Loans - Contractual Maturities (Details) - USD ($) $ in Millions		Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
2018		$ 28,516
2019		8,790
2020		6,356
2021		5,673
2022		5,057
Thereafter		18,171
Total loans		72,563		$ 73,875		$ 82,917
Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		53,035		54,216
Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		19,528		19,659
Real Estate, Including Construction [Member] | Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
2018		4,870
2019		1,538
2020		1,231
2021		1,098
2022		977
Thereafter		819
Total loans		10,533		10,890		10,000
Business and Corporate Banking [Member] | Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
2018		5,781
2019		1,825
2020		1,461
2021		1,304
2022		1,160
Thereafter		973
Total loans		12,504		14,080		14,365
Global Banking [Member] | Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
2018		9,287
2019		2,932
2020		2,347
2021		2,095
2022		1,863
Thereafter		1,564
Total loans		20,088	[1],[2]	23,481	[1],[2]	29,905
Other Commercial [Member] | Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
2018		6,710
2019		866
2020		693
2021		616
2022		539
Thereafter		486
Total loans		9,910	[1]	5,765	[1]	8,183
Residential Mortgage [Member] | Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
2018		1,214
2019		485
2020		452
2021		456
2022		452
Thereafter		14,214
Total loans		17,273		17,181		17,758
Home Equity Mortgages [Member] | Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
2018	[3]	505
2019	[3]	261
2020	[3]	158
2021	[3]	96
2022	[3]	62
Thereafter	[3]	109
Total loans		1,191	[3]	1,408		1,600
Credit Cards [Member] | Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
2018	[4]	0
2019	[4]	721
2020	[4]	0
2021	[4]	0
2022	[4]	0
Thereafter	[4]	0
Total loans		721	[4]	688		699
Other consumer | Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
2018		149
2019		162
2020		14
2021		8
2022		4
Thereafter		6
Total loans		$ 343		$ 382		$ 407

[1] During 2017, in conjunction with the creation of the new Corporate Center segment as discussed further in Note 22, "Business Segments," we reclassified loans to HSBC affiliates from global banking to other commercial and revised prior periods to conform with the current year presentation. As a result, other commercial includes loans to HSBC affiliates which totaled $6,750 million and $3,274 million at December 31, 2017 and 2016, respectively. All tables below have been restated to reflect this reclassification, as applicable. See Note 21, "Related Party Transactions," for additional information regarding loans to HSBC affiliates.

[2] Represents large multinational firms including globally focused U.S. corporate and financial institutions, U.S. dollar lending to multinational banking clients managed by HSBC on a global basis and complex large business clients supported by Global Banking and Markets relationship managers.

[3] Home equity mortgage maturities reflect estimates based on historical payment patterns.

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