Segment Information Segment Information (Major Product Revenues for Each Reportable Segment) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	$ 33,279	$ 29,178	$ 65,377	$ 58,626
Commercial Specialty Business Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	9,550	8,789	19,041	18,150
Government Business Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	20,066	17,242	39,349	34,708
IngenioRx Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	6,219	5,269	12,081	10,466
Other Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	2,517	1,452	4,887	2,479
Segment Eliminations [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	(5,073)	(3,574)	(9,981)	(7,177)
Managed Care Products [Member] | Commercial Specialty Business Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	7,772	7,132	15,461	14,700
Managed Care Products [Member] | Government Business Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	19,965	17,149	39,147	34,524
Managed Care Services [Member] | Commercial Specialty Business Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	1,416	1,263	2,802	2,645
Managed Care Services [Member] | Government Business Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	101	93	202	184
Dental Vision Products And Services [Member] | Commercial Specialty Business Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	335	284	671	599
Other Products [Member] | Commercial Specialty Business Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	27	110	107	206
Other Products [Member] | Other Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	151	76	272	154
Pharmacy products and services [Member] | IngenioRx Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	6,219	5,269	12,081	10,466
Integrated health services | Other Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	$ 2,366	$ 1,376	$ 4,615	$ 2,325