Retirement and Other Postretirement Benefit Plans - Schedule of Net Periodic Pension Expenses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net Periodic Pension Expense
Defined benefit retirement plans	$ 0.1	$ (1.0)	$ (1.6)
Union sponsored multi-employer pension plan	2.0	2.5	2.1
Retirement savings plans-matching contributions	5.9	11.4	10.2
Retirement savings plans-profit sharing contributions	2.7	10.4	10.2
Net periodic expense	$ 10.7	$ 23.3	$ 20.9