Restructuring Charges- Additional Information (Detail) (Operational Efficiency Initiatives 2011, USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2013	Dec. 31, 2012	Dec. 31, 2012	Dec. 31, 2011 Person
Operational Efficiency Initiatives 2011
Restructuring Cost and Reserve [Line Items]
Estimated reduction in workforce due to restructuring (positions)				1,500
Restructuring charge	$ 5	$ (2)	$ 2	$ (107)

Amount charged against earnings in the period for incurred and estimated costs, excluding asset retirement obligations, associated with exit from or disposal of business activities or restructurings pursuant to a program that is planned and controlled by management, and materially changes either the scope of a business undertaken by an entity, or the manner in which that business is conducted. Also includes credit adjustments of prior amounts charged against earnings.

No definition available.

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Namespace Prefix:	bk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration