Document and Entity Information	12 Months Ended
	Dec. 31, 2011	Feb. 24, 2012
Document and Entity Information [Abstract]
Entity Registrant Name	HSBC USA INC /MD/
Entity Central Index Key	0000083246
Document Type	10-K
Document Period End Date	Dec. 31, 2011
Amendment Flag	false
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		712