v3.26.3
Segment Information - Revenue (Net of Reimbursable Expenses) of the Reported Segments (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Segment Reporting Information [Line Items]        
Total revenue $ 2,460 $ 2,288 $ 7,338 $ 6,772
Depreciation     166 167
Income from operations 429 418 1,241 1,218
HWC [Member]        
Segment Reporting Information [Line Items]        
Total revenue 1,371 1,277 3,947 3,657
R&B [Member]        
Segment Reporting Information [Line Items]        
Total revenue 1,092 1,010 3,379 3,090
Corporate [Member]        
Segment Reporting Information [Line Items]        
Total revenue [1] (3) 1 12 25
Operating Segments [Member]        
Segment Reporting Information [Line Items]        
Segment revenue excluding interest income 2,404 2,232 7,155 6,592
Interest income 33 36 97 95
Total revenue 2,437 2,268 7,252 6,687
Other segment expense 1,782 1,677 5,352 4,974
Depreciation 41 41 124 124
Total segment expense 1,823 1,718 5,476 5,098
Income from operations 614 550 1,776 1,589
Operating Segments [Member] | HWC [Member]        
Segment Reporting Information [Line Items]        
Segment revenue excluding interest income 1,343 1,253 3,863 3,584
Interest income 7 8 22 22
Total revenue 1,350 1,261 3,885 3,606
Other segment expense 921 869 2,741 2,560
Depreciation 31 31 94 94
Total segment expense 952 900 2,835 2,654
Income from operations 398 361 1,050 952
Operating Segments [Member] | R&B [Member]        
Segment Reporting Information [Line Items]        
Segment revenue excluding interest income 1,061 979 3,292 3,008
Interest income 26 28 75 73
Total revenue 1,087 1,007 3,367 3,081
Other segment expense 861 808 2,611 2,414
Depreciation 10 10 30 30
Total segment expense 871 818 2,641 2,444
Income from operations $ 216 $ 189 $ 726 $ 637
[1] Reimbursable expenses and other, as well as Corporate revenue, are excluded from segment revenue, but included in total revenue on the condensed consolidated statements of comprehensive income. Amounts included in Corporate revenue may include eliminations, adjustments to reserves and impacts from hedged revenue transactions.