Legal settlements and loss contingencies - Additional Information (Detail) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | |||
|---|---|---|---|---|---|
Sep. 30, 2026 |
Sep. 30, 2025 |
Sep. 30, 2026 |
Sep. 30, 2025 |
Dec. 31, 2025 |
|
| Commitments and Contingencies Disclosure [Abstract] | |||||
| Legal settlements and loss contingencies, expenses | $ 202 | $ 60 | $ 504 | $ 312 | |
| Accrued amount for legal settlements and loss contingencies | $ 4,720 | $ 4,720 | $ 4,753 | ||