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Asset Retirement Obligation - Reconciliation of Total Reclamation Liability for Asset Retirement Obligations (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Beginning balance $ 14,996 $ 6,142
Additions and revisions of prior estimates 419 8,458
Accretion expenses 740 396
Settlement of liability 0 0
Ending balance $ 16,155 $ 14,996