Schedule of Property and Equipment Net (Detail) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Land	$ 50	$ 51
Buildings and leasehold improvements	567	565
Capitalized software	460	485
Furniture, fixtures and equipment	332	392
Buses and support vehicles	93	78
Projects in process	89	82
Property and Equipment, gross	1,591	1,653
Less: Accumulated depreciation and amortization	(910)	(1,015)
Property, Plant and Equipment, Net, Total	$ 681	$ 638