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Note 11. Derivative Instruments (Detail) - Summary of base metals committed under forward sales contracts (USD $) | 3 Months Ended | 9 Months Ended
--- | --- | ---
Dec. 31, 2011 | Sep. 30, 2012
Zinc [Member] | Settlements 2012 [Member] |  |
Contracts on provisional sales |  |
Metric tonnes under contract - provisional sales | 9,600 | 8,525
Zinc [Member] | Settlements 2013 [Member] |  |
Contracts on provisional sales |  |
Metric tonnes under contract - provisional sales |  | 2,200
Zinc [Member] | Settlements 2012 [Member] |  |
Contracts on forecasted sales |  |
Metric tonnes under contract - forecasted sales | 20,500 |
Zinc [Member] | Settlements 2013 [Member] |  |
Contracts on forecasted sales |  |
Metric tonnes under contract - forecasted sales | 8,275 | 10,250
Lead [Member] | Settlements 2012 [Member] |  |
Contracts on provisional sales |  |
Metric tonnes under contract - provisional sales | 2,600 | 3,400
Lead [Member] | Settlements 2012 [Member] |  |
Contracts on forecasted sales |  |
Metric tonnes under contract - forecasted sales | 15,900 | 600
Lead [Member] | Settlements 2013 [Member] |  |
Contracts on forecasted sales |  |
Metric tonnes under contract - forecasted sales | 11,150 | 16,850
Zinc [Member] | Settlements 2012 [Member] |  |
Contracts on provisional sales |  |
Average price per pound - provisional sales (in Dollars) | $ 0.86 | $ 0.88
Zinc [Member] | Settlements 2013 [Member] |  |
Contracts on provisional sales |  |
Average price per pound - provisional sales (in Dollars) |  | 0.97
Zinc [Member] | Settlements 2012 [Member] |  |
Contracts on forecasted sales |  |
Average price per pound - forecasted sales (in Dollars) | 1.12 |
Zinc [Member] | Settlements 2013 [Member] |  |
Contracts on forecasted sales |  |
Average price per pound - forecasted sales (in Dollars) | 1.14 | 1.06
Lead [Member] | Settlements 2012 [Member] |  |
Contracts on provisional sales |  |
Average price per pound - provisional sales (in Dollars) | 0.89 | 0.96
Lead [Member] | Settlements 2012 [Member] |  |
Contracts on forecasted sales |  |
Average price per pound - forecasted sales (in Dollars) | 1.12 | 1.12
Lead [Member] | Settlements 2013 [Member] |  |
Contracts on forecasted sales |  |
Average price per pound - forecasted sales (in Dollars) | $ 1.17 | $ 1.12

X
- Definition Average settlement price in forward contracts on forecasted sales + References No definition available. + Details
Name: | hl_ContractsOnForcastedSales
Namespace Prefix: | hl_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | hl_ContractsOnForecastedSalesAbstract
Namespace Prefix: | hl_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Average settlement price in forward contracts on provisional sales + References No definition available. + Details
Name: | hl_ContractsOnProvisionalSales
Namespace Prefix: | hl_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | hl_ContractsOnProvisionalSalesAbstract
Namespace Prefix: | hl_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Metric tonnes included in open forward contracts on forecasted sales + References No definition available. + Details
Name: | hl_MetricTonnesUnderContractForecastedSales
Namespace Prefix: | hl_
Data Type: | num:massItemType
Balance Type: | na
Period Type: | instant

X
- Definition Metric tonnes included in open forward contracts on provisional sales + References No definition available. + Details
Name: | hl_MetricTonnesUnderContractProvisionalSales
Namespace Prefix: | hl_
Data Type: | num:massItemType
Balance Type: | na
Period Type: | instant