000	usd
	us-gaap	Restructuring Charges RestructuringCharges	170000000	usd
CY2022Q4	us-gaap	Restructuring Reserve RestructuringReserve	146000000	usd
CY2023	us-gaap	Restructuring Charges RestructuringCharges	301000000	usd
CY2023	us-gaap	Payments For Restructuring PaymentsForRestructuring	271000000	usd
CY2023	us-gaap	Restructuring Reserve Settled Without Cash2 RestructuringReserveSettledWithoutCash2	46000000	usd
CY2023Q4	us-gaap	Restructuring Reserve RestructuringReserve	130000000	usd
	us-gaap	Payments For Restructuring PaymentsForRestructuring	195000000	usd
	us-gaap	Restructuring Reserve Settled Without Cash2 RestructuringReserveSettledWithoutCash2	9000000	usd
CY2024Q3	us-gaap	Restructuring Reserve RestructuringReserve	66000000	usd
	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	900000000	usd
	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	5100000	shares
	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	900000000	usd
	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Shares Issued In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod	3300000	shares
	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Shares Issued In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod	3300000	shares
CY2024Q2	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.710
CY2024Q3	us-gaap	Restructuring And Related Cost Expected Cost1 RestructuringAndRelatedCostExpectedCost1	650000000	usd
CY2024Q3	us-gaap	Restructuring And Related Cost Cost Incurred To Date1 RestructuringAndRelatedCostCostIncurredToDate1	540000000	usd
CY2024Q3	us-gaap	Restructuring Charges RestructuringCharges	54000000	usd
	us-gaap	Restructuring Charges RestructuringCharges	140000000	usd
CY2023Q3	us-gaap	Restructuring Charges RestructuringCharges	52000000	usd
	us-gaap	Restructuring Charges RestructuringCharges	170000000	usd
CY2024Q3	us-gaap	Restructuring Charges RestructuringCharges	54000000	usd
CY2023Q3	us-gaap	Restructuring Charges RestructuringCharges	52000000	usd
	us-gaap	Restructuring Charges RestructuringCharges	140000000	usd
	us-gaap	Restructuring Charges RestructuringCharges	170000000	usd
CY2022Q4	us-gaap	Restructuring Reserve RestructuringReserve	146000000	usd
CY2023	us-gaap	Restructuring Charges RestructuringCharges	301000000	usd
CY2023	us-gaap	Payments For Restructuring PaymentsForRestructuring	271000000	usd
CY2023	us-gaap	Restructuring Reserve Settled Without Cash2 RestructuringReserveSettledWithoutCash2	46000000	usd
CY2023Q4	us-gaap	Restructuring Reserve RestructuringReserve	130000000	usd
	us-gaap	Payments For Restructuring PaymentsForRestructuring	195000000	usd
	us-gaap	Restructuring Reserve Settled Without Cash2 RestructuringReserveSettledWithoutCash2	9000000	usd
CY2024Q3	us-gaap	Restructuring Reserve RestructuringReserve	66000000	usd
	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	900000000	usd
	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	5100000	shares
	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	900000000	usd
	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Shares Issued In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod	3300000	shares
	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Shares Issued In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod	3300000	shares
CY2024Q2	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.710
CY2024Q1	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.710
CY2024Q3	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.815
CY2024Q3	us-gaap	Dividends Payable Amount Per Share DividendsPayableAmountPerShare	0.815
CY2024Q1	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.710
CY2024Q3	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.815
CY2024Q3	us-gaap	Dividends Payable Amount Per Share DividendsPayableAmountPerShare	0.815
CY2024Q3	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	5697000000	usd
CY2024Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	1108000000	usd
	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	18391000000	usd
	us-gaap	Operating Income Loss OperatingIncomeLoss	4675000000	usd
CY2023Q3	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	5382000000	usd
CY2023Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	996000000	usd
	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	17182000000	usd
	us-gaap	Operating Income Loss OperatingIncomeLoss	4179000000	usd
CY2024Q3	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	5697000000	usd
CY2023Q3	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	5382000000	usd
	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	18391000000	usd
	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	17182000000	usd
CY2024Q3	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	5697000000	usd
CY2024Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	1108000000	usd
	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	18391000000	usd
	us-gaap	Operating Income Loss OperatingIncomeLoss	4675000000	usd
CY2023Q3	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	5382000000	usd
CY2023Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	996000000	usd
	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	17182000000	usd
	us-gaap	Operating Income Loss OperatingIncomeLoss	4179000000	usd
CY2024Q3	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	5697000000	usd
CY2023Q3	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	5382000000	usd
	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	18391000000	usd
	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	17182000000	usd

Files In Submission

Name	View Source	Status
FilingSummary.xml	Edgar Link	unprocessable
mmc-20240930_htm.xml	Edgar Link	completed
0000062709-24-000092-index-headers.html	Edgar Link	pending
0000062709-24-000092-index.html	Edgar Link	pending
0000062709-24-000092.txt	Edgar Link	pending
0000062709-24-000092-xbrl.zip	Edgar Link	pending
Financial_Report.xlsx	Edgar Link	pending
MetaLinks.json	Edgar Link	pending
mmc-20240930.htm	Edgar Link	pending
mmc-20240930.xsd	Edgar Link	pending
mmc-20240930_g1.jpg	Edgar Link	pending
mmc0930202410qex_101.htm	Edgar Link	pending
mmc0930202410qex_311.htm	Edgar Link	pending
mmc0930202410qex_312.htm	Edgar Link	pending
mmc0930202410qex_321.htm	Edgar Link	pending
R1.htm	Edgar Link	pending
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R4.htm	Edgar Link	pending
mmc-20240930_cal.xml	Edgar Link	unprocessable
mmc-20240930_def.xml	Edgar Link	unprocessable
mmc-20240930_lab.xml	Edgar Link	unprocessable
mmc-20240930_pre.xml	Edgar Link	unprocessable
R40.htm	Edgar Link	pending
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R8.htm	Edgar Link	pending
R9.htm	Edgar Link	pending
report.css	Edgar Link	pending
Show.js	Edgar Link	pending

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

2024 Q4 Form 10-Q Financial Statement

#000006270924000092 Filed on October 17, 2024

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

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

2024 Q4 Form 10-Q Financial Statement

#000006270924000092 Filed on October 17, 2024

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

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