Income and Mining Taxes - Income (Loss) Before Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Tax Examination [Line Items]
Total	$ 14,846	$ (15,839)
Tax (expense) benefit	12,786	(3,939)
United States
Income Tax Examination [Line Items]
United States, Income (loss) before tax	(8,531)	(11,005)
Tax (expense) benefit	(1,625)	(736)
Canada
Income Tax Examination [Line Items]
Foreign, Income (loss) before tax	(12,785)	(26,029)
Tax (expense) benefit	0	15
Mexico
Income Tax Examination [Line Items]
Foreign, Income (loss) before tax	32,914	21,359
Tax (expense) benefit	(11,161)	4,631
Other jurisdictions
Income Tax Examination [Line Items]
Foreign, Income (loss) before tax	3,248	(164)
Tax (expense) benefit	$ 0	$ 29