Related Party Transactions - Additional Information (Detail) (USD $)	12 Months Ended			3 Months Ended		1 Months Ended					12 Months Ended			24 Months Ended		3 Months Ended	1 Months Ended		12 Months Ended					12 Months Ended			3 Months Ended								12 Months Ended									1 Months Ended			12 Months Ended				12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Mar. 31, 2012 Card and Retail Services	Dec. 31, 2011 Card and Retail Services	Dec. 31, 2012 Series C (1,000 shares authorized, $0.01 par value, 1,000 shares issued and outstanding)	Dec. 31, 2011 Series C (1,000 shares authorized, $0.01 par value, 1,000 shares issued and outstanding)	Nov. 30, 2010 Series C (1,000 shares authorized, $0.01 par value, 1,000 shares issued and outstanding)	Jun. 30, 2005 Series C (1,000 shares authorized, $0.01 par value, 1,000 shares issued and outstanding)	Dec. 31, 2011 Revolving Credit Facility [Member] Card and Retail Services	Dec. 31, 2012 HSBC USA Inc [Member]	Dec. 31, 2011 HSBC USA Inc [Member]	Dec. 31, 2010 HSBC USA Inc [Member]	Dec. 31, 2004 HSBC USA Inc [Member]	Jan. 31, 2009 HSBC USA Inc [Member] GM and UP portfolios [Member]	Dec. 31, 2011 HSBC USA Inc [Member] Revolving Credit Facility [Member]	Mar. 31, 2010 HSBC Bank USA Subsidiaries [Member]	Jan. 31, 2009 HSBC Bank USA Subsidiaries [Member]	Dec. 31, 2009 HSBC Bank USA Subsidiaries [Member]	Dec. 31, 2010 HSBC Trust Company [Member]	Dec. 31, 2011 HSBC Holdings, Inc. [Member] Commercial paper back-stop credit facility [Member]	Sep. 30, 2012 HSBC Holdings, Inc. [Member] Commercial Back Facility Maturity 2014 [Member]	Sep. 30, 2012 HSBC Holdings, Inc. [Member] Commercial Back Facility Maturity 2012 [Member]	Dec. 31, 2012 HSBC Global Resourcing UK Ltd [Member]	Dec. 31, 2011 HSBC Global Resourcing UK Ltd [Member]	Dec. 31, 2010 HSBC Global Resourcing UK Ltd [Member]	Mar. 31, 2012 HSBC Investments [Member] agreements	Oct. 31, 2012 HSBC Investments [Member]	Dec. 31, 2012 HSBC Investments [Member] Commercial paper back-stop credit facility [Member]	Dec. 31, 2011 HSBC Investments [Member] Commercial paper back-stop credit facility [Member]	Dec. 31, 2012 HSBC North America [Member]	Dec. 31, 2011 HSBC North America [Member]	Dec. 31, 2012 HSBC Trinkaus & Burkhardt AG [Member] Commercial paper back-stop credit facility [Member]	Dec. 31, 2011 HSBC Trinkaus & Burkhardt AG [Member] Commercial paper back-stop credit facility [Member]	Dec. 31, 2010 HSBC Securities USA, Inc. [Member]	Dec. 31, 2012 Parent Company [Member]	Dec. 31, 2011 Parent Company [Member]	Dec. 31, 2012 Amended Credit Agreement [Member] HSBC USA Inc [Member] Revolving Credit Facility [Member]	Jun. 30, 2012 Amended Credit Agreement [Member] HSBC USA Inc [Member] Revolving Credit Facility [Member]	Dec. 31, 2011 Amended Credit Agreement [Member] HSBC USA Inc [Member] Revolving Credit Facility [Member]	Dec. 31, 2012 HSBC 2008 Agreement [Member] HSBC USA Inc [Member] Revolving Credit Facility [Member]	Dec. 31, 2011 HSBC 2008 Agreement [Member] HSBC USA Inc [Member] Revolving Credit Facility [Member]	Dec. 31, 2008 HSBC 2008 Agreement [Member] HSBC USA Inc [Member] Revolving Credit Facility [Member]	May 31, 2012 May 2012 Agreement [Member] HSBC USA Inc [Member] Revolving Credit Facility [Member]	Dec. 31, 2012 May 2012 Agreement [Member] HSBC USA Inc [Member] Revolving Credit Facility [Member]	Dec. 31, 2011 May 2012 Agreement [Member] HSBC USA Inc [Member] Revolving Credit Facility [Member]	Dec. 31, 2012 HSBC Bank Nevada Facility [Member] HSBC USA Inc [Member]	Dec. 31, 2011 HSBC Bank Nevada Facility [Member] HSBC USA Inc [Member]	Dec. 31, 2012 Delayed Draw Term Loan [Member] HSBC North America [Member]	Jul. 31, 2011 Delayed Draw Term Loan [Member] HSBC North America [Member] Draw	Dec. 31, 2012 Delayed Draw Term Loan [Member] Minimum [Member] HSBC North America [Member]	Dec. 31, 2012 Delayed Draw Term Loan [Member] Maximum [Member] HSBC North America [Member]	Dec. 31, 2012 Real Estate Secured Receivable Portfolio [Member] HSBC USA Inc [Member]	Dec. 31, 2011 Real Estate Secured Receivable Portfolio [Member] HSBC USA Inc [Member]	Dec. 31, 2010 Real Estate Secured Receivable Portfolio [Member] HSBC USA Inc [Member]	Dec. 31, 2011 Financing Receivable [Member] HSBC Bank USA Subsidiaries [Member]
