| **Organization Review (Tables)**                    | 9 Months Ended                                                                                                                                                                                                                                                                                                                                                                                       |
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| **Restructuring and Related Activities [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                 |
| Restructuring and Related Costs [Table Text Block]  | The costs by reportable segment for the periods ended September 30, 2016, are presented in the following table.Periods ended September 30, 2016Three Months Nine Months(In millions) Specialty$3 $4Commercial7 12International— —Life & Group Non-Core1 1Corporate & Other Non-Core— —Total organization review costs$11 $17 |

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| - References
No definition available.
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| - Definition
Tabular disclosure of costs incurred for restructuring including, but not limited to, exit and disposal activities, remediation, implementation, integration, asset impairment, and charges against earnings from the write-down of assets.
+ References
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