Share-Based Compensation Expense (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Expense (benefit) recognized in integration-related costs	$ 18	$ 34
Special Charges
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Expense (benefit) recognized in integration-related costs		$ 3

Costs incurred to effect a business combination which have been expensed during the period. Such costs could include business integration costs, systems integration and conversion costs, and severance and other employee-related costs.

No definition available.

Name:	us-gaap_BusinessCombinationIntegrationRelatedCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration