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Segment Information - Additional Information (Detail)
$ in Thousands
 12 Months Ended
Dec. 31, 2015
USD ($)
Segment
Person
Dec. 31, 2014
USD ($)
Dec. 31, 2013
USD ($)
Segment Reporting Information [Line Items]      
Number of operating segments | Segment 3    
Number of reportable segments | Segment 2    
Cost of sales $ 608,073 $ 613,372 $ 563,122
Number of persons employed by Chemical Business | Person 576    
Number of persons represented by unions under agreements | Person 197    
Chemical [Member] | Natural Gas Properties      
Segment Reporting Information [Line Items]      
Net loss $ 42,800    
Net sales 3,400    
Cost of sales 6,300    
Depreciation, depletion and amortization 5,200    
Production costs 1,100    
Selling, general and administrative expense 200    
Non-cash impairment charge $ 39,700