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Property, Plant and Equipment, Net - Additional Information (Detail) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Sep. 30, 2016
Sep. 30, 2015
Dec. 31, 2015
Dec. 31, 2014
Property Plant And Equipment [Abstract]            
Depreciation expenses $ 1,647 $ 1,393 $ 4,821 $ 3,682 $ 5,276 $ 3,611
Interest expense capitalized $ 0 $ 541 $ 139 $ 1,520 1,808 453
Depletion expense         $ 13 $ 14