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Retirement plans - Additional information (Details) - USD ($)
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Disclosure of net defined benefit liability (asset) [line items]    
Retirement obligation (asset) $ 31,852,000 $ 22,170,000
Weighted average duration of defined benefit obligation 8 years  
Unfunded | Chile    
Disclosure of net defined benefit liability (asset) [line items]    
Retirement obligation (asset) $ 35,300,000 28,100,000
Estimate of contributions expected to be paid to plan for next annual reporting period 9,500,000  
Funded    
Disclosure of net defined benefit liability (asset) [line items]    
Retirement obligation (asset) (4,800,000) (5,700,000)
Estimate of contributions expected to be paid to plan for next annual reporting period 0  
Funded | Europe    
Disclosure of net defined benefit liability (asset) [line items]    
Retirement obligation (asset) 1,400,000 $ (200,000)
Estimate of contributions expected to be paid to plan for next annual reporting period $ 500,000