| **Reinsurance (Life Insurance Contract Holders' Benefits Incurred On Ceded Business) (Details) (USD $)In Millions, unless otherwise specified** | 12 Months Ended                                                                                                                                |
|-------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------|
||
| Net incurred loss and loss expenses                                                                                                             | $ 2,856us-gaap_PolicyholderBenefitsAndClaimsIncurredNet                                                                                        | $ 2,505us-gaap_PolicyholderBenefitsAndClaimsIncurredNet | $ 2,322us-gaap_PolicyholderBenefitsAndClaimsIncurredNet |
| Life Insurance Segment                                                                                                                          |                                                                                                                                           |   |   |
| Direct contract holders' benefits incurred                                                                                                      | 299us-gaap_PolicyholderBenefitsAndClaimsIncurredGross/ us-gaap_StatementBusinessSegmentsAxis= us-gaap_LifeInsuranceSegmentMember               | 266us-gaap_PolicyholderBenefitsAndClaimsIncurredGross/ us-gaap_StatementBusinessSegmentsAxis= us-gaap_LifeInsuranceSegmentMember | 232us-gaap_PolicyholderBenefitsAndClaimsIncurredGross/ us-gaap_StatementBusinessSegmentsAxis= us-gaap_LifeInsuranceSegmentMember |
| Ceded contract holders' benefits incurred                                                                                                       | (70)us-gaap_ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded/ us-gaap_StatementBusinessSegmentsAxis= us-gaap_LifeInsuranceSegmentMember | (62)us-gaap_ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded/ us-gaap_StatementBusinessSegmentsAxis= us-gaap_LifeInsuranceSegmentMember | (47)us-gaap_ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded/ us-gaap_StatementBusinessSegmentsAxis= us-gaap_LifeInsuranceSegmentMember |
| Net incurred loss and loss expenses                                                                                                             | $ 229us-gaap_PolicyholderBenefitsAndClaimsIncurredNet/ us-gaap_StatementBusinessSegmentsAxis= us-gaap_LifeInsuranceSegmentMember               | $ 204us-gaap_PolicyholderBenefitsAndClaimsIncurredNet/ us-gaap_StatementBusinessSegmentsAxis= us-gaap_LifeInsuranceSegmentMember | $ 185us-gaap_PolicyholderBenefitsAndClaimsIncurredNet/ us-gaap_StatementBusinessSegmentsAxis= us-gaap_LifeInsuranceSegmentMember |

| 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=d3e573970-122913Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 5 -Article 7
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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 SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 5 -Article 7Reference 3: 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
+ Details**Name:**us-gaap_PolicyholderBenefitsAndClaimsIncurredNet**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of reduction of provision for policy benefits and costs incurred for policies ceded.
+ 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
+ Details**Name:**us-gaap_ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_StatementBusinessSegmentsAxis=us-gaap_LifeInsuranceSegmentMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |