10-K Goodwill And Other Intangible Assets (Components Of Other Intangible Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Intangible Assets [Line Items]
Gross Carrying Amount, Finite Lived Intangibles		$ 7,127	$ 6,532
Accumulated Amortization, Finite Lived Intangibles		(4,279)	(3,506)
Net Carrying Amount, Finite Lived Intangibles		2,848	3,026
Gross Carrying Amount, Indefinite Lived Intangibles		7,467	7,589
Gross Carrying Amount, Indefinite Lived Intangibles		7,467	7,589
Gross Carrying Amount, Total Intangible Assets		14,594	14,121
Accumulated Amortization, Total Intangible Assets		(4,279)	(3,506)
Net Carrying Amount, Total Intangible Assets	$ 10,491	10,315	10,615
Blue Cross And Blue Shield And Other Trademarks [Member]
Intangible Assets [Line Items]
Gross Carrying Amount, Indefinite Lived Intangibles		5,991	6,299
Gross Carrying Amount, Indefinite Lived Intangibles		5,991	6,299
State Medicaid Licenses [Member]
Intangible Assets [Line Items]
Gross Carrying Amount, Indefinite Lived Intangibles		1,476	1,290
Gross Carrying Amount, Indefinite Lived Intangibles		1,476	1,290
Customer Relationships [Member]
Intangible Assets [Line Items]
Gross Carrying Amount, Finite Lived Intangibles		5,791	5,598
Accumulated Amortization, Finite Lived Intangibles		(3,693)	(3,236)
Net Carrying Amount, Finite Lived Intangibles		2,098	2,362
Provider And Hospital Relationships [Member]
Intangible Assets [Line Items]
Gross Carrying Amount, Finite Lived Intangibles		326	324
Accumulated Amortization, Finite Lived Intangibles		(146)	(129)
Net Carrying Amount, Finite Lived Intangibles		180	195
Other [Member]
Intangible Assets [Line Items]
Gross Carrying Amount, Finite Lived Intangibles		1,010	610
Accumulated Amortization, Finite Lived Intangibles		(440)	(141)
Net Carrying Amount, Finite Lived Intangibles		$ 570	$ 469