Revenue Recognition (Net Contract Assets (Liabilities)) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Revenue Recognition and Deferred Revenue [Abstract]
Contract with Customer, Liability, Revenue Recognized	$ 1.6	$ 1.5
Contract with Customer, Liability, Current	(8.2)		$ (5.5)
Contract with Customer, Liability, Current, Net, Change in Timeframe, Performance Obligation Satisfied Revenue Recognized	$ (2.7)
Contract with Customer, Liability, Current, Net, Change in Timeframe, Performance Obligation Satisfied Revenue Recognized, Percent	49.10%
Contract with Customer, Liability, Noncurrent	$ (5.5)		(5.6)
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	$ (13.7)		$ (11.1)
Contract with Customer, Asset (Liability), Change in Timeframe, Performance Obligation Satisfied Revenue Recognized	$ (2.6)