Goodwill and Other Intangibles - Goodwill (Details) - USD ($)	3 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Roll Forward]
Balance, beginning of the period			$ 79,552,000,000	$ 79,749,000,000
Acquisitions				308,000,000
Divestiture of Workers’ Compensation business				(505,000,000)
Impairment	$ 0	$ 0	(431,000,000)	0	$ 0
Balance, end of the period			79,121,000,000	79,552,000,000	79,749,000,000
Health Care Benefits
Goodwill [Roll Forward]
Balance, beginning of the period			45,130,000,000	45,361,000,000
Acquisitions				274,000,000
Divestiture of Workers’ Compensation business				(505,000,000)
Impairment			0
Balance, end of the period			45,130,000,000	45,130,000,000	45,361,000,000
Pharmacy Services
Goodwill [Roll Forward]
Balance, beginning of the period			23,615,000,000	23,581,000,000
Acquisitions				34,000,000
Divestiture of Workers’ Compensation business				0
Impairment			0
Balance, end of the period			23,615,000,000	23,615,000,000	23,581,000,000
Retail/ LTC
Goodwill [Roll Forward]
Balance, beginning of the period			10,807,000,000	10,807,000,000
Acquisitions				0
Divestiture of Workers’ Compensation business				0
Impairment			(431,000,000)
Balance, end of the period			$ 10,376,000,000	$ 10,807,000,000	$ 10,807,000,000