Employee Retirement Plans (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Expense Components
Service cost	$ 0.4	$ 0.5	$ 0.5
Interest	20.8	20.0	20.2
Expected return on plan assets	(27.2)	(30.5)	(31.0)
Amortization of actuarial loss	5.1	5.0	2.1
Defined benefit expense	(0.9)	(5.0)	(8.2)
Profit sharing	15.2	18.7	17.4
Multiemployer plan	2.3	2.4	0.8
Net expense	$ 16.6	$ 16.1	$ 10.0