Goodwill and Intangible Assets - Summary of Changes in Goodwill (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, Balance beginning	$ 18,812	$ 19,771
Acquisition and purchase accounting adjustments		1,077
Divestitures	(933)	(1,533)
Reallocation		0
Impairments	(348)	(370)
Translation impact	27	(133)
Goodwill, Balance ending	17,558	18,812
Medicaid
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, Balance beginning	10,198	10,194
Acquisition and purchase accounting adjustments		0
Divestitures	0	0
Reallocation		4
Impairments	0	0
Translation impact	0	0
Goodwill, Balance ending	10,198	10,198
Medicare
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, Balance beginning	1,592	1,592
Acquisition and purchase accounting adjustments		0
Divestitures	0	0
Reallocation		0
Impairments	0	0
Translation impact	0	0
Goodwill, Balance ending	1,592	1,592
Commercial
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, Balance beginning	5,424	5,424
Acquisition and purchase accounting adjustments		0
Divestitures	0	0
Reallocation		0
Impairments	0	0
Translation impact	0	0
Goodwill, Balance ending	5,424	5,424
Other
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, Balance beginning	1,598	2,561
Acquisition and purchase accounting adjustments		1,077
Divestitures	(933)	(1,533)
Reallocation		(4)
Impairments	(348)	(370)
Translation impact	27	(133)
Goodwill, Balance ending	$ 344	$ 1,598