Revenue Recognition (Net Contract Assets (Liabilities)) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Revenue Recognition and Deferred Revenue [Abstract]
Contract with Customer, Liability, Revenue Recognized	$ 0.6	$ 1.4	$ 2.9	$ 5.9
Contract with Customer, Liability, Current	(8.3)		(8.3)		$ (5.5)
Contract with Customer, Liability, Current, Net, Change in Timeframe, Performance Obligation Satisfied Revenue Recognized			$ (2.8)
Contract with Customer, Liability, Current, Net, Change in Timeframe, Performance Obligation Satisfied Revenue Recognized, Percent			50.90%
Contract with Customer, Liability, Noncurrent	(5.2)		$ (5.2)		(5.6)
Contract with Customer, Liability, Noncurrent, Net, Change in Timeframe, Performance Obligation Satisfied Revenue Recognized			$ 0.4
Contract with Customer, Liability, Noncurrent, Net, Change in Timeframe, Performance Obligation Satisfied Revenue Recognized, Percent			(7.10%)
Contract with Customer, Asset (Liability), Net	$ (13.5)		$ (13.5)		$ (11.1)
Contract with Customer, Asset (Liability), Change in Timeframe, Performance Obligation Satisfied Revenue Recognized			$ (2.4)