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Inventories - Schedule of Inventories (Detail) - USD ($)
$ in Thousands
Jun. 30, 2019
Dec. 31, 2018
Inventory [Line Items]    
Total inventory $ 12,381 $ 18,575
Sand    
Inventory [Line Items]    
Raw material 628 1,201
Work in progress 6,067 10,070
Finished goods 4,769 4,648
Spare parts 917 1,356
Total inventory $ 12,381 $ 17,275