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v3.19.1

Segment Information (Selected Information And Details For MMC's Operating Segments) (Details) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2019 | Mar. 31, 2018
Segment Reporting Information [Line Items] |  |  |
Revenue |  | $ 4,071 | $ 4,000
Operating Income (Loss) |  | 938 | 908
Equity method income |  | 2 | 7
Risk and Insurance Services Segment |  |  |
Segment Reporting Information [Line Items] |  |  |
Interest on fiduciary funds |  | 23 |
Operating Segments |  |  |
Segment Reporting Information [Line Items] |  |  |
Revenue |  | 4,096 | 4,012
Operating Income (Loss) |  | 1,012 | 963
Operating Segments | Risk and Insurance Services Segment |  |  |
Segment Reporting Information [Line Items] |  |  |
Revenue | [1] | 2,423 | 2,344
Operating Income (Loss) | [1] | 733 | 716
Interest on fiduciary funds |  | 23 | 13
Equity method income |  | 2 | (1)
Operating Segments | Consulting Segment |  |  |
Segment Reporting Information [Line Items] |  |  |
Revenue | [2] | 1,673 | 1,668
Operating Income (Loss) | [2] | 279 | 247
Interest on fiduciary funds |  | 1 | 1
Equity method income |  | 5 | 3
Corporate and Eliminations |  |  |
Segment Reporting Information [Line Items] |  |  |
Revenue |  | (25) | (12)
Operating Income (Loss) |  | (74) | (55)
Intersegment Eliminations | Risk and Insurance Services Segment |  |  |
Segment Reporting Information [Line Items] |  |  |
Revenue |  | 1 | 1
Intersegment Eliminations | Consulting Segment |  |  |
Segment Reporting Information [Line Items] |  |  |
Revenue |  | $ 24 | $ 11
[1] | Includes inter-segment revenue of $1 million in 2019 and 2018, respectively, interest income on fiduciary funds of $23 million and $13 million in 2019 and 2018, respectively, and equity method income (loss) of $2 million and $(1) million in 2019 and 2018, respectively
[2] | Includes inter-segment revenue of $24 million and $11 million in 2019 and 2018, respectively, interest income on fiduciary funds of $1 million in 2019 and 2018, respectively, and equity method income of $5 million and $3 million in 2019 and in 2018, respectively.

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