Fair Value (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Corporate And Other Bonds [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	$ 21,276	$ 20,878
States, Municipalities And Political Subdivisions [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	10,183	9,782
Residential Mortgage-Backed [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	5,994	5,775
Commercial Mortgage-Backed [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	1,329	1,354
Other Asset-Backed [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	1,039	955
Asset-Backed Securities [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	8,362	8,084
U.S. Treasury And Obligations Of Government-Sponsored Enterprises [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	236	493
Foreign Government [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	655	636
Redeemable Preferred Stock [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	113	58
Fixed Maturities Available-For-Sale [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	40,825	39,931
Fixed Maturities, Trading [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	348	109
Fixed Maturities [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	41,173	40,040
Equity Securities Available-For-Sale [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	298	304
Equity Securities, Trading [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	728	623
Equity Securities [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	1,026	927
Short Term Investments [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	5,300	5,105
Other Invested Assets [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	11	11
Receivables [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	85	87
Life Settlement Contracts [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	115	117
Separate Account Business [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	402	417
Payable To Brokers [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of liabilities, measured on a recurring basis	(282)	(75)
Level 1 [Member] | U.S. Treasury And Obligations Of Government-Sponsored Enterprises [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	194	451
Level 1 [Member] | Foreign Government [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	124	92
Level 1 [Member] | Redeemable Preferred Stock [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	5	5
Level 1 [Member] | Fixed Maturities Available-For-Sale [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	323	548
Level 1 [Member] | Fixed Maturities, Trading [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	208
Level 1 [Member] | Fixed Maturities [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	531	548
Level 1 [Member] | Equity Securities Available-For-Sale [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	115	124
Level 1 [Member] | Equity Securities, Trading [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	715	609
Level 1 [Member] | Equity Securities [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	830	733
Level 1 [Member] | Short Term Investments [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	4,717	4,570
Level 1 [Member] | Separate Account Business [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	5	21
Level 1 [Member] | Payable To Brokers [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of liabilities, measured on a recurring basis	(254)	(32)
Level 2 [Member] | Corporate And Other Bonds [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	20,791	20,396
Level 2 [Member] | States, Municipalities And Political Subdivisions [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	10,010	9,611
Level 2 [Member] | Residential Mortgage-Backed [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	5,547	5,323
Level 2 [Member] | Commercial Mortgage-Backed [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	1,224	1,295
Level 2 [Member] | Other Asset-Backed [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	655	612
Level 2 [Member] | Asset-Backed Securities [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	7,426	7,230
Level 2 [Member] | U.S. Treasury And Obligations Of Government-Sponsored Enterprises [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	42	42
Level 2 [Member] | Foreign Government [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	531	544
Level 2 [Member] | Redeemable Preferred Stock [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	55	53
Level 2 [Member] | Fixed Maturities Available-For-Sale [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	38,855	37,876
Level 2 [Member] | Fixed Maturities, Trading [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	39	8
Level 2 [Member] | Fixed Maturities [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	38,894	37,884
Level 2 [Member] | Equity Securities Available-For-Sale [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	109	113
Level 2 [Member] | Equity Securities, Trading [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	2
Level 2 [Member] | Equity Securities [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	111	113
Level 2 [Member] | Short Term Investments [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	583	508
Level 2 [Member] | Receivables [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	81	79
Level 2 [Member] | Separate Account Business [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	393	373
Level 2 [Member] | Payable To Brokers [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of liabilities, measured on a recurring basis	(16)	(20)
Level 3 [Member] | Corporate And Other Bonds [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	485	482
Level 3 [Member] | States, Municipalities And Political Subdivisions [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	173	171
Level 3 [Member] | Residential Mortgage-Backed [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	447	452
Level 3 [Member] | Commercial Mortgage-Backed [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	105	59
Level 3 [Member] | Other Asset-Backed [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	384	343
Level 3 [Member] | Asset-Backed Securities [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	936	854
Level 3 [Member] | Redeemable Preferred Stock [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	53
Level 3 [Member] | Fixed Maturities Available-For-Sale [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	1,647	1,507
Level 3 [Member] | Fixed Maturities, Trading [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	101	101
Level 3 [Member] | Fixed Maturities [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	1,748	1,608
Level 3 [Member] | Equity Securities Available-For-Sale [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	74	67
Level 3 [Member] | Equity Securities, Trading [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	11	14
Level 3 [Member] | Equity Securities [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	85	81
Level 3 [Member] | Short Term Investments [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis		27
Level 3 [Member] | Other Invested Assets [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	11	11
Level 3 [Member] | Receivables [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	4	8
Level 3 [Member] | Life Settlement Contracts [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	115	117
Level 3 [Member] | Separate Account Business [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	4	23
Level 3 [Member] | Payable To Brokers [Member]
Fair Value, Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of liabilities, measured on a recurring basis	$ (12)	$ (23)