Note 5 - Income Taxes (Details Textual) - USD ($) $ in Thousands	11 Months Ended	12 Months Ended
	Dec. 13, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred Tax Liabilities, Net, Total		$ 134,745	$ 171,550
Income Tax Expense (Benefit), Total		(24,101)	(6,701)	$ 20,963
Deferred Tax Assets, Valuation Allowance, Total		$ 86,634	94,981	78,684	$ 99,602
Operating Loss Carryforwards Expiration Period		20 years
Unrecognized Tax Benefits, Ending Balance		$ 0	$ 0
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability				$ 30,000
Domestic Tax Authority [Member]
Deferred Tax Assets, Valuation Allowance, Total		81,600
Operating Loss Carryforwards, Total		704,500
Foreign Tax Authority [Member]
Operating Loss Carryforwards, Total		49,800
Foreign Tax Authority [Member] | Canada Revenue Agency [Member]
Deferred Tax Assets, Valuation Allowance, Total		2,900
Foreign Tax Authority [Member] | Mexican Tax Authority [Member]
Deferred Tax Assets, Valuation Allowance, Total		2,100
State and Local Jurisdiction [Member]
Operating Loss Carryforwards, Total		412,200
Klondex Mines Ltd [Member]
Deferred Tax Liabilities, Net, Total		59,500
Income Tax Expense (Benefit), Total	$ (6,300)	$ (15,100)