Income and Mining Taxes (Details Textual) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Income Tax Contingency [Line Items]
Foreign Exchange Income Tax Expense (Benefit)	$ 1,400		$ 7,200
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount				$ 40,800
Deferred Income Tax Expense (Benefit)				15,000
Income Tax Expense (Benefit)	14,232	$ (54,455)	23,180	$ (53,118)
Unrecognized Tax Benefits	17,500		17,500		$ 19,600
Income Tax Examination, Penalties and Interest Expense			8,700		$ 8,700
Minimum [Member]
Income Tax Contingency [Line Items]
Decrease in Unrecognized Tax Benefits is Reasonably Possible	1,500		1,500
Maximum [Member]
Income Tax Contingency [Line Items]
Decrease in Unrecognized Tax Benefits is Reasonably Possible	$ 2,500		$ 2,500