Earnings Per Share - Computation of Earnings Per Common Share Attributable to Unisys Corporation (Detail) - USD ($) $ / shares in Units, shares in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Basic earnings (loss) per common share computation:
Net loss from continuing operations attributable to Unisys Corporation	$ (53,200,000)	$ (32,700,000)
Income from discontinued operations, net of tax	1,068,500,000	13,300,000
Net income (loss) attributable to Unisys Corporation	$ 1,015,300,000	$ (19,400,000)
Weighted average shares (in shares)	62,650	51,418
Basic earnings (loss) per share attributable to Unisys Corporation
Continuing operations (in dollars per share)	$ (0.85)	$ (0.64)
Discontinued operations (in dollars per share)	17.06	0.26
Total (in dollars per share)	$ 16.21	$ (0.38)
Diluted earnings (loss) per common share computation:
Net loss from continuing operations attributable to Unisys Corporation	$ (53,200,000)	$ (32,700,000)
Add interest expense on convertible senior notes, net of tax of zero	0	0
Interest expense on convertible senior notes, tax	0	0
Net loss from continuing operations attributable to Unisys Corporation for diluted earnings per share	(53,200,000)	(32,700,000)
Income from discontinued operations, net of tax	1,068,500,000	13,300,000
Net loss attributable to Unisys Corporation for diluted earnings per share	$ 1,015,300,000	$ (19,400,000)
Weighted average shares (in shares)	62,650	51,418
Plus incremental shares from assumed conversions:
Employee stock plans (in shares)	0	0
Convertible senior notes (in shares)	0	0
Adjusted weighted average shares (in shares)	62,650	51,418
Diluted earnings (loss) per share attributable to Unisys Corporation
Continuing operations (in dollars per share)	$ (0.85)	$ (0.64)
Discontinued operations (in dollars per share)	17.06	0.26
Total (in dollars per share)	$ 16.21	$ (0.38)
Stock options and restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive weighted average securities (in shares)	875	1,401
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
Convertible senior notes interest rate	5.50%