Schedule II, Valuation and Qualifying Accounts (Details) - Allowance for Bad Debts - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Jan. 1	$ 23.5	$ 21.3	$ 20.0
Charged to costs and expenses	13.0	16.2	15.7
Charged to other accounts	6.5	4.1	3.8
Deductions from reserves	(20.0)	(18.1)	(18.2)
Balance at Dec. 31	$ 23.0	$ 23.5	$ 21.3