Shareholders' Equity - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Summary of the components of accumulated other comprehensive income, net of tax
Balance at beginning of period	$ 917.1	$ 905.1	$ 733.5
Balance at end of period	974.3	917.1	905.1
Accumulated Other Comprehensive Income (Loss)
Summary of the components of accumulated other comprehensive income, net of tax
Balance at beginning of period	(25.5)	17.0	27.0
Other comprehensive income (loss)	24.3	(44.6)	(13.4)
Realized loss on reclassification	4.9	2.1	3.4
Balance at end of period	3.7	(25.5)	17.0
Foreign Currency Translation
Summary of the components of accumulated other comprehensive income, net of tax
Balance at beginning of period	27.4	46.9	72.2
Other comprehensive income (loss)	22.0	(19.5)	(25.3)
Realized loss on reclassification	0.0	0.0	0.0
Balance at end of period	49.4	27.4	46.9
Pension Liability Adjustment
Summary of the components of accumulated other comprehensive income, net of tax
Balance at beginning of period	(52.9)	(29.9)	(45.2)
Other comprehensive income (loss)	2.3	(25.1)	11.9
Realized loss on reclassification	4.9	2.1	3.4
Balance at end of period	$ (45.7)	$ (52.9)	$ (29.9)