Details of Loan Distribution and Industry Concentrations of Credit Risk (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012		Mar. 31, 2012	Dec. 31, 2011		Jun. 30, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 45,431			$ 43,979
Financial Institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	10,516			11,144
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,387			1,280
Wealth Management Loans and Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	7,916			7,342
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,595			1,449
Overdrafts
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	5,655			4,849
Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	35,249			33,971
Domestic | Financial Institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	4,835			4,606
Domestic | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	814			752
Domestic | Wealth Management Loans and Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	7,916			7,342
Domestic | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,595			1,449
Domestic | Lease Financings
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,505	[1]		1,558	[1]
Domestic | Other Residential Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,773			1,923
Domestic | Overdrafts
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	2,750		1,971	2,958		4,629
Domestic | Other loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	599		849	623		597
Domestic | Margin Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	13,462		13,144	12,760		9,520
Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	10,182			10,008
Foreign | Financial Institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	5,681			6,538
Foreign | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	573			528
Foreign | Lease Financings
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,023	[1]		1,051	[1]
Foreign | Other loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 2,905			$ 1,891

[1] Net of unearned income on domestic and foreign lease financings of $1,225 million at June 30, 2012 and $1,343 million at Dec. 31, 2011.