XML 60 R49.htm IDEA: XBRL DOCUMENT
v3.20.2

Derivatives, Hedging Programs and Other Financial Instruments - Summary of Derivative Positions (Details) - Designated as Hedging Instrument mmlb in Millions | 9 Months Ended
--- | ---
Sep. 30, 2020 EUR (€) mmlb MMBTU MWh
Purchase | Aluminum |
Derivative [Line Items] |
Derivative non-monetary notional amount | 80.1
Purchase | Aluminum | Minimum |
Derivative [Line Items] |
Derivative maturity period | 2020-10
Purchase | Aluminum | Maximum |
Derivative [Line Items] |
Derivative maturity period | 2022-12
Purchase | Midwest premium swap contracts |
Derivative [Line Items] |
Derivative non-monetary notional amount | 79.1
Purchase | Midwest premium swap contracts | Minimum |
Derivative [Line Items] |
Derivative maturity period | 2020-10
Purchase | Midwest premium swap contracts | Maximum |
Derivative [Line Items] |
Derivative maturity period | 2022-12
Purchase | Alloying Metals |
Derivative [Line Items] |
Derivative non-monetary notional amount | 12.0
Purchase | Alloying Metals | Minimum |
Derivative [Line Items] |
Derivative maturity period | 2020-10
Purchase | Alloying Metals | Maximum |
Derivative [Line Items] |
Derivative maturity period | 2021-12
Purchase | Natural Gas |
Derivative [Line Items] |
Derivative non-monetary notional amount | MMBTU | 7,070,000
Purchase | Natural Gas | Minimum |
Derivative [Line Items] |
Derivative maturity period | 2020-10
Purchase | Natural Gas | Maximum |
Derivative [Line Items] |
Derivative maturity period | 2024-12
Purchase | Foreign Exchange Contract |
Derivative [Line Items] |
Derivative monetary notional amount | € | € 355,662
Purchase | Foreign Exchange Contract | Minimum |
Derivative [Line Items] |
Derivative maturity period | 2020-12
Purchase | Foreign Exchange Contract | Maximum |
Derivative [Line Items] |
Derivative maturity period | 2021-01
Purchase | Electricity |
Derivative [Line Items] |
Derivative non-monetary notional amount | MWh | 525,980
Purchase | Electricity | Minimum |
Derivative [Line Items] |
Derivative maturity period | 2020-10
Purchase | Electricity | Maximum |
Derivative [Line Items] |
Derivative maturity period | 2022-12
Sales | Aluminum |
Derivative [Line Items] |
Derivative non-monetary notional amount | 1.0
Sales | Aluminum | Minimum |
Derivative [Line Items] |
Derivative maturity period | 2020-10
Sales | Aluminum | Maximum |
Derivative [Line Items] |
Derivative maturity period | 2021-11
Sales | Alloying Metals |
Derivative [Line Items] |
Derivative non-monetary notional amount | 5.0
Sales | Alloying Metals | Minimum |
Derivative [Line Items] |
Derivative maturity period | 2020-10
Sales | Alloying Metals | Maximum |
Derivative [Line Items] |
Derivative maturity period | 2021-12

X
- Definition Derivative maturity period. + References No definition available. + Details
Name: | kalu_DerivativeMaturityPeriod
Namespace Prefix: | kalu_
Data Type: | xbrli:gYearMonthItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DerivativeLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Nominal number of units used to calculate payment on derivative. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5580258-113959 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5579245-113959 + Details
Name: | us-gaap_DerivativeNonmonetaryNotionalAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition Nominal or face amount used to calculate payment on derivative. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5580258-113959 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5579245-113959 + Details
Name: | us-gaap_DerivativeNotionalAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_HedgingDesignationAxis=us-gaap_DesignatedAsHedgingInstrumentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PositionAxis=us-gaap_LongMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=kalu_AluminumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=kalu_MidwestPremiumSwapContractsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=kalu_AlloyMetalHedgeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=kalu_NaturalGasMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeContractMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=us-gaap_ElectricityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PositionAxis=us-gaap_ShortMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |