Fiduciary Assets and Liabilities (Details) - USD ($) $ in Millions |
3 Months Ended | ||
|---|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
Dec. 31, 2025 |
|
| Fiduciary Assets and Liabilities [Line Items] | |||
| Net uncollected premiums and claims receivable and payable | $ 16,200 | $ 14,600 | |
| Operating Segments | Risk and Insurance Services | |||
| Fiduciary Assets and Liabilities [Line Items] | |||
| Interest on fiduciary funds | $ 85 | $ 103 | |