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v3.24.0.1

Segment Information (Details For MMC's Operating Segments) (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2022 | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Segment Reporting Information [Line Items] |  |  |  |
Revenue |  | $ 22,736 | $ 20,720 | $ 19,820
Operating Income (Loss) |  | 5,282 | 4,280 | 4,312
Total Assets |  | 48,030 | 44,114 | 44,010
Depreciation and Amortization |  | 713 | 719 | 747
Capital Expenditures |  | 416 | 470 | 406
Equity method investments |  | 266 | 215 |
Deconsolidation, Gain (Loss), Amount | $ (39) | 0 | (39) | 0
Risk and Insurance Services |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Interest income, fiduciary assets |  | 453 | 120 | 15
Operating Segments |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Revenue |  | 22,798 | 20,784 | 19,874
Operating Income (Loss) |  | 5,611 | 4,642 | 4,584
Total Assets |  | 45,910 | 43,468 | 41,964
Depreciation and Amortization |  | 639 | 627 | 676
Capital Expenditures |  | 347 | 392 | 323
Operating Segments | Mercer U.S. Affinity Business |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Pre-tax gain (loss) on sale |  |  |  | 50
Operating Segments | Risk and Insurance Services |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Revenue |  | 14,089 | 12,645 | 12,085
Operating Income (Loss) |  | 3,945 | 3,089 | 3,080
Total Assets |  | 34,449 | 33,022 | 31,233
Depreciation and Amortization |  | 487 | 469 | 505
Capital Expenditures |  | 242 | 283 | 214
Interest income, fiduciary assets |  | 453 | 120 | 15
Equity method income |  | 18 | 12 | 31
Pre-tax gain (loss) on sale |  |  |  | 50
Equity method investments |  | 57 | 50 | 53
Operating Segments | Risk and Insurance Services | RUSSIAN FEDERATION |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Deconsolidation, Gain (Loss), Amount |  |  | (27) |
Operating Segments | Risk and Insurance Services | Marsh India |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Gain (loss) on consolidation of business |  |  |  | 267
Operating Segments | Consulting |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Revenue |  | 8,709 | 8,139 | 7,789
Operating Income (Loss) |  | 1,666 | 1,553 | 1,504
Total Assets |  | 11,461 | 10,446 | 10,731
Depreciation and Amortization |  | 152 | 158 | 171
Capital Expenditures |  | 105 | 109 | 109
Equity method income |  |  | 1 |
Equity method investments |  | 6 | 6 | 5
Operating Segments | Consulting | RUSSIAN FEDERATION |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Deconsolidation, Gain (Loss), Amount |  |  | (12) |
Operating Segments | Consulting | Small Individual Financial Advisory Business |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Pre-tax gain (loss) on sale |  | (17) |  |
Operating Segments | Consulting | Mercer U.S. Affinity Business |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Pre-tax gain (loss) on sale |  |  | 112 |
Corporate/Eliminations |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Revenue |  | (62) | (64) | (54)
Operating Income (Loss) |  | (329) | (362) | (272)
Total Assets |  | 2,120 | 646 | 2,046
Depreciation and Amortization |  | 74 | 92 | 71
Capital Expenditures |  | 69 | 78 | 83
Inter-segment | Risk and Insurance Services |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Revenue |  | 6 | 5 | 5
Inter-segment | Consulting |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Revenue |  | $ 56 | $ 59 | $ 49

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