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Note 8 - Employee Benefit Plans - Reconciliation of Level 3 Assets (Details) - Fair Value, Inputs, Level 3 [Member] - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016
Real Estate [Member] | Hecla Mining Company Retirement Plan [Member] |  |
Beginning balance | $ 8,974 | $ 10,326
Net unrealized gains on assets held at the reporting date | 350 | 283
Purchases | 1,830 | 333
Sales |  | (1,968)
Ending balance | 11,154 | 8,974
Real Estate [Member] | Lucky Friday Pension Plan [Member] |  |
Beginning balance | 2,389 | 2,856
Net unrealized gains on assets held at the reporting date | 94 | 71
Purchases | 540 | 90
Sales |  | (628)
Ending balance | 3,023 | 2,389
Common Collective Funds [Member] | Hecla Mining Company Retirement Plan [Member] |  |
Beginning balance | 2,108 | 4,462
Net unrealized gains on assets held at the reporting date | 104 | 80
Purchases | 2,108 |
Sales | (2,019) | (2,434)
Ending balance | 2,301 | 2,108
Common Collective Funds [Member] | Lucky Friday Pension Plan [Member] |  |
Beginning balance | 550 | 1,309
Net unrealized gains on assets held at the reporting date | 28 | 20
Purchases | 550 |
Sales | (527) | (779)
Ending balance | $ 601 | $ 550

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- Definition Amount of increase (decrease) of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
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- Definition Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
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- Definition Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
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- Definition Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
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