Note 8 - Employee Benefit Plans - Employee Allocations of Investments and Measurement Dates by Asset Category (Details)	Dec. 31, 2019	Dec. 31, 2018
Hecla Mining Company Retirement Plan [Member]
Allocation of investments	100.00%	100.00%
Lucky Friday Pension Plan [Member]
Allocation of investments	100.00%	100.00%
Cash [Member] | Hecla Mining Company Retirement Plan [Member]
Allocation of investments	6.00%	1.00%
Cash [Member] | Lucky Friday Pension Plan [Member]
Allocation of investments	6.00%	1.00%
Large Cap US Equity [Member] | Hecla Mining Company Retirement Plan [Member]
Allocation of investments	14.00%	15.00%
Large Cap US Equity [Member] | Lucky Friday Pension Plan [Member]
Allocation of investments	14.00%	15.00%
Small Cap US Equity [Member] | Hecla Mining Company Retirement Plan [Member]
Allocation of investments	7.00%	6.00%
Small Cap US Equity [Member] | Lucky Friday Pension Plan [Member]
Allocation of investments	7.00%	6.00%
Debt Security, Government, Non-US [Member] | Hecla Mining Company Retirement Plan [Member]
Allocation of investments	22.00%	23.00%
Debt Security, Government, Non-US [Member] | Lucky Friday Pension Plan [Member]
Allocation of investments	22.00%	23.00%
Fixed Income Funds [Member] | Hecla Mining Company Retirement Plan [Member]
Allocation of investments	19.00%	24.00%
Fixed Income Funds [Member] | Lucky Friday Pension Plan [Member]
Allocation of investments	19.00%	24.00%
Real Estate [Member] | Hecla Mining Company Retirement Plan [Member]
Allocation of investments	14.00%	15.00%
Real Estate [Member] | Lucky Friday Pension Plan [Member]
Allocation of investments	15.00%	17.00%
Hedge Funds [Member] | Hecla Mining Company Retirement Plan [Member]
Allocation of investments	5.00%	6.00%
Hedge Funds [Member] | Lucky Friday Pension Plan [Member]
Allocation of investments	5.00%	6.00%
Common Stock [Member] | Hecla Mining Company Retirement Plan [Member]
Allocation of investments	13.00%	10.00%
Common Stock [Member] | Lucky Friday Pension Plan [Member]
Allocation of investments	12.00%	8.00%