Investments (Fair Value And Gross Unrealized Losses In A Continuous Unrealized Loss Position) (Details) $ in Millions	Jun. 30, 2017 USD ($) security	Dec. 31, 2016 USD ($) security
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	$ 10,065	$ 17,813
Greater Than Twelve Months	3,063	4,155
Continuous Unrealized Loss Position, Total	13,128	21,968
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	279	659
Greater Than Twelve Months	339	507
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	$ 618	$ 1,166
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | security	1,155	1,744
Equity AFS securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	$ 10	$ 4
Greater Than Twelve Months	15	44
Continuous Unrealized Loss Position, Total	25	48
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	4	2
Greater Than Twelve Months	1	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	5	4
Fixed maturity securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	10,055	17,809
Greater Than Twelve Months	3,048	4,111
Continuous Unrealized Loss Position, Total	13,103	21,920
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	275	657
Greater Than Twelve Months	338	505
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	613	1,162
Corporate bonds [Member] | Fixed maturity securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	8,521	15,820
Greater Than Twelve Months	2,417	3,187
Continuous Unrealized Loss Position, Total	10,938	19,007
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	223	569
Greater Than Twelve Months	279	403
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	502	972
ABS [Member] | Fixed maturity securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	84	201
Greater Than Twelve Months	260	298
Continuous Unrealized Loss Position, Total	344	499
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	3	4
Greater Than Twelve Months	21	25
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	24	29
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	172	18
Continuous Unrealized Loss Position, Total	172	18
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	2	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	2	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		29
Continuous Unrealized Loss Position, Total		29
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	805	989
Greater Than Twelve Months	146	392
Continuous Unrealized Loss Position, Total	951	1,381
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	35	58
Greater Than Twelve Months	5	23
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	40	81
CMBS [Member] | Fixed maturity securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	92	190
Greater Than Twelve Months	8	19
Continuous Unrealized Loss Position, Total	100	209
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	2	4
Greater Than Twelve Months	2	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	4	6
CLOs [Member] | Fixed maturity securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Less Than or Equal to Twelve Months	227	259
Greater Than Twelve Months	19	25
Continuous Unrealized Loss Position, Total	246	284
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	2	3
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	132	227
Greater Than Twelve Months	47	47
Continuous Unrealized Loss Position, Total	179	274
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	7	12
Greater Than Twelve Months	5	8
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	12	20
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	22	76
Greater Than Twelve Months	151	143
Continuous Unrealized Loss Position, Total	173	219
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses and OTTI
Less Than or Equal to Twelve Months	1	4
Greater Than Twelve Months	26	44
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	$ 27	$ 48