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v3.20.2

Note 1 - Basis of Preparation of Financial Statements (Details Textual) $ in Millions | 9 Months Ended
--- | ---
Sep. 30, 2020 USD ($)
Casa Berardi [Member] |
Suspension Costs | $ 1.6
San Sebastian [Member] |
Suspension Costs | 1.1
Greens Creek [Member] |
Suspension Costs from Quarantining Employee Per Week | $ 1.9

X
- Definition Amount of suspension costs during the period. + References No definition available. + Details
Name: | hl_SuspensionCosts
Namespace Prefix: | hl_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of costs incurred per week from the employee quarantine. + References No definition available. + Details
Name: | hl_SuspensionCostsFromQuarantiningEmployeePerWeek
Namespace Prefix: | hl_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=hl_CasaBerardiMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=hl_SanSebastianMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=hl_GreensCreekMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |