Equity - Reconciliation of accumulated other comprehensive loss (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Increase (Decrease) in Equity [Roll Forward]
Beginning balance	$ 662.4
Total other comprehensive loss, net of income tax	(6.3)	$ (10.6)
Ending balance	661.5
Gains and Losses on Cash Flow Hedges
Increase (Decrease) in Equity [Roll Forward]
Other comprehensive loss before reclassifications	(0.3)
Amounts reclassified from accumulated other comprehensive income (loss)	0.1
Total other comprehensive loss, net of income tax	(0.2)
Ending balance	(0.2)
Pension & Postretirement
Increase (Decrease) in Equity [Roll Forward]
Beginning balance	(32.3)	(47.9)
Other comprehensive loss before reclassifications	(1.1)	(1.2)
Amounts reclassified from accumulated other comprehensive income (loss)	0.5	0.6
Total other comprehensive loss, net of income tax	(0.6)	(0.6)
Ending balance	(32.9)	(48.5)
Foreign Currency Translation
Increase (Decrease) in Equity [Roll Forward]
Beginning balance	(70.1)	(49.6)
Other comprehensive loss before reclassifications	(5.5)	(10.0)
Total other comprehensive loss, net of income tax	(5.5)	(10.0)
Ending balance	(75.6)	(59.6)
Accumulated Other Comprehensive Loss
Increase (Decrease) in Equity [Roll Forward]
Beginning balance	(102.4)	(97.5)
Other comprehensive loss before reclassifications	(6.9)	(11.2)
Amounts reclassified from accumulated other comprehensive income (loss)	0.6	0.6
Total other comprehensive loss, net of income tax	(6.3)	(10.6)
Ending balance	$ (108.7)	$ (108.1)