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Consulting Revenue, Payment Terms

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Estimated Brokerage Revenue, Payment Terms

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Insurance Brokerage Commissions, Payment Terms

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Reinsurance Brokerage Revenue, Payment Terms

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- Definition

Revenue From Contract With Customer Threshold Percentage Of Total Revenue

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Revenue from Contract with Customer, Percent

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- Definition

Amount of amortization expense for asset recognized from cost incurred to obtain or fulfill contract with customer.

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Amortization period of cost capitalized in obtaining or fulfilling contract with customer, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount, after accumulated amortization and accumulated impairment loss, of asset recognized from cost incurred to obtain or fulfill contract with customer.

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- Definition

Amount of revenue recognized from performance obligation satisfied or partially satisfied in previous reporting periods. Includes, but is not limited to, change in transaction price.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Revenue (Narrative) (Details) $ in Millions	12 Months Ended
Revenue (Narrative) (Details) $ in Millions	Dec. 31, 2025 USD ($) installment	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Disaggregation of Revenue [Line Items]
Percentage of total revenue	1.00%
Number of installments for brokerage revenue \| installment	4
Contract with customer, performance obligation satisfied in previous period	$ 83	$ 73	$ 71
Capitalized contract cost, amortization	2,100	1,900	$ 1,800
Deferred Implementation Costs
Disaggregation of Revenue [Line Items]
Capitalized contract cost, net	1	3
Costs to Obtain
Disaggregation of Revenue [Line Items]
Capitalized contract cost, net	459	396
Costs to Fulfill
Disaggregation of Revenue [Line Items]
Capitalized contract cost, net	$ 438	$ 397
Mercer Consulting Group
Disaggregation of Revenue [Line Items]
Consulting revenue, payment terms (in days)	30 days
Risk and Insurance Services
Disaggregation of Revenue [Line Items]
Insurance brokerage commissions, payment terms (in days)	30 days
Consulting \| Mercer Consulting Group
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, percent	51.00%
Minimum
Disaggregation of Revenue [Line Items]
Capitalized contract cost, amortization period	3 months
Minimum \| Risk and Insurance Services
Disaggregation of Revenue [Line Items]
Estimated brokerage revenue, payment terms (in months)	12 months
Reinsurance brokerage revenue, payment terms (in months)	12 months
Minimum \| Consulting \| Marsh Management Consulting
Disaggregation of Revenue [Line Items]
Consulting revenue, payment terms (in days)	30 days
Maximum
Disaggregation of Revenue [Line Items]
Capitalized contract cost, amortization period	6 months
Maximum \| Risk and Insurance Services
Disaggregation of Revenue [Line Items]
Estimated brokerage revenue, payment terms (in months)	18 months
Reinsurance brokerage revenue, payment terms (in months)	18 months
Maximum \| Consulting \| Marsh Management Consulting
Disaggregation of Revenue [Line Items]
Consulting revenue, payment terms (in days)	60 days