Accumulated Other Comprehensive Income (Loss) - Reclassification (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of sales	$ 576.8		$ 865.6		$ 1,360.6	$ 1,781.2
Interest expense, net	11.7		9.9		22.0	20.1
Pension settlement loss						0.7
Income before income taxes	63.7		(43.7)		111.9	(90.3)
Provision for income taxes	64.7		15.7		52.8	26.5
Net income	128.4	$ 36.3	(28.0)	$ (35.8)	164.7	(63.8)
Pension and Other Postretirement Benefit Plans, Net | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Pension settlement loss						0.7
Income before income taxes	0.8		0.5		1.7	1.7
Provision for income taxes	(0.3)		(0.2)		(0.6)	(0.4)
Net income	0.5		0.3		1.1	1.3
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Prior service credit	(0.3)		(0.3)		(0.6)	(0.6)
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net actuarial loss	1.1		0.8		2.3	1.6
Accumulated Gain Loss Net Cash Flow Hedge Parent | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of sales	(0.5)		(1.6)		(0.6)	(2.2)
Interest expense, net	0.7		(0.3)		0.7	(0.7)
Income before income taxes	0.2		(1.9)		0.1	(2.9)
Net income	$ 0.2		$ (1.9)		$ 0.1	$ (2.9)