Income and Mining Taxes - Valuation Allowance (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Income Tax Examination [Line Items]
Valuation allowance	$ 430,053	$ 401,304
United States
Income Tax Examination [Line Items]
Valuation allowance	228,942	215,396
Canada
Income Tax Examination [Line Items]
Valuation allowance	165,561	146,611
Mexico
Income Tax Examination [Line Items]
Valuation allowance	13,277	15,885
New Zealand
Income Tax Examination [Line Items]
Valuation allowance	21,822	22,740
Other jurisdictions
Income Tax Examination [Line Items]
Valuation allowance	$ 451	$ 672