Income and Mining Taxes - Income (Loss) Before Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Tax Examination [Line Items]
Total	$ 39,969	$ (14,059)	$ 25,765	$ (89,921)
Tax (expense) benefit	13,113	218	12,018	(13,986)
United States
Income Tax Examination [Line Items]
United States, Income (loss) before tax	24,592	968	26,132	(21,914)
Tax (expense) benefit	(6,003)	13	(5,913)	(3,549)
Canada
Income Tax Examination [Line Items]
Foreign, Income (loss) before tax	(12,895)	(24,844)	(54,544)	(78,937)
Tax (expense) benefit	0	1,123	232	18,462
Mexico
Income Tax Examination [Line Items]
Foreign, Income (loss) before tax	28,320	9,882	54,483	11,403
Tax (expense) benefit	(7,110)	(1,363)	(6,366)	(938)
Other jurisdictions
Income Tax Examination [Line Items]
Foreign, Income (loss) before tax	(48)	(65)	(306)	(473)
Tax (expense) benefit	$ 0	$ 9	$ 29	$ 11