Litigation and Regulatory Matters - Additional Information (Details)		1 Months Ended													3 Months Ended	12 Months Ended		36 Months Ended
	Feb. 17, 2016 USD ($)	Feb. 22, 2016 USD ($)	Dec. 31, 2015 USD ($) financial_institution complaint	Nov. 30, 2015 USD ($)	Oct. 31, 2015 USD ($)	Sep. 30, 2015 USD ($) complaint	May. 31, 2015 USD ($) plaintiff financial_institution	Jan. 31, 2015 USD ($)	Dec. 31, 2013 mortgage_loan	Nov. 30, 2013 USD ($)	Feb. 28, 2013 USD ($) mortgage_servicer	Jan. 31, 2013	Dec. 31, 2012 USD ($)	Oct. 31, 2012 county	Jun. 30, 2013 USD ($) class_action	Dec. 31, 2015 USD ($) financial_institution	Dec. 31, 2012 USD ($)	Dec. 31, 2007 USD ($)	Dec. 31, 2014 USD ($)	Jun. 30, 2014 trust	Feb. 29, 2012 state	Dec. 31, 2011 USD ($)
Loss Contingencies [Line Items]
Estimate of loss			$ 160,000,000													$ 160,000,000
Insurance Variance to Price Threshold												20.00%
Checking Account Overdraft Litigation [Member]
Loss Contingencies [Line Items]
Number of class actions filed | class_action															3
Litigation settlement amount					$ 30,000,000
DeKalb County, et al. v. HSBC North America Holdings Inc., et al. [Member]
Loss Contingencies [Line Items]
Loss Contingency, Number of Plaintiffs | county														3
Number of Counties in the Area | county														5
Credit Default Swaps Antitrust Litigation [Member]
Loss Contingencies [Line Items]
Litigation settlement amount						$ 25,000,000
European Commission Statement of Objections [Member]
Loss Contingencies [Line Items]
Number of Investment Banks Involved in Closed Case | financial_institution			13
Foreign Exchange Class Action [Member]
Loss Contingencies [Line Items]
Litigation settlement amount						$ 285,000,000
Number of putative class action complaints filed | complaint						2
Number of non-HSBC financial institutions with resolved Department of Justice investigations | financial_institution							5
Number of non-HSBC financial institutions that pleaded guilty | financial_institution							4
Criminal fines agreed to by institutions that pleaded guilty							$ 2,500,000,000
Hau Yin To v. HSBC Bank plc, et al. [Member]
Loss Contingencies [Line Items]
Damages sought, per violation (up to)							$ 8,000,000
Number of putative class action complaints filed | plaintiff							2
FIRREA and Other Mortgage-backed Securities Matters [Member]
Loss Contingencies [Line Items]
Number of non-HSBC financial institutions with resolved Department of Justice investigations | financial_institution																5
Residential Funding Litigation [Member]
Loss Contingencies [Line Items]
Mortgage Loans on Real Estate, Number of Loans | mortgage_loan									8,800
Mortgage Securitization Pool Trust Litigation [Member]
Loss Contingencies [Line Items]
Damages sought, per violation (up to)			$ 285,000,000													$ 37,900,000,000
Number of Identified Trusts | trust																				284
Number of putative class action complaints filed | complaint			3
Alfredo Villoldo, et al. v. HSBC Bank USA, NA, et. al. [Member]
Loss Contingencies [Line Items]
Damages sought, per violation (up to)								$ 30,000,000
Litigation settlement amount								$ 2,900,000,000
Ramiro Giron, et al. v. Hong Kong and Shanghai Bank Company et al. [Member]
Loss Contingencies [Line Items]
Loss Contingency, Alleged Bank Transfers				$ 37,000,000
Saber Ahmed v. HSBC Bank USA [Member]
Loss Contingencies [Line Items]
Damages sought, per violation (up to)					$ 1,500
HSBC Bank USA [Member] | Credit Default Swaps Antitrust Litigation [Member]
Loss Contingencies [Line Items]
Litigation settlement amount						$ 12,500,000
HSBC Bank USA [Member] | Foreign Exchange Class Action [Member]
Loss Contingencies [Line Items]
Litigation settlement amount						$ 14,250,000
Mortgage Securitization Activity Related Litigation [Member] | HSBC Securities [Member]
Loss Contingencies [Line Items]
Mortgage Securitization Loan Purchased And Sold																		$ 24,000,000,000
Mortgage Securitization Outstanding Loan Purchase And Sold			$ 5,200,000,000													$ 5,200,000,000			$ 5,700,000,000
Deutche Bank Alleged Breach of Representation [Member]
Loss Contingencies [Line Items]
Damages sought, per violation (up to)										$ 508,000,000
Foreclosure Practices [Member]
Loss Contingencies [Line Items]
Loss Contingency, Number of Mortgage Servicers | mortgage_servicer											12
Loss Contingency, Threshold of Cash Payments, Mortgage Servicers Subject to Foreclosure											$ 9,300,000,000
Loss Contingency, Loss in Period																	$ 19,000,000
Foreclosure Practices [Member] | HSBC Bank USA [Member]
Loss Contingencies [Line Items]
Number of States Under Different Departments | state																					49
Number of Largest Domestic Mortgage Servicers | state																					5
Product Liability Accrual, Component Amount																						$ 38,000,000
Product Liability Accrual Recoveries															$ 6,000,000
Foreclosure Practices [Member] | Hsbc North America [Member]
Loss Contingencies [Line Items]
Loss Contingency, Cash Payment Into Fund											$ 96,000,000
Loss Contingency, Loss in Period																	$ 104,000,000
Aml Bsa Related Litigation [Member]
Loss Contingencies [Line Items]
Litigation Settlement Agreement, Compliance Period													5 years
Aml Bsa Related Litigation [Member] | HSBC Bank USA [Member]
Loss Contingencies [Line Items]
Payments for Legal Settlements													$ 1,381,000,000
Aml Bsa Related Litigation [Member] | Hsbc North America [Member]
Loss Contingencies [Line Items]
Payments for Legal Settlements													$ 1,921,000,000
Subsequent Event [Member] | Checking Account Overdraft Litigation [Member]
Loss Contingencies [Line Items]
Litigation settlement amount		$ 32,000,000
Subsequent Event [Member] | Lender-Placed Insurance Matters [Member]
Loss Contingencies [Line Items]
Litigation settlement amount	$ 4,075,000
Subsequent Event [Member] | Foreclosure Practices [Member] | HSBC Bank USA [Member]
Loss Contingencies [Line Items]
Litigation settlement amount		32,000,000
Subsequent Event [Member] | Federal and State Parties [Member] | Foreclosure Practices [Member] | HSBC Bank USA [Member]
Loss Contingencies [Line Items]
Litigation settlement amount		100,000,000
Subsequent Event [Member] | Consumer Relief [Member] | Foreclosure Practices [Member] | HSBC Bank USA [Member]
Loss Contingencies [Line Items]
Litigation settlement amount		$ 370,000,000