Litigation and Regulatory Matters - Additional Information (Details)		1 Months Ended											3 Months Ended		6 Months Ended	12 Months Ended		36 Months Ended
	Jan. 06, 2017 USD ($) mortgage_loan	Apr. 30, 2016 USD ($)	Feb. 29, 2016 USD ($)	Nov. 30, 2015 USD ($)	Oct. 31, 2015 USD ($)	Sep. 30, 2015 USD ($) complaint	May 31, 2015 USD ($) plaintiff financial_institution	Dec. 31, 2013 mortgage_loan	Nov. 30, 2013 USD ($)	Feb. 28, 2013 USD ($) mortgage_servicer	Dec. 31, 2012 USD ($)	Oct. 31, 2012 plaintiff county	Dec. 31, 2016 USD ($)	Jun. 30, 2013 USD ($)	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($) financial_institution	Dec. 31, 2012 USD ($)	Dec. 31, 2007 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jun. 30, 2014 trust	Feb. 29, 2012 state mortgage_servicer	Dec. 31, 2011 USD ($)
Loss Contingencies [Line Items]
Estimate of loss													$ 390,000,000			$ 390,000,000
DeKalb County, et al. v. HSBC North America Holdings Inc., et al. [Member]
Loss Contingencies [Line Items]
Loss contingency, number of plaintiffs | plaintiff												3
Number of counties in the area | county												5
Credit Default Swaps Antitrust Litigation [Member]
Loss Contingencies [Line Items]
Litigation settlement						$ 25,000,000
Foreign Exchange Class Action [Member]
Loss Contingencies [Line Items]
Litigation settlement						$ 285,000,000
Number of putative class action complaints | 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]
Number of putative class action complaints | plaintiff							2
Damages sought							$ 8,000,000
FIRREA and Other Mortgage-backed Securities Matters [Member]
Loss Contingencies [Line Items]
Number of non-HSBC financial institutions sued by the Department of Justice | financial_institution																1
Number of non-HSBC financial institutions with resolved Department of Justice investigations | financial_institution																8
Residential Funding Litigation [Member]
Loss Contingencies [Line Items]
Number of mortgage loans | mortgage_loan								8,800
Mortgage Securitization Pool Trust Litigation [Member]
Loss Contingencies [Line Items]
Damages sought															$ 38,000,000,000
Number of identified trusts | trust																					280
Ramiro Giron, et al. v. Hong Kong and Shanghai Bank Company et al. [Member]
Loss Contingencies [Line Items]
Alleged bank transfers				$ 37,000,000
Saber Ahmed v. HSBC Bank USA [Member]
Loss Contingencies [Line Items]
Damages sought, per violation					$ 1,500
Monteleone v. HSBC Finance Corporation, et al. [Member]
Loss Contingencies [Line Items]
Damages sought, per violation		$ 500
HSBC Bank USA [Member] | Credit Default Swaps Antitrust Litigation [Member]
Loss Contingencies [Line Items]
Litigation settlement						$ 12,500,000
HSBC Bank USA [Member] | Foreign Exchange Class Action [Member]
Loss Contingencies [Line Items]
Litigation settlement						$ 14,250,000
Deutche Bank Alleged Breach of Representation [Member]
Loss Contingencies [Line Items]
Damages sought									$ 508,000,000
Foreclosure Practices [Member]
Loss Contingencies [Line Items]
Number of mortgage servicers | mortgage_servicer										12
Threshold of cash payments and other assistance to help eligible borrowers										$ 9,300,000,000
Cash payment into fund										$ 96,000,000
Foreclosure practice deficiency expense													$ 27,500,000				$ 19,000,000
Foreclosure Practices [Member] | HSBC Bank USA [Member]
Loss Contingencies [Line Items]
Litigation settlement			$ 32,000,000
Number of states under different departments | state																						49
Number of largest domestic mortgage servicers | mortgage_servicer																						5
Product liability accrual, component amount																							$ 38,000,000
Product liability accrual recoveries														$ 6,000,000
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
HSBC Securities [Member] | Mortgage Securitization Activity Related Litigation [Member]
Loss Contingencies [Line Items]
Mortgage securitization loan purchased and sold																		$ 24,000,000,000
Mortgage securitization outstanding loan purchase and sold																			$ 4,600,000,000	$ 5,200,000,000
Federal and State Parties [Member] | Foreclosure Practices [Member] | HSBC Bank USA [Member]
Loss Contingencies [Line Items]
Litigation settlement			100,000,000
Consumer Relief [Member] | Foreclosure Practices [Member] | HSBC Bank USA [Member]
Loss Contingencies [Line Items]
Litigation settlement			$ 370,000,000
Subsequent Event [Member] | Foreclosure Practices [Member]
Loss Contingencies [Line Items]
Number of mortgage loans | mortgage_loan	1,700
Remediation to borrowers	$ 3,500,000
Civil money penalty assessed by the OCC	$ 32,500,000