Earnings Per Share - Basic Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Income (loss) from continuing operations	$ 31,000,000	$ 105,000,000	$ 118,000,000	$ 230,000,000
Preferred Stock Dividends Income Statement Impact Included in Diluted Earnings Per Share From Continuing Operations	6,000,000	12,000,000	19,000,000	37,000,000
Dividends on convertible preferred stock	(6,000,000)	(79,000,000)	(19,000,000)	(104,000,000)
Deemed Dividend on Preferred Stock Redemption	0	67,000,000	0	67,000,000
Income from continuing operations attributable to NCR common stockholders	25,000,000	26,000,000	99,000,000	126,000,000
Loss from discontinued operations, net of tax	0	(15,000,000)	0	(15,000,000)
Net income (loss) attributable to NCR common stockholders	$ 25,000,000	$ 11,000,000	$ 99,000,000	$ 111,000,000
Denominator:
Weighted average outstanding shares of common stock (in shares)	128.5	121.4	128.2	120.3
Basic earnings per share:
From continuing operations (in dollars per share)	$ 0.19	$ 0.21	$ 0.77	$ 1.05
From discontinued operations (in dollars per share)	0	(0.12)	0	(0.13)
Total basic earnings (loss) per share (in dollars per share)	$ 0.19	$ 0.09	$ 0.77	$ 0.92