| **Reinsurance (Incurred Consolidated Property Casualty Insurance Loss And Loss Expenses On Assumed And Ceded Business) (Details) - USD ($) $ in Millions** | 12 Months Ended |
|------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------|
||
| Net incurred loss and loss expenses                                                                                                                        | $ 3,107         | $ 2,808 | $ 2,856 |
| Property, Liability and Casualty Insurance Product Line [Member]                                                                                           |            |   |   |
| Direct incurred loss and loss expenses                                                                                                                     | 2,874           | 2,596 | 2,661 |
| Assumed incurred loss and loss expenses                                                                                                                    | 43              | 12 | 6 |
| Ceded incurred loss and loss expenses                                                                                                                      | (56)            | (36) | (40) |
| Net incurred loss and loss expenses                                                                                                                        | $ 2,861         | $ 2,572 | $ 2,627 |

| X                                                                                                                                                                                                                                                                                                                      |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Reinsurance Effect on Claims and Benefits Incurred, Amount Ceded, Net
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount, before effect of policies assumed or ceded, of expense related to provision for policy benefits and costs incurred.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.5) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount, after effects of policies assumed or ceded, of expense related to the provision for policy benefits and costs incurred.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.5) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6480758&loc=d3e6811-158387
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of policy benefits and costs incurred for policies assumed.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6480758&loc=d3e6811-158387
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| X                                                                                                                                                                                        |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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