Related Party Transactions - Receivable Portfolios (Detail) (HSBC Bank USA [Member], USD $) In Billions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Receivables sold on daily basis	$ 7.9
Private Label [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Receivables sold on daily basis	3.3
General Motors [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Receivables sold on daily basis	2.9
Union Privilege [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Receivables sold on daily basis	0.7
Other [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Receivables sold on daily basis	$ 1.0