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Deferred Consideration - Additional Information (Detail)
$ in Thousands
Sep. 30, 2021
USD ($)
oz
Dec. 31, 2020
USD ($)
oz
Business Acquisition [Line Items]    
Deferred consideration $ 224,953 $ 230,137
Deferred consideration, current 15,961 17,374
Deferred consideration, non-current $ 208,992 $ 212,763
April 1, 2018 through March 31, 2058 [Member]    
Business Acquisition [Line Items]    
Fixed payment ounces of gold | oz 9,500 9,500
April 1, 2058 and Thereafter [Member]    
Business Acquisition [Line Items]    
Fixed payment ounces of gold | oz 6,333 6,333