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Accounts receivable and other - Summary of Accounts Receivable and Other (Details) - USD ($)
$ in Thousands
Dec. 31, 2020
Dec. 31, 2019
Trade and other current receivables [abstract]    
Trade receivables $ 35,649 $ 35,107
Value added tax and other taxes recoverable 12,171 17,658
Other receivables and advances 5,843 10,756
Prepaid expenses and deposits 19,359 11,789
Marketable securities 194 3,828
Accounts receivable and other $ 73,216 $ 79,138