XML 37 R24.htm IDEA: XBRL DOCUMENT v3.7.0.1
Basis of Presentation - Additional Information (Detail)
3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2017
USD ($)
Jun. 30, 2016
USD ($)
Jun. 30, 2017
USD ($)
Project
Jun. 30, 2016
USD ($)
Dec. 31, 2016
USD ($)
Mar. 31, 2016
USD ($)
Significant Accounting Policies [Line Items]            
Number of projects suspended | Project     2      
Percentage of suspended projects relating to two projects     93.00%      
Projects completed percentage     90.00%      
Deferred tax assets, valuation allowance $ 19,703,000   $ 19,703,000      
Restricted cash 11,266,000   11,266,000   $ 0  
Lower of cost or market inventory adjustment     0 $ 0    
Production cost $ 10,797,000 $ 13,515,000 $ 22,009,000 $ 23,222,000    
Impairment charge related to manufacturing plant asset groups         $ 0  
Bauxite raw materials            
Significant Accounting Policies [Line Items]            
Impairment of long-term portion of the bauxite raw material           $ 1,065,000