Goodwill and Other Intangibles - Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Roll Forward]
Balance, beginning of the period	$ 79,749	$ 78,678
Segment realignment		0
Purchase accounting adjustments		1,071
Other		0
Acquisitions	308
Divestiture of Workers’ Compensation business	(505)
Balance, end of the period	79,552	79,749
Pharmacy Services
Goodwill [Roll Forward]
Balance, beginning of the period	23,581	23,388
Segment realignment		194
Purchase accounting adjustments		0
Other		(1)
Acquisitions	34
Divestiture of Workers’ Compensation business	0
Balance, end of the period	23,615	23,581
Retail/ LTC
Goodwill [Roll Forward]
Balance, beginning of the period	10,807	10,806
Segment realignment		0
Purchase accounting adjustments		0
Other		1
Acquisitions	0
Divestiture of Workers’ Compensation business	0
Balance, end of the period	10,807	10,807
Health Care Benefits
Goodwill [Roll Forward]
Balance, beginning of the period	45,361	44,484
Segment realignment		(194)
Purchase accounting adjustments		1,071
Other		0
Acquisitions	274
Divestiture of Workers’ Compensation business	(505)
Balance, end of the period	$ 45,130	$ 45,361