Property and Equipment, Net - Summary of Property and Equipment, Net (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Cost	$ 1,081	$ 1,024
Accumulated depreciation	(668)	(596)
Net	413	428
Capitalized Software [Member]
Property, Plant and Equipment [Line Items]
Cost	702	650
Accumulated depreciation	(498)	(449)
Net	204	201
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Cost	288	281
Accumulated depreciation	(161)	(139)
Net	127	142
Building and Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Cost	19	17
Accumulated depreciation	(9)	(8)
Net	10	9
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Cost	72	76
Accumulated depreciation
Net	$ 72	$ 76