Share-based Compensation - Share-based Compensation Expense (Parenthetical) (Detail) $ in Millions	12 Months Ended
Dec. 31, 2014 USD ($)
Discontinued Operations
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Pre-tax share-based compensation benefit related to discontinued operations	$ 4

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration