Revenue Revenue - Textuals (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Maximum Percentage Of Revenue For Which Individual Customer Accounts For	10.70%	11.10%	10.50%
Service and Repair Revenue, Percentage of Total	3.00%
Net Contract Liability, Change from Prior Year	$ (20.0)
Net Contract Liability, Percentage Change from Prior Period	108.10%
Contract with Customer, Liability, Revenue Recognized	$ 52.7
Revenue, Remaining Performance Obligation, Amount	50.6
Capitalized Contract Cost, Net	6.9
Capitalized Contract Cost, Amortization	$ 0.7