Earnings Per Share - Diluted 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
Preferred Stock Dividends Income Statement Impact Included in Diluted Earnings Per Share From Continuing Operations	4	6
Income from continuing operations attributable to NCR common stockholders	26	17
Loss from discontinued operations, net of tax	0	0
Net income attributable to NCR common stockholders	$ 26	$ 17
Weighted average outstanding shares of common stock (in shares)	130.0	128.0
Dilutive effect of restricted stock units (in shares)	4.7	2.5
Denominator (in shares)	134.7	130.5
Diluted earnings per share:
From continuing operations (in dollars per share)	$ 0.19	$ 0.13
From discontinued operations (in dollars per share)	0	0
Total diluted earnings (loss) per share (in dollars per share)	$ 0.19	$ 0.13
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Preferred Stock Dividends Income Statement Impact Included in Diluted Earnings Per Share From Continuing Operations	$ 4	$ 6
Series A Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from diluted per share count (in shares)	9.2	13.2
Restricted Stock Units (RSUs) and Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from diluted per share count (in shares)	5.0	7.8