Employee Retirement Plans (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Components of Net Retirement Cost
Service cost	$ 0.1	$ 0.1
Interest	4.9	5.2
Expected return on plan assets	(6.8)	(6.8)
Amortization of actuarial loss	1.2	1.3
Defined benefit expense	(0.6)	(0.2)
Profit sharing	4.0	4.6
Multiemployer plan	0.6	0.6
Net expense	$ 4.0	$ 5.0