Schedule II-Condensed Financial Information Of Registrant (Balance Sheets) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 10,919		$ 7,387			$ 4,880
Fixed maturity securities, current, amortized cost	27,811		25,952			26,267
Equity securities	165		953			1,881
Other receivables	5,293		4,298			3,749
Other current assets	5,358		5,281			4,654
Total current assets	61,185		55,617			51,122
Other invested assets	6,118		5,685			5,225
Property and equipment, net	4,248		4,316			3,919
Other noncurrent assets	2,329		1,687			1,715
Total assets	110,478		102,755			97,456
Current Liabilities:
Accounts payable and accrued expenses	5,983		5,607			4,970
Other current liabilities	10,366		9,683			7,849
Current portion of long-term debt	799		1,500			1,599
Total current liabilities	43,337		39,696			34,885
Long-term debt, less current portion	24,045		22,349			21,157
Other noncurrent liabilities	1,971		1,562			1,683
Total liabilities	71,939		66,425			61,293
Commitments and contingencies-Note 5
Shareholders' equity
Preferred stock, without par value, shares authorized - 100,000,000; shares issued and outstanding - none	0		0			0
Common stock, par value $0.01, shares authorized - 900,000,000; shares issued and outstanding - 237,958,067 and 241,770,746	2		2			2
Additional paid-in capital	8,830		9,084			9,148
Retained earnings	32,103		29,647			27,142
Accumulated other comprehensive loss	(2,512)	$ (2,166)	(2,490)	$ (2,779)	$ (2,151)	(197)	$ 150	$ (296)
Total Shareholders' Balance, beginning	38,423		36,243	$ 36,055		36,095
Total liabilities and equity	$ 110,478		$ 102,755			$ 97,456
Preferred stock, shares authorized	100,000,000		100,000,000			100,000,000
Preferred stock, shares issued	0		0			0
Preferred stock, shares outstanding	0		0			0
Anthem, Inc. [Member]
Current assets:
Cash and cash equivalents			$ 942			$ 630
Fixed maturity securities, current, amortized cost			163			515
Equity securities			104			49
Other current assets			721			655
Total current assets			1,985			2,335
Other invested assets			783			808
Property and equipment, net			187			207
Deferred tax assets, net			313			77
Investment in subsidiaries			58,978			56,410
Other noncurrent assets			240			265
Total assets			62,486			60,102
Current Liabilities:
Accounts payable and accrued expenses			894			559
Current portion of long-term debt			1,500			1,599
Total current liabilities			3,544			2,502
Long-term debt, less current portion			22,324			21,132
Other noncurrent liabilities			375			373
Total liabilities			26,243			24,007
Commitments and contingencies-Note 5
Shareholders' equity
Preferred stock, without par value, shares authorized - 100,000,000; shares issued and outstanding - none			0			0
Common stock, par value $0.01, shares authorized - 900,000,000; shares issued and outstanding - 237,958,067 and 241,770,746			2			2
Additional paid-in capital			9,084			9,148
Retained earnings			29,647			27,142
Accumulated other comprehensive loss			(2,490)			(197)
Total Shareholders' Balance, beginning			36,243			36,095
Total liabilities and equity			$ 62,486			60,102
Preferred stock, shares authorized			100,000,000
Preferred stock, shares issued			0
Preferred stock, shares outstanding			0
Anthem, Inc. [Member] | Nonrelated Party [Member]
Current assets:
Other receivables			$ 55			40
Current Liabilities:
Other current liabilities			361			344
Anthem, Inc. [Member] | Subsidiaries [Member]
Current assets:
Other receivables			0			446
Current Liabilities:
Other current liabilities			$ 789			$ 0