Revenue from Contract with Customer Revenue from Contract with Customer (Textuals) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
	Jan. 01, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Revenue from Contract with Customer [Abstract]
Contract with Customer, Asset, Credit Loss Expense		$ 2.1	$ 5.0	$ 0.0	$ 0.0
Deferred Revenue, Revenue Recognized	$ 179.7
Deferred revenue		416.1		416.1		$ 437.5
Revenue, Remaining Performance Obligation		$ 2,600.0		$ 2,600.0