Employee Retirement Plans (Details Textual) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Defined Benefit Plan Disclosure [Line Items]
Actual employer contributions to defined benefit plans	$ 4.7	$ 3.5	$ 8.1	$ 7.6
Expected full year contributions by the employer to defined benefit plans			19.7
Contributions to multiemployer plan	$ 0.6		1.3
Expected full year contributions by the employer to the multiemployer plan			$ 2.0