Income and Mining Taxes - Income (Loss) Before Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Tax Examination [Line Items]
Tax (expense) benefit	$ 218	$ 3,785	$ (13,986)	$ 19,451
Total	(14,059)	(49,259)	(89,921)	(29,972)
United States
Income Tax Examination [Line Items]
United States, Income (loss) before tax	968	(35,250)	(21,914)	(45,397)
Tax (expense) benefit	13	(908)	(3,549)	(2,700)
Canada
Income Tax Examination [Line Items]
Tax (expense) benefit	1,123	4,432	18,462	6,476
Foreign, Income (loss) before tax	(24,844)	(13,194)	(78,937)	(17,103)
Mexico
Income Tax Examination [Line Items]
Tax (expense) benefit	(1,363)	(7,234)	(938)	(23,055)
Foreign, Income (loss) before tax	9,882	1,419	11,403	35,088
Other jurisdictions
Income Tax Examination [Line Items]
Tax (expense) benefit	9	(75)	11	(172)
Foreign, Income (loss) before tax	$ (65)	$ (2,234)	$ (473)	$ (2,560)