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Contingencies - Additional Information (Detail) - USD ($)
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Dec. 31, 2018
Site Contingency [Line Items]      
Environmental losses accrual $ 23,400,000   $ 23,400,000
Cash expenitures related to legal and environmental matters $ 200,000 $ 200,000  
Contribution for future response costs 5.00%    
Wilmington Site [Member]      
Site Contingency [Line Items]      
Payment of environmental response costs $ 2,700,000    
Minimum [Member]      
Site Contingency [Line Items]      
Environmental and legal losses 23,400,000    
Maximum [Member]      
Site Contingency [Line Items]      
Environmental and legal losses $ 44,700,000