Note 8 - Employee Benefit Plans - Fair Value by Asset Category (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Total fair value	$ 116,067	$ 96,329	$ 99,922
Hecla Mining Company Retirement Plan [Member]
Total fair value	93,111	77,653
Lucky Friday Pension Plan [Member]
Total fair value	22,956	18,676
Fair Value, Inputs, Level 1 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	63,861	52,223
Fair Value, Inputs, Level 1 [Member] | Lucky Friday Pension Plan [Member]
Total fair value	15,267	11,970
Fair Value, Inputs, Level 2 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	0	0
Fair Value, Inputs, Level 2 [Member] | Lucky Friday Pension Plan [Member]
Total fair value	0	0
Fair Value, Inputs, Level 3 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	0	0
Fair Value, Inputs, Level 3 [Member] | Lucky Friday Pension Plan [Member]
Total fair value	0	0
Fair Value, Inputs, Level 1, 2 and 3 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	63,861	52,223
Fair Value, Inputs, Level 1, 2 and 3 [Member] | Lucky Friday Pension Plan [Member]
Total fair value	15,267	11,970
Fair Value Measured at Net Asset Value Per Share [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	29,250	25,430
Fair Value Measured at Net Asset Value Per Share [Member] | Lucky Friday Pension Plan [Member]
Total fair value	7,689	6,706
Interest-bearing Deposits [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	5,709	389
Interest-bearing Deposits [Member] | Lucky Friday Pension Plan [Member]
Total fair value	1,441	111
Interest-bearing Deposits [Member] | Fair Value, Inputs, Level 1 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	5,709	389
Interest-bearing Deposits [Member] | Fair Value, Inputs, Level 1 [Member] | Lucky Friday Pension Plan [Member]
Total fair value	1,441	111
Interest-bearing Deposits [Member] | Fair Value, Inputs, Level 2 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	0	0
Interest-bearing Deposits [Member] | Fair Value, Inputs, Level 2 [Member] | Lucky Friday Pension Plan [Member]
Total fair value	0	0
Interest-bearing Deposits [Member] | Fair Value, Inputs, Level 3 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	0	0
Interest-bearing Deposits [Member] | Fair Value, Inputs, Level 3 [Member] | Lucky Friday Pension Plan [Member]
Total fair value	0	0
Common Stock [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	11,835	7,874
Common Stock [Member] | Lucky Friday Pension Plan [Member]
Total fair value	2,827	1,428
Common Stock [Member] | Fair Value, Inputs, Level 1 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	11,835	7,874
Common Stock [Member] | Fair Value, Inputs, Level 1 [Member] | Lucky Friday Pension Plan [Member]
Total fair value	2,827	1,428
Common Stock [Member] | Fair Value, Inputs, Level 2 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	0	0
Common Stock [Member] | Fair Value, Inputs, Level 2 [Member] | Lucky Friday Pension Plan [Member]
Total fair value	0	0
Common Stock [Member] | Fair Value, Inputs, Level 3 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	0	0
Common Stock [Member] | Fair Value, Inputs, Level 3 [Member] | Lucky Friday Pension Plan [Member]
Total fair value	0	0
Mutual Funds [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	46,317	43,960
Mutual Funds [Member] | Lucky Friday Pension Plan [Member]
Total fair value	10,999	10,431
Mutual Funds [Member] | Fair Value, Inputs, Level 1 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	46,317	43,960
Mutual Funds [Member] | Fair Value, Inputs, Level 1 [Member] | Lucky Friday Pension Plan [Member]
Total fair value	10,999	10,431
Mutual Funds [Member] | Fair Value, Inputs, Level 2 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	0	0
Mutual Funds [Member] | Fair Value, Inputs, Level 2 [Member] | Lucky Friday Pension Plan [Member]
Total fair value	0	0
Mutual Funds [Member] | Fair Value, Inputs, Level 3 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	0	0
Mutual Funds [Member] | Fair Value, Inputs, Level 3 [Member] | Lucky Friday Pension Plan [Member]
Total fair value	0	0
Real Estate Investments [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	12,659	11,926
Real Estate Investments [Member] | Lucky Friday Pension Plan [Member]
Total fair value	3,445	3,231
Hedge Funds [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	4,336	4,283
Hedge Funds [Member] | Lucky Friday Pension Plan [Member]
Total fair value	1,161	1,149
Common Collective Funds [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	12,255	9,221
Common Collective Funds [Member] | Lucky Friday Pension Plan [Member]
Total fair value	$ 3,083	$ 2,326