Discontinued Operations - Additional Information (Detail) (USD $) In Millions, unless otherwise specified			0 Months Ended	12 Months Ended	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Mar. 29, 2013 Insurance business	Dec. 31, 2012 Insurance business	Jun. 30, 2012 Card and Retail Services	May 02, 2012 Card and Retail Services	Jun. 30, 2013 Card and Retail Services HSBC USA, Inc. [Member]	Jun. 30, 2012 Card and Retail Services HSBC USA, Inc. [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestiture of businesses			$ 153		$ 11,800
Pre-tax gain			21		2,200
After-tax gain			13		1,400
Lower of amortized cost or fair value less cost to sell adjustment, before tax				119
Lower of amortized cost or fair value less cost to sell adjustment, after tax				90
Sold business, premium percentage of receivables						8.75%
Gain on sale of intangible assets								79
Incremental increase in industry review enhancement expense							100
Provision for legal expenses and other							40
Other Liabilities for enhancement services products	$ 158	$ 59