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Revenue - Schedule of Revenue by Geography (Detail) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024
Disaggregation Of Revenue [Line Items] |  |  |  |  |
Revenue from Contract with Customer, Excluding Assessed Tax |  | $ 2,240 | $ 2,238 | $ 6,635 | $ 6,752
Service [Member] |  |  |  |  |
Disaggregation Of Revenue [Line Items] |  |  |  |  |
Revenue from Contract with Customer, Excluding Assessed Tax |  | 2,226 | 2,223 | 6,577 | 6,697
Operating Segments [Member] | Service [Member] |  |  |  |  |
Disaggregation Of Revenue [Line Items] |  |  |  |  |
Revenue from Contract with Customer, Excluding Assessed Tax |  | 2,226 | 2,223 | 6,577 | 6,697
HWC [Member] |  |  |  |  |
Disaggregation Of Revenue [Line Items] |  |  |  |  |
Revenue from Contract with Customer, Excluding Assessed Tax |  | 1,269 | 1,334 | 3,632 | 3,944
HWC [Member] | Service [Member] |  |  |  |  |
Disaggregation Of Revenue [Line Items] |  |  |  |  |
Revenue from Contract with Customer, Excluding Assessed Tax |  | 1,253 | 1,317 | 3,581 | 3,895
HWC [Member] | Operating Segments [Member] | Service [Member] |  |  |  |  |
Disaggregation Of Revenue [Line Items] |  |  |  |  |
Revenue from Contract with Customer, Excluding Assessed Tax |  | 1,253 | 1,317 | 3,581 | 3,895
R&B [Member] |  |  |  |  |
Disaggregation Of Revenue [Line Items] |  |  |  |  |
Revenue from Contract with Customer, Excluding Assessed Tax |  | 976 | 909 | 3,004 | 2,810
R&B [Member] | Service [Member] |  |  |  |  |
Disaggregation Of Revenue [Line Items] |  |  |  |  |
Revenue from Contract with Customer, Excluding Assessed Tax |  | 973 | 906 | 2,995 | 2,801
R&B [Member] | Operating Segments [Member] | Service [Member] |  |  |  |  |
Disaggregation Of Revenue [Line Items] |  |  |  |  |
Revenue from Contract with Customer, Excluding Assessed Tax |  | 973 | 906 | 2,995 | 2,801
Corporate [Member] |  |  |  |  |
Disaggregation Of Revenue [Line Items] |  |  |  |  |
Revenue from Contract with Customer, Excluding Assessed Tax | [1] | (5) | (5) | (1) | (2)
Corporate [Member] | Service [Member] |  |  |  |  |
Disaggregation Of Revenue [Line Items] |  |  |  |  |
Revenue from Contract with Customer, Excluding Assessed Tax | [1] | 0 | 0 | 1 | 1
North America [Member] | Operating Segments [Member] | Service [Member] |  |  |  |  |
Disaggregation Of Revenue [Line Items] |  |  |  |  |
Revenue from Contract with Customer, Excluding Assessed Tax |  | 1,084 | 1,194 | 3,122 | 3,536
North America [Member] | HWC [Member] | Operating Segments [Member] | Service [Member] |  |  |  |  |
Disaggregation Of Revenue [Line Items] |  |  |  |  |
Revenue from Contract with Customer, Excluding Assessed Tax |  | 719 | 830 | 2,029 | 2,480
North America [Member] | R&B [Member] | Operating Segments [Member] | Service [Member] |  |  |  |  |
Disaggregation Of Revenue [Line Items] |  |  |  |  |
Revenue from Contract with Customer, Excluding Assessed Tax |  | 365 | 364 | 1,092 | 1,056
North America [Member] | Corporate [Member] | Service [Member] |  |  |  |  |
Disaggregation Of Revenue [Line Items] |  |  |  |  |
Revenue from Contract with Customer, Excluding Assessed Tax |  | 0 | 0 | 1 | 0
Europe [Member] | Operating Segments [Member] | Service [Member] |  |  |  |  |
Disaggregation Of Revenue [Line Items] |  |  |  |  |
Revenue from Contract with Customer, Excluding Assessed Tax |  | 857 | 759 | 2,632 | 2,387
Europe [Member] | HWC [Member] | Operating Segments [Member] | Service [Member] |  |  |  |  |
Disaggregation Of Revenue [Line Items] |  |  |  |  |
Revenue from Contract with Customer, Excluding Assessed Tax |  | 400 | 362 | 1,183 | 1,069
Europe [Member] | R&B [Member] | Operating Segments [Member] | Service [Member] |  |  |  |  |
Disaggregation Of Revenue [Line Items] |  |  |  |  |
Revenue from Contract with Customer, Excluding Assessed Tax |  | 457 | 397 | 1,449 | 1,317
Europe [Member] | Corporate [Member] | Service [Member] |  |  |  |  |
Disaggregation Of Revenue [Line Items] |  |  |  |  |
Revenue from Contract with Customer, Excluding Assessed Tax |  | 0 | 0 | 0 | 1
International [Member] | Operating Segments [Member] | Service [Member] |  |  |  |  |
Disaggregation Of Revenue [Line Items] |  |  |  |  |
Revenue from Contract with Customer, Excluding Assessed Tax |  | 285 | 270 | 823 | 774
International [Member] | HWC [Member] | Operating Segments [Member] | Service [Member] |  |  |  |  |
Disaggregation Of Revenue [Line Items] |  |  |  |  |
Revenue from Contract with Customer, Excluding Assessed Tax |  | 134 | 125 | 369 | 346
International [Member] | R&B [Member] | Operating Segments [Member] | Service [Member] |  |  |  |  |
Disaggregation Of Revenue [Line Items] |  |  |  |  |
Revenue from Contract with Customer, Excluding Assessed Tax |  | 151 | 145 | 454 | 428
International [Member] | Corporate [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.

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