Goodwill And Other Intangible Assets (Summary Of The Change In The Carrying Amount Of Goodwill By Reportable Segment) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Change in the carrying amount of goodwill by reportable segment
Goodwill, Beginning Balance	$ 20,500	$ 20,504
Adjustments	1,191	(4)
Goodwill, Ending Balance	21,691	20,500
Accumulated impairment as of December 31	(41)
Commercial and Specialty Business [Member]
Change in the carrying amount of goodwill by reportable segment
Goodwill, Beginning Balance	11,551	11,551
Adjustments	42	0
Goodwill, Ending Balance	11,593	11,551
Accumulated impairment as of December 31	(41)
Government Business [Member]
Change in the carrying amount of goodwill by reportable segment
Goodwill, Beginning Balance	8,279	8,953
Adjustments	52	(674)
Goodwill, Ending Balance	8,331	8,279
Accumulated impairment as of December 31	0
IngenioRx Segment [Member]
Change in the carrying amount of goodwill by reportable segment
Goodwill, Beginning Balance	0	0
Adjustments	48	0
Goodwill, Ending Balance	48	0
Accumulated impairment as of December 31	0
Other [Member]
Change in the carrying amount of goodwill by reportable segment
Goodwill, Beginning Balance	670	0
Adjustments	1,049	670
Goodwill, Ending Balance	1,719	$ 670
Accumulated impairment as of December 31	$ 0

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(10)(1))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=120320667&loc=SL49117168-202975

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13770-109266

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Amount of accumulated impairment loss for an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267

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Amount of increase (decrease) of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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