Investments (Continuous Gross Unrealized Losses for Fixed Maturity and Equity Securities Available-For-Sale) (Details) $ in Millions	Mar. 31, 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	3,904	6,366
Total number of securities in an unrealized loss position equal to or greater than 12 months	1,837	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	$ 44,315	$ 92,421
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,741	3,475
Equal to or Greater than 12 Months Estimated Fair Value	20,214	15,799
Gross Unrealized Temporary Loss	1,957	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	14,740	27,526
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	708	1,629
Equal to or Greater than 12 Months Estimated Fair Value	5,276	3,762
Gross Unrealized Temporary Loss	612	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	1,549	19,628
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	13	222
Equal to or Greater than 12 Months Estimated Fair Value	500	298
Gross Unrealized Temporary Loss	25	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	8,960	14,447
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	479	911
Equal to or Greater than 12 Months Estimated Fair Value	6,210	5,251
Gross Unrealized Temporary Loss	798	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	1,996	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	535	429
Gross Unrealized Temporary Loss	49	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	7,026	13,467
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	234	287
Equal to or Greater than 12 Months Estimated Fair Value	2,989	2,431
Gross Unrealized Temporary Loss	254	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	322	1,618
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	4	55
Equal to or Greater than 12 Months Estimated Fair Value	168	168
Gross Unrealized Temporary Loss	20	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	8,025	7,329
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	188	124
Equal to or Greater than 12 Months Estimated Fair Value	3,569	2,823
Gross Unrealized Temporary Loss	138	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	1,697	4,876
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	32	81
Equal to or Greater than 12 Months Estimated Fair Value	967	637
Gross Unrealized Temporary Loss	61	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	298	282
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	55	107
Equal to or Greater than 12 Months Estimated Fair Value	178	220
Gross Unrealized Temporary Loss	62	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	168	203
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	46	105
Equal to or Greater than 12 Months Estimated Fair Value	2	20
Gross Unrealized Temporary Loss	2	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	130	79
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	9	2
Equal to or Greater than 12 Months Estimated Fair Value	176	200
Gross Unrealized Temporary Loss	$ 60	$ 49