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v3.20.4

Segment Information (Details For MMC's Operating Segments) (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2020 | Sep. 30, 2020 | Jun. 30, 2020 | Mar. 31, 2020 | Dec. 31, 2019 | Sep. 30, 2019 | Jun. 30, 2019 | Mar. 31, 2019 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue | $ 4,416 | $ 3,968 | $ 4,189 | $ 4,651 | $ 4,264 | $ 3,968 | $ 4,349 | $ 4,071 | $ 17,224 | $ 16,652 | $ 14,950
Operating Income (Loss) | 571 | $ 540 | $ 885 | $ 1,070 | 592 | $ 467 | $ 680 | $ 938 | 3,066 | 2,677 | 2,761
Total Assets | 33,049 |  |  |  | 31,357 |  |  |  | 33,049 | 31,357 | 21,578
Depreciation and Amortization |  |  |  |  |  |  |  |  | 741 | 647 | 494
Capital Expenditures |  |  |  |  |  |  |  |  | 348 | 421 | 314
Equity method income |  |  |  |  |  |  |  |  |  | 12 | 17
Equity method investments | 280 |  |  |  | 434 |  |  |  | 280 | 434 |
Risk and Insurance Services |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 10,337 | 9,599 | 8,228
Interest income, fiduciary assets |  |  |  |  |  |  |  |  | 46 | 105 | 65
Consulting |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 6,976 | 7,143 | 6,779
Interest income, fiduciary assets |  |  |  |  |  |  |  |  | 1 | 4 | 3
Operating Segments |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 17,313 | 16,742 | 15,007
Operating Income (Loss) |  |  |  |  |  |  |  |  | 3,340 | 3,043 | 2,963
Total Assets | 30,183 |  |  |  | 35,820 |  |  |  | 30,183 | 35,820 | 23,871
Depreciation and Amortization |  |  |  |  |  |  |  |  | 674 | 572 | 420
Capital Expenditures |  |  |  |  |  |  |  |  | 277 | 334 | 255
Operating Segments | Risk and Insurance Services |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 10,337 | 9,599 | 8,228
Operating Income (Loss) |  |  |  |  |  |  |  |  | 2,346 | 1,833 | 1,864
Total Assets | 20,612 |  |  |  | 26,098 |  |  |  | 20,612 | 26,098 | 15,868
Depreciation and Amortization |  |  |  |  |  |  |  |  | 500 | 416 | 290
Capital Expenditures |  |  |  |  |  |  |  |  | 170 | 184 | 158
Interest income, fiduciary assets |  |  |  |  |  |  |  |  | 46 | 105 | 65
Equity method income |  |  |  |  |  |  |  |  | 27 | 25 | 13
Proceeds from sale of business |  |  |  |  |  |  |  |  |  |  | 40
Equity method investments | 165 |  |  |  | 179 |  |  |  | 165 | 179 | 57
Operating Segments | Consulting |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 6,976 | 7,143 | 6,779
Operating Income (Loss) |  |  |  |  |  |  |  |  | 994 | 1,210 | 1,099
Total Assets | 9,571 |  |  |  | 9,722 |  |  |  | 9,571 | 9,722 | 8,003
Depreciation and Amortization |  |  |  |  |  |  |  |  | 174 | 156 | 130
Capital Expenditures |  |  |  |  |  |  |  |  | 107 | 150 | 97
Interest income, fiduciary assets |  |  |  |  |  |  |  |  | 1 | 4 | 3
Equity method income |  |  |  |  |  |  |  |  | 5 | 16 | 8
Equity method investments | 5 |  |  |  | 149 |  |  |  | 5 | 149 | 148
Corporate/Eliminations |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | (89) | (90) | (57)
Operating Income (Loss) |  |  |  |  |  |  |  |  | (274) | (366) | (202)
Total Assets | $ 2,866 |  |  |  | $ (4,463) |  |  |  | 2,866 | (4,463) | (2,293)
Depreciation and Amortization |  |  |  |  |  |  |  |  | 67 | 75 | 74
Capital Expenditures |  |  |  |  |  |  |  |  | 71 | 87 | 59
Inter-segment | Risk and Insurance Services |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 5 | 8 | 6
Inter-segment | Consulting |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | $ 84 | $ 82 | $ 51

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