Note 9 - Employee Benefit Plans - Fair Value by Asset Category (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Total fair value	$ 148,052	$ 116,067	$ 96,329
Hecla Mining Company Retirement Plan [Member]
Total fair value	120,384	93,111
Lucky Friday Pension Plan [Member]
Total fair value	27,668	22,956
Fair Value, Inputs, Level 1 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	84,308	63,861
Fair Value, Inputs, Level 1 [Member] | Lucky Friday Pension Plan [Member]
Total fair value	19,100	15,267
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	84,308	63,861
Fair Value, Inputs, Level 1, 2 and 3 [Member] | Lucky Friday Pension Plan [Member]
Total fair value	19,100	15,267
Fair Value Measured at Net Asset Value Per Share [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	36,076	29,250
Fair Value Measured at Net Asset Value Per Share [Member] | Lucky Friday Pension Plan [Member]
Total fair value	8,568	7,689
Interest-bearing Deposits [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	367	5,709
Interest-bearing Deposits [Member] | Lucky Friday Pension Plan [Member]
Total fair value	111	1,441
Interest-bearing Deposits [Member] | Fair Value, Inputs, Level 1 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	367	5,709
Interest-bearing Deposits [Member] | Fair Value, Inputs, Level 1 [Member] | Lucky Friday Pension Plan [Member]
Total fair value	111	1,441
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	13,947	11,835
Common Stock [Member] | Lucky Friday Pension Plan [Member]
Total fair value	3,203	2,827
Common Stock [Member] | Fair Value, Inputs, Level 1 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	13,947	11,835
Common Stock [Member] | Fair Value, Inputs, Level 1 [Member] | Lucky Friday Pension Plan [Member]
Total fair value	3,203	2,827
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	69,994	46,317
Mutual Funds [Member] | Lucky Friday Pension Plan [Member]
Total fair value	15,786	10,999
Mutual Funds [Member] | Fair Value, Inputs, Level 1 [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	69,994	46,317
Mutual Funds [Member] | Fair Value, Inputs, Level 1 [Member] | Lucky Friday Pension Plan [Member]
Total fair value	15,786	10,999
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	12,708	12,659
Real Estate Investments [Member] | Lucky Friday Pension Plan [Member]
Total fair value	3,428	3,445
Hedge Funds [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	5,823	4,336
Hedge Funds [Member] | Lucky Friday Pension Plan [Member]
Total fair value	1,215	1,161
Common Collective Funds [Member] | Hecla Mining Company Retirement Plan [Member]
Total fair value	17,545	12,255
Common Collective Funds [Member] | Lucky Friday Pension Plan [Member]
Total fair value	$ 3,925	$ 3,083