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Basis of Presentation - Additional Information (Detail)
3 Months Ended 9 Months Ended
Sep. 30, 2016
USD ($)
Sep. 30, 2015
USD ($)
Sep. 30, 2016
USD ($)
Project
Sep. 30, 2015
USD ($)
Mar. 31, 2016
USD ($)
Significant Accounting Policies [Line Items]          
Number of projects suspended | Project     2    
Percentage of suspended projects relating to two projects     92.00%    
Projects completed percentage     90.00%    
Lower of cost or market inventory adjustment $ 115,000 $ 0 $ 115,000 $ 4,372,000  
Production cost $ 12,845,000 $ 5,528,000 $ 36,067,000 $ 25,157,000  
Bauxite raw materials          
Significant Accounting Policies [Line Items]          
Impairment of long-term portion of the bauxite raw material         $ 1,065,000