Property, Plant, and Equipment, Net - Schedule of Property, Plant, and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Total property, equipment and mine development costs	$ 806,074	$ 746,043
Less accumulated depreciation, depletion and amortization	(443,856)	(382,423)
Total property, plant, and equipment, net	362,218	363,620
Plant and mining equipment
Property, Plant and Equipment [Line Items]
Total property, equipment and mine development costs	642,874	603,463
Mine development
Property, Plant and Equipment [Line Items]
Total property, equipment and mine development costs	115,357	96,008
Land
Property, Plant and Equipment [Line Items]
Total property, equipment and mine development costs	26,389	26,606
Office equipment, software and other
Property, Plant and Equipment [Line Items]
Total property, equipment and mine development costs	1,462	1,379
Construction in progress
Property, Plant and Equipment [Line Items]
Total property, equipment and mine development costs	$ 19,992	$ 18,587