Revenue Revenue - Contract Assets and Liabilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Contract assets	$ 19.1	$ 18.0
Current Contract Assets, Percentage Change from Prior Period	6.10%
Contract with Customer, Liability, Current	$ (56.2)	(57.4)
Current Contract Liabilities, Percentage Change from Prior Period	(2.10%)
Contract with Customer, Liability, Noncurrent	$ 0.1	0.0
Noncurrent Contract Liabilities, Percentage Change from Prior Period	0
Net Contract Liabilities	$ (37.2)	$ (39.4)
Net Contract Liability, Percentage Change from Prior Period	(5.60%)