Investments (Fair Values And Unrealized Losses By Investment Category And By The Duration Of The Securities' Continuous Unrealized Loss Position) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Investments, Unrealized Loss Position
Less than 12 months fair value	$ 1,654	$ 393
Less than 12 months unrealized losses	119	11
12 months or more fair value	284	446
12 months or more unrealized losses	37	11
Total fair value	1,938	839
Total unrealized losses	156	22
Fixed Maturities
Investments, Unrealized Loss Position
Less than 12 months fair value	1,349	292
Less than 12 months unrealized losses	68	8
12 months or more fair value	284	429
12 months or more unrealized losses	37	10
Total fair value	1,633	721
Total unrealized losses	105	18
Fixed Maturities | Corporate Securities
Investments, Unrealized Loss Position
Less than 12 months fair value	1,099	261
Less than 12 months unrealized losses	63	8
12 months or more fair value	133	90
12 months or more unrealized losses	33	3
Total fair value	1,232	351
Total unrealized losses	96	11
Fixed Maturities | States, Municipalities and Political Subdivisions
Investments, Unrealized Loss Position
Less than 12 months fair value	47	17
Less than 12 months unrealized losses	1	0
12 months or more fair value	22	135
12 months or more unrealized losses	0	2
Total fair value	69	152
Total unrealized losses	1	2
Fixed Maturities | Commercial Mortgage Backed Securities
Investments, Unrealized Loss Position
Less than 12 months fair value	103	3
Less than 12 months unrealized losses	2	0
12 months or more fair value	2	23
12 months or more unrealized losses	0	0
Total fair value	105	26
Total unrealized losses	2	0
Fixed Maturities | Government-Sponsored Enterprises
Investments, Unrealized Loss Position
Less than 12 months fair value	100	11
Less than 12 months unrealized losses	2	0
12 months or more fair value	127	181
12 months or more unrealized losses	4	5
Total fair value	227	192
Total unrealized losses	6	5
Equity Securities
Investments, Unrealized Loss Position
Less than 12 months fair value	305	101
Less than 12 months unrealized losses	51	3
12 months or more fair value	0	17
12 months or more unrealized losses	0	1
Total fair value	305	118
Total unrealized losses	51	4
Equity Securities | Common Equities
Investments, Unrealized Loss Position
Less than 12 months fair value	270	85
Less than 12 months unrealized losses	51	3
12 months or more fair value	0	0
12 months or more unrealized losses	0	0
Total fair value	270	85
Total unrealized losses	51	3
Equity Securities | Nonredeemable Preferred Equities
Investments, Unrealized Loss Position
Less than 12 months fair value	35	16
Less than 12 months unrealized losses	0	0
12 months or more fair value	0	17
12 months or more unrealized losses	0	1
Total fair value	35	33
Total unrealized losses	$ 0	$ 1