Intangible Assets - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Outstanding principal balances at period end of residential mortgage loans serviced for others		$ 18,930
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
Residential mortgage banking revenue [Member]
Finite-Lived Intangible Assets [Line Items]
Servicing fees collected	$ 36	$ 57	$ 68
Purchased credit card relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Useful life				10 years