Schedule II-Condensed Financial Information Of Registrant (Statement Of Cash Flows) (Details) - USD ($) $ in Millions	3 Months Ended											9 Months Ended		12 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating activities
Net cash provided by operating activities												$ 11,032	$ 9,917	$ 8,399	$ 8,364	$ 10,688
Investing activities
Purchases of investments												(24,337)	(19,612)	(24,946)	(18,669)	(19,492)
Changes in securities lending collateral												55	(677)	(301)	(956)	(849)
Payments for (Proceeds from) Other Investing Activities												(82)	(91)	(120)	(63)	(45)
Net cash used in investing activities												(4,543)	(4,849)	(4,560)	(9,638)	(7,324)
Financing activities
Net (repayments of) proceeds from commercial paper borrowings												0	375	(300)	50	(150)
Proceeds from long-term borrowings												2,574	1,286	3,071	3,462	2,484
Repayments of long-term borrowings												(1,908)	(982)	(1,899)	(1,068)	(1,932)
Changes in securities lending payable												(54)	685	302	956	849
Repurchase and retirement of common stock												(1,748)	(1,748)	(2,316)	(1,900)	(2,700)
Total	$ (348)	$ (350)	$ (351)	$ (305)	$ (306)	$ (309)	$ (309)	$ (273)	$ (276)	$ (278)	$ (277)	(1,049)	(924)	(1,229)	(1,104)	(954)
Proceeds from issuance of common stock under employee stock plans												112	152	182	203	176
Taxes paid through withholding of common stock under employee stock plans												(99)	(91)	(93)	(102)	(128)
Other, net												5	16	41	27	2
Net cash (used in) provided by financing activities												(2,955)	(1,060)	(1,318)	423	(2,567)
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect												3,532	3,992	2,507	(861)	804
Cash and cash equivalents at end of year	$ 10,919			7,387	$ 8,872			4,880				$ 10,919	$ 8,872	7,387	4,880	5,741	$ 4,937
Anthem, Inc. [Member]
Operating activities
Net cash provided by operating activities														1,447	2,038	4,810
Investing activities
Purchases of investments														(367)	(2,059)	(2,729)
Proceeds from sales, maturities, calls and redemptions of investments														618	2,449	2,593
Issuance of note to subsidiary														1,500	(1,500)	0
Capitalization of subsidiaries														(411)	(807)	(2,460)
Changes in securities lending collateral														36	173	(234)
Purchases of property and equipment, net of sales														(47)	(77)	(107)
Payments for (Proceeds from) Other Investing Activities														0	0	11
Net cash used in investing activities														1,329	(1,821)	(2,926)
Financing activities
Net (repayments of) proceeds from commercial paper borrowings														(300)	50	(150)
Proceeds from long-term borrowings														3,071	3,462	2,484
Repayments of long-term borrowings														(1,899)	(1,068)	(1,932)
Changes in securities lending payable														(36)	(173)	234
Repurchase and retirement of common stock														(2,316)	(1,900)	(2,700)
Total														(1,290)	(1,158)	(1,000)
Proceeds from issuance of common stock under employee stock plans														182	203	176
Taxes paid through withholding of common stock under employee stock plans														(93)	(102)	(128)
Other, net														217	399	14
Net cash (used in) provided by financing activities														(2,464)	(287)	(3,002)
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect														312	(70)	(1,118)
Cash and cash equivalents at end of year				$ 942				$ 630						$ 942	$ 630	$ 700	$ 1,818