Discontinued Operations - Operating Results of Discontinued Operations (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (loss) from discontinued operations before income tax		$ (7)	$ 0
Commercial Business [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net interest income and other revenues		4	7
Income (loss) from discontinued operations before income tax		2	4
Card and Retail Services [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net interest income and other revenues		0	0
Income (loss) from discontinued operations before income tax	[1]	(9)	$ (4)
Incremental expenses for legal matters		$ 7

[1] The three months ended March 31, 2016 includes incremental expenses of $7 million for legal matters. For the three months ended March 31, 2015, the amount includes expenses related to activities to complete the separation of the credit card operational infrastructure between us and Capital One