Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for doubtful accounts:
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance Beginning of Year	$ 3.5	$ 3.8	$ 4.2
Charged to Expense	1.8	1.5	1.3
Deductions	(1.7)	(1.8)	(1.7)
Balance End of Year	3.6	3.5	3.8
Deferred income tax asset valuation allowance:
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance Beginning of Year	0.4	0.9	1.2
Additions	0.0	0.0	0.0
Deductions	(0.2)	(0.5)	(0.3)
Balance End of Year	$ 0.2	$ 0.4	$ 0.9