Basis of Presentation - Additional Information (Detail) $ in Thousands	3 Months Ended
Mar. 31, 2016 USD ($) Project	Mar. 31, 2015 USD ($)
Significant Accounting Policies [Line Items]
Number of projects suspended \| Project	2
Percentage of suspended assets relating to two projects	90.00%
Projects completed percentage	90.00%
Lower of Cost or Market Inventory Adjustments		$ 4,372
Production cost	$ 9,707	$ 8,421
Bauxite raw materials
Significant Accounting Policies [Line Items]
Impairment of long-term portion of the bauxite raw material	$ 1,065

- Definition

The capitalized costs incurred during the period (excluded from amortization) to operate and maintain wells and related equipment and facilities, including depreciation and applicable operating costs of support equipment and facilities and other costs of operating and maintaining those wells and related equipment and facilities. They become part of the cost of oil and gas produced. Examples of production costs (sometimes called lifting costs) are: costs of labor to operate the wells and related equipment and facilities; repairs and maintenance; materials, supplies, and fuel consumed and supplies utilized in operating the wells and related equipment and facilities; property taxes and insurance applicable to proved properties and wells and related equipment and facilities; severance taxes; some support equipment or facilities may serve two or more oil and gas producing activities and may also serve transportation, refining, and marketing activities. To the extent that the support equipment and facilities are used in oil and gas producing activities, their depreciation and applicable operating costs become exploration, development or production costs, as appropriate. Depreciation, depletion, and amortization of capitalized acquisition, exploration, and development costs are not production costs but also become part of the cost of oil and gas produced along with production (lifting) costs identified above.

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