Earnings Per Share - Computation of Earnings (Loss) Per Common Share Attributable to Unisys Corporation (Detail) - USD ($) $ / shares in Units, shares in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Basic earnings (loss) per common share computation:
Net income (loss) from continuing operations attributable to Unisys Corporation	$ (76,500,000)	$ 700,000	$ (129,700,000)	$ (32,000,000.0)
Income (loss) from discontinued operations, net of tax	(2,100,000)	25,500,000	1,066,400,000	38,800,000
Net income (loss) attributable to Unisys Corporation	$ (78,600,000)	$ 26,200,000	$ 936,700,000	$ 6,800,000
Weighted average shares (in shares)	63,010	51,782	62,830	51,600
Basic earnings (loss) per share attributable to Unisys Corporation
Continuing operations (in dollars per share)	$ (1.21)	$ 0.01	$ (2.06)	$ (0.62)
Discontinued operations (in dollars per share)	(0.04)	0.50	16.97	0.75
Total (in dollars per share)	$ (1.25)	$ 0.51	$ 14.91	$ 0.13
Diluted earnings (loss) per common share computation:
Net income (loss) from continuing operations attributable to Unisys Corporation	$ (76,500,000)	$ 700,000	$ (129,700,000)	$ (32,000,000.0)
Add interest expense on convertible senior notes, net of tax of zero	0	0	0	0
Interest expense on convertible senior notes, tax	0	0	0	0
Net income (loss) from continuing operations attributable to Unisys Corporation for diluted earnings per share	(76,500,000)	700,000	(129,700,000)	(32,000,000.0)
Income from discontinued operations, net of tax	(2,100,000)	25,500,000	1,066,400,000	38,800,000
Net income (loss) attributable to Unisys Corporation for diluted earnings per share	$ (78,600,000)	$ 26,200,000	$ 936,700,000	$ 6,800,000
Weighted average shares (in shares)	63,010	51,782	62,830	51,600
Plus incremental shares from assumed conversions:
Employee stock plans (in shares)	0	328	0	0
Convertible senior notes (in shares)	0	0	0	0
Adjusted weighted average shares (in shares)	63,010	52,110	62,830	51,600
Diluted earnings (loss) per share attributable to Unisys Corporation
Continuing operations (in dollars per share)	$ (1.21)	$ 0.01	$ (2.06)	$ (0.62)
Discontinued operations (in dollars per share)	(0.04)	0.49	16.97	0.75
Total (in dollars per share)	$ (1.25)	$ 0.50	$ 14.91	$ 0.13
Stock options and restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive weighted average securities (in shares)	1,274	1,572	1,074	1,360
Common shares issuable upon conversion of the 5.50% convertible senior notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive weighted average securities (in shares)	8,625	21,868	8,625	21,868
Convertible senior notes interest rate	5.50%		5.50%

Interest on Convertible Debt, Tax

No definition available.

Name:	uis_InterestonConvertibleDebtTax
Namespace Prefix:	uis_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.