Loans - Components of Loans (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012		Jun. 30, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 66,705		$ 63,258		$ 56,064
Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial	47,264		44,150
Total loans	47,264		44,150
Commercial Loan [Member] | Construction and Other Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial	8,529		8,457
Total loans	8,529		8,457		7,977
Commercial Loan [Member] | Business and Corporate Banking [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial	12,391		12,608
Total loans	12,391		12,608		11,256
Commercial Loan [Member] | Global Banking [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial	23,339	[1],[2]	20,009	[1],[2]
Total loans	23,339		20,009		15,042
Commercial Loan [Member] | Other Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial	3,005		3,076
Total loans	3,005		3,076		3,142
Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer	19,441		19,108
Total loans	19,441		19,108
Consumer Loans [Member] | Home Equity Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer	2,172		2,324
Total loans	2,172		2,324		2,455
Consumer Loans [Member] | Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer	15,837		15,371
Total loans	15,837		15,371		14,758
Consumer Loans [Member] | Credit Card Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer	858		815
Total loans	858		815		783
Consumer Loans [Member] | Other Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer	574		598
Total loans	$ 574		$ 598		$ 651

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

[2] Includes loans to HSBC affiliates of $7.0 billion and $4.5 billion at June 30, 2013 and December 31, 2012, respectively. See Note 15, "Related Party Transactions" for additional information regarding loans to HSBC affiliates.