Special Charges And Merger Related Expenses (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2013	Dec. 31, 2012
Restructuring Cost and Reserve [Line Items]
Principal terms of new business, headcount reduced	10,500	10,500
Business Combination, Integration Related Costs	$ 16

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