Schedule II - Valuation and Qualifying Accounts and Reserves (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at end of year	$ 4.3
SEC Schedule, 12-09, Allowance, Credit Loss [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	5.9	$ 6.7	$ 6.3
Additions charged to cost and expenses	4.8	3.9	2.4
Write-offs	(3.7)	(5.6)	(2.7)
Recoveries	0.6	0.9	0.9
Other	(1.3)	0.0	(0.2)
Balance at end of year	$ 6.3	$ 5.9	$ 6.7