Significant Accounting Policies - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation of Revenue [Line Items]
Revenues	$ 80,490	$ 72,327	$ 157,148	$ 141,127
Net investment income (loss)	146	289	314	586
Total revenues	80,636	72,616	157,462	141,713
Pharmacy
Disaggregation of Revenue [Line Items]
Revenues	51,326	45,932	98,816	88,884
Front Store
Disaggregation of Revenue [Line Items]
Revenues	5,736	5,254	11,049	9,896
Premiums
Disaggregation of Revenue [Line Items]
Revenues	21,260	18,983	42,891	37,943
Other
Disaggregation of Revenue [Line Items]
Revenues	2,168	2,158	4,392	4,404
Health Care Benefits
Disaggregation of Revenue [Line Items]
Total revenues	22,756	20,525	45,865	41,008
Pharmacy Services
Disaggregation of Revenue [Line Items]
Total revenues	42,812	38,314	82,273	74,635
Retail/ LTC
Disaggregation of Revenue [Line Items]
Total revenues	26,286	24,728	51,704	48,002
Operating Segments | Health Care Benefits
Disaggregation of Revenue [Line Items]
Revenues	22,645	20,367	45,642	40,682
Net investment income (loss)	88	137	177	285
Total revenues	22,756	20,525	45,865	41,008
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	21,245	18,968	42,859	37,910
Operating Segments | Health Care Benefits | Other
Disaggregation of Revenue [Line Items]
Revenues	1,423	1,420	2,829	2,813
Operating Segments | Pharmacy Services
Disaggregation of Revenue [Line Items]
Revenues	39,859	35,745	76,055	69,058
Net investment income (loss)	0	0	0	0
Total revenues	42,812	38,314	82,273	74,635
Operating Segments | Pharmacy Services | Pharmacy network
Disaggregation of Revenue [Line Items]
Total revenues	24,537	22,918	47,361	44,811
Operating Segments | Pharmacy Services | Mail choice
Disaggregation of Revenue [Line Items]
Total revenues	18,030	15,235	34,404	29,483
Operating Segments | Pharmacy Services | Other
Disaggregation of Revenue [Line Items]
Total revenues	245	161	508	341
Operating Segments | Pharmacy Services | Pharmacy
Disaggregation of Revenue [Line Items]
Revenues	42,567	38,153	81,765	74,294
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	245	161	508	341
Operating Segments | Retail/ LTC
Disaggregation of Revenue [Line Items]
Revenues	17,952	16,185	35,386	31,325
Net investment income (loss)	(18)	0	(34)	46
Total revenues	26,286	24,728	51,704	48,002
Operating Segments | Retail/ LTC | Pharmacy
Disaggregation of Revenue [Line Items]
Revenues	20,017	18,873	39,549	36,758
Operating Segments | Retail/ LTC | Front Store
Disaggregation of Revenue [Line Items]
Revenues	5,736	5,254	11,049	9,896
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	551	601	1,140	1,302
Corporate/ Other
Disaggregation of Revenue [Line Items]
Revenues	34	30	65	62
Net investment income (loss)	76	152	171	255
Total revenues	110	182	236	317
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	15	15	32	33
Corporate/ Other | Other
Disaggregation of Revenue [Line Items]
Revenues	19	15	33	29
Intersegment Eliminations
Disaggregation of Revenue [Line Items]
Net investment income (loss)	0	0	0	0
Total revenues	(11,328)	(11,133)	(22,616)	(22,249)
Intersegment Eliminations | Pharmacy
Disaggregation of Revenue [Line Items]
Revenues	(11,258)	(11,094)	(22,498)	(22,168)
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	$ (70)	$ (39)	$ (118)	$ (81)