v3.25.2
Segment Information (Details of Operating Segment Revenue) (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Segment Reporting Information [Line Items]        
Revenue $ 6,974 $ 6,221 $ 14,035 $ 12,694
Operating Segments        
Segment Reporting Information [Line Items]        
Revenue 6,996 6,238 14,072 12,725
Operating Segments | Risk and Insurance Services        
Segment Reporting Information [Line Items]        
Revenue 4,625 4,022 9,387 8,295
Operating Segments | Risk and Insurance Services | Marsh        
Segment Reporting Information [Line Items]        
Revenue 3,915 3,342 7,435 6,423
Operating Segments | Risk and Insurance Services | Guy Carpenter        
Segment Reporting Information [Line Items]        
Revenue 710 680 1,952 1,872
Operating Segments | Consulting        
Segment Reporting Information [Line Items]        
Revenue 2,371 2,216 4,685 4,430
Operating Segments | Consulting | Mercer        
Segment Reporting Information [Line Items]        
Revenue 1,498 1,379 2,994 2,804
Operating Segments | Consulting | Oliver Wyman Group        
Segment Reporting Information [Line Items]        
Revenue 873 837 1,691 1,626
Corporate/Eliminations        
Segment Reporting Information [Line Items]        
Revenue $ (22) $ (17) $ (37) $ (31)