Shareholders' Equity Stockholders Equity (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Jan. 01, 2017
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 374		$ 374		$ 722	$ 737
Cumulative Effect on Retained Earnings, Net of Tax			15
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest			(125)
Other comprehensive income, Attributable to NCR			(26)
Stock Repurchased and Retired During Period, Value			(210)
Dividends, Preferred Stock			(24)
Employee stock compensation expense	26	$ 22	40	$ 41
Tax Withholding for Share-based Compensation			(29)
Proceeds from employee stock plans			$ 11	$ 8
Stock Repurchased and Retired During Period, Shares			6.1
Parent [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	371		$ 371		719	734
Cumulative Effect on Retained Earnings, Net of Tax			15
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest			(125)
Other comprehensive income, Attributable to NCR			(26)
Stock Repurchased and Retired During Period, Value			(210)
Dividends, Preferred Stock			(24)
Employee stock compensation expense			40
Tax Withholding for Share-based Compensation			(29)
Proceeds from employee stock plans			11
Noncontrolling Interest [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 3		3		$ 3	$ 3
Cumulative Effect on Retained Earnings, Net of Tax			0
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest			0
Other comprehensive income, Attributable to NCR			0
Stock Repurchased and Retired During Period, Value			0
Dividends, Preferred Stock			0
Employee stock compensation expense			0
Tax Withholding for Share-based Compensation			0
Proceeds from employee stock plans			$ 0