Segment Information Segment Information (Major Product Revenues for Each Reportable Segment) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	$ 29,178	$ 25,177	$ 58,626	$ 49,565
Commercial Specialty Business Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	8,789	9,417	18,150	18,809
Government Business Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	17,242	15,538	34,708	30,464
IngenioRx Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	5,269	248	10,466	248
Other Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	1,452	546	2,479	1,094
Segment Eliminations [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	(3,574)	(572)	(7,177)	(1,050)
Managed Care Products [Member] | Commercial Specialty Business Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	7,132	7,646	14,700	15,264
Managed Care Products [Member] | Government Business Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	17,149	15,444	34,524	30,264
Managed Care Services [Member] | Commercial Specialty Business Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	1,263	1,353	2,645	2,719
Managed Care Services [Member] | Government Business Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	93	94	184	200
Dental Vision Products And Services [Member] | Commercial Specialty Business Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	284	327	599	650
Other Products [Member] | Commercial Specialty Business Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	110	91	206	176
Pharmacy products and services [Member] | IngenioRx Segment [Member]
Major Product Revenue By Segment [Line Items]
Insurance Services Revenue	$ 5,269	$ 248	$ 10,466	$ 248