Investments (Continuous Gross Unrealized Losses for Fixed Maturity and Equity Securities Available-For-Sale) (Details) $ in Millions	Jun. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)
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	2,783	6,366
Total number of securities in an unrealized loss position equal to or greater than 12 months	1,965	1,489
Fixed Maturity Securities
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Less than 12 months Estimated Fair Value	$ 29,820	$ 92,421
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,472	3,475
Equal to or Greater than 12 Months Estimated Fair Value	21,688	15,799
Gross Unrealized Temporary Loss	1,903	1,970
U.S. corporate
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Less than 12 months Estimated Fair Value	7,932	27,526
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	394	1,629
Equal to or Greater than 12 Months Estimated Fair Value	5,581	3,762
Gross Unrealized Temporary Loss	511	626
U.S. government and agency
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Less than 12 months Estimated Fair Value	1,026	19,628
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	3	222
Equal to or Greater than 12 Months Estimated Fair Value	164	298
Gross Unrealized Temporary Loss	18	4
Foreign corporate
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Less than 12 months Estimated Fair Value	8,135	14,447
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	585	911
Equal to or Greater than 12 Months Estimated Fair Value	6,477	5,251
Gross Unrealized Temporary Loss	881	913
Foreign government
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Less than 12 months Estimated Fair Value	1,298	3,530
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	83	166
Equal to or Greater than 12 Months Estimated Fair Value	807	429
Gross Unrealized Temporary Loss	62	55
RMBS
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Less than 12 months Estimated Fair Value	5,221	13,467
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	183	287
Equal to or Greater than 12 Months Estimated Fair Value	3,033	2,431
Gross Unrealized Temporary Loss	232	196
State and political subdivision
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Less than 12 months Estimated Fair Value	172	1,618
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	3	55
Equal to or Greater than 12 Months Estimated Fair Value	89	168
Gross Unrealized Temporary Loss	14	22
ABS
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Less than 12 months Estimated Fair Value	5,136	7,329
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	176	124
Equal to or Greater than 12 Months Estimated Fair Value	4,555	2,823
Gross Unrealized Temporary Loss	136	111
CMBS
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Less than 12 months Estimated Fair Value	900	4,876
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	45	81
Equal to or Greater than 12 Months Estimated Fair Value	982	637
Gross Unrealized Temporary Loss	49	43
Equity securities
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Less than 12 months Estimated Fair Value	164	282
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	24	107
Equal to or Greater than 12 Months Estimated Fair Value	175	220
Gross Unrealized Temporary Loss	58	51
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	114	203
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	18	105
Equal to or Greater than 12 Months Estimated Fair Value	7	20
Gross Unrealized Temporary Loss	0	2
Non-redeemable preferred stock
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Less than 12 months Estimated Fair Value	50	79
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	6	2
Equal to or Greater than 12 Months Estimated Fair Value	168	200
Gross Unrealized Temporary Loss	$ 58	$ 49