Intangible Assets - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]
Outstanding principal balances at period end		$ 26,003		$ 26,951
Residential mortgage banking revenue service fees		18	21
Service fees		43,126	44,039
Intangible assets, net		262		295
Purchased from HSBC FInance account of credit card	746
Credit card receivables not being sold to Capital One at a fair value	108
Fair value of Intangible asset related to account relationships purchased include in branch sale	43
Fair value of Intangible asset related to account relationships purchased retained	65
Useful life	10 years
Favorable lease argeement
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net		3		4
Increase in other assets held-for-sale		8
Mortgage Servicing Rights - Commercial Real Estate [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net		$ 2		$ 10