Investments (Continuous Gross Unrealized Losses for Fixed Maturity and Equity Securities Available-For-Sale) (Details) (USD $) In Millions, unless otherwise specified	Jun. 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	4,443	1,941
Total number of securities in an unrealized loss position equal to or greater than 12 months	886	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	$ 68,014	$ 13,721
Less than 12 Months Gross Unrealized Loss	2,632	293
Equal to or Greater than 12 Months Estimated Fair Value	8,137	13,447
Equal to or Greater than 12 Months Gross Unrealized Loss	1,040	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	15,848	3,799
Less than 12 Months Gross Unrealized Loss	749	88
Equal to or Greater than 12 Months Estimated Fair Value	2,291	3,695
Equal to or Greater than 12 Months Gross Unrealized Loss	268	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	11,417	2,783
Less than 12 Months Gross Unrealized Loss	486	96
Equal to or Greater than 12 Months Estimated Fair Value	1,602	2,873
Equal to or Greater than 12 Months Gross Unrealized Loss	149	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	5,802	1,431
Less than 12 Months Gross Unrealized Loss	237	22
Equal to or Greater than 12 Months Estimated Fair Value	290	543
Equal to or Greater than 12 Months Gross Unrealized Loss	38	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	9,711	735
Less than 12 Months Gross Unrealized Loss	288	31
Equal to or Greater than 12 Months Estimated Fair Value	2,531	4,098
Equal to or Greater than 12 Months Gross Unrealized Loss	414	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	16,198	1,951
Less than 12 Months Gross Unrealized Loss	511	11
Equal to or Greater than 12 Months Estimated Fair Value	0	0
Equal to or Greater than 12 Months Gross Unrealized Loss	0	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	3,198	842
Less than 12 Months Gross Unrealized Loss	149	11
Equal to or Greater than 12 Months Estimated Fair Value	278	577
Equal to or Greater than 12 Months Gross Unrealized Loss	25	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	3,797	1,920
Less than 12 Months Gross Unrealized Loss	88	30
Equal to or Greater than 12 Months Estimated Fair Value	919	1,410
Equal to or Greater than 12 Months Gross Unrealized Loss	91	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	2,043	260
Less than 12 Months Gross Unrealized Loss	124	4
Equal to or Greater than 12 Months Estimated Fair Value	226	251
Equal to or Greater than 12 Months Gross Unrealized Loss	55	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	449	201
Less than 12 Months Gross Unrealized Loss	25	18
Equal to or Greater than 12 Months Estimated Fair Value	266	309
Equal to or Greater than 12 Months Gross Unrealized Loss	69	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	70	201
Less than 12 Months Gross Unrealized Loss	7	18
Equal to or Greater than 12 Months Estimated Fair Value	16	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	379	0
Less than 12 Months Gross Unrealized Loss	18	0
Equal to or Greater than 12 Months Estimated Fair Value	250	295
Equal to or Greater than 12 Months Gross Unrealized Loss	$ 68	$ 140