Intangible Assets - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended		9 Months Ended
	Mar. 31, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Service fees				$ 45,200,000,000
Residential mortgage banking revenue service fees		20,000,000	21,000,000	62,000,000	68,000,000
Intangible assets, net		295,000,000		295,000,000		247,000,000
Purchased from HSBC FInance account of credit card	746,000,000
Credit card receivables not being sold to Capital One at a fair value	108,000,000
Fair value of Intangible asset related to account relationships purchased include in branch sale	43,000,000
Fair value of Intangible asset related to account relationships purchased retained	65,000,000
Useful life	10 years
Mortgage Servicing Rights - Commercial Real Estate [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net		$ 11,000,000		$ 11,000,000		$ 11,000,000