Revenue Recognition (Net Contract Assets (Liabilities)) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Revenue Recognition and Deferred Revenue [Abstract]
Contract with Customer, Asset, Net	$ 2.1	$ 2.1
Contract with Customer, Asset, Cumulative Catch-up Adjustment to Revenue, Change in Measure of Progress	$ 0.0
Contract with Customer, Asset, Cumulative Catch-up Adjustment to Revenue, Change in Measure of Progress, Percent	0.00%
Contract with Customer, Liability, Current	$ (6.5)	(7.3)
Contract with Customer, Liability, Current, Net, Change in Timeframe, Performance Obligation Satisfied Revenue Recognized	$ 0.8
Contract with Customer, Liability, Current, Net, Change in Timeframe, Performance Obligation Satisfied Revenue Recognized, Percent	(11.00%)
Contract with Customer, Liability, Noncurrent	$ (5.4)	(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	$ (9.8)	$ (10.7)
Contract with Customer, Asset (Liability), Change in Timeframe, Performance Obligation Satisfied Revenue Recognized	$ 0.9