Accumulated Other Comprehensive Income (Loss) Accumulated Other Comprehensive Income (Loss) (AOCI) - Reclassifications (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Cost of products	$ 451	$ 478	$ 871	$ 902
Cost of services	683	654	1,360	1,296
Selling, general and administrative expenses	261	228	506	458
Research and development expenses	65	58	131	125
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(144)	97	(88)	154
Income tax (benefit) expense	(12)	33	(5)	47
Net (loss) income attributable to NCR common stockholders	(157)	90	(149)	73
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Cost of products	1	(1)		(3)
Cost of services	0	(1)	2	2
Selling, general and administrative expenses	1	3	1	3
Research and development expenses	1	1	1	1
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(3)	(4)	(4)	(9)
Income tax (benefit) expense	0	(1)	(1)	(2)
Net (loss) income attributable to NCR common stockholders	(3)	(3)	(3)	(7)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Cost of products	1	(1)		(3)
Cost of services	0	0		0
Selling, general and administrative expenses	0	0		0
Research and development expenses	0	0		0
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(1)	(1)		(3)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Cost of products	0	0		0
Cost of services	1	0	3	2
Selling, general and administrative expenses	1	2	1	2
Research and development expenses	1	1	1	1
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(3)	(3)	(5)	(5)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Cost of products	0	0		0
Cost of services	(1)	(1)	(1)	0
Selling, general and administrative expenses	0	1	0	1
Research and development expenses	0	0	0	0
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	$ 1	$ 0	$ 1	$ (1)