INCOME AND MINING TAXES (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
INCOME TAXES
Statutory tax rate (as a percent)			21.00%		35.00%
Income (loss) before income taxes	$ (14,903)	$ (8,636)	$ (28,772)	$ (15,867)	$ 18,700
Reduction of deferred income tax liability			(4,891)	(3,067)
Deferred income tax recovery due to increased explorations	1,600		4,900
Taxable income offset by non-operating losses			18,700
Remaining balance of operating losses					$ 149,400
Deferred income tax recovery due to currency devaluation		600		3,100
Tax expense	$ (1,613)	$ (564)	(4,891)	$ (3,067)
Black Fox
INCOME TAXES
Tax expense			$ 300