v3.26.1
Revenue - Schedule of Revenue by Geography (Detail) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax $ 2,428 $ 2,215 $ 4,791 $ 4,395
Service [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 2,399 2,192 4,740 4,351
Operating Segments [Member] | Service [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 2,399 2,192 4,740 4,351
HWC [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 1,284 1,190 2,559 2,363
HWC [Member] | Service [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 1,262 1,172 2,518 2,328
HWC [Member] | Operating Segments [Member] | Service [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 1,262 1,172 2,518 2,328
R&B [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 1,141 1,022 2,227 2,028
R&B [Member] | Service [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 1,137 1,019 2,220 2,022
R&B [Member] | Operating Segments [Member] | Service [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 1,137 1,019 2,220 2,022
Corporate [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax [1] 3 3 5 4
Corporate [Member] | Service [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax [1] 0 1 2 1
Corporate [Member] | Operating Segments [Member] | Service [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 0 1 2 1
North America [Member] | Operating Segments [Member] | Service [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 1,181 1,067 2,201 2,038
North America [Member] | HWC [Member] | Operating Segments [Member] | Service [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 712 665 1,385 1,310
North America [Member] | R&B [Member] | Operating Segments [Member] | Service [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 469 401 816 727
North America [Member] | Corporate [Member] | Operating Segments [Member] | Service [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 0 1 0 1
Europe [Member] | Operating Segments [Member] | Service [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 907 846 1,945 1,775
Europe [Member] | HWC [Member] | Operating Segments [Member] | Service [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 419 392 863 783
Europe [Member] | R&B [Member] | Operating Segments [Member] | Service [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 488 454 1,080 992
Europe [Member] | Corporate [Member] | Operating Segments [Member] | Service [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 0 0 2 0
International [Member] | Operating Segments [Member] | Service [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 311 279 594 538
International [Member] | HWC [Member] | Operating Segments [Member] | Service [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 131 115 270 235
International [Member] | R&B [Member] | Operating Segments [Member] | Service [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax 180 164 324 303
International [Member] | Corporate [Member] | Operating Segments [Member] | Service [Member]        
Disaggregation Of Revenue [Line Items]        
Revenue from Contract with Customer, Excluding Assessed Tax $ 0 $ 0 $ 0 $ 0
[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.