Note 8 - Employee Benefit Plans - Reconciliation of Level 3 Assets (Details) - Fair Value, Inputs, Level 3 [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Real Estate [Member] | Hecla Mining Company Retirement Plan [Member]
Beginning balance	$ 8,974	$ 10,326
Net unrealized gains on assets held at the reporting date	350	283
Purchases	1,830	333
Sales		(1,968)
Ending balance	11,154	8,974
Real Estate [Member] | Lucky Friday Pension Plan [Member]
Beginning balance	2,389	2,856
Net unrealized gains on assets held at the reporting date	94	71
Purchases	540	90
Sales		(628)
Ending balance	3,023	2,389
Common Collective Funds [Member] | Hecla Mining Company Retirement Plan [Member]
Beginning balance	2,108	4,462
Net unrealized gains on assets held at the reporting date	104	80
Purchases	2,108
Sales	(2,019)	(2,434)
Ending balance	2,301	2,108
Common Collective Funds [Member] | Lucky Friday Pension Plan [Member]
Beginning balance	550	1,309
Net unrealized gains on assets held at the reporting date	28	20
Purchases	550
Sales	(527)	(779)
Ending balance	$ 601	$ 550