Income and Mining Taxes - Income (Loss) Before Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Tax Examination [Line Items]
Total	$ 1,635	$ (42,310)	$ (14,204)	$ (75,862)
Tax (expense) benefit	2,844	(5,546)	(1,095)	(14,204)
United States
Income Tax Examination [Line Items]
United States, Income (loss) before tax	12,546	(16,835)	1,540	(22,882)
Tax (expense) benefit	827	(1,399)	91	(3,561)
Canada
Income Tax Examination [Line Items]
Foreign, Income (loss) before tax	(15,621)	(27,568)	(41,650)	(54,093)
Tax (expense) benefit	217	7,547	232	17,339
Mexico
Income Tax Examination [Line Items]
Foreign, Income (loss) before tax	4,805	2,292	26,163	1,521
Tax (expense) benefit	(3,888)	(600)	743	424
Other jurisdictions
Income Tax Examination [Line Items]
Foreign, Income (loss) before tax	(95)	(199)	(257)	(408)
Tax (expense) benefit	$ 0	$ (2)	$ 29	$ 2