Insurance subsidiary disclosures - Insurance premiums by type (Detail) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
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| Property/Casualty [Member] | |||
| Effects of Reinsurance [Line Items] | |||
| Premiums written - Direct | $ 66,693 | $ 65,495 | $ 61,990 |
| Premiums written - Assumed | 19,255 | 20,422 | 20,751 |
| Premiums written - Ceded | (1,874) | (2,231) | (2,402) |
| Premiums written | 84,074 | 83,686 | 80,339 |
| Premiums earned - Direct | 66,351 | 64,880 | 60,437 |
| Premiums earned - Assumed | 19,303 | 20,738 | 20,442 |
| Premiums earned - Ceded | (2,021) | (2,359) | (2,548) |
| Premiums earned | 83,633 | 83,259 | 78,331 |
| Life/Health [Member] | |||
| Effects of Reinsurance [Line Items] | |||
| Premiums written - Direct | 14 | 19 | |
| Premiums written - Assumed | 5,319 | 5,016 | 5,126 |
| Premiums written - Ceded | (31) | (28) | (33) |
| Premiums written | 5,302 | 5,007 | 5,093 |
| Premiums earned - Direct | 14 | 18 | |
| Premiums earned - Assumed | 5,286 | 5,008 | 5,105 |
| Premiums earned - Ceded | (31) | (28) | (33) |
| Premiums earned | $ 5,269 | $ 4,998 | $ 5,072 |
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- Definition Amount of earned premiums assumed from other entities. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of written premiums assumed from other entities. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of earned premiums ceded to other entities. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of written premiums ceded to other entities. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount, before premiums ceded to other entities and premiums assumed by the entity, of premiums earned. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount, before premiums ceded to other entities and premiums assumed by the entity, of premiums written. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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- Definition Amount, after premiums ceded to other entities and premiums assumed by the entity, of premiums earned. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount, after premiums ceded to other entities and premiums assumed by the entity, of premiums written. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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