Segment Information - Revenue and Operating Income By Segments (Details) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) segment	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment										3
Total revenue										$ 6,405	$ 6,516	$ 6,543
Income from operations		$ 63	$ 125	$ (106)	$ 109	$ 202	$ 199	$ 175	$ 115	191	691	674
Asset Impairment Charges										227	0	0
Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenue										6,405	6,516	6,543
Operating income by segment										688	840	830
Operating Segments [Member] | Software
Segment Reporting Information [Line Items]
Total revenue										1,912	1,900	1,841
Operating income by segment										492	563	573
Operating Segments [Member] | Services
Segment Reporting Information [Line Items]
Total revenue										2,460	2,373	2,306
Operating income by segment										321	282	198
Operating Segments [Member] | Hardware
Segment Reporting Information [Line Items]
Total revenue	[1]									2,033	2,243	2,396
Operating income by segment	[1]									(125)	(5)	59
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Other adjustments	[2]									497	149	156
Restructuring and other asset-related charges										223	29	26
Acquisition Related Amortization Costs Included in Other Adjustments										85	115	123
Acquisiton Related Costs Included In Other Adjustments										6	5	7
Asset Impairment Charges										183	0	0
Software License [Member] | Operating Segments [Member] | Software
Segment Reporting Information [Line Items]
Total revenue										308	336	341
Software Maintenance [Member] | Operating Segments [Member] | Software
Segment Reporting Information [Line Items]
Total revenue										366	374	372
Cloud [Member] | Operating Segments [Member] | Software
Segment Reporting Information [Line Items]
Total revenue										631	592	556
Professional Services [Member] | Operating Segments [Member] | Software
Segment Reporting Information [Line Items]
Total revenue										607	598	572
ATM [Member] | Operating Segments [Member] | Hardware
Segment Reporting Information [Line Items]
Total revenue										979	1,012	1,221
SCO [Member] | Operating Segments [Member] | Hardware
Segment Reporting Information [Line Items]
Total revenue										346	407	351
POS [Member] | Operating Segments [Member] | Hardware
Segment Reporting Information [Line Items]
Total revenue										708	806	674
IPS [Member] | Operating Segments [Member] | Hardware
Segment Reporting Information [Line Items]
Total revenue										$ 0	$ 18	$ 150

[1] On May 27, 2016, NCR completed the sale of substantially all of its IPS business to Atlas Holdings. The sale included all dedicated assets of the IPS division worldwide, other than in the MEA region. Accordingly, the revenue and operating income results exclude the results of the IPS operations, except for the IPS MEA operations, from May 27, 2016 through the end of the fourth quarter of 2016.

[2] (2) The following table presents the other adjustments for NCR for the years ended December 31:In millions 2018 2017 2016Transformation and restructuring costs $223 $29 $26Acquisition-related amortization of intangibles 85 115 123Acquisition-related costs 6 5 7Goodwill and long-lived asset impairment charges 183 — —Total other adjustments $497 $149 $156