| **Investments (Activity related to the pretax fixed maturity credit loss component reflected within retained earnings for securities still held for which a portion of an OTTI loss was recognized in OCI) (Details) - USD ($) $ in Millions** | 3 Months Ended | 9 Months Ended |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------|----------------|
||
| **Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]**                                                                                                                                                       |           |           |   |   |
| Beginning balance of credit losses on fixed maturity securities                                                                                                                                                                                | $ 41           | $ 59           | $ 53 | $ 62 |
| Reductions for securities sold during the period                                                                                                                                                                                               | (2)            | (2)            | (14) | (5) |
| Reductions for securities the Company intends to sell or more likely than not will be required to sell                                                                                                                                         | (1)            | 0              | (1) | 0 |
| Ending balance of credit losses on fixed maturity securities                                                                                                                                                                                   | $ 38           | $ 57           | $ 38 | $ 57 |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The cumulative amount of credit losses recognized in earnings related to debt securities held for which a portion of an other than temporary impairment (OTTI) was recognized in other comprehensive income (a component of shareholders' equity).
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27340-111563
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
This item represents reductions in the amount of cumulative losses recognized in earnings for other than temporary impairments (OTTI) for which a portion of the impairment had been recognized in other comprehensive income (a component of shareholders' equity) due to a change in status of the impaired security because of a change in the entity's intent to either sell the impaired security or it has become more likely than not that the entity will be required to sell the security before recovery of its cost basis.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 8 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27340-111563
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
This item represents reductions in the cumulative amount of credit losses recognized in earnings for an other than temporary impairment (OTTI) of a debt security because of the sale of impaired securities during the period.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 8 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27340-111563
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| X                                                                                                                                                                                                                                                                                                                                                                     |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.
+ References
No definition available.
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