Investments (Continuous Gross Unrealized Losses for Fixed Maturity and Equity Securities Available-For-Sale) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
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	2,704	3,153
Total number of securities in an unrealized loss position equal to or greater than 12 months	1,122	1,435
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	$ 33,129	$ 40,798
Less than 12 Months Gross Unrealized Loss	1,439	1,101
Equal to or Greater than 12 Months Estimated Fair Value	8,812	13,881
Equal to or Greater than 12 Months Gross Unrealized Loss	769	888
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	8,366	11,389
Less than 12 Months Gross Unrealized Loss	322	331
Equal to or Greater than 12 Months Estimated Fair Value	2,545	4,658
Equal to or Greater than 12 Months Gross Unrealized Loss	235	293
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	10,108	9,410
Less than 12 Months Gross Unrealized Loss	849	505
Equal to or Greater than 12 Months Estimated Fair Value	1,657	2,074
Equal to or Greater than 12 Months Gross Unrealized Loss	166	166
U.S. Treasury 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	4,600	8,927
Less than 12 Months Gross Unrealized Loss	31	12
Equal to or Greater than 12 Months Estimated Fair Value	302	1,314
Equal to or Greater than 12 Months Gross Unrealized Loss	3	18
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	1,241	1,085
Less than 12 Months Gross Unrealized Loss	54	80
Equal to or Greater than 12 Months Estimated Fair Value	435	630
Equal to or Greater than 12 Months Gross Unrealized Loss	75	81
RMBS
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Less than 12 months Estimated Fair Value	3,276	4,180
Less than 12 Months Gross Unrealized Loss	65	92
Equal to or Greater than 12 Months Estimated Fair Value	2,018	2,534
Equal to or Greater than 12 Months Gross Unrealized Loss	221	228
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	287	83
Less than 12 Months Gross Unrealized Loss	5	1
Equal to or Greater than 12 Months Estimated Fair Value	109	297
Equal to or Greater than 12 Months Gross Unrealized Loss	23	25
CMBS (1)
Continuous Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Less than 12 months Estimated Fair Value	1,579	1,268
Less than 12 Months Gross Unrealized Loss	46	23
Equal to or Greater than 12 Months Estimated Fair Value	362	934
Equal to or Greater than 12 Months Gross Unrealized Loss	10	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	3,672	4,456
Less than 12 Months Gross Unrealized Loss	67	57
Equal to or Greater than 12 Months Estimated Fair Value	1,384	1,440
Equal to or Greater than 12 Months Gross Unrealized Loss	36	55
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	174	178
Less than 12 Months Gross Unrealized Loss	28	30
Equal to or Greater than 12 Months Estimated Fair Value	189	193
Equal to or Greater than 12 Months Gross Unrealized Loss	41	37
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	137	111
Less than 12 Months Gross Unrealized Loss	25	28
Equal to or Greater than 12 Months Estimated Fair Value	0	1
Equal to or Greater than 12 Months Gross Unrealized Loss	0	0
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	37	67
Less than 12 Months Gross Unrealized Loss	3	2
Equal to or Greater than 12 Months Estimated Fair Value	189	192
Equal to or Greater than 12 Months Gross Unrealized Loss	$ 41	$ 37