Investments (Aggregate Fair Value And Gross Unrealized Loss Of Fixed Maturity Securities In An Unrealized Loss Position) (Details) - Fixed Maturities [Member] $ in Millions	Sep. 30, 2021 USD ($) securities	Dec. 31, 2020 USD ($) securities
Schedule of Investments [Line Items]
Number of securities, less than 12 months | securities	2,660	1,201
Estimated fair value, less than 12 months	$ 5,846	$ 2,125
Gross unrealized loss, less than 12 months	$ (75)	$ (39)
Number of securities, 12 months or greater | securities	426	333
Estimated fair value, 12 months or greater	$ 660	$ 469
Gross unrealized loss, 12 months or greater	$ (33)	$ (29)
United States Government Securities [Member]
Schedule of Investments [Line Items]
Number of securities, less than 12 months | securities	62	27
Estimated fair value, less than 12 months	$ 702	$ 301
Gross unrealized loss, less than 12 months	$ (8)	$ (2)
Number of securities, 12 months or greater | securities	17	0
Estimated fair value, 12 months or greater	$ 141	$ 0
Gross unrealized loss, 12 months or greater	$ (4)	$ 0
Government Sponsored Securities [Member]
Schedule of Investments [Line Items]
Number of securities, less than 12 months | securities	1	0
Estimated fair value, less than 12 months	$ 1	$ 0
Gross unrealized loss, less than 12 months	$ 0	$ 0
Number of securities, 12 months or greater | securities	0	1
Estimated fair value, 12 months or greater	$ 0	$ 0
Gross unrealized loss, 12 months or greater	$ 0	$ 0
Foreign Government Securities [Member]
Schedule of Investments [Line Items]
Number of securities, less than 12 months | securities	191	55
Estimated fair value, less than 12 months	$ 155	$ 35
Gross unrealized loss, less than 12 months	$ (7)	$ (2)
Number of securities, 12 months or greater | securities	22	9
Estimated fair value, 12 months or greater	$ 10	$ 4
Gross unrealized loss, 12 months or greater	$ (2)	$ 0
States, Municipalities And Political Subdivisions [Member]
Schedule of Investments [Line Items]
Number of securities, less than 12 months | securities	254	36
Estimated fair value, less than 12 months	$ 516	$ 57
Gross unrealized loss, less than 12 months	$ (6)	$ (1)
Number of securities, 12 months or greater | securities	4	1
Estimated fair value, 12 months or greater	$ 11	$ 3
Gross unrealized loss, 12 months or greater	$ (1)	$ 0
Corporate Securities [Member]
Schedule of Investments [Line Items]
Number of securities, less than 12 months | securities	1,478	646
Estimated fair value, less than 12 months	$ 2,321	$ 765
Gross unrealized loss, less than 12 months	$ (38)	$ (20)
Number of securities, 12 months or greater | securities	225	150
Estimated fair value, 12 months or greater	$ 273	$ 169
Gross unrealized loss, 12 months or greater	$ (11)	$ (11)
Residential Mortgage-Backed Securities [Member]
Schedule of Investments [Line Items]
Number of securities, less than 12 months | securities	418	224
Estimated fair value, less than 12 months	$ 1,430	$ 442
Gross unrealized loss, less than 12 months	$ (13)	$ (8)
Number of securities, 12 months or greater | securities	101	90
Estimated fair value, 12 months or greater	$ 108	$ 110
Gross unrealized loss, 12 months or greater	$ (7)	$ (9)
Commercial Mortgage-Backed Securities [Member]
Schedule of Investments [Line Items]
Number of securities, less than 12 months | securities	1	6
Estimated fair value, less than 12 months	$ 1	$ 16
Gross unrealized loss, less than 12 months	$ 0	$ (1)
Number of securities, 12 months or greater | securities	4	3
Estimated fair value, 12 months or greater	$ 7	$ 4
Gross unrealized loss, 12 months or greater	$ (3)	$ (3)
Other Securities [Member]
Schedule of Investments [Line Items]
Number of securities, less than 12 months | securities	255	207
Estimated fair value, less than 12 months	$ 720	$ 509
Gross unrealized loss, less than 12 months	$ (3)	$ (5)
Number of securities, 12 months or greater | securities	53	79
Estimated fair value, 12 months or greater	$ 110	$ 179
Gross unrealized loss, 12 months or greater	$ (5)	$ (6)