XML 57 R47.htm IDEA: XBRL DOCUMENT v3.8.0.1
Contingencies - Additional Information (Detail) - USD ($)
9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Dec. 31, 2016
Site Contingency [Line Items]      
Environmental and legal losses $ 25,000,000   $ 25,800,000
Cash outlays related to legal and environmental matters $ 1,400,000 $ 1,000,000  
Contribution for future response costs 5.00%    
Wilmington Site [Member]      
Site Contingency [Line Items]      
Payment of environmental response costs $ 2,500,000    
Minimum [Member]      
Site Contingency [Line Items]      
Environmental and legal losses 25,000,000    
Maximum [Member]      
Site Contingency [Line Items]      
Environmental and legal losses $ 46,100,000