Segment Reporting - Reconciliation of Financial Measures of Segments to Consolidated Totals (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Revenues from external customers	$ 290,912	$ 267,908	$ 255,765
Net investment income	1,199	798	1,011
Total revenues	292,111	268,706	256,776
Adjusted operating income (loss)	17,312	16,008	15,339
Depreciation and amortization	4,512	4,441	4,371
Operating Segments | Health Care Benefits
Segment Reporting Information [Line Items]
Revenues from external customers	81,515	74,926	68,979
Net investment income	586	483	599
Total revenues	82,186	75,467	69,604
Adjusted operating income (loss)	5,012	6,188	5,202
Depreciation and amortization	1,837	1,832	1,721
Operating Segments | Pharmacy Services
Segment Reporting Information [Line Items]
Revenues from external customers	143,194	132,663	130,428
Net investment income	0	0	0
Total revenues	153,022	141,938	141,491
Adjusted operating income (loss)	6,859	5,688	5,129
Depreciation and amortization	576	612	766
Co-payments	11,600	10,900	11,500
Operating Segments | Retail/ LTC
Segment Reporting Information [Line Items]
Revenues from external customers	66,078	60,208	56,258
Net investment income	17	0	0
Total revenues	100,105	91,198	86,608
Adjusted operating income (loss)	7,623	6,146	6,705
Depreciation and amortization	1,884	1,801	1,723
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues	(43,923)	(40,323)	(41,439)
Net investment income	0	0	0
Total revenues	(43,923)	(40,323)	(41,439)
Adjusted operating income (loss)	(711)	(708)	(697)
Depreciation and amortization	0	0	0
Intersegment Eliminations | Health Care Benefits
Segment Reporting Information [Line Items]
Revenues	85	58	26
Intersegment Eliminations | Pharmacy Services
Segment Reporting Information [Line Items]
Revenues	9,828	9,275	11,063
Intersegment Eliminations | Retail/ LTC
Segment Reporting Information [Line Items]
Revenues	34,010	30,990	30,350
Corporate/ Other
Segment Reporting Information [Line Items]
Revenues from external customers	125	111	100
Net investment income	596	315	412
Total revenues	721	426	512
Adjusted operating income (loss)	(1,471)	(1,306)	(1,000)
Depreciation and amortization	$ 215	$ 196	$ 161