Fair Value (Assets and liabilities measured at fair value on a recurring basis) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Fixed maturity securities	$ 41,431	$ 42,633
Equity securities	199	249
Other invested assets	36	59
Short term investments	1,531	1,832
Separate account business	247	312
Derivative financial instruments, included in Other liabilities		(3)
Fair Value, Measurements, Recurring [Member]
Fixed maturity securities	41,431	42,633
Equity securities	199	249
Other invested assets	36	59
Short term investments	1,480	1,792
Life settlement contracts, included in Other assets	91	100
Separate account business	247	312
Total assets	43,484	45,145
Derivative financial instruments, included in Other liabilities		(3)
Total liabilities		(3)
Fair Value, Measurements, Recurring [Member] \| Corporate and other bonds [Member]
Fixed maturity securities	21,788	22,236
Fair Value, Measurements, Recurring [Member] \| States, municipalities and political subdivisions [Member]
Fixed maturity securities	10,739	10,783
Fair Value, Measurements, Recurring [Member] \| Residential mortgage-backed [Member]
Fixed maturity securities	5,096	5,920
Fair Value, Measurements, Recurring [Member] \| Commercial mortgage-backed [Member]
Fixed maturity securities	2,009	1,822
Fair Value, Measurements, Recurring [Member] \| Other asset-backed [Member]
Fixed maturity securities	947	952
Fair Value, Measurements, Recurring [Member] \| Total asset-backed [Member]
Fixed maturity securities	8,052	8,694
Fair Value, Measurements, Recurring [Member] \| U.S. Treasury and obligations of government-sponsored enterprises [Member]
Fixed maturity securities	176	182
Fair Value, Measurements, Recurring [Member] \| Foreign government [Member]
Fixed maturity securities	544	613
Fair Value, Measurements, Recurring [Member] \| Redeemable preferred stock [Member]
Fixed maturity securities	132	125
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member]
Fixed maturity securities	324	344
Equity securities	134	117
Other invested assets
Short term investments	1,057	987
Life settlement contracts, included in Other assets
Separate account business	6	4
Total assets	1,521	1,452
Derivative financial instruments, included in Other liabilities
Total liabilities
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| Corporate and other bonds [Member]
Fixed maturity securities	30	6
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| States, municipalities and political subdivisions [Member]
Fixed maturity securities
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| Residential mortgage-backed [Member]
Fixed maturity securities
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| Commercial mortgage-backed [Member]
Fixed maturity securities
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| Other asset-backed [Member]
Fixed maturity securities
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| Total asset-backed [Member]
Fixed maturity securities
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| U.S. Treasury and obligations of government-sponsored enterprises [Member]
Fixed maturity securities	147	158
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| Foreign government [Member]
Fixed maturity securities	98	140
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| Redeemable preferred stock [Member]
Fixed maturity securities	49	40
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member]
Fixed maturity securities	39,760	41,038
Equity securities	52	98
Other invested assets	36	58
Short term investments	423	799
Life settlement contracts, included in Other assets
Separate account business	239	306
Total assets	40,510	42,299
Derivative financial instruments, included in Other liabilities		(2)
Total liabilities		(2)
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Corporate and other bonds [Member]
Fixed maturity securities	21,556	22,011
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| States, municipalities and political subdivisions [Member]
Fixed maturity securities	10,599	10,687
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Residential mortgage-backed [Member]
Fixed maturity securities	4,668	5,507
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Commercial mortgage-backed [Member]
Fixed maturity securities	1,844	1,693
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Other asset-backed [Member]
Fixed maturity securities	560	584
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Total asset-backed [Member]
Fixed maturity securities	7,072	7,784
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| U.S. Treasury and obligations of government-sponsored enterprises [Member]
Fixed maturity securities	29	24
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Foreign government [Member]
Fixed maturity securities	446	473
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Redeemable preferred stock [Member]
Fixed maturity securities	58	59
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member]
Fixed maturity securities	1,347	1,251
Equity securities	13	34
Other invested assets		1
Short term investments		6
Life settlement contracts, included in Other assets	91	100
Separate account business	2	2
Total assets	1,453	1,394
Derivative financial instruments, included in Other liabilities		(1)
Total liabilities		(1)
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Corporate and other bonds [Member]
Fixed maturity securities	202	219
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| States, municipalities and political subdivisions [Member]
Fixed maturity securities	140	96
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Residential mortgage-backed [Member]
Fixed maturity securities	428	413
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Commercial mortgage-backed [Member]
Fixed maturity securities	165	129
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Other asset-backed [Member]
Fixed maturity securities	387	368
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Total asset-backed [Member]
Fixed maturity securities	980	910
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| U.S. Treasury and obligations of government-sponsored enterprises [Member]
Fixed maturity securities
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Foreign government [Member]
Fixed maturity securities
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Redeemable preferred stock [Member]
Fixed maturity securities	$ 25	$ 26

This element represents the aggregate of the assets reported on the balance sheet at period end measured at fair value by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)

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Fair value of derivative liability, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-Paragraph 205G

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

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-Paragraph 4B

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This element represents the aggregate of the liabilities reported on the balance sheet at period end measured at fair value by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

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Fair value amount of life settlement contracts accounted for under the fair value method.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Life Settlement Contract

-URI http://asc.fasb.org/extlink&oid=6516907

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 325

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

For an unclassified balance sheet, this item represents investments in common and preferred stocks and other forms of securities that provide ownership interests in a corporation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Subparagraph b

-Article 7

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- Definition

Other investments not otherwise specified in the taxonomy.

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-Topic 210

-SubTopic 10

-Section S99

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- Definition

The fair value of the assets held by the Entity for the benefit of separate account policyholders.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 10

-Article 9

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-Publisher AICPA

-Name Statement of Position (SOP)

-Number 03-1

-Paragraph 10-18

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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Investments which are intended to be sold in the short term (usually less than one year or the normal operating cycle, whichever is longer) including trading securities, available-for-sale securities, held-to-maturity securities, and other short-term investments not otherwise listed in the existing taxonomy.

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