Employee Benefit Plans - Net Pension Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)
Interest cost	$ 1.8	$ 2.2	$ 2.1
Expected return on plan assets	(3.3)	(2.9)	(3.3)
Amortization of net loss	1.2	1.3	0.9
Total net periodic pension (income) expense	$ (0.3)	$ 0.6	$ (0.3)