Earnings Per Share - Basic Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Income (loss) from continuing operations	$ 85	$ 118	$ (3)	$ 272
Series A convertible preferred stock dividends	(12)	(12)	(36)	(36)
Deemed dividend on modification of Series A convertible preferred stock	0	0	0	(4)
Deemed dividend on Series A convertible preferred stock related to redemption	0	0	0	(58)
Net Income (Loss) from Continuing Operations Available to Common Shareholders, Basic	73	106	(39)	174
(Loss) income from discontinued operations, net of tax	(1)	0	(38)	5
Net income (loss) attributable to NCR common stockholders	$ 72	$ 106	$ (77)	$ 179
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Weighted average outstanding shares of common stock (in shares)	118.0	121.5	118.4	121.9
Earnings Per Share, Basic [Abstract]
Basic earnings from continuing operations (in dollars per share)	$ 0.62	$ 0.87	$ (0.33)	$ 1.43
Basic earnings from discontinued operations (in dollars per share)	(0.01)	0.00	(0.32)	0.04
Basic (in dollars per share)	$ 0.61	$ 0.87	$ (0.65)	$ 1.47