Investments (Details 16) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Total number of securities in an unrealized loss position less than 12 months	3,191	3,978
Total number of securities in an unrealized loss position equal to or greater than 12 months	1,646	1,963
Fixed maturity securities [Member]
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Less than 12 months Estimated Fair Value	39,866	54,112
Less than 12 Months Gross Unrealized Loss	1,093	2,247
Equal to or Greater than 12 Months Estimated Fair Value	16,415	20,666
Equal to or Greater than 12 Months Gross Unrealized Loss	2,389	3,266
Total Estimated Fair Value	56,281	74,778
Total Gross Unrealized Loss	3,482	5,513
U.S. corporate securities [Member]
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Less than 12 months Estimated Fair Value	9,639	15,642
Less than 12 Months Gross Unrealized Loss	276	590
Equal to or Greater than 12 Months Estimated Fair Value	4,461	5,135
Equal to or Greater than 12 Months Gross Unrealized Loss	567	790
Total Estimated Fair Value	14,100	20,777
Total Gross Unrealized Loss	843	1,380
Foreign corporate securities [Member]
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Less than 12 months Estimated Fair Value	7,694	12,618
Less than 12 Months Gross Unrealized Loss	279	639
Equal to or Greater than 12 Months Estimated Fair Value	3,733	5,957
Equal to or Greater than 12 Months Gross Unrealized Loss	370	700
Total Estimated Fair Value	11,427	18,575
Total Gross Unrealized Loss	649	1,339
Foreign government debt securities [Member]
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Less than 12 months Estimated Fair Value	1,811	11,227
Less than 12 Months Gross Unrealized Loss	97	230
Equal to or Greater than 12 Months Estimated Fair Value	784	1,799
Equal to or Greater than 12 Months Gross Unrealized Loss	72	127
Total Estimated Fair Value	2,595	13,026
Total Gross Unrealized Loss	169	357
RMBS [Member]
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Less than 12 months Estimated Fair Value	2,532	4,040
Less than 12 Months Gross Unrealized Loss	342	547
Equal to or Greater than 12 Months Estimated Fair Value	4,734	4,724
Equal to or Greater than 12 Months Gross Unrealized Loss	1,049	1,189
Total Estimated Fair Value	7,266	8,764
Total Gross Unrealized Loss	1,391	1,736
U.S. Treasury, agency and government guaranteed securities [Member]
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Less than 12 months Estimated Fair Value	13,208	2,611
Less than 12 Months Gross Unrealized Loss	5	1
Equal to or Greater than 12 Months Estimated Fair Value	0	50
Equal to or Greater than 12 Months Gross Unrealized Loss	0	1
Total Estimated Fair Value	13,208	2,661
Total Gross Unrealized Loss	5	2
CMBS [Member]
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Less than 12 months Estimated Fair Value	1,159	2,825
Less than 12 Months Gross Unrealized Loss	28	135
Equal to or Greater than 12 Months Estimated Fair Value	775	678
Equal to or Greater than 12 Months Gross Unrealized Loss	75	91
Total Estimated Fair Value	1,934	3,503
Total Gross Unrealized Loss	103	226
ABS [Member]
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Less than 12 months Estimated Fair Value	3,484	4,972
Less than 12 Months Gross Unrealized Loss	62	103
Equal to or Greater than 12 Months Estimated Fair Value	1,513	1,316
Equal to or Greater than 12 Months Gross Unrealized Loss	168	214
Total Estimated Fair Value	4,997	6,288
Total Gross Unrealized Loss	230	317
State and political subdivision securities [Member]
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Less than 12 months Estimated Fair Value	339	177
Less than 12 Months Gross Unrealized Loss	4	2
Equal to or Greater than 12 Months Estimated Fair Value	415	1,007
Equal to or Greater than 12 Months Gross Unrealized Loss	88	154
Total Estimated Fair Value	754	1,184
Total Gross Unrealized Loss	92	156
Equity Securities [Member]
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Less than 12 months Estimated Fair Value	565	785
Less than 12 Months Gross Unrealized Loss	70	126
Equal to or Greater than 12 Months Estimated Fair Value	332	375
Equal to or Greater than 12 Months Gross Unrealized Loss	151	173
Total Estimated Fair Value	897	1,160
Total Gross Unrealized Loss	221	299
Common Stock
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Less than 12 months Estimated Fair Value	527	581
Less than 12 Months Gross Unrealized Loss	59	96
Equal to or Greater than 12 Months Estimated Fair Value	20	5
Equal to or Greater than 12 Months Gross Unrealized Loss	2	1
Total Estimated Fair Value	547	586
Total Gross Unrealized Loss	61	97
Non-redeemable preferred stock [Member]
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Less than 12 months Estimated Fair Value	38	204
Less than 12 Months Gross Unrealized Loss	11	30
Equal to or Greater than 12 Months Estimated Fair Value	312	370
Equal to or Greater than 12 Months Gross Unrealized Loss	149	172
Total Estimated Fair Value	350	574
Total Gross Unrealized Loss	160	202