Earnings Per Share - Basic Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Numerator:
Income (loss) from continuing operations	$ 30	$ 23
Dividends on convertible preferred stock	(4)	(6)
Income from continuing operations attributable to NCR common stockholders	26	17
Loss from discontinued operations, net of tax	0	0
Net income (loss) attributable to NCR common stockholders	$ 26	$ 17
Denominator:
Weighted average outstanding shares of common stock (in shares)	130.0	128.0
Basic earnings per share:
From continuing operations (in dollars per share)	$ 0.20	$ 0.13
From discontinued operations (in dollars per share)	0	0
Total basic earnings (loss) per share (in dollars per share)	$ 0.20	$ 0.13