Write-downs, Reserves, and Project Opening Costs, net of Recoveries (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
Write-downs and reserves, and project opening costs, net of recoveries:
Remediation costs	$ 5.4	$ 6.4	$ 24.4	$ 12.4
Divestitures and abandonments	2.4	28.1	16.3	36.2
Project opening costs	7.0	2.8	11.6	4.7
Other	(14.3)	(4.5)	(7.6)	3.6
Total write-downs, reserves, and project opening costs, net of recoveries	$ 0.5	$ 32.8	$ 44.7	$ 56.9