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- Definition

Interest income earned on both U.S. and foreign fiduciary funds held in trust.

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Liabilities for Errors and Omissions, Current

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Liability for Errors and Omissions, Current and Noncurrent

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No definition available.

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Net uncollected premiums and claims and the related payables are not assets and liabilities of MMC and are not included in the accompanying consolidated balance sheets.

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No definition available.

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- Definition

For each balance sheet presented, the amount of accumulated amortization for capitalized computer software costs.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

The carrying amount of capitalized computer software costs net of accumulated amortization as of the balance sheet date.

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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Amount of realized and unrealized gain (loss) on investment.

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- Definition

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.

+ References

No definition available.

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- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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No definition available.

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Amount of cash and cash equivalents restricted as to withdrawal or usage, classified as current. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions		12 Months Ended
	Feb. 24, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loss on deconsolidation of russian entities and other charges	$ 52
Restricted cash		$ 348	$ 303
Investment income (loss)		21	61	$ (22)
Capitalized computer software costs		492	475
Accumulated amortization		1,800	1,700
Liability for errors and omission, current and noncurrent		419	434
Net uncollected premiums and claims and related payables		13,000	13,000
Risk and Insurance Services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Interest income, fiduciary assets		120	15	$ 46
Accounts Payable and Accrued Liabilities
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Liabilities for errors and omissions, current		$ 64	$ 79
Minimum \| Customer Lists
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Intangible assets, useful life		10 years
Maximum \| Customer Lists
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Intangible assets, useful life		15 years
Furniture and equipment \| Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, useful life		3 years
Furniture and equipment \| Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, useful life		10 years
Building \| Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, useful life		30 years
Building \| Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, useful life		40 years
Software Development \| Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, useful life		3 years
Software Development \| Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, useful life		10 years
Office Space \| Lease Obligations \| Lease Concentration Risk
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Concentration risk (as a percent)		99.00%