Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Consolidated net income (loss) from continuing operations	$ (317.2)	$ (88.3)	$ 25.0
Income from discontinued operations, net of tax	1,068.4	75.0	53.9
Total	751.2	(13.3)	78.9
Other comprehensive income
Foreign currency translation	49.3	24.4	(81.8)
Postretirement adjustments, net of tax of $(9.2) in 2020, $(11.3) in 2019 and $7.1 in 2018	106.9	(38.9)	33.8
Total other comprehensive income (loss)	156.2	(14.5)	(48.0)
Comprehensive income (loss)	907.4	(27.8)	30.9
Comprehensive income (loss) attributable to noncontrolling interests	7.6	(6.8)	15.7
Comprehensive income (loss) attributable to Unisys Corporation	$ 899.8	$ (21.0)	$ 15.2