Note 8 - Employee Benefit Plans - Employee Allocations of Investments and Measurement Dates by Asset Category (Details)	Dec. 31, 2017	Dec. 31, 2016
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		3.00%
Cash [Member] | Lucky Friday Pension Plan [Member]
Allocation of investments		3.00%
Large Cap US Equity [Member] | Hecla Mining Company Retirement Plan [Member]
Allocation of investments	19.00%	18.00%
Large Cap US Equity [Member] | Lucky Friday Pension Plan [Member]
Allocation of investments	18.00%	17.00%
Small Cap US Equity [Member] | Hecla Mining Company Retirement Plan [Member]
Allocation of investments	9.00%	9.00%
Small Cap US Equity [Member] | Lucky Friday Pension Plan [Member]
Allocation of investments	10.00%	9.00%
Foreign Government Debt Securities [Member] | Hecla Mining Company Retirement Plan [Member]
Allocation of investments	27.00%	24.00%
Foreign Government Debt Securities [Member] | Lucky Friday Pension Plan [Member]
Allocation of investments	26.00%	25.00%
Fixed Income Funds [Member] | Hecla Mining Company Retirement Plan [Member]
Allocation of investments	21.00%	20.00%
Fixed Income Funds [Member] | Lucky Friday Pension Plan [Member]
Allocation of investments	20.00%	20.00%
Real Estate [Member] | Hecla Mining Company Retirement Plan [Member]
Allocation of investments	14.00%	13.00%
Real Estate [Member] | Lucky Friday Pension Plan [Member]
Allocation of investments	15.00%	13.00%
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	6.00%	6.00%
Common Stock [Member] | Hecla Mining Company Retirement Plan [Member]
Allocation of investments	5.00%	7.00%
Common Stock [Member] | Lucky Friday Pension Plan [Member]
Allocation of investments	5.00%	7.00%