Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Product revenue	$ 526.0	$ 554.0
Service revenue	991.0	924.0
Total revenue	1,517.0	1,478.0
Cost of products	420.0	424.0
Cost of services	677.0	642.0
Selling, general and administrative expenses	245.0	230.0
Research and development expenses	66.0	67.0
Total operating expenses	1,408.0	1,363.0
Income from operations	109.0	115.0
Interest expense	(41.0)	(39.0)
Other (expense), net	(5.0)	(5.0)
Income from continuing operations before income taxes	63.0	71.0
Income tax expense	7.0	14.0
Income from continuing operations	56.0	57.0
Loss from discontinued operations, net of tax	(35.0)	0.0
Net income	21.0	57.0
Net income attributable to noncontrolling interests	1.0	0.0
Net income attributable to NCR	20.0	57.0
Amounts attributable to NCR common stockholders:
Income from continuing operations	55.0	57.0
Series A convertible preferred stock dividends	(12.0)	(12.0)
Deemed dividend on modification of Series A Convertible Preferred Stock	0.0	(4.0)
Deemed dividend on preferred stock redemption	0.0	(58.0)
Income (loss) from continuing operations attributable to NCR common stockholders	43.0	(17.0)
Loss from discontinued operations, net of tax	(35.0)	0.0
Net income (loss) attributable to NCR common stockholders	$ 8.0	$ (17.0)
Income (loss) per common share from continuing operations
Basic earnings from continuing operations (in dollars per share)	$ 0.36	$ (0.14)
Income (Loss) from Continuing Operations, Per Diluted Share	0.35	(0.14)
Net income (loss) per common share
Basic (in dollars per share)	0.07	(0.14)
Diluted (in dollars per share)	$ 0.06	$ (0.14)
Weighted average common shares outstanding
Weighted average outstanding shares of common stock (in shares)	119.2	122.8
Diluted (in shares)	123.8	122.8