Quarterly Information (unaudited) Statement of Operations (Details) - USD ($) $ / shares in Units, $ 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
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 1,782	$ 1,663	$ 1,593	$ 1,478	$ 1,802	$ 1,677	$ 1,620	$ 1,444	$ 6,516	$ 6,543	$ 6,373
Gross Profit	515	473	463	413	479	477	446	380
Income (loss) from operations	181	200	178	117	146	189	163	101	676	599	135
Income from continuing operations	(35)	118	97	57	68	107	76	32	237	283	(154)
Income (loss) from discontinued operations, net of tax	(10)	0	5	0	(11)	(2)	0	0	(5)	(13)	(24)
Net income (loss) attributable to NCR	$ (56)	$ 106	$ 90	$ (17)	$ 45	$ 92	$ 63	$ 21	$ 232	$ 270	$ (178)
From continuing operations (in dollars per share)	$ (0.38)	$ 0.87	$ 0.70	$ (0.14)	$ 0.45	$ 0.76	$ 0.51	$ 0.16	$ 1.05	$ 1.86	$ (0.94)
From continuing operations (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)
Net income per common share:
Basic (in dollars per share)	(0.46)	0.87	0.74	(0.14)	0.36	0.74	0.51	0.16	1.01	1.76	(1.09)
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)