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Acquisitions and Dispositions of Businesses - Completed Acquisitions (Details) $ in Millions |  | 12 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Sep. 01, 2021 USD ($) | Dec. 31, 2022 USD ($) acquisition | Dec. 31, 2021 acquisition | Nov. 01, 2022 | May 03, 2022 | Dec. 22, 2021 | Aug. 31, 2021
Business Acquisition [Line Items] |  |  |  |  |  |  |
Number of business acquired under business combination | acquisition |  | 5 | 2 |  |  |  |
Weighted average useful life |  | 9 years |  |  |  |  |
Revenues from acquisitions included in the Company's Consolidated Statement of Income |  | $ 25 |  |  |  |  |
E.R.N. Evaluacion de Riesgos Naturales y Antropogenicos, S.A. de C.V |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |
Percentage of capital acquired |  |  |  | 100.00% |  |  |
Karl Köllner Group |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |
Percentage of capital acquired |  |  |  |  | 100.00% |  |
For Welfare S.r.l |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |
Percentage of capital acquired |  |  |  |  |  | 100.00% |
Aon India Insurance Brokers Limited |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |
Percentage of capital acquired | 51.00% |  |  |  |  |  |
Equity interest in acquiree, percentage |  |  |  |  |  |  | 49.00%
Equity interest in acquiree | $ 15 |  |  |  |  |  |

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- Definition Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (a)(3) -URI https://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275 + Details
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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. + Details
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- Definition Percentage of voting equity interests acquired at the acquisition date in the business combination. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI https://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 + Details
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- Definition This element represents the amount of revenue of the acquiree since the acquisition date included in the consolidated income statement for the reporting period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1) -URI https://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 + Details
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- Definition Fair value at acquisition-date of the equity interest in the acquiree held by the acquirer, immediately before the acquisition date for businesses combined in stages. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (g)(1) -URI https://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 + Details
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- Definition Percentage of equity in the acquiree held by the acquirer immediately before the acquisition date in a business combination. + References No definition available. + Details
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