Loans - Components of Loans (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 63,258		$ 51,867		$ 49,809
Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial	44,150		33,649
Total	44,150		33,649
Commercial Loan [Member] | Construction and Other Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial	8,457		7,860
Total	8,457		7,860		8,228
Commercial Loan [Member] | Business Banking and Middle Markets Enterprises [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial	12,608		10,225
Total	12,608		10,225		7,945
Commercial Loan [Member] | Global Banking [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial	20,009	[1]	12,658	[1]
Total	20,009		12,658		10,745
Commercial Loan [Member] | Other Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial	3,076		2,906
Total	3,076		2,906		3,085
Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer	19,108		18,218
Total	19,108		18,218
Consumer Loans [Member] | Home Equity Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer	2,324		2,563
Total	2,324	[2]	2,563		3,820
Consumer Loans [Member] | Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer	15,371		14,113
Total	15,371		14,113		13,697
Consumer Loans [Member] | Credit Card Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer	815		828
Total	815	[3]	828		1,250
Consumer Loans [Member] | Other Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer	598		714
Total	$ 598		$ 714		$ 1,039

[1] Represents large multinational firms including globally focused U.S. corporate and financial institutions and USD lending to select high quality Latin American and other multinational customers managed by HSBC on a global basis.

[2] Home equity mortgages maturities reflect estimates based on historical payment patterns.

[3] As credit card receivables do not have stated maturities, the table reflects estimates based on historical payment patterns.