v3.24.3
Revenue - Schedule of Revenue by Geography (Detail) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2024
Sep. 30, 2023
Sep. 30, 2024
Sep. 30, 2023
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax $ 2,238 $ 2,124 $ 6,752 $ 6,445
Service        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 2,223 2,107 6,697 6,378
Operating Segments [Member] | Service        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 2,223 2,107 6,697 6,378
HWC [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 1,334 1,291 3,944 3,811
HWC [Member] | Service        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 1,317 1,275 3,895 3,762
HWC [Member] | Operating Segments [Member] | Service        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 1,317 1,275 3,895 3,762
R&B [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 909 831 2,810 2,605
R&B [Member] | Service        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 906 828 2,801 2,596
R&B [Member] | Operating Segments [Member] | Service        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 906 828 2,801 2,596
Corporate Segment [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax (5) [1] 2 [1] (2) 29
Corporate Segment [Member] | Service        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 0 [1] 4 [1] 1 20
North America [Member] | Operating Segments [Member] | Service        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 1,194 1,177 3,536 3,441
North America [Member] | HWC [Member] | Operating Segments [Member] | Service        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 830 830 2,480 2,445
North America [Member] | R&B [Member] | Operating Segments [Member] | Service        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 364 344 1,056 990
North America [Member] | Corporate Segment [Member] | Service        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 0 3 0 6
Europe [Member] | Operating Segments [Member] | Service        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 759 685 2,387 2,217
Europe [Member] | HWC [Member] | Operating Segments [Member] | Service        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 362 330 1,069 991
Europe [Member] | R&B [Member] | Operating Segments [Member] | Service        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 397 354 1,317 1,214
Europe [Member] | Corporate Segment [Member] | Service        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 0 1 1 12
International [Member] | Operating Segments [Member] | Service        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 270 245 774 720
International [Member] | HWC [Member] | Operating Segments [Member] | Service        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 125 115 346 326
International [Member] | R&B [Member] | Operating Segments [Member] | Service        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 145 130 428 392
International [Member] | Corporate Segment [Member] | Service        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax $ 0 $ 0 $ 0 $ 2
[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.