Loans - Components of Loans (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014		Mar. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 81,458		$ 77,741		$ 68,897
Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial	61,647		58,087
Total loans	61,647		58,087
Commercial Loans [Member] | Construction and Other Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial	10,901		10,300
Total loans	10,901		10,300		9,165
Commercial Loans [Member] | Business and Corporate Banking [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial	19,251		17,819
Total loans	19,251		17,819		15,698
Commercial Loans [Member] | Global Banking [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial	28,029	[1]	26,387	[1]
Total loans	28,029		26,387		21,979
Commercial Loans [Member] | Other Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial	3,466		3,581
Total loans	3,466		3,581		3,051
Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer	19,811		19,654
Total loans	19,811		19,654
Consumer Loans [Member] | Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer	16,991		16,661
Total loans	16,991		16,661		15,900
Consumer Loans [Member] | Home Equity Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer	1,716		1,784
Total loans	1,716		1,784		1,938
Consumer Loans [Member] | Credit Cards [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer	680		720
Total loans	680		720		683
Consumer Loans [Member] | Other consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer	424		489
Total loans	$ 424		$ 489		$ 483

[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 $5,016 million and $4,821 million at March 31, 2015 and December 31, 2014, respectively. See Note 13, "Related Party Transactions," for additional information regarding loans to HSBC affiliates.