Loans - Components of Loans (Details) - USD ($) $ in Millions	Mar. 31, 2016		Dec. 31, 2015		Mar. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 81,732		$ 82,917		$ 81,458
Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	61,612		62,453
Commercial Loans [Member] | Construction and Other Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	10,170		10,000		10,901
Commercial Loans [Member] | Business and Corporate Banking [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	19,412		19,116		19,251
Commercial Loans [Member] | Global Banking [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	28,966	[1]	29,969	[1]	28,029
Commercial Loans [Member] | Other Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	3,064		3,368		3,466
Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	20,120		20,464
Consumer Loans [Member] | Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	17,521	[2],[3]	17,758		16,991
Consumer Loans [Member] | Home Equity Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,544		1,600		1,716
Consumer Loans [Member] | Credit Cards [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	660		699		680
Consumer Loans [Member] | Other consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 395		$ 407		$ 424

[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 $5,107 million and $4,815 million at March 31, 2016 and December 31, 2015, respectively. See Note 14, "Related Party Transactions," for additional information regarding loans to HSBC affiliates.

[2] The decrease in nonaccrual loans at March 31, 2016 reflects the impact of the transfer of certain residential mortgage loans with a carrying value of $345 million to held for sale during the first quarter of 2016.

[3] The decrease in past due loans at March 31, 2016 reflects the impact of the transfer of certain residential mortgage loans with a carrying value of $345 million to held for sale during the first quarter of 2016. See Note 6, "Loans Held for Sale," for additional details.