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Plant, Equipment, and Mine Development, Net - Narrative (Details) - USD ($) $ in Thousands	2 Months Ended	3 Months Ended		6 Months Ended
	Feb. 28, 2021	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Capitalized interest		$ 0	$ 290	$ 654	$ 334
Plant, equipment and mine development, gross		96,068		96,068		$ 85,256
Mineral properties		40		40		40
Process equipment
Property, Plant and Equipment [Line Items]
Additions to property, plant and equipment				1,500
Plant, equipment and mine development, gross		17,555		17,555		16,065
Mine equipment
Property, Plant and Equipment [Line Items]
Additions to property, plant and equipment				2,300
Plant, equipment and mine development, gross		8,242		8,242		5,961
Construction in progress and other
Property, Plant and Equipment [Line Items]
Additions to property, plant and equipment	$ 3,200
Capitalized interest	700
Plant, equipment and mine development, gross	$ 34,100	36,529		36,529		33,185
Leach pads not in use
Property, Plant and Equipment [Line Items]
Plant, equipment and mine development, gross		$ 11,200		$ 11,200		$ 11,200