Loss Per Share - Computation of Earnings (Loss) Per Common Share Attributable to Unisys Corporation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Basic loss per common share computation:
Net loss attributable to Unisys Corporation	$ (17.1)	$ (140.8)	$ (74.4)	$ (298.6)
Weighted average shares (in shares)	67,694	67,080	67,541	65,752
Basic loss per common share (in dollars per share)	$ (0.25)	$ (2.10)	$ (1.10)	$ (4.54)
Diluted loss per common share computation:
Net loss attributable to Unisys Corporation	$ (17.1)	$ (140.8)	$ (74.4)	$ (298.6)
Weighted average shares (in shares)	67,694	67,080	67,541	65,752
Plus incremental shares from assumed conversions of employee stock plans (in shares)	0	0	0	0
Adjusted weighted average shares (in shares)	67,694	67,080	67,541	65,752
Diluted loss per common share (in dollars per share)	$ (0.25)	$ (2.10)	$ (1.10)	$ (4.54)
Stock options and restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive weighted average securities (in shares)	418	740	628	903