Related Party Transactions - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended			3 Months Ended			6 Months Ended		3 Months Ended				6 Months Ended				3 Months Ended		6 Months Ended			1 Months Ended	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended				1 Months Ended									3 Months Ended											3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended				24 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Jun. 30, 2013 Series C Preferred Stock [Member]	Jun. 30, 2012 Series C Preferred Stock [Member]	Dec. 31, 2010 Series C Preferred Stock [Member]	Jun. 30, 2013 Series C Preferred Stock [Member]	Jun. 30, 2012 Series C Preferred Stock [Member]	Jun. 30, 2013 Subsidiary of Common Parent [Member]		Jun. 30, 2012 Subsidiary of Common Parent [Member]		Jun. 30, 2013 Subsidiary of Common Parent [Member]		Jun. 30, 2012 Subsidiary of Common Parent [Member]		Jun. 30, 2013 Affiliated Entity [Member]	Jun. 30, 2012 Affiliated Entity [Member]	Jun. 30, 2013 Affiliated Entity [Member]	Jun. 30, 2012 Affiliated Entity [Member]	Dec. 31, 2012 Affiliated Entity [Member]	Jul. 31, 2004 HSBC USA, Inc. [Member]	Jun. 30, 2013 HSBC USA, Inc. [Member]	Jun. 30, 2012 HSBC USA, Inc. [Member]	Jun. 30, 2013 HSBC USA, Inc. [Member]	Jun. 30, 2012 HSBC USA, Inc. [Member]	Dec. 31, 2011 HSBC USA, Inc. [Member] Revolving Credit Facility [Member]	Jan. 31, 2009 HSBC USA, Inc. [Member] GM and UP portfolios [Member]	Jun. 30, 2012 HSBC USA, Inc. [Member] Card and Retail Services	Dec. 31, 2011 HSBC USA, Inc. [Member] Card and Retail Services	Jun. 30, 2013 HSBC Global Resourcing UK Ltd [Member]	Jun. 30, 2012 HSBC Global Resourcing UK Ltd [Member]	Jun. 30, 2013 HSBC Global Resourcing UK Ltd [Member]	Jun. 30, 2012 HSBC Global Resourcing UK Ltd [Member]	Mar. 31, 2012 HSBC Investments [Member] agreements	Jun. 30, 2013 HSBC Investments [Member]	Dec. 31, 2012 HSBC Investments [Member]	Oct. 31, 2012 HSBC Investments [Member]	Feb. 29, 2012 HSBC Investments [Member] Revolving Credit Facility [Member]	Jun. 30, 2013 HSBC Investments [Member] Revolving Credit Facility [Member]	Dec. 31, 2012 HSBC Investments [Member] Revolving Credit Facility [Member]	Dec. 31, 2011 HSBC Investments [Member] Revolving Credit Facility [Member]	Jun. 30, 2013 HSBC North America [Member] Delayed Draw Term Loan [Member]	Dec. 31, 2012 HSBC North America [Member] Delayed Draw Term Loan [Member]	Jun. 30, 2011 HSBC North America [Member] Delayed Draw Term Loan [Member] borrowing	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]	Jun. 30, 2011 Minimum [Member] HSBC North America [Member] Delayed Draw Term Loan [Member]	Jun. 30, 2011 Maximum [Member] HSBC North America [Member] Delayed Draw Term Loan [Member]	Jun. 30, 2013 Amended Credit Agreement [Member] HSBC USA, Inc. [Member] Revolving Credit Facility [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]	Jun. 30, 2013 HSBC 2008 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, 2008 HSBC 2008 Agreement [Member] HSBC USA, Inc. [Member] Revolving Credit Facility [Member]	Jun. 30, 2013 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]	May 30, 2012 May 2012 Agreement [Member] HSBC USA, Inc. [Member] Revolving Credit Facility [Member]	Jun. 30, 2013 Real Estate Secured Receivable Portfolio [Member] HSBC USA, Inc. [Member]	Jun. 30, 2012 Real Estate Secured Receivable Portfolio [Member] HSBC USA, Inc. [Member]	Jun. 30, 2013 Real Estate Secured Receivable Portfolio [Member] HSBC USA, Inc. [Member]	Jun. 30, 2012 Real Estate Secured Receivable Portfolio [Member] HSBC USA, Inc. [Member]	Jun. 30, 2013 Borrowings [Member] Subsidiary of Common Parent [Member]	Jun. 30, 2012 Borrowings [Member] Subsidiary of Common Parent [Member]	Jun. 30, 2013 Borrowings [Member] Subsidiary of Common Parent [Member]	Jun. 30, 2012 Borrowings [Member] Subsidiary of Common Parent [Member]	Jun. 30, 2013 Hsbc Technology And Services Usa Inc Htsu [Member]	Jun. 30, 2012 Hsbc Technology And Services Usa Inc Htsu [Member]	Jun. 30, 2013 Hsbc Technology And Services Usa Inc Htsu [Member]	Jun. 30, 2012 Hsbc Technology And Services Usa Inc Htsu [Member]	Jun. 30, 2013 Parent Company [Member]	Dec. 31, 2012 Parent Company [Member]	Dec. 31, 2004 Real Estate Secured [Member] Sale of Receivable [Member] HSBC USA, Inc. [Member]
Related Party Transaction [Line Items]
Administrative fees and rental revenue											$ 3,000,000	[1]	$ 4,000,000	[1]	$ 6,000,000	[1]	$ 8,000,000	[1]																																																			$ 3,000,000	$ 4,000,000	$ 6,000,000	$ 7,000,000
Proceeds from sale of real estate secured receivable to affiliate																																																																											3,700,000,000
Receivables services to affiliates																							1,200,000,000		1,100,000,000		1,100,000,000
Cash flows between transferror and transferree, servicing fees																			1,000,000	1,000,000	2,000,000	2,000,000
Fees paid for servicing activities																																																													15,000,000	14,000,000	31,000,000	28,000,000
Notional values of derivative contracts	20,506,000,000		20,506,000,000		26,060,000,000																																																																				20,400,000,000	26,000,000,000
Fair value of our agreements with affiliate counterparties required the affiliate to provide collateral	661,000,000		661,000,000		75,000,000
Borrowing capacity of credit facility																													3,000,000,000											100,000,000	455,000,000			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
Expiration period																													15 years
Repayments of principal in fifth year																																																				1,500,000,000
Amount outstanding																																						0	0			0	0					0				2,000,000,000	2,000,000,000		0	0		0	0
Repayment of principal in year four																																																				512,000,000
Principal amount outstanding of loans held-in-portfolio																														12,400,000,000
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
Gain on daily sales of receivalbes to affiliate																									0	10,000,000	0	89,000,000
Fees received for servicing receivable portfolios																									0	50,000,000	0	207,000,000
Support services from HSBC affiliates	67,000,000	79,000,000	135,000,000	145,000,000							67,000,000		79,000,000		135,000,000		145,000,000																1,000,000	3,000,000	3,000,000	6,000,000
Due to affiliate carried at fair value	478,000,000		478,000,000		514,000,000
Gain (loss) on FVO debt with affiliate																																																																	34,000,000	(5,000,000)	37,000,000	(19,000,000)
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																																													600,000,000	600,000,000
Number of shares of stock issed (shares)								1,000
Value of issued stock								1,000,000,000
Dividend paid on preferred stock						$ 21,000,000	$ 21,000,000		$ 43,000,000	$ 43,000,000

[1] Rental revenue/(expense) from HTSU totaled $3 million and $6 million during the three and six months ended June 30, 2013, respectively, compared with $4 million and $7 million during the three and six months ended June 30, 2012, respectively.