Related Party Transactions (Details Textual) (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						3 Months Ended			6 Months Ended		12 Months Ended			6 Months Ended			12 Months Ended	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended				6 Months Ended			6 Months Ended		6 Months Ended	12 Months Ended			3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011	Jun. 30, 2012 Maximum [Member]	Jun. 30, 2012 Maximum [Member]	Jun. 30, 2012 Series C Preferred Stock [Member]	Jun. 30, 2011 Series C Preferred Stock [Member]	Jun. 30, 2012 Series C Preferred Stock [Member]	Jun. 30, 2011 Series C Preferred Stock [Member]	Jun. 30, 2012 Commercial Back Facility [Member]	Dec. 31, 2011 Commercial Back Facility [Member]	Jun. 30, 2012 HSBC Technology and Services (USA) Inc. (HTSU) [Member]	Jun. 30, 2011 HSBC Technology and Services (USA) Inc. (HTSU) [Member]	Jun. 30, 2012 HSBC Technology and Services (USA) Inc. (HTSU) [Member]	Jun. 30, 2011 HSBC Technology and Services (USA) Inc. (HTSU) [Member]	Jun. 30, 2012 Related Parties [Member]	Dec. 31, 2011 Related Parties [Member]	Jun. 30, 2012 Related Parties [Member] Accrued Interest Receivable [Member]	Dec. 31, 2011 Related Parties [Member] Accrued Interest Receivable [Member]	Jun. 30, 2012 HSBC Bank USA [Member]	Mar. 31, 2012 HSBC Bank USA [Member]	Jun. 30, 2011 HSBC Bank USA [Member]	Jun. 30, 2012 HSBC Bank USA [Member]	Jun. 30, 2011 HSBC Bank USA [Member]	Dec. 31, 2011 HSBC Bank USA [Member]	Jun. 30, 2012 HSBC Bank USA [Member] Commercial paper back-stop credit facility [Member]	Dec. 31, 2011 HSBC Bank USA [Member] Commercial paper back-stop credit facility [Member]	Jun. 30, 2012 HSBC Bank USA [Member] Commercial Back Facility Maturity 2012 [Member]	Jun. 30, 2012 HSBC Bank USA [Member] Commercial Back Facility Maturity 2014 [Member]	Jan. 31, 2009 HSBC Bank USA [Member] GM and UP Loan Portfolio [Member]	Dec. 31, 2011 HSBC Bank USA Subsidiaries [Member]	Jun. 30, 2012 HSBC Global Resourcing UK Ltd [Member]	Jun. 30, 2011 HSBC Global Resourcing UK Ltd [Member]	Jun. 30, 2012 HSBC Global Resourcing UK Ltd [Member]	Jun. 30, 2011 HSBC Global Resourcing UK Ltd [Member]	Jun. 30, 2012 HSBC USA Inc. [Member]	Jun. 30, 2011 HSBC USA Inc. [Member]	Jun. 30, 2012 HSBC USA Inc. [Member]	Jun. 30, 2011 HSBC USA Inc. [Member]	Dec. 31, 2011 HSBC USA Inc. [Member]	Jun. 30, 2012 HSBC USA Inc. [Member] Committed Revolving Credit Facility [Member]	Jun. 30, 2012 HSBC Investments [Member]	Mar. 31, 2012 HSBC Investments [Member]	Dec. 31, 2011 HSBC Investments [Member]	Jun. 30, 2012 HSBC Investments [Member] Commercial paper back-stop credit facility [Member]	Dec. 31, 2011 HSBC Investments [Member] Commercial paper back-stop credit facility [Member]	Jun. 30, 2012 HSBC North America [Member]	Dec. 31, 2010 HSBC North America [Member]	Dec. 31, 2011 HSBC North America [Member]	Jun. 30, 2011 HSBC North America [Member]	Dec. 31, 2010 HSBC North America [Member] Series C Preferred Stock [Member]	Dec. 31, 2010 HSBC North America [Member] Uncommitted Revolving Credit Facility [Member]	Jun. 30, 2012 HSBC Trinkaus and Burkhardt AG [Member] Commercial paper back-stop credit facility [Member]	Dec. 31, 2011 HSBC Trinkaus and Burkhardt AG [Member] Commercial paper back-stop credit facility [Member]	Dec. 31, 2010 HSBC Bank plc ("HBEU") [Member]
Related party transactions (Textual) [Abstract]
Other liabilities related to accrued interest receivable on derivative positions	$ 1,287,000,000		$ 1,287,000,000		$ 1,688,000,000													$ 72,000,000	$ 47,000,000	$ 4,000,000	$ 55,000,000
Rental revenue														4,000,000	(2,000,000)	7,000,000	(1,000,000)
Real estate secured receivables sold																									3,700,000,000
Receivables serviced for HSBC Bank USA																						1,300,000,000			1,300,000,000		1,300,000,000
Total servicing and other fees from HSBC affiliates																						1,000,000		2,000,000	2,000,000	3,000,000
