Related Party Transactions - Additional Information (Details) (USD $)			9 Months Ended				1 Months Ended						1 Months Ended	9 Months Ended			0 Months Ended		3 Months Ended	9 Months Ended									9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 HNAH [Member]	Dec. 31, 2012 HNAH [Member]	Apr. 30, 2011 HNAH [Member]	Aug. 31, 2009 HNAH [Member]	Apr. 30, 2011 HNAH [Member] Senior Notes [Member] installment	Aug. 31, 2009 HNAH [Member] Senior Notes [Member]	Sep. 30, 2013 HSBC Investment [Member]	Sep. 30, 2013 HSBC Holdings Plc [Member]	Dec. 31, 2012 HSBC Holdings Plc [Member]	Sep. 30, 2013 Hsbc North America [Member]	Jan. 31, 2009 HSBC Finance Corporation [Member]	Sep. 30, 2012 HSBC Finance Corporation [Member]	Sep. 30, 2013 HSBC Finance Corporation [Member]	Dec. 31, 2012 HSBC Finance Corporation [Member]	Mar. 29, 2012 HSBC Finance Corporation [Member] Credit Card Customer Relationship [Member]	Jul. 31, 2004 HSBC Finance Corporation [Member] Credit Card Customer Relationship [Member]	Mar. 31, 2012 HSBC Finance Corporation [Member] Credit Card Receivable [Member]	Sep. 30, 2013 HSBC Finance Corporation [Member] Extended Uncommitted Revolving Credit Facility	Dec. 31, 2012 HSBC Finance Corporation [Member] Extended Uncommitted Revolving Credit Facility	Sep. 30, 2013 HSBC Finance Corporation [Member] Extended Uncommitted Revolving Credit Facility Maturity Date, September 2017 [Member]	Sep. 30, 2013 HSBC Finance Corporation [Member] Extended Uncommitted Revolving Credit Facility Maturity Date, January 2018 [Member]	Sep. 30, 2013 HSBC Finance Corporation [Member] Extended Uncommitted Revolving Credit Facility Maturity Date, September 2018 [Member]	Sep. 30, 2013 HSBC Finance Corporation [Member] Extended committed revolving credit facility [Member]	Dec. 31, 2012 HSBC Finance Corporation [Member] Extended committed revolving credit facility [Member]	Sep. 30, 2013 HSBC Finance Corporation [Member] Residential Mortgage [Member]	Dec. 31, 2012 HSBC Finance Corporation [Member] Residential Mortgage [Member]	Sep. 30, 2013 HMUS [Member]	Dec. 31, 2012 HMUS [Member]	Sep. 30, 2013 HSBC Panama [Member] Extended Uncommitted Revolving Credit Facility	Dec. 31, 2012 HSBC Panama [Member] Extended Uncommitted Revolving Credit Facility	Sep. 30, 2013 HSBC Mexico [Member]	Dec. 31, 2012 HSBC Mexico [Member]	Sep. 30, 2013 HSBC Bank Brasil [Member]	Dec. 31, 2012 HSBC Bank Brasil [Member]	Sep. 30, 2013 Other Affiliates [Member]	Dec. 31, 2012 Other Affiliates [Member]	Sep. 30, 2013 Other Affiliates [Member] Extended committed revolving credit facility [Member]	Sep. 30, 2013 Regency [Member]	Sep. 30, 2013 Hsbc Finance And Other Hsbc Affiliates [Member]	Dec. 31, 2012 Hsbc Finance And Other Hsbc Affiliates [Member]
Related Party Transaction [Line Items]
Extended loans and lines of credit															$ 4,000,000,000															$ 3,800,000,000	$ 752,000,000	$ 752,000,000	$ 800,000,000	$ 500,000,000	$ 1,500,000,000	$ 1,000,000,000
Long-term debt	22,151,000,000	21,745,000,000										4,000,000,000
Senior notes					3,000,000,000	1,000,000,000
Term of floating rate debt								5 years
Number of equal installments							3
Notes mature installments period one			1,000,000,000
Senior note interest rate period			90 days
Loan and lease receivable unused line of credit facility									900,000,000	500,000,000	500,000,000	150,000,000
Extended unsecured uncommitted credit facility to certain subsidiary maturity																				15 years
Amount outstanding under the loan agreement			0	0																3,000,000,000	3,000,000,000				0	0
Loan And Lease Receivable Revolving Line Of Credit Outstanding										0	0																									1,000,000,000	0	0
Maturing amount of credit agreement																						512,000,000	1,500,000,000	1,000,000,000
Extended secured uncommitted credit facility and loans and lines of credit																													3,800,000,000
Loans and lines of credit amount outstanding																													929,000,000	310,000,000
Due from Affiliates	5,854,000,000	4,514,000,000													3,015,000,000	2,019,000,000													929,000,000	310,000,000	200,000,000	372,000,000			1,000,000,000	1,000,000,000	710,000,000	813,000,000
Extended line of credit																				1,500,000,000					2,000,000,000														2,600,000,000
Related Party Transaction, Liquidity Facility, Notional Amount																																								2,500,000,000
Derivative, notional amount	5,318,500,000,000	4,729,800,000,000																																							1,164,100,000,000	1,066,500,000,000
Fair value of derivative receivables																																									789,000,000	691,000,000
Residential mortgage loans servicing																											1,000,000,000	1,200,000,000
Credit card receivables																	108,000,000	970,000,000
Related party transaction																	746,000,000
Credit card receivables purchased														9,900,000,000					492,000,000
Purchase of Portfolios with an outstanding principal													12,400,000,000
Net premium of outstanding principal													113,000,000
Servicing fees concerning discontinued operations														$ 199,000,000