Cost Reduction Plans - Summary of the CIP Reserve Activity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring Reserve [Roll Forward]
Beginning balance	$ 9.8	$ 23.2	$ 33.4
Accrual/other	0.8	5.5	5.9
Payments	(8.8)	(18.9)	(16.1)
Ending balance	1.8	9.8	23.2
Severance
Restructuring Reserve [Roll Forward]
Beginning balance	5.2	18.1	30.0
Accrual/other	(1.0)	0.0	0.2
Payments	(3.3)	(12.9)	(12.1)
Ending balance	0.9	5.2	18.1
Retention
Restructuring Reserve [Roll Forward]
Beginning balance	4.6	5.1	3.4
Accrual/other	1.8	5.5	5.7
Payments	(5.5)	(6.0)	(4.0)
Ending balance	$ 0.9	$ 4.6	$ 5.1