Note 9 - Employee Benefit Plans - Fair Value by Asset Category (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Total fair value	$ 96,329	$ 99,922	$ 87,357
Hecla Mining Company Retirement Plan [Member]
Total fair value	77,653	79,557
Lucky Friday Pension Plan [Member]
Total fair value	18,676	20,365
Fair Value, Inputs, Level 1 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	52,223	51,300
Fair Value, Inputs, Level 1 [Member] | Lucky Friday Pension Plan [Member]
Total fair value	11,970	12,626
Fair Value, Inputs, Level 2 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value
Fair Value, Inputs, Level 2 [Member] | Lucky Friday Pension Plan [Member]
Total fair value
Fair Value, Inputs, Level 3 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value
Fair Value, Inputs, Level 3 [Member] | Lucky Friday Pension Plan [Member]
Total fair value
Fair Value, Inputs, Level 1, 2 and 3 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	52,223	51,300
Fair Value, Inputs, Level 1, 2 and 3 [Member] | Lucky Friday Pension Plan [Member]
Total fair value	11,970	12,626
Fair Value Measured at Net Asset Value Per Share [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	25,430	28,257
Fair Value Measured at Net Asset Value Per Share [Member] | Lucky Friday Pension Plan [Member]
Total fair value	6,706	7,739
Interest-bearing Deposits [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	389	351
Interest-bearing Deposits [Member] | Lucky Friday Pension Plan [Member]
Total fair value	111	100
Interest-bearing Deposits [Member] | Fair Value, Inputs, Level 1 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	389	351
Interest-bearing Deposits [Member] | Fair Value, Inputs, Level 1 [Member] | Lucky Friday Pension Plan [Member]
Total fair value	111	100
Interest-bearing Deposits [Member] | Fair Value, Inputs, Level 2 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value
Interest-bearing Deposits [Member] | Fair Value, Inputs, Level 2 [Member] | Lucky Friday Pension Plan [Member]
Total fair value
Interest-bearing Deposits [Member] | Fair Value, Inputs, Level 3 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value
Interest-bearing Deposits [Member] | Fair Value, Inputs, Level 3 [Member] | Lucky Friday Pension Plan [Member]
Total fair value
Common Stock [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	7,874	3,768
Common Stock [Member] | Lucky Friday Pension Plan [Member]
Total fair value	1,428	1,015
Common Stock [Member] | Fair Value, Inputs, Level 1 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	7,874	3,768
Common Stock [Member] | Fair Value, Inputs, Level 1 [Member] | Lucky Friday Pension Plan [Member]
Total fair value	1,428	1,015
Common Stock [Member] | Fair Value, Inputs, Level 2 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value
Common Stock [Member] | Fair Value, Inputs, Level 2 [Member] | Lucky Friday Pension Plan [Member]
Total fair value
Common Stock [Member] | Fair Value, Inputs, Level 3 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value
Common Stock [Member] | Fair Value, Inputs, Level 3 [Member] | Lucky Friday Pension Plan [Member]
Total fair value
Mutual Funds [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	43,960	47,181
Mutual Funds [Member] | Lucky Friday Pension Plan [Member]
Total fair value	10,431	11,511
Mutual Funds [Member] | Fair Value, Inputs, Level 1 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	43,960	47,181
Mutual Funds [Member] | Fair Value, Inputs, Level 1 [Member] | Lucky Friday Pension Plan [Member]
Total fair value	10,431	11,511
Mutual Funds [Member] | Fair Value, Inputs, Level 2 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value
Mutual Funds [Member] | Fair Value, Inputs, Level 2 [Member] | Lucky Friday Pension Plan [Member]
Total fair value
Mutual Funds [Member] | Fair Value, Inputs, Level 3 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value
Mutual Funds [Member] | Fair Value, Inputs, Level 3 [Member] | Lucky Friday Pension Plan [Member]
Total fair value
Real Estate Investments [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	11,926	11,154
Real Estate Investments [Member] | Lucky Friday Pension Plan [Member]
Total fair value	3,231	3,023
Hedge Funds [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	4,283	4,247
Hedge Funds [Member] | Lucky Friday Pension Plan [Member]
Total fair value	1,149	1,140
Common Collective Funds [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	9,221	12,856
Common Collective Funds [Member] | Lucky Friday Pension Plan [Member]
Total fair value	$ 2,326	$ 3,576