Schedule II - Valuation And Qualifying Accounts And Reserves (Details) - Valuation allowance-deferred tax assets [Member] - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2016
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year		$ 31.3	$ 42.8	$ 15.1
Additions Charged to Costs and Expense		11.5	3.4	16.2
Other (Deductions) Additions	[1]	$ 0.0	0.0	0.0
Balance at end of year			$ 46.2	$ 31.3

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