Revenue Recognition (Net Contract Assets (Liabilities)) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Revenue Recognition and Deferred Revenue [Abstract]
Contract with Customer, Liability, Revenue Recognized	$ 1.3	$ 2.9
Contract with Customer, Asset, Net	3.5	3.5	$ 2.1
Contract with Customer, Asset, Cumulative Catch-up Adjustment to Revenue, Change in Measure of Progress		$ 1.4
Contract with Customer, Asset, Cumulative Catch-up Adjustment to Revenue, Change in Measure of Progress, Percent		66.70%
Contract with Customer, Liability, Current	(5.0)	$ (5.0)	(7.3)
Contract with Customer, Liability, Current, Net, Change in Timeframe, Performance Obligation Satisfied Revenue Recognized		$ 2.3
Contract with Customer, Liability, Current, Net, Change in Timeframe, Performance Obligation Satisfied Revenue Recognized, Percent		(31.50%)
Contract with Customer, Liability, Noncurrent	(5.6)	$ (5.6)	(5.5)
Contract with Customer, Liability, Noncurrent, Net, Change in Timeframe, Performance Obligation Satisfied Revenue Recognized		$ (0.1)
Contract with Customer, Liability, Noncurrent, Net, Change in Timeframe, Performance Obligation Satisfied Revenue Recognized, Percent		1.80%
Contract with Customer, Asset (Liability), Net	$ (7.1)	$ (7.1)	$ (10.7)
Contract with Customer, Asset (Liability), Change in Timeframe, Performance Obligation Satisfied Revenue Recognized		$ 3.6