Investments (Fair Value And Gross Unrealized Losses In A Continuous Unrealized Loss Position) (Details) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2016 USD ($) security	Dec. 31, 2015 USD ($) security
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	$ 9,170	$ 21,873
Greater Than Twelve Months	5,578	3,263
Continuous Unrealized Loss Position, Total	14,748	25,136
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	543	1,411
Greater Than Twelve Months	947	724
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	$ 1,490	$ 2,135
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | security	1,362	2,007
Equity AFS securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	$ 49	$ 47
Greater Than Twelve Months
Continuous Unrealized Loss Position, Total	$ 49	47
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	$ 6	6
Greater Than Twelve Months
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	$ 6	6
Fixed maturity securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	9,121	21,826
Greater Than Twelve Months	5,578	3,263
Continuous Unrealized Loss Position, Total	14,699	25,089
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	537	1,405
Greater Than Twelve Months	947	724
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	1,484	2,129
Corporate bonds [Member] | Fixed maturity securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	8,275	20,380
Greater Than Twelve Months	4,466	2,383
Continuous Unrealized Loss Position, Total	12,741	22,763
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	507	1,364
Greater Than Twelve Months	820	623
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	1,327	1,987
ABS [Member] | Fixed maturity securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	225	213
Greater Than Twelve Months	268	274
Continuous Unrealized Loss Position, Total	493	487
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	9	4
Greater Than Twelve Months	33	29
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	42	33
U.S. government bonds [Member] | Fixed maturity securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months		15
Greater Than Twelve Months	17
Continuous Unrealized Loss Position, Total	17	15
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months		2
Greater Than Twelve Months	1
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	1	2
Foreign government bonds [Member] | Fixed maturity securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months		37
Continuous Unrealized Loss Position, Total		37
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months		1
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses		1
RMBS [Member] | Fixed maturity securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	337	627
Greater Than Twelve Months	578	371
Continuous Unrealized Loss Position, Total	915	998
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	15	21
Greater Than Twelve Months	34	22
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	49	43
CMBS [Member] | Fixed maturity securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	12	116
Greater Than Twelve Months	10	11
Continuous Unrealized Loss Position, Total	22	127
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	1	2
Greater Than Twelve Months	1	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	2	4
CLOs [Member] | Fixed maturity securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	194	271
Greater Than Twelve Months	43	49
Continuous Unrealized Loss Position, Total	237	320
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	2	2
Greater Than Twelve Months		1
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	2	3
State and municipal bonds [Member] | Fixed maturity securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	40	129
Greater Than Twelve Months	55	27
Continuous Unrealized Loss Position, Total	95	156
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	2	8
Greater Than Twelve Months	7	4
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	9	12
Hybrid and redeemable preferred securities [Member] | Fixed maturity securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	38	38
Greater Than Twelve Months	141	148
Continuous Unrealized Loss Position, Total	179	186
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	1	1
Greater Than Twelve Months	51	43
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	$ 52	$ 44