Acquisitions and Dispositions - Dispositions (Details) - USD ($) $ in Millions		12 Months Ended
	May. 29, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale		$ 5	$ 2	$ (5)
Proceeds from dispositions, net of expenses paid		$ 4	$ 270	$ 18
Electronic Funds Source LLC | Network & Security Solutions
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percentage of ownership sold	30.00%
Proceeds from dispositions, net of expenses paid	$ 264
Associated deal costs	166
Income tax provision	7
Electronic Funds Source LLC | Network & Security Solutions | Other income (expense)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale	$ 98