Retirement and Other Postretirement Benefit Plans - Schedule of Net Periodic Pension Expenses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net Periodic Pension Expense
Defined benefit retirement plans	$ 0.6	$ 1.6	$ 2.7
Union sponsored multi-employer pension plan	1.9	2.1	2.2
Retirement savings plans-matching contributions	9.7	7.9	4.2
Retirement savings plans-profit sharing contributions	9.2	10.6	9.7
Net periodic expense	$ 21.4	$ 22.2	$ 18.8