Employee Retirement Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Retirement Benefits [Abstract]
Service cost—benefits earning during the period	$ 0.0	$ 0.0
Interest cost on projected benefit obligation	5.3	5.3
Expected return on assets	(6.7)	(7.5)
Actuarial (gain) loss	7.9	6.7
Foreign currency gain (loss)	0.0	0.1
Net pension (benefit) cost	$ 6.5	$ 4.6