Payment of service fees																						14,000,000		15,000,000	28,000,000	32,000,000
Borrowing capacity of credit facility																												1,100,000,000	1,100,000,000	600,000,000	500,000,000											3,000,000,000	2,000,000,000				500,000,000	500,000,000						1,000,000,000	400,000,000	400,000,000
Line of Credit Facility Maximum Borrowing Capacity after Amendment																																						4,000,000,000		4,000,000,000
Expiration period																											15 years
Outstanding balance												0	0									0			0		0						0														0	0							0	0
Uncommitted secured credit facility to subsidiaries																						1,500,000,000			1,500,000,000		1,500,000,000
Outstanding principal balance																																12,400,000,000
Purchase account receivable related to credit card account relation																									970,000,000
Intangible assets of discontinued credit card operations																											29,000,000
Gain on sale of account relation																							79,000,000		79,000,000
Extended Amount																									1,000,000,000								1,000,000,000
Gains on the daily sales of the receivables	1,254,000,000	123,000,000	1,604,000,000	324,000,000																		10,000,000		148,000,000	89,000,000	261,000,000
Fees received for servicing receivable portfolios																						50,000,000		156,000,000	207,000,000	305,000,000
Expiration year																														2012-09	2014-09
Support services from HSBC affiliates	79,000,000	72,000,000	145,000,000	139,000,000																														3,000,000	2,000,000	6,000,000	6,000,000
Notional values of derivative contracts	30,939,000,000		30,939,000,000		40,854,000,000																	30,500,000,000			30,500,000,000		40,400,000,000
Fair value amount recognized for derivative instruments	337,000,000		337,000,000		584,000,000																																	337,000,000		337,000,000		584,000,000
Loss on debt and related derivatives fair value																																						(5,000,000)	5,000,000	(19,000,000)	(7,000,000)
Debt fair value under fair value Due to affiliates																		466,000,000	447,000,000
Loan agreements with affiliates																																													250,000,000							600,000,000
Maturity year of short term debt			2012-09																																									2012-08
Outstanding amount under loan																																												500,000,000
First borrowing amount																																																	200,000,000
Second borrowing amount																																																	200,000,000
Third borrowing amount																																																	200,000,000
Maturity year of long term debt			2035																																														2034
Long-term debt	33,590,000,000		33,590,000,000		39,790,000,000																																												600,000,000		600,000,000
Maturity year of line of credit																																															2014-04								2012-12
Maturity Period of Line of Credit																																																		15 years
Deposit																																												500,000,000		500,000,000
Number of shares issued																																																					1,000
Price of shares issued																																																					1,000,000,000
Dividend paid on preferred stock								21,000,000	22,000,000	43,000,000	47,000,000
Interest bearing deposits with banks	2,830,000,000		2,830,000,000		1,140,000,000																																																				1,000,000,000
Interest income from HSBC affiliates	858,000,000	1,128,000,000	1,765,000,000	2,220,000,000
Fees received for guarantee		2,000,000		3,000,000		1,000,000	1,000,000
Related party transactions (Additional Textual) [Abstract]
Due to affiliate, carried at fair value	466,000,000		466,000,000		447,000,000
Interest income on securities	$ 1,000,000	$ 1,000,000	$ 2,000,000	$ 2,000,000