Description of Business and Significant Accounting Policies - Earnings Per Share (Diluted) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share Reconciliation [Abstract]
Income from continuing operations	$ (35)	$ 118	$ 97	$ 57	$ 68	$ 107	$ 76	$ 32	$ 237	$ 283	$ (154)
Preferred Stock Dividends Income Statement Impact Included in Diluted Earnings Per Share From Continuing Operations									(47)	0	(4)
Deemed dividend on modification of Series A convertible preferred stock									(4)	0	0
Deemed dividend on preferred stock redemption									(58)	0	0
Net Income (Loss) from Continuing Operations Available to Common Shareholders, Diluted									128	283	(158)
Income (loss) from discontinued operations, net of tax	$ (10)	$ 0	$ 5	$ 0	$ (11)	$ (2)	$ 0	$ 0	(5)	(13)	(24)
Preferred Stock Dividends Income Statement Impact Included in Diluted Earnings Per Share									0	49	0
Net income (loss) attributable to NCR common stockholders									$ 123	$ 221	$ (182)
Weighted average outstanding shares of common stock									121.9	125.6	167.6
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Preferred Stock									0.0	28.2	0.0
Dilutive effect of employee stock options and restricted stock									5.1	3.6	0.0
Diluted (continuing operations)									127.0	157.4	167.6
Weighted Average Number of Shares Outstanding, Diluted									127.0	129.2	167.6
Diluted earnings (loss) per share [Abstract]
Diluted (in dollars per share)	$ (0.38)	$ 0.77	$ 0.64	$ (0.14)	$ 0.43	$ 0.69	$ 0.49	$ 0.16	$ 1.01	$ 1.80	$ (0.94)
From discontinued operations (in dollars per share)									(0.04)	(0.10)	(0.15)
Diluted (in dollars per share)	$ (0.46)	$ 0.77	$ 0.67	$ (0.14)	$ 0.35	$ 0.68	$ 0.49	$ 0.16	$ 0.97	$ 1.71	$ (1.09)
Antidilutive options to purchase excluded from computation of diluted earnings per share									0.8	0.4	0.0
Earnings Per Share, Potentially Dilutive Securities									27.4		2
WeightedAverageDilutedSharesOutstanding										172.2