10-Q 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, 2023 USD ($) securities	Dec. 31, 2022 USD ($) securities	Dec. 31, 2021 USD ($) securities
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months | securities	4,141	7,781	3,571
Estimated fair value, less than 12 months	$ 10,733	$ 16,035	$ 8,755
Gross unrealized loss, less than 12 months	$ (426)	$ (1,071)	$ (131)
Number of securities, 12 months or greater | securities	7,181	4,060	686
Estimated fair value, 12 months or greater	$ 15,767	$ 7,537	$ 985
Gross unrealized loss, 12 months or greater	$ (2,009)	$ (1,307)	$ (51)
United States Government Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months | securities	55	61	51
Estimated fair value, less than 12 months	$ 1,170	$ 701	$ 990
Gross unrealized loss, less than 12 months	$ (58)	$ (40)	$ (11)
Number of securities, 12 months or greater | securities	55	38	27
Estimated fair value, 12 months or greater	$ 423	$ 442	$ 176
Gross unrealized loss, 12 months or greater	$ (71)	$ (63)	$ (7)
Government Sponsored Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months | securities	6	39	0
Estimated fair value, less than 12 months	$ 50	$ 73	$ 0
Gross unrealized loss, less than 12 months	$ (2)	$ (4)	$ 0
Number of securities, 12 months or greater | securities	40	6	1
Estimated fair value, 12 months or greater	$ 52	$ 5	$ 1
Gross unrealized loss, 12 months or greater	$ (6)	$ (1)	$ (1)
Foreign Government Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months | securities	5	150	188
Estimated fair value, less than 12 months	$ 5	$ 100	$ 143
Gross unrealized loss, less than 12 months	$ 0	$ (10)	$ (8)
Number of securities, 12 months or greater | securities	5	198	68
Estimated fair value, 12 months or greater	$ 7	$ 142	$ 41
Gross unrealized loss, 12 months or greater	$ (2)	$ (36)	$ (5)
States, Municipalities And Political Subdivisions [Member]
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months | securities	833	1,398	281
Estimated fair value, less than 12 months	$ 1,503	$ 2,615	$ 634
Gross unrealized loss, less than 12 months	$ (55)	$ (147)	$ (9)
Number of securities, 12 months or greater | securities	1,132	396	8
Estimated fair value, 12 months or greater	$ 1,876	$ 652	$ 16
Gross unrealized loss, 12 months or greater	$ (270)	$ (118)	$ (1)
Corporate Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months | securities	2,160	3,551	1,846
Estimated fair value, less than 12 months	$ 4,995	$ 7,826	$ 3,310
Gross unrealized loss, less than 12 months	$ (180)	$ (549)	$ (57)
Number of securities, 12 months or greater | securities	2,908	2,204	403
Estimated fair value, 12 months or greater	$ 7,542	$ 3,521	$ 485
Gross unrealized loss, 12 months or greater	$ (976)	$ (669)	$ (21)
Residential Mortgage-Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months | securities	583	1,341	422
Estimated fair value, less than 12 months	$ 1,339	$ 1,435	$ 1,295
Gross unrealized loss, less than 12 months	$ (59)	$ (121)	$ (19)
Number of securities, 12 months or greater | securities	1,583	496	63
Estimated fair value, 12 months or greater	$ 1,895	$ 982	$ 44
Gross unrealized loss, 12 months or greater	$ (379)	$ (203)	$ (3)
Commercial Mortgage-Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months | securities	176	457	272
Estimated fair value, less than 12 months	$ 517	$ 1,082	$ 676
Gross unrealized loss, less than 12 months	$ (22)	$ (76)	$ (8)
Number of securities, 12 months or greater | securities	579	324	66
Estimated fair value, 12 months or greater	$ 1,395	$ 719	$ 137
Gross unrealized loss, 12 months or greater	$ (166)	$ (100)	$ (8)
Other Asset-Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months | securities	323	784	511
Estimated fair value, less than 12 months	$ 1,154	$ 2,203	$ 1,707
Gross unrealized loss, less than 12 months	$ (50)	$ (124)	$ (19)
Number of securities, 12 months or greater | securities	879	398	50
Estimated fair value, 12 months or greater	$ 2,577	$ 1,074	$ 85
Gross unrealized loss, 12 months or greater	$ (139)	$ (117)	$ (5)