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Note 8. Employee Benefit Plans (Detail) - Components Of Net Periodic Benefit Cost To Be Recognized Over Next Fiscal Year (USD $) In Thousands, unless otherwise specified | Dec. 31, 2011
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Pension Benefits [Member] |
Amortization of net (gain)/loss | $ 2,826
Amortization of prior service cost | 401
Other Benefits [Member] |
Amortization of net (gain)/loss | (30)
Amortization of prior service cost | $ 44

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- Definition No authoritative reference available. + References No definition available. + Details
Name: | hl_DefinedBenefitPlanExpectedAmortizationOfNetgainloss
Namespace Prefix: | hl_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition No authoritative reference available. + References No definition available. + Details
Name: | hl_DefinedBenefitPlanExpectedAmortizationOfPriorServiceCost
Namespace Prefix: | hl_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant