Investments (Fair Value And Gross Unrealized Losses In A Continuous Unrealized Loss Position) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013 item	Dec. 31, 2012 item
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	$ 4,529	$ 3,343
Greater Than Twelve Months	1,383	1,616
Continuous Unrealized Loss Position, Total	5,912	4,959
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	238	214
Greater Than Twelve Months	250	301
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	488	515
Available For Sale Securities In Unrealized Loss Position Qualitative Disclosure Number Of Positions	663	626
Fixed Maturity Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	4,522	3,336
Greater Than Twelve Months	1,383	1,616
Continuous Unrealized Loss Position, Total	5,905	4,952
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	236	212
Greater Than Twelve Months	250	301
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	486	513
Equity AFS Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	7	7
Continuous Unrealized Loss Position, Total	7	7
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	2	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	2	2
Corporate Bonds [Member] | Fixed Maturity Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	4,005	2,853
Greater Than Twelve Months	802	934
Continuous Unrealized Loss Position, Total	4,807	3,787
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	186	145
Greater Than Twelve Months	144	182
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	330	327
RMBS [Member] | Fixed Maturity Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	350	272
Greater Than Twelve Months	161	199
Continuous Unrealized Loss Position, Total	511	471
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	27	39
Greater Than Twelve Months	16	24
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	43	63
CMBS [Member] | Fixed Maturity Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	29	66
Greater Than Twelve Months	65	113
Continuous Unrealized Loss Position, Total	94	179
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	14	16
Greater Than Twelve Months	17	19
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	31	35
CDOs [Member] | Fixed Maturity Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	9	10
Greater Than Twelve Months	51	53
Continuous Unrealized Loss Position, Total	60	63
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	7	8
Greater Than Twelve Months	2	3
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	9	11
State And Municipal Bonds [Member] | Fixed Maturity Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	63	64
Greater Than Twelve Months	26	24
Continuous Unrealized Loss Position, Total	89	88
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	1	1
Greater Than Twelve Months	4	6
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	5	7
Hybrid And Redeemable Preferred Securities [Member] | Fixed Maturity Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	66	71
Greater Than Twelve Months	278	293
Continuous Unrealized Loss Position, Total	344	364
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	1	3
Greater Than Twelve Months	67	67
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	$ 68	$ 70