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 [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning of Period	$ 9.9	$ 12.4	$ 12.4
Charge (Benefit) to Expenses	6.9	9.4	8.5
(To) From Other Accounts	0.0	(2.0)	0.0
Deductions	6.4	9.9	8.5
End of Period	10.4	9.9	12.4
Valuation Allowance of Deferred Tax Assets [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning of Period	54.4	58.4	64.4
Charge (Benefit) to Expenses	(9.2)	(3.6)	(5.5)
(To) From Other Accounts	0.3	(0.4)	(0.5)
Deductions	0.0	0.0	0.0
End of Period	$ 45.5	$ 54.4	$ 58.4