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, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share [Abstract]
(Loss) income from continuing operations	$ (143)	$ 97	$ (88)	$ 154
Series A convertible preferred stock dividends	(12)	(12)	(24)	(24)
Deemed dividend on modification of Series A Convertible Preferred Stock	0	0	0	(4)
Deemed dividend on preferred stock redemption	0	0	0	(58)
Net Income (Loss) from Continuing Operations Available to Common Shareholders, Basic	(155)	85	(112)	68
(Loss) income from discontinued operations, net of tax	(2)	5	(37)	5
Net (loss) income attributable to NCR common stockholders	$ (157)	$ 90	$ (149)	$ 73
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Weighted average outstanding shares of common stock (in shares)	117.9	121.4	118.6	122.1
Earnings Per Share, Basic [Abstract]
Basic earnings from continuing operations (in dollars per share)	$ (1.31)	$ 0.70	$ (0.94)	$ 0.56
Basic earnings from discontinued operations (in dollars per share)	(0.02)	0.04	(0.32)	0.04
Basic (in dollars per share)	$ (1.33)	$ 0.74	$ (1.26)	$ 0.60