XML 92 R58.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Note 6 - Income Taxes - Changes in the Valuation Allowance (Details) - USD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Balance at beginning of year | $ (94,981) | $ (78,684) | $ (99,602) | $ (115,806)
Increase Due to Uncertainty of Recovery [Member] |  |  |  |
Valuation allowance, deferred tax asset, increase (decrease) | (5,700) | (14,964) | (2,868) |
Decrease Related to Utilization and Expiration [Member] |  |  |  |
Valuation allowance, deferred tax asset, increase (decrease) | 873 | 35,882 | 19,072 |
Klondex Mines Ltd [Member] |  |  |  |
Valuation allowance on deferred tax assets acquired with the Klondex acquisition | $ (11,470) |  |  |

X
- Definition Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319 + Details
Name: | us-gaap_DeferredTaxAssetsValuationAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount of the valuation allowance recorded in a business combination against deductible temporary differences for which related tax benefits will be recorded as a reduction of the acquired entity's income tax expense (after such benefits are first being applied to reduce goodwill and then other noncurrent intangible assets to zero). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 740 -Section 25 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=109126419&loc=d3e9901-128506 + Details
Name: | us-gaap_DeferredTaxesBusinessCombinationValuationAllowanceAvailableToReduceIncomeTaxExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=84176650&loc=d3e32123-109318 + Details
Name: | us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_ValuationAllowanceByDeferredTaxAssetAxis=hl_IncreaseDueToUncertaintyOfRecoveryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationAllowanceByDeferredTaxAssetAxis=hl_DecreaseRelatedToUtilizationAndExpirationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=hl_KlondexMinesLtdMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |