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v3.22.2.2

Acquisitions and Dispositions (Narrative) (Details) $ in Millions | 1 Months Ended | 3 Months Ended | 9 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | ---
Apr. 30, 2022 USD ($) | Sep. 30, 2022 USD ($) | Mar. 31, 2022 USD ($) | Sep. 30, 2021 USD ($) | Sep. 30, 2022 USD ($) acquisition | Sep. 30, 2021 USD ($) | Dec. 31, 2021 acquisition | Nov. 30, 2021
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Total consideration |  |  |  |  | $ 227 | $ 546 |  |
Cash paid |  |  |  |  | 210 | 405 |  |
Estimated fair value of deferred/contingent consideration |  |  |  |  | 17 | 141 |  |
Deferred purchase consideration from prior years' acquisitions |  |  |  |  | 116 | 84 |  |
Contingent consideration from prior year's acquisitions |  |  |  |  | 28 | 26 |  |
Deconsolidation of Russian businesses |  |  | $ (39) |  | (39) | 0 |  |
U.S. Affinity Business |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Disposal group, consideration | $ 140 |  |  |  |  |  |  |
Gain on disposal | $ 112 |  |  |  |  |  |  |
Certain Businesses Primarily in the U.S. and U.K. |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Disposal group, consideration |  |  |  |  |  | 84 |  |
Gain on disposal |  |  |  |  |  | 50 |  |
Certain Businesses Primarily in Brazil |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Disposal group, consideration |  |  |  |  | 7 |  |  |
Marsh India Insurance Brokers Limited |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Percentage of ownership in equity investment |  |  |  |  |  |  | 92.00% | 49.00%
Prior Fiscal Periods Acquisitions |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Deferred purchase consideration from prior years' acquisitions |  |  |  |  |  | 84 |  |
Contingent consideration from prior year's acquisitions |  |  |  |  | 66 | 72 |  |
Pro forma revenue |  |  |  | $ 38 |  | 73 |  |
Operating income (loss) related to acquisitions |  |  |  | $ 3 |  | $ 4 |  |
Current Fiscal Period Acquisitions |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Total consideration |  |  |  |  | 227 |  |  |
Cash paid |  |  |  |  | 210 |  |  |
Estimated fair value of deferred/contingent consideration |  |  |  |  | 17 |  |  |
Pro forma revenue |  | $ 16 |  |  | 22 |  |  |
Operating income (loss) related to acquisitions |  | $ (1) |  |  | $ (1) |  |  |
Risk and Insurance Services |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Number of acquisitions made (in acquisitions) | acquisition |  |  |  |  | 8 |  | 8 |
Consulting |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Number of acquisitions made (in acquisitions) | acquisition |  |  |  |  | 3 |  | 1 |
Minimum |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Revenue target period (in years) |  |  |  |  | 2 years | 2 years |  |
Maximum |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Revenue target period (in years) |  |  |  |  | 4 years | 4 years |  |

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