Property And Equipment (Summary Of Property And Equipment) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 7,327	$ 6,479
Accumulated depreciation and amortization	(3,844)	(3,346)
Property and equipment, net	3,483	3,133
Computer Software, Purchased and Internally Developed [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	5,247	4,314
Computer Equipment, Furniture and Other Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,218	1,264
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	671	715
Buildings and Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	174	169
Land and Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 17	$ 17

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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