MODERNIZATION - Schedule of Modernization Expense (Details) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2026 |
Sep. 30, 2025 |
Sep. 30, 2026 |
Sep. 30, 2025 |
|
| Modernization Costs [Line Items] | ||||
| Modernization | $ 6 | $ 53 | $ 32 | $ 97 |
| Advisory services | ||||
| Modernization Costs [Line Items] | ||||
| Modernization | 0 | 21 | (1) | 52 |
| Implementation Consultants | ||||
| Modernization Costs [Line Items] | ||||
| Modernization | 5 | 11 | 18 | 18 |
| Transition costs | ||||
| Modernization Costs [Line Items] | ||||
| Modernization | 1 | 14 | 6 | 15 |
| Technology | ||||
| Modernization Costs [Line Items] | ||||
| Modernization | 2 | 5 | 9 | 7 |
| Other | ||||
| Modernization Costs [Line Items] | ||||
| Modernization | $ (2) | $ 2 | $ 0 | $ 5 |