Schedule II - Valuation and Qualifying Accounts (Details) - Allowance for Credit Losses - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allowance for credit losses (deducted from accounts receivable):
Balance at Beginning of Period	$ 11.8	$ 13.7	$ 22.0
Additions Charged to Costs and Expenses	(0.3)	(1.6)	(5.1)
Deductions	(2.3)	(0.3)	(3.2)
Balance at End of Period	$ 9.2	$ 11.8	$ 13.7