Investments (Details 16) (USD $) In Millions, unless otherwise specified	Mar. 31, 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	3,555	3,978
Total number of securities in an unrealized loss position equal to or greater than 12 months	1,674	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	41,899	54,112
Less than 12 Months Gross Unrealized Loss	1,249	2,247
Equal to or Greater than 12 Months Estimated Fair Value	17,369	20,666
Equal to or Greater than 12 Months Gross Unrealized Loss	2,484	3,266
Total Estimated Fair Value	59,268	74,778
Total Gross Unrealized Loss	3,733	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	10,097	15,642
Less than 12 Months Gross Unrealized Loss	293	590
Equal to or Greater than 12 Months Estimated Fair Value	4,125	5,135
Equal to or Greater than 12 Months Gross Unrealized Loss	588	790
Total Estimated Fair Value	14,222	20,777
Total Gross Unrealized Loss	881	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	8,410	12,618
Less than 12 Months Gross Unrealized Loss	265	639
Equal to or Greater than 12 Months Estimated Fair Value	4,719	5,957
Equal to or Greater than 12 Months Gross Unrealized Loss	387	700
Total Estimated Fair Value	13,129	18,575
Total Gross Unrealized Loss	652	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	4,831	11,227
Less than 12 Months Gross Unrealized Loss	84	230
Equal to or Greater than 12 Months Estimated Fair Value	1,322	1,799
Equal to or Greater than 12 Months Gross Unrealized Loss	92	127
Total Estimated Fair Value	6,153	13,026
Total Gross Unrealized Loss	176	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	4,698	4,040
Less than 12 Months Gross Unrealized Loss	406	547
Equal to or Greater than 12 Months Estimated Fair Value	4,565	4,724
Equal to or Greater than 12 Months Gross Unrealized Loss	1,045	1,189
Total Estimated Fair Value	9,263	8,764
Total Gross Unrealized Loss	1,451	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	8,512	2,611
Less than 12 Months Gross Unrealized Loss	83	1
Equal to or Greater than 12 Months Estimated Fair Value	37	50
Equal to or Greater than 12 Months Gross Unrealized Loss	4	1
Total Estimated Fair Value	8,549	2,661
Total Gross Unrealized Loss	87	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	1,189	2,825
Less than 12 Months Gross Unrealized Loss	33	135
Equal to or Greater than 12 Months Estimated Fair Value	714	678
Equal to or Greater than 12 Months Gross Unrealized Loss	78	91
Total Estimated Fair Value	1,903	3,503
Total Gross Unrealized Loss	111	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	3,810	4,972
Less than 12 Months Gross Unrealized Loss	80	103
Equal to or Greater than 12 Months Estimated Fair Value	1,343	1,316
Equal to or Greater than 12 Months Gross Unrealized Loss	182	214
Total Estimated Fair Value	5,153	6,288
Total Gross Unrealized Loss	262	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	352	177
Less than 12 Months Gross Unrealized Loss	5	2
Equal to or Greater than 12 Months Estimated Fair Value	544	1,007
Equal to or Greater than 12 Months Gross Unrealized Loss	108	154
Total Estimated Fair Value	896	1,184
Total Gross Unrealized Loss	113	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	409	785
Less than 12 Months Gross Unrealized Loss	31	126
Equal to or Greater than 12 Months Estimated Fair Value	330	375
Equal to or Greater than 12 Months Gross Unrealized Loss	146	173
Total Estimated Fair Value	739	1,160
Total Gross Unrealized Loss	177	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	347	581
Less than 12 Months Gross Unrealized Loss	22	96
Equal to or Greater than 12 Months Estimated Fair Value	4	5
Equal to or Greater than 12 Months Gross Unrealized Loss	0	1
Total Estimated Fair Value	351	586
Total Gross Unrealized Loss	22	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	62	204
Less than 12 Months Gross Unrealized Loss	9	30
Equal to or Greater than 12 Months Estimated Fair Value	326	370
Equal to or Greater than 12 Months Gross Unrealized Loss	146	172
Total Estimated Fair Value	388	574
Total Gross Unrealized Loss	155	202