Write-downs, Reserves, and Project Opening Costs, net of Recoveries - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Gain (Loss) on Disposition of Property Plant Equipment	$ (22.8)	$ (59.1)	$ (10.1)
Potential Joint Venture [Member]
Gain (Loss) on Disposition of Property Plant Equipment		15.0
Mississippi [Member]
Gain (Loss) on Disposition of Property Plant Equipment	$ 16.5	$ 28.8	$ 8.3