Other Retirement Plans (Schedule of Multiemployer Plan Contributions and Covered Employees) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Multiemployer Plans [Line Items]
Multiemployer plan, period contributions	$ 15.8	$ 9.0	$ 32.5	$ 21.9
Multiemployer Plans, Pension [Member]
Multiemployer Plans [Line Items]
Multiemployer plan, period contributions	14.8	8.7	29.6	21.1
Multiemployer Plans, Postretirement Benefit [Member]
Multiemployer Plans [Line Items]
Multiemployer plan, period contributions	$ 1.0	$ 0.3	$ 2.9	$ 0.8
Workforce Subject to Collective Bargaining Arrangements [Member] | Minimum [Member]
Multiemployer Plans [Line Items]
Entity number of employees during period	2,392	1,575	778	308
Workforce Subject to Collective Bargaining Arrangements [Member] | Maximum [Member]
Multiemployer Plans [Line Items]
Entity number of employees during period	2,734	2,509	2,734	2,509