Earnings Per Share - Basic Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share [Abstract]
Income from continuing operations	$ 97	$ 76	$ 154	$ 108
Series A convertible preferred stock dividends	(12)	(13)	(24)	(24)
Deemed dividend on modification of Series A convertible preferred stock	0	0	(4)	0
Deemed dividend on preferred stock redemption	0	0	(58)	0
Net Income (Loss) from Continuing Operations Available to Common Shareholders, Basic	85	63	68	84
Income from discontinued operations, net of tax	5	0	5	0
Net income attributable to NCR common stockholders	$ 90	$ 63	$ 73	$ 84
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Weighted average outstanding shares of common stock (in shares)	121.4	123.8	122.1	127.1
Earnings Per Share, Basic [Abstract]
Basic earnings from continuing operations (in dollars per share)	$ 0.70	$ 0.51	$ 0.56	$ 0.66
Basic earnings from discontinued operations (in dollars per share)	0.04	0.00	0.04	0.00
Basic (in dollars per share)	$ 0.74	$ 0.51	$ 0.60	$ 0.66