Other Retirement Plans (Schedule of Multiemployer Plan Contributions and Covered Employees) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Multiemployer Plans [Line Items]
Multiemployer plan, period contributions	$ 8.3	$ 9.3	$ 16.3	$ 12.9
Multiemployer Plans, Pension [Member]
Multiemployer Plans [Line Items]
Multiemployer plan, period contributions	7.9	9.1	15.5	12.5
Multiemployer Plans, Postretirement Benefit [Member]
Multiemployer Plans [Line Items]
Multiemployer plan, period contributions	$ 0.4	$ 0.2	$ 0.8	$ 0.4
Workforce Subject to Collective Bargaining Arrangements [Member] | Minimum [Member]
Multiemployer Plans [Line Items]
Entity number of employees during period	1,149	1,608	778	308
Workforce Subject to Collective Bargaining Arrangements [Member] | Maximum [Member]
Multiemployer Plans [Line Items]
Entity number of employees during period	2,392	2,509	2,392	2,509