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, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Numerator
Income (loss) from continuing operations	$ 105	$ 85	$ 230	$ (3)
Preferred Stock Dividends Income Statement Impact Included in Diluted Earnings Per Share From Continuing Operations	12	0	37
Dividends on convertible preferred stock	(79)	(12)	(104)	(36)
Deemed Dividend on Preferred Stock Redemption	(67)	0	(67)	0
Income from continuing operations attributable to NCR common stockholders	26	73	126	(39)
Loss from discontinued operations, net of tax	(15)	(1)	(15)	(38)
Net income (loss) attributable to NCR common stockholders	$ 11	$ 72	$ 111	$ (77)
Denominator
Weighted average outstanding shares of common stock (in shares)	121.4	118.0	120.3	118.4
Basic earnings per share:
From continuing operations (in dollars per share)	$ 0.21	$ 0.62	$ 1.05	$ (0.33)
From discontinued operations (in dollars per share)	(0.12)	(0.01)	(0.13)	(0.32)
Total basic earnings (loss) per share (in dollars per share)	$ 0.09	$ 0.61	$ 0.92	$ (0.65)