Litigation and Regulatory Matters - Additional Information (Details) (USD $)	1 Months Ended		3 Months Ended	9 Months Ended	1 Months Ended					1 Months Ended	12 Months Ended	1 Months Ended	0 Months Ended	12 Months Ended	0 Months Ended	12 Months Ended			36 Months Ended			1 Months Ended		1 Months Ended		9 Months Ended	1 Months Ended
	Feb. 29, 2012 entity	Nov. 30, 2011 class_action	Jun. 30, 2013	Sep. 30, 2013 Officers	May 31, 2013 Bayerische Landesbank [Member]	Jul. 22, 2013 Levin, Jura and Hanes [Member] class_action	Oct. 31, 2012 DeKalb County [Member] county	Aug. 31, 2013 ISDA, Markit and Other Defendants [Member] class_action	Jul. 31, 2013 ISDA, Markit and Other Defendants [Member] class_action	Dec. 31, 2010 Madoff Litigation [Member]	Dec. 31, 2012 AML/BSA Related Litigation [Member] Hsbc North America [Member]	Dec. 31, 2012 AML/BSA Related Litigation [Member] HSBC Bank USA [Member]	Feb. 28, 2013 Foreclosure Practices [Member] mortgage_servicer	Dec. 31, 2012 Foreclosure Practices [Member]	Feb. 28, 2013 Foreclosure Practices [Member] Hsbc North America [Member]	Dec. 31, 2012 Foreclosure Practices [Member] Hsbc North America [Member]	Feb. 29, 2012 Foreclosure Practices [Member] HSBC Bank USA [Member] state Services	Dec. 31, 2011 Foreclosure Practices [Member] HSBC Bank USA [Member]	Dec. 31, 2007 Mortgage Securitization Activity Related Litigation [Member] HSBC Securities [Member]	Sep. 30, 2013 Mortgage Securitization Activity Related Litigation [Member] HSBC Securities [Member]	Dec. 31, 2012 Mortgage Securitization Activity Related Litigation [Member] HSBC Securities [Member]	Jan. 31, 2012 Residential Mortgage Backed Securities Related Litigation [Member]	Sep. 30, 2013 Residential Mortgage Backed Securities Related Litigation [Member] Institution class_action	Feb. 29, 2012 Residential Mortgage Backed Securities Related Litigation [Member] HSH Nordbank AG [Member]	Sep. 30, 2013 Residential Mortgage Backed Securities Related Litigation [Member] HSBC Securities [Member]	Sep. 30, 2013 DBNTC Litication [Member]	Oct. 31, 2013 DBNTC Litication [Member] Subsequent Event [Member]
Loss Contingencies [Line Items]
Estimate of loss				$ 1,800,000,000
Number of actions						3		4	3														1
Number of counties acting as plaintiff							3
Number of counties in area							5
Percentage threshold				20.00%
Number of class actions		3
Damages and additional recoveries sought										9,000,000,000																	508,000,000
Loans sold to HIS																			24,000,000,000
Outstanding principal balance on loan																				6,600,000,000	7,400,000,000
Number of former and current officers and directors				5
Unpaid principal balance of securities																									1,600,000,000
Number of financial institutions																							17
Alleged purchased by plaintiff					75,000,000																	122,400,000		41,300,000
Number of entities	2
Number of mortgage servicers													12
Cash payments mortgage servicers would pay in excess													9,300,000,000
Cash payment into a fund that will be used to make payments to borrowers															96,000,000
Recorded expenses of loss contingency														19,000,000		104,000,000
Number of states under different departments																	49
Number of U.S. mortgage servicers with which settlement is announced																	5
Accrual portion of HSBC North																		38,000,000
Recoveries			6,000,000
Settlement agreement term											5 years
Payments to authorities											$ 1,921,000,000	$ 1,381,000,000
Compliance period, one																										5 years
Compliance period, two																										2 years