v3.25.4
BUSINESS SEGMENTS - Summary of Segment Revenue, Segment Expenses, and Segment Profits (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]      
Revenue $ 26,186 $ 25,100 $ 23,713
Depreciation, amortization, and other 213 183 189
General and administrative [1] 870 945 867
OPERATING INCOME 4,141 3,767 3,864
Net fee revenues      
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]      
Gross fee revenues 5,438 5,170 4,824
Contract investment amortization (135) (103) (88)
Revenue 5,303 5,067 4,736
Owned, leased, and other      
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]      
Revenue 1,679 1,551 1,564
Operating costs [1] 1,461 1,329 1,309
Reimbursements      
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]      
Revenue [2] 19,204 18,482 17,413
Operating costs [2] 19,503 18,799 17,424
Total segment      
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]      
Revenue 23,419 22,576 21,394
Total segment | U.S. & Canada      
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]      
Revenue 19,349 18,612 17,696
Depreciation, amortization, and other 108 84 84
General and administrative 118 113 114
Other segment items (5) (5) (5)
OPERATING INCOME 2,679 2,640 2,724
Total segment | EMEA      
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]      
Revenue 2,407 2,406 2,268
Depreciation, amortization, and other 40 38 40
General and administrative 104 90 84
Other segment items (3) (5) (2)
OPERATING INCOME 525 512 441
Total segment | Greater China      
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]      
Revenue 590 582 600
Depreciation, amortization, and other 12 9 10
General and administrative 52 45 42
Other segment items (2) (1) (2)
OPERATING INCOME 185 186 208
Total segment | APEC      
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]      
Revenue 1,073 976 830
Depreciation, amortization, and other 9 8 9
General and administrative 63 53 47
Other segment items 2 (4) (8)
OPERATING INCOME 301 280 243
Total segment | Net fee revenues | U.S. & Canada      
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]      
Gross fee revenues 3,004 2,951 2,799
Contract investment amortization (83) (76) (65)
Revenue 2,921 2,875 2,734
Total segment | Net fee revenues | EMEA      
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]      
Gross fee revenues 640 589 529
Contract investment amortization (19) (14) (13)
Revenue 621 575 516
Total segment | Net fee revenues | Greater China      
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]      
Gross fee revenues 261 250 265
Contract investment amortization (1) (1) 0
Revenue 260 249 265
Total segment | Net fee revenues | APEC      
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]      
Gross fee revenues 376 345 288
Contract investment amortization (6) (5) (4)
Revenue 370 340 284
Total segment | Owned, leased, and other | U.S. & Canada      
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]      
Revenue 528 437 506
Operating costs 434 399 380
Total segment | Owned, leased, and other | EMEA      
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]      
Revenue 592 595 574
Operating costs 530 519 537
Total segment | Owned, leased, and other | Greater China      
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]      
Revenue 26 27 18
Operating costs 28 24 25
Total segment | Owned, leased, and other | APEC      
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]      
Revenue 162 141 135
Operating costs 146 129 130
Total segment | Reimbursements | U.S. & Canada      
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]      
Revenue 15,900 15,300 14,456
Operating costs 16,015 15,381 14,399
Total segment | Reimbursements | EMEA      
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]      
Revenue 1,194 1,236 1,178
Operating costs 1,211 1,252 1,168
Total segment | Reimbursements | Greater China      
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]      
Revenue 304 306 317
Operating costs 315 319 317
Total segment | Reimbursements | APEC      
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]      
Revenue 541 495 411
Operating costs $ 552 $ 510 $ 409
[1] In the 2025 fourth quarter, we reclassified amounts attributable to other expenses previously reported under the “General, administrative, and other” caption to the “Owned, leased, and other expense” caption of our Income Statements. See Note 1 for additional information.
[2] See Note 15 for disclosure of related party amounts.