Accumulated Other Comprehensive Loss - Components of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Changes in the Components of Accumulated Other Comprehensive Loss, Net of Tax [Roll Forward]
Beginning balance	$ 1,829.0	$ 1,854.5	$ 1,490.2	$ 1,573.2	$ 1,854.5	$ 1,573.2
Other comprehensive income (loss) before reclassifications					(26.5)
Amounts reclassified out from accumulated other comprehensive income (loss)					3.9
Other comprehensive income (loss), net of tax	7.0	(29.6)	4.5	(42.7)	(22.6)	(38.2)
Ending balance	2,032.6	1,829.0	1,606.3	1,490.2	2,032.6	1,606.3
(Losses) gains on derivatives
Changes in the Components of Accumulated Other Comprehensive Loss, Net of Tax [Roll Forward]
Beginning balance		(1.9)			(1.9)
Other comprehensive income (loss) before reclassifications					(3.9)
Amounts reclassified out from accumulated other comprehensive income (loss)					3.3
Other comprehensive income (loss), net of tax					(0.6)
Ending balance	(2.5)				(2.5)
Change in equity affiliate investment AOCI
Changes in the Components of Accumulated Other Comprehensive Loss, Net of Tax [Roll Forward]
Beginning balance		0.6			0.6
Other comprehensive income (loss) before reclassifications					0.0
Amounts reclassified out from accumulated other comprehensive income (loss)					0.0
Other comprehensive income (loss), net of tax					0.0
Ending balance	0.6				0.6
Defined benefit pension and other postretirement plans
Changes in the Components of Accumulated Other Comprehensive Loss, Net of Tax [Roll Forward]
Beginning balance		(40.5)			(40.5)
Other comprehensive income (loss) before reclassifications					0.1
Amounts reclassified out from accumulated other comprehensive income (loss)					0.6
Other comprehensive income (loss), net of tax					0.7
Ending balance	(39.8)				(39.8)
Foreign currency translation
Changes in the Components of Accumulated Other Comprehensive Loss, Net of Tax [Roll Forward]
Beginning balance		(68.8)			(68.8)
Other comprehensive income (loss) before reclassifications					(22.7)
Amounts reclassified out from accumulated other comprehensive income (loss)					0.0
Other comprehensive income (loss), net of tax					(22.7)
Ending balance	(91.5)				(91.5)
Accumulated other comprehensive loss
Changes in the Components of Accumulated Other Comprehensive Loss, Net of Tax [Roll Forward]
Beginning balance	(140.2)	(110.6)	(192.3)	(149.6)	(110.6)	(149.6)
Other comprehensive income (loss), net of tax	7.0	(29.6)	4.5	(42.7)
Ending balance	$ (133.2)	$ (140.2)	$ (187.8)	$ (192.3)	$ (133.2)	$ (187.8)