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v3.23.1

Segment Information (Details of Operating Segment Revenue) (Details) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2023 | Mar. 31, 2022
Segment Reporting Information [Line Items] |  |
Revenue | $ 5,924 | $ 5,549
Risk and Insurance Services |  |
Segment Reporting Information [Line Items] |  |
Revenue | 3,906 | 3,549
Risk and Insurance Services | Marsh |  |
Segment Reporting Information [Line Items] |  |
Revenue | 2,744 | 2,546
Risk and Insurance Services | Guy Carpenter |  |
Segment Reporting Information [Line Items] |  |
Revenue | 1,071 | 999
Consulting |  |
Segment Reporting Information [Line Items] |  |
Revenue | 2,031 | 2,010
Consulting | Mercer |  |
Segment Reporting Information [Line Items] |  |
Revenue | 1,344 | 1,343
Consulting | Oliver Wyman Group |  |
Segment Reporting Information [Line Items] |  |
Revenue | 687 | 667
Operating Segments |  |
Segment Reporting Information [Line Items] |  |
Revenue | 5,937 | 5,559
Operating Segments | Risk and Insurance Services |  |
Segment Reporting Information [Line Items] |  |
Revenue | 3,906 | 3,549
Operating Segments | Risk and Insurance Services | Marsh |  |
Segment Reporting Information [Line Items] |  |
Revenue | 2,800 | 2,549
Operating Segments | Risk and Insurance Services | Guy Carpenter |  |
Segment Reporting Information [Line Items] |  |
Revenue | 1,106 | 1,000
Operating Segments | Consulting |  |
Segment Reporting Information [Line Items] |  |
Revenue | 2,031 | 2,010
Operating Segments | Consulting | Mercer |  |
Segment Reporting Information [Line Items] |  |
Revenue | 1,344 | 1,343
Operating Segments | Consulting | Oliver Wyman Group |  |
Segment Reporting Information [Line Items] |  |
Revenue | 687 | 667
Corporate/Eliminations |  |
Segment Reporting Information [Line Items] |  |
Revenue | $ (13) | $ (10)

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