Schedule II- Valuation and Qualifying Account - Allowance for Doubtful Accounts (Details) - Allowance for Doubtful Accounts - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 5.5	$ 4.9	$ 5.7
Charged to (Reversed from) Costs and Expenses	4.4	1.7	(0.8)
Write-offs, Net of Recoveries	0.0	(1.1)	0.0
Balance at End of Year	$ 9.9	$ 5.5	$ 4.9