Significant Accounting Policies - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Disaggregation of Revenue [Line Items]
Revenues	$ 80,958	$ 73,548	$ 238,106	$ 214,675
Net investment income (loss)	201	246	515	832
Total revenues	81,159	73,794	238,621	215,507
Pharmacy
Disaggregation of Revenue [Line Items]
Revenues	52,375	47,033	151,191	135,917
Front Store
Disaggregation of Revenue [Line Items]
Revenues	5,581	5,359	16,630	15,255
Premiums
Disaggregation of Revenue [Line Items]
Revenues	21,003	18,984	63,894	56,927
Other
Disaggregation of Revenue [Line Items]
Revenues	1,999	2,172	6,391	6,576
Health Care Benefits
Disaggregation of Revenue [Line Items]
Total revenues	22,511	20,479	68,376	61,487
Pharmacy Services
Disaggregation of Revenue [Line Items]
Total revenues	43,216	39,046	125,489	113,681
Retail/ LTC
Disaggregation of Revenue [Line Items]
Total revenues	26,706	24,992	78,410	72,994
Operating Segments | Health Care Benefits
Disaggregation of Revenue [Line Items]
Revenues	22,387	20,311	68,029	60,993
Net investment income (loss)	101	147	278	432
Total revenues	22,511	20,479	68,376	61,487
Operating Segments | Health Care Benefits | Pharmacy
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Operating Segments | Health Care Benefits | Front Store
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Operating Segments | Health Care Benefits | Premiums
Disaggregation of Revenue [Line Items]
Revenues	20,989	18,959	63,848	56,869
Operating Segments | Health Care Benefits | Other
Disaggregation of Revenue [Line Items]
Revenues	1,421	1,373	4,250	4,186
Operating Segments | Pharmacy Services
Disaggregation of Revenue [Line Items]
Revenues	40,545	36,851	116,600	105,909
Net investment income (loss)	0	0	0	0
Total revenues	43,216	39,046	125,489	113,681
Operating Segments | Pharmacy Services | Pharmacy network
Disaggregation of Revenue [Line Items]
Total revenues	25,012	23,665	72,373	68,476
Operating Segments | Pharmacy Services | Mail choice
Disaggregation of Revenue [Line Items]
Total revenues	17,935	15,202	52,339	44,685
Operating Segments | Pharmacy Services | Other
Disaggregation of Revenue [Line Items]
Total revenues	269	179	777	520
Operating Segments | Pharmacy Services | Pharmacy
Disaggregation of Revenue [Line Items]
Revenues	42,947	38,867	124,712	113,161
Operating Segments | Pharmacy Services | Front Store
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Operating Segments | Pharmacy Services | Premiums
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Operating Segments | Pharmacy Services | Other
Disaggregation of Revenue [Line Items]
Revenues	269	179	777	520
Operating Segments | Retail/ LTC
Disaggregation of Revenue [Line Items]
Revenues	17,994	16,347	53,380	47,672
Net investment income (loss)	(10)	(33)	(44)	13
Total revenues	26,706	24,992	78,410	72,994
Operating Segments | Retail/ LTC | Pharmacy
Disaggregation of Revenue [Line Items]
Revenues	20,759	19,023	60,308	55,781
Operating Segments | Retail/ LTC | Front Store
Disaggregation of Revenue [Line Items]
Revenues	5,581	5,359	16,630	15,255
Operating Segments | Retail/ LTC | Premiums
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Operating Segments | Retail/ LTC | Other
Disaggregation of Revenue [Line Items]
Revenues	376	643	1,516	1,945
Corporate/ Other
Disaggregation of Revenue [Line Items]
Revenues	32	39	97	101
Net investment income (loss)	110	132	281	387
Total revenues	142	171	378	488
Corporate/ Other | Pharmacy
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Corporate/ Other | Front Store
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Corporate/ Other | Premiums
Disaggregation of Revenue [Line Items]
Revenues	14	25	46	58
Corporate/ Other | Other
Disaggregation of Revenue [Line Items]
Revenues	18	14	51	43
Intersegment Eliminations
Disaggregation of Revenue [Line Items]
Net investment income (loss)	0	0	0	0
Total revenues	(11,416)	(10,894)	(34,032)	(33,143)
Intersegment Eliminations | Pharmacy
Disaggregation of Revenue [Line Items]
Revenues	(11,331)	(10,857)	(33,829)	(33,025)
Intersegment Eliminations | Front Store
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Intersegment Eliminations | Premiums
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Intersegment Eliminations | Other
Disaggregation of Revenue [Line Items]
Revenues	$ (85)	$ (37)	$ (203)	$ (118)