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, 2018	Dec. 31, 2017
Investments, Unrealized Loss Position
Less than 12 months fair value		$ 809
Less than 12 Months, Unrealized losses		20
12 months or more fair value		682
12 Months or more, unrealized losses		18
Total fair value		1,491
Total Unrealized Losses		38
Fixed Maturities
Investments, Unrealized Loss Position
Less than 12 months fair value	$ 3,031	580
Less than 12 Months, Unrealized losses	70	6
12 months or more fair value	1,149	682
12 Months or more, unrealized losses	58	18
Total fair value	4,180	1,262
Total Unrealized Losses	128	24
Fixed Maturities | Corporate Securities
Investments, Unrealized Loss Position
Less than 12 months fair value	2,082	330
Less than 12 Months, Unrealized losses	51	4
12 months or more fair value	501	252
12 Months or more, unrealized losses	36	9
Total fair value	2,583	582
Total Unrealized Losses	87	13
Fixed Maturities | States, Municipalities and Political Subdivisions
Investments, Unrealized Loss Position
Less than 12 months fair value	823	88
Less than 12 Months, Unrealized losses	18	1
12 months or more fair value	340	264
12 Months or more, unrealized losses	13	5
Total fair value	1,163	352
Total Unrealized Losses	31	6
Fixed Maturities | Commercial Mortgage Backed Securities
Investments, Unrealized Loss Position
Less than 12 months fair value	77	33
Less than 12 Months, Unrealized losses	0	0
12 months or more fair value	64	36
12 Months or more, unrealized losses	2	1
Total fair value	141	69
Total Unrealized Losses	2	1
Fixed Maturities | Government-Sponsored Enterprises
Investments, Unrealized Loss Position
Less than 12 months fair value	49	96
Less than 12 Months, Unrealized losses	1	1
12 months or more fair value	211	124
12 Months or more, unrealized losses	6	3
Total fair value	260	220
Total Unrealized Losses	7	4
Fixed Maturities | Foreign government
Investments, Unrealized Loss Position
Less than 12 months fair value		10
Less than 12 Months, Unrealized losses		0
12 months or more fair value		0
12 Months or more, unrealized losses		0
Total fair value		10
Total Unrealized Losses		0
Fixed Maturities | United States Government
Investments, Unrealized Loss Position
Less than 12 months fair value	0	23
Less than 12 Months, Unrealized losses	0	0
12 months or more fair value	33	6
12 Months or more, unrealized losses	1	0
Total fair value	33	29
Total Unrealized Losses	$ 1	0
Equity Securities
Investments, Unrealized Loss Position
Less than 12 months fair value		229
Less than 12 Months, Unrealized losses		14
12 months or more fair value		0
12 Months or more, unrealized losses		0
Total fair value		229
Total Unrealized Losses		14
Equity Securities | Common Equities
Investments, Unrealized Loss Position
Less than 12 months fair value		229
Less than 12 Months, Unrealized losses		14
12 months or more fair value		0
12 Months or more, unrealized losses		0
Total fair value		229
Total Unrealized Losses		$ 14