MINERAL PROPERTY INTERESTS, PLANT AND EQUIPMENT AND CONSTRUCTION IN PROGRESS (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Subtotal	$ 476,443	$ 459,006
Less: accumulated depreciation	(40,784)	(35,127)
Net carrying value	435,659	423,879
Mineral property interests
Property, Plant and Equipment [Line Items]
Subtotal	336,372	326,086
Land
Property, Plant and Equipment [Line Items]
Subtotal	8,708	8,699
Construction in process
Property, Plant and Equipment [Line Items]
Subtotal	2,508	74,643
Plant and equipment
Property, Plant and Equipment [Line Items]
Subtotal	128,855	49,578
Gold Bar mine \| Construction in process
Interest expense
Interest Expense, Debt	$ 1,400	$ 800

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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