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, 2019	Dec. 31, 2018
Change in the carrying amount of goodwill by reportable segment
Goodwill, Beginning Balance	$ 20,504	$ 19,231
Acquisitions		1,285
Other adjustments	(4)	(12)
Goodwill, Ending Balance	20,500	20,504
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	11,818
Acquisitions		0
Other adjustments	0	(267)
Goodwill, Ending Balance	11,551	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	8,953	7,402
Acquisitions		1,285
Other adjustments	(674)	266
Goodwill, Ending Balance	8,279	8,953
Accumulated impairment as of December 31	0
Other [Member]
Change in the carrying amount of goodwill by reportable segment
Goodwill, Beginning Balance	0	11
Acquisitions		0
Other adjustments	670	(11)
Goodwill, Ending Balance	670	$ 0
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.

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

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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
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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.

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