Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Consolidated Statements of Comprehensive Income (Loss)
Foreign currency translation adjustment, tax expense (benefit)	$ (1.2)	$ 1.1	$ 0.3
Defined benefit retirement plan, tax expense (benefit)	(2.1)	(2.1)	$ 0.2
Derivatives qualifying as hedges, tax expense (benefit)	$ (3.8)	$ (0.4)