Fair Value (Assets and liabilities measured at fair value on a recurring basis) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Fixed maturity securities	$ 42,799	$ 42,633
Equity securities	201	249
Other invested assets	49	59
Short term investments	1,555	1,832
Separate account business	279	312
Derivative financial instruments, included in Other liabilities	(1)	(3)
Fair Value, Measurements, Recurring [Member]
Fixed maturity securities	42,799	42,633
Equity securities	201	249
Other invested assets	49	59
Short term investments	1,504	1,792
Life settlement contracts, included in Other assets	95	100
Separate account business	279	312
Total assets	44,927	45,145
Derivative financial instruments, included in Other liabilities	(1)	(3)
Total liabilities	(1)	(3)
Fair Value, Measurements, Recurring [Member] \| Corporate and other bonds [Member]
Fixed maturity securities	22,354	22,236
Fair Value, Measurements, Recurring [Member] \| States, municipalities and political subdivisions [Member]
Fixed maturity securities	10,948	10,783
Fair Value, Measurements, Recurring [Member] \| Residential mortgage-backed [Member]
Fixed maturity securities	5,683	5,920
Fair Value, Measurements, Recurring [Member] \| Commercial mortgage-backed [Member]
Fixed maturity securities	1,990	1,822
Fair Value, Measurements, Recurring [Member] \| Other asset-backed [Member]
Fixed maturity securities	955	952
Fair Value, Measurements, Recurring [Member] \| Total asset-backed [Member]
Fixed maturity securities	8,628	8,694
Fair Value, Measurements, Recurring [Member] \| U.S. Treasury and obligations of government-sponsored enterprises [Member]
Fixed maturity securities	181	182
Fair Value, Measurements, Recurring [Member] \| Foreign government [Member]
Fixed maturity securities	552	613
Fair Value, Measurements, Recurring [Member] \| Redeemable preferred stock [Member]
Fixed maturity securities	136	125
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member]
Fixed maturity securities	342	344
Equity securities	120	117
Other invested assets
Short term investments	1,102	987
Life settlement contracts, included in Other assets
Separate account business	11	4
Total assets	1,575	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	32	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	155	158
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| Foreign government [Member]
Fixed maturity securities	104	140
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| Redeemable preferred stock [Member]
Fixed maturity securities	51	40
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member]
Fixed maturity securities	40,977	41,038
Equity securities	62	98
Other invested assets	49	58
Short term investments	397	799
Life settlement contracts, included in Other assets
Separate account business	266	306
Total assets	41,751	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	22,020	22,011
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| States, municipalities and political subdivisions [Member]
Fixed maturity securities	10,819	10,687
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Residential mortgage-backed [Member]
Fixed maturity securities	5,233	5,507
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Commercial mortgage-backed [Member]
Fixed maturity securities	1,813	1,693
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Other asset-backed [Member]
Fixed maturity securities	559	584
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Total asset-backed [Member]
Fixed maturity securities	7,605	7,784
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| U.S. Treasury and obligations of government-sponsored enterprises [Member]
Fixed maturity securities	26	24
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Foreign government [Member]
Fixed maturity securities	448	473
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Redeemable preferred stock [Member]
Fixed maturity securities	59	59
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member]
Fixed maturity securities	1,480	1,251
Equity securities	19	34
Other invested assets		1
Short term investments	5	6
Life settlement contracts, included in Other assets	95	100
Separate account business	2	2
Total assets	1,601	1,394
Derivative financial instruments, included in Other liabilities	(1)	(1)
Total liabilities	(1)	(1)
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Corporate and other bonds [Member]
Fixed maturity securities	302	219
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| States, municipalities and political subdivisions [Member]
Fixed maturity securities	129	96
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Residential mortgage-backed [Member]
Fixed maturity securities	450	413
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Commercial mortgage-backed [Member]
Fixed maturity securities	177	129
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Other asset-backed [Member]
Fixed maturity securities	396	368
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Total asset-backed [Member]
Fixed maturity securities	1,023	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	$ 26	$ 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

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-SubTopic 10

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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.

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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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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Life Settlement Contract

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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.

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-Name Regulation S-X (SX)

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Other investments not otherwise specified in the taxonomy.

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

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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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