Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-09, Allowance, Uncollectible Customer's Liability for Acceptances [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Beginning Balance	$ 4.1	$ 4.3
Valuation Allowances and Reserves, Ending Balance	4.6	4.1	$ 4.3
SEC Schedule, 12-09, Allowance, Credit Loss [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Beginning Balance	9.7	9.7	8.7
Valuation Allowances and Reserves, Charged to Cost and Expense	1.0	1.2	1.9
Valuation Allowances and Reserves, Adjustments	0.3	(1.2)	(0.9)
SEC Schedule, 12-09, Valuation Allowances and Reserves, Deduction	0.6	0.0	0.0
Valuation Allowances and Reserves, Ending Balance	$ 10.4	$ 9.7	$ 9.7