Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 Facility	Dec. 31, 2011	Dec. 31, 2010
Commitment And Contingencies [Line Items]
Committed total of property, plant and equipment expenditure	$ 77.1
Severance payments related to restructuring	36.6
Authorized expenditures on incomplete projects for purchase of property, plant and equipment	23.4
Commitment to purchase natural gas	110.7
Purchase commitment for outsourced services	6.6
Operating lease commitments	532.7
Rent expense	143.7	152.7	212.5
Minimum non-cancelable sublease rentals aggregating	$ 40.5
Number of sites cited as potentially responsible party	10
Number of previously and currently owned sites with potential remediation obligations	11