Income and Mining Taxes - Income (Loss) Before Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Tax Examination [Line Items]
Tax (expense) benefit	$ (8,658)	$ 11,949
Total	(33,552)	12,640
United States
Income Tax Examination [Line Items]
United States, Income (loss) before tax	(6,047)	1,187
Tax (expense) benefit	(2,162)	517
Canada
Income Tax Examination [Line Items]
Tax (expense) benefit	9,792	0
Foreign, Income (loss) before tax	(26,525)	0
Mexico
Income Tax Examination [Line Items]
Tax (expense) benefit	1,024	(13,222)
Foreign, Income (loss) before tax	(772)	13,126
Other jurisdictions
Income Tax Examination [Line Items]
Tax (expense) benefit	4	756
Foreign, Income (loss) before tax	$ (208)	$ (1,673)