Investments (Reconciliation Of Available-For-Sale Securities From Cost Basis To Fair Value) (Details) - USD ($) $ in Millions		Sep. 30, 2018	Dec. 31, 2017
Amortized cost, gross unrealized gains, losses, OTTI and fair value of AFS securities
Amortized cost		$ 90,808	$ 87,240
Gross unrealized gains		4,237	8,233
Gross unrealized losses		1,939	450
OTTI	[1]	(55)	(63)
Fair value		93,161	95,086
Fixed Maturity AFS Securities [Member]
Amortized cost, gross unrealized gains, losses, OTTI and fair value of AFS securities
Amortized cost		90,808	86,993
Gross unrealized gains			8,217
Gross unrealized losses			433
OTTI	[1]		(63)
Fair value		93,161	94,840
Fixed Maturity AFS Securities [Member] | Corporate Bonds [Member]
Amortized cost, gross unrealized gains, losses, OTTI and fair value of AFS securities
Amortized cost		78,496	75,701
Gross unrealized gains		3,299	6,862
Gross unrealized losses		1,724	354
OTTI	[1]	(9)	(7)
Fair value		80,080	82,216
Fixed Maturity AFS Securities [Member] | ABS [Member]
Amortized cost, gross unrealized gains, losses, OTTI and fair value of AFS securities
Amortized cost		934	903
Gross unrealized gains		41	51
Gross unrealized losses		7	7
OTTI	[1]	(17)	(27)
Fair value		985	974
Fixed Maturity AFS Securities [Member] | U.S. Government Bonds [Member]
Amortized cost, gross unrealized gains, losses, OTTI and fair value of AFS securities
Amortized cost		392	527
Gross unrealized gains		23	41
Gross unrealized losses		6	1
Fair value		409	567
Fixed Maturity AFS Securities [Member] | Foreign Government Bonds [Member]
Amortized cost, gross unrealized gains, losses, OTTI and fair value of AFS securities
Amortized cost		418	395
Gross unrealized gains		41	56
Fair value		459	451
Fixed Maturity AFS Securities [Member] | RMBS [Member]
Amortized cost, gross unrealized gains, losses, OTTI and fair value of AFS securities
Amortized cost		3,267	3,327
Gross unrealized gains		113	155
Gross unrealized losses		114	39
OTTI	[1]	(21)	(22)
Fair value		3,287	3,465
Fixed Maturity AFS Securities [Member] | CMBS [Member]
Amortized cost, gross unrealized gains, losses, OTTI and fair value of AFS securities
Amortized cost		766	590
Gross unrealized gains		2	10
Gross unrealized losses		23	2
OTTI	[1]	(3)	(2)
Fair value		748	600
Fixed Maturity AFS Securities [Member] | CLOs [Member]
Amortized cost, gross unrealized gains, losses, OTTI and fair value of AFS securities
Amortized cost		1,371	803
Gross unrealized gains			2
Gross unrealized losses		14	2
OTTI	[1]	(5)	(5)
Fair value		1,362	808
Fixed Maturity AFS Securities [Member] | State And Municipal Bonds [Member]
Amortized cost, gross unrealized gains, losses, OTTI and fair value of AFS securities
Amortized cost		4,588	4,172
Gross unrealized gains		656	953
Gross unrealized losses		26	6
Fair value		5,218	5,119
Fixed Maturity AFS Securities [Member] | Hybrid And Redeemable Preferred Securities [Member]
Amortized cost, gross unrealized gains, losses, OTTI and fair value of AFS securities
Amortized cost		576	575
Gross unrealized gains		62	87
Gross unrealized losses		25	22
Fair value		$ 613	640
Equity Securities [Member]
Amortized cost, gross unrealized gains, losses, OTTI and fair value of AFS securities
Amortized cost			247
Gross unrealized gains			16
Gross unrealized losses			17
Fair value			$ 246

[1] Includes unrealized (gains) and losses on impaired securities related to changes in the fair value of such securities subsequent to the impairment measurement date.