Schedule of Property and Equipment Net (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Land	$ 49	$ 48
Buildings and leasehold improvements	592	565
Capitalized software	918	789
Furniture, fixtures and equipment	417	400
Buses and support vehicles	86	88
Projects in process	60	180
Property and Equipment, gross	2,122	2,070
Less: Accumulated depreciation and amortization	(1,465)	(1,278)
Property, Plant and Equipment, Net, Total	$ 657	$ 792

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 of building structures held for productive use including addition, improvement, or renovation to the structure, including, but not limited to, interior masonry, interior flooring, electrical, and plumbing.

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Amount before accumulated amortization of capitalized costs for computer software, including but not limited to, acquired and internally developed computer software.

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Amount of structure or a modification to a structure under construction. Includes recently completed structures or modifications to structures that have not been placed into service.

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Amount before accumulated depreciation of equipment commonly used in offices and stores that have no permanent connection to the structure of a building or utilities. Examples include, but are not limited to, desks, chairs, tables, and bookcases.

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Amount before accumulated depletion of real estate held for productive use, excluding land held for sale.

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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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Period end book value of vehicles owned by the public utility.

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