v3.25.4

Revenue (Disaggregation of Revenue) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2025 | Dec. 31, 2024 | Dec. 31, 2023
Disaggregation of Revenue [Line Items] |  |  |
Revenue | $ 26,981 | $ 24,458 | $ 22,736
Operating Segments |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue | 27,059 | 24,528 | 22,798
Corporate/Eliminations |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue | (78) | (70) | (62)
Risk and Insurance Services |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Fiduciary interest income | 403 | 497 | 453
Risk and Insurance Services | Operating Segments |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Fiduciary interest income | 403 | 497 | 453
Revenue | 17,265 | 15,395 | 14,089
Risk and Insurance Services | Operating Segments | Marsh & Guy Carpenter |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue, excluding fiduciary interest income | 16,862 | 14,898 | 13,636
Risk and Insurance Services | Operating Segments | Marsh Insurance Group |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue, excluding fiduciary interest income | 14,366 | 12,536 | 11,378
Revenue | 14,630 | 12,851 | 11,657
Risk and Insurance Services | Operating Segments | Guy Carpenter Reinsurance Group |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue, excluding fiduciary interest income | 2,496 | 2,362 | 2,258
Revenue | 2,635 | 2,544 | 2,432
Risk and Insurance Services | Operating Segments | Total International |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue, excluding fiduciary interest income | 5,843 | 5,519 | 5,116
Risk and Insurance Services | Operating Segments | EMEA |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue, excluding fiduciary interest income | 3,812 | 3,530 | 3,262
Risk and Insurance Services | Operating Segments | Asia Pacific |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue, excluding fiduciary interest income | 1,460 | 1,414 | 1,295
Risk and Insurance Services | Operating Segments | Latin America |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue, excluding fiduciary interest income | 571 | 575 | 559
Risk and Insurance Services | Operating Segments | U.S./Canada |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue, excluding fiduciary interest income | 8,523 | 7,017 | 6,262
Consulting | Operating Segments |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue | 9,794 | 9,133 | 8,709
Consulting | Operating Segments | U.S. Health And Benefits And U.K Pension Administration Businesses |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Pre-tax gain (loss) on sale |  | 35 |
Consulting | Operating Segments | Wealth |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue | 2,819 | 2,584 | 2,507
Consulting | Operating Segments | Wealth | U.S. Health And Benefits And U.K Pension Administration Businesses |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Pre-tax gain (loss) on sale |  | 70 |
Consulting | Operating Segments | Health |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue | 2,284 | 2,100 | 2,061
Consulting | Operating Segments | Health | U.S. Health And Benefits And U.K Pension Administration Businesses |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Pre-tax gain (loss) on sale |  | (35) |
Consulting | Operating Segments | Career |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue | 1,087 | 1,059 | 1,019
Consulting | Operating Segments | Mercer Consulting Group |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue | 6,190 | 5,743 | 5,587
Consulting | Operating Segments | Marsh Management Consulting |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue | $ 3,604 | 3,390 | $ 3,122
Pre-tax gain (loss) on sale |  | $ 20 |

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