Legal Proceedings and Other Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012 site
Total accruals for losses related to litigation	$ 1.9
Number of sites	17
Accruals for remediation and restoration costs	$ 15.9

Total costs accrued as of the balance sheet date for environmental loss contingencies.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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