XML 116 R82.htm IDEA: XBRL DOCUMENT v3.19.3
Deferred Consideration - Additional Information (Detail)
 9 Months Ended 12 Months Ended
Sep. 30, 2019
USD ($)
oz
Dec. 31, 2018
USD ($)
Business Acquisition [Line Items]    
Upfront consideration paid $ 0  
Deferred consideration 167,640,000 $ 161,540,000
Deferred consideration, current 13,403,000 11,765,000
Deferred consideration, non-current $ 154,237,000 $ 149,775,000
Discount rate used to value the deferred consideration 10.00% 10.00%
Perpetual Growth Rate 1.50% 1.50%
April 1, 2018 through March 31, 2058 [Member]    
Business Acquisition [Line Items]    
Fixed payment ounces of gold | oz 9,500  
April 1, 2058 and Thereafter [Member]    
Business Acquisition [Line Items]    
Fixed payment ounces of gold | oz 6,333