Note 5 - Income Taxes - Components of the Net Deferred Tax Asset (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Deferred tax assets:
Accrued reclamation costs	$ 30,188	$ 26,473
Deferred exploration	26,785	29,120
Foreign net operating losses	1,058	21,140
Domestic net operating losses	82,359	82,116
AMT credit carryforwards	20,405	11,607
Pension and benefit obligation	18,115	18,916
Foreign exchange loss	34,977	38,779
Foreign tax credit carryforward	7,283	6,692
Miscellaneous	30,166	27,205
Total deferred tax assets	251,336	262,048
Valuation allowance	(99,602)	(115,806)	$ (32,094)	$ (27,155)
Total deferred tax assets	151,734	146,242
Deferred tax liabilities:
Miscellaneous	(3,046)	(2,394)
Properties, plants and equipment	(235,700)	(209,577)
Total deferred tax liabilities	(238,746)	(211,971)
Net deferred tax liability	$ (87,012)	$ (65,729)