Accrued Liabilities - Additional Information (Detail) (2010 Class Action Litigation, USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
2010 Class Action Litigation
 
Schedule of Accrued Liabilities [Line Items]  
Accrued legal and environmental $ 27.0
Amount to be settled through the issuance of common stock $ 13.5