Accumulated Other Comprehensive Income (Loss) - Change in AOCI Balances (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 596.6	$ 500.0	$ 569.5	$ 456.9
Other comprehensive income (loss) before reclassification	0.3	(9.2)	(28.6)	(12.3)
Amounts reclassified from accumulated other comprehensive income	1.7	0.3	3.7	1.0
Ending balance	611.4	523.7	611.4	523.7
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(219.7)	(188.9)	(192.8)	(186.5)
Ending balance	(217.7)	(197.8)	(217.7)	(197.8)
Pension and Other Postretirement Benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(144.2)	(137.6)	(147.0)	(140.4)
Other comprehensive income (loss) before reclassification	0.0	0.0	0.0	0.4
Amounts reclassified from accumulated other comprehensive income	1.8	1.1	4.6	3.5
Ending balance	(142.4)	(136.5)	(142.4)	(136.5)
Derivatives Designated as Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(4.3)	0.4	0.1	2.0
Other comprehensive income (loss) before reclassification	(0.5)	0.1	(5.2)	(0.8)
Amounts reclassified from accumulated other comprehensive income	0.4	(0.3)	0.7	(1.0)
Ending balance	(4.4)	0.2	(4.4)	0.2
Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(71.2)	(51.7)	(45.9)	(48.1)
Other comprehensive income (loss) before reclassification	0.8	(9.3)	(23.4)	(11.9)
Amounts reclassified from accumulated other comprehensive income	(0.5)	(0.5)	(1.6)	(1.5)
Ending balance	$ (70.9)	$ (61.5)	$ (70.9)	$ (61.5)