Discontinued Operations - Operating Results of Discontinued Operations (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (loss) from discontinued operations before income tax		$ (9)	$ (9)	$ (9)	$ (20)
Commercial Business [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net interest income and other revenues		1	4	8	6
Income (loss) from discontinued operations before income tax		1	3	5	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	0	0
Income (loss) from discontinued operations before income tax	[1]	$ (10)	$ (12)	$ (14)	$ (24)

[1] For the three and six months ended June 30, 2015, the amounts primarily relate to legal accruals. For the three and six months ended June 30, 2014, the amounts include expenses related to activities to complete the separation of the credit card operational infrastructure between us and Capital One.