Related Party Transaction [Line Items]
Gain on Daily Sales of Receivables to Affiliate											$ 89,000,000	$ 567,000,000	$ 540,000,000
Proceeds from sale of real estate secured receivable to affiliate														3,700,000,000
Servicing Asset at Fair Value, Amount											1,200,000,000	1,300,000,000
Cash Flows Between Transferor and Transferee, Servicing Fees											(4,000,000)	(4,000,000)	(5,000,000)																																								58,000,000	62,000,000	34,000,000
Notional values of derivative contracts	26,060,000,000	40,854,000,000																																		26,000,000,000	40,400,000,000
Fair value of our agreements with affiliate counterparties required the affiliate to provide collateral	75,000,000	584,000,000
Borrowing capacity of credit facility										650,000,000						3,000,000,000					1,100,000,000	600,000,000	500,000,000					100,000,000		500,000,000				400,000,000					4,000,000,000				1,500,000,000		2,000,000,000
Debt Instrument, Term																364 days																												364 days
Principal Amount Outstanding of Loans Held-in-portfolio															12,400,000,000
Expiration period												15 years
Credit card receivables					355,000,000						0	0									0								0	0			0	0				2,000,000,000		0	0	0			0	0		0
Long-term Debt, Maturities, Repayments of Principal in Year Five	1,659,000,000																																					512,000,000
Long-term Debt, Maturities, Repayments of Principal after Year Five	4,065,000,000																																					1,500,000,000
Purchase account receivable related to credit card account relation											970,000,000
Net intangible assets related to account relationships purchased					29,000,000
Gain on sale of intangible assets				79,000,000
Fees received for servicing receivable portfolios											207,000,000	594,000,000	625,000,000
Extended Amount																																															1,000,000,000									1,000,000,000
Disposal Group, Including Discontinued Operations, Servicing Fees and Ancilliary Fees, Amount																				58,000,000
Disposal Group Including Discontinued Operations, Origination Fees, Amount																				4,000,000
Financing Receivable, Significant Sales																		3,000,000,000
Disposal Group Including Discontinued Operations, Gain (Loss) on Sale of Financing Receivables																			7,000,000
Payments to Acquire Finance Receivables																	379,000,000
Support services from HSBC affiliates	310,000,000	270,000,000	241,000,000																					11,000,000	13,000,000	21,000,000
Due to Affiliate																															514,000,000	447,000,000
Related Party, Number of Loan Agreements																											2
Loan agreements with affiliates																											250,000,000																							600,000,000
Number of draws allowed																																																		3
Amount per draw																																																	200,000,000
Maturity year of long term debt																																																			2034	2035
Long-term debt	28,426,000,000	39,790,000,000																														600,000,000																	600,000,000
Number of shares of stock issed									1,000
Value of issued stock								1,000,000,000
Dividend paid on preferred stock						86,000,000	89,000,000
Deposit asset with affiliate			1,000,000,000
Expenses related to underwriting fees and debt service																																			13,000,000
Loans and Leases Receivable, Related Parties																																																								$ 0