Other Retirement Plans (Schedule of Covered Employees and Contributions, Multi-Employer Plans) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Covered Employees and Contributions, Multi-Employer Plans [Line Items]
Multi-employer plans, contributions	$ 12.7	$ 15.9	$ 29.8	$ 33.2
Multi-Employer Plans, Pension [Member]
Covered Employees and Contributions, Multi-Employer Plans [Line Items]
Multi-employer plans, contributions	11.6	14.9	27.3	30.2
Multi-Employer Plans, Postretirement Benefit [Member]
Covered Employees and Contributions, Multi-Employer Plans [Line Items]
Multi-employer plans, contributions	$ 1.1	$ 1.0	$ 2.5	$ 3.0
Workforce Subject to Collective Bargaining Arrangements [Member] | Unionized Employees [Member] | Minimum [Member] | Multi-Employer Plans, Pension And Postretirement Benefit [Member]
Covered Employees and Contributions, Multi-Employer Plans [Line Items]
Multi-employer plans, covered employees	2,029	2,392	1,098	778
Workforce Subject to Collective Bargaining Arrangements [Member] | Unionized Employees [Member] | Maximum [Member] | Multi-Employer Plans, Pension And Postretirement Benefit [Member]
Covered Employees and Contributions, Multi-Employer Plans [Line Items]
Multi-employer plans, covered employees	2,167	2,734	2,167	2,734