Schedule of Property and Equipment Net (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Land	$ 47	$ 50
Buildings and leasehold improvements	597	567
Capitalized software	524	460
Furniture, fixtures and equipment	354	332
Buses and support vehicles	91	93
Projects in process	99	89
Property and Equipment, gross	1,712	1,591
Less: Accumulated depreciation and amortization	(1,027)	(910)
Property, Plant and Equipment, Net, Total	$ 685	$ 681