Basis of Presentation and Summary of Significant Accounting Policies - Allowance for Doubtful Accounts Activity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 10.3	$ 14.0	$ 14.2
Bad debt (benefit) expense (1)	(0.4)	1.4	1.1
Write-offs, net of recoveries	(1.6)	(4.1)	(0.9)
Other (2)	0.1	(1.0)	(0.4)
Ending balance	$ 8.4	$ 10.3	$ 14.0