Equity - Reconciliation of accumulated other comprehensive loss (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Increase (Decrease) in Equity [Roll Forward]
Beginning balance	$ 643.5
Total other comprehensive income (loss), net of income tax	(4.9)	$ 23.5	$ (4.4)
Ending balance	662.4	643.5
Gains (Losses) on Cash Flow Hedges
Increase (Decrease) in Equity [Roll Forward]
Other comprehensive income (loss) before reclassifications	(1.1)	(0.3)
Amounts reclassified from accumulated other comprehensive income	1.1	0.3
Pension & Postretirement
Increase (Decrease) in Equity [Roll Forward]
Beginning balance	(47.9)	(39.9)
Other comprehensive income (loss) before reclassifications	(14.5)	(9.9)
Amounts reclassified from accumulated other comprehensive income	1.1	1.9
Total other comprehensive income (loss), net of income tax	(15.6)	(8.0)
Ending balance	(32.3)	(47.9)	(39.9)
Foreign Currency Translation
Increase (Decrease) in Equity [Roll Forward]
Beginning balance	(49.6)	(81.1)
Other comprehensive income (loss) before reclassifications	(20.5)	31.5
Total other comprehensive income (loss), net of income tax	(20.5)	31.5
Ending balance	(70.1)	(49.6)	(81.1)
Accumulated Other Comprehensive Loss
Increase (Decrease) in Equity [Roll Forward]
Beginning balance	(97.5)	(121.0)
Other comprehensive income (loss) before reclassifications	(7.1)	21.3
Amounts reclassified from accumulated other comprehensive income		2.2
Total other comprehensive income (loss), net of income tax	(4.9)	23.5
Ending balance	$ (102.4)	$ (97.5)	$ (121.0)