Loans - Components of Loans (Details) - USD ($) $ in Millions		Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		$ 84,942	$ 77,741	$ 73,439
Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial		64,752	58,087
Total loans		64,752	58,087
Commercial Loans [Member] | Construction and Other Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial		12,096	10,300
Total loans		12,096	10,300	9,661
Commercial Loans [Member] | Business and Corporate Banking [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial		19,514	17,819
Total loans		19,514	17,819	17,355
Commercial Loans [Member] | Global Banking [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial	[1]	29,808	26,387
Total loans		29,808	26,387	24,001
Commercial Loans [Member] | Other Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial		3,334	3,581
Total loans		3,334	3,581	3,045
Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer		20,190	19,654
Total loans		20,190	19,654
Consumer Loans [Member] | Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer		17,460	16,661
Total loans		17,460	16,661	16,402
Consumer Loans [Member] | Home Equity Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer		1,639	1,784
Total loans		1,639	1,784	1,824
Consumer Loans [Member] | Credit Cards [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer		682	720
Total loans		682	720	686
Consumer Loans [Member] | Other consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer		409	489
Total loans		$ 409	$ 489	$ 465

[1] Represents large multinational firms including globally focused U.S. corporate and financial institutions and U.S. dollar lending to multinational banking customers managed by HSBC on a global basis. Also includes loans to HSBC affiliates which totaled $5,447 million and $4,821 million at September 30, 2015 and December 31, 2014, respectively. See Note 13, "Related Party Transactions," for additional information regarding loans to HSBC affiliates.