Property and Equipment, Net (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Property, Plant and Equipment [Line Items]
Land	$ 20	$ 18
Buildings and leasehold improvements	620	523
Equipment	728	606
Computer software	1,145	935
Property, Plant and Equipment, Gross, Total	2,513	2,082
Accumulated depreciation	(1,415)	(1,170)
Property and equipment, net	$ 1,098	$ 912