Investments (Continuous Gross Unrealized Losses for Fixed Maturity and Equity Securities Available-For-Sale) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
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	4,868	1,941
Total number of securities in an unrealized loss position equal to or greater than 12 months	807	1,335
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	$ 64,191	$ 13,721
Less than 12 Months Gross Unrealized Loss	3,206	293
Equal to or Greater than 12 Months Estimated Fair Value	7,717	13,447
Equal to or Greater than 12 Months Gross Unrealized Loss	978	1,455
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	17,625	3,799
Less than 12 Months Gross Unrealized Loss	978	88
Equal to or Greater than 12 Months Estimated Fair Value	2,427	3,695
Equal to or Greater than 12 Months Gross Unrealized Loss	288	342
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	10,709	2,783
Less than 12 Months Gross Unrealized Loss	484	96
Equal to or Greater than 12 Months Estimated Fair Value	1,491	2,873
Equal to or Greater than 12 Months Gross Unrealized Loss	113	180
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	6,431	1,431
Less than 12 Months Gross Unrealized Loss	332	22
Equal to or Greater than 12 Months Estimated Fair Value	247	543
Equal to or Greater than 12 Months Gross Unrealized Loss	33	49
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	8,457	735
Less than 12 Months Gross Unrealized Loss	263	31
Equal to or Greater than 12 Months Estimated Fair Value	2,357	4,098
Equal to or Greater than 12 Months Gross Unrealized Loss	369	633
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	11,326	1,951
Less than 12 Months Gross Unrealized Loss	734	11
Equal to or Greater than 12 Months Estimated Fair Value	47	0
Equal to or Greater than 12 Months Gross Unrealized Loss	5	0
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	3,893	842
Less than 12 Months Gross Unrealized Loss	147	11
Equal to or Greater than 12 Months Estimated Fair Value	228	577
Equal to or Greater than 12 Months Gross Unrealized Loss	17	46
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	2,949	1,920
Less than 12 Months Gross Unrealized Loss	70	30
Equal to or Greater than 12 Months Estimated Fair Value	695	1,410
Equal to or Greater than 12 Months Gross Unrealized Loss	88	139
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	2,801	260
Less than 12 Months Gross Unrealized Loss	198	4
Equal to or Greater than 12 Months Estimated Fair Value	225	251
Equal to or Greater than 12 Months Gross Unrealized Loss	65	66
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	453	201
Less than 12 Months Gross Unrealized Loss	72	18
Equal to or Greater than 12 Months Estimated Fair Value	213	309
Equal to or Greater than 12 Months Gross Unrealized Loss	61	141
Common 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	92	201
Less than 12 Months Gross Unrealized Loss	13	18
Equal to or Greater than 12 Months Estimated Fair Value	15	14
Equal to or Greater than 12 Months Gross Unrealized Loss	1	1
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	361	0
Less than 12 Months Gross Unrealized Loss	59	0
Equal to or Greater than 12 Months Estimated Fair Value	198	295
Equal to or Greater than 12 Months Gross Unrealized Loss	$ 60	$ 140