XML 99 R86.htm IDEA: XBRL DOCUMENT
v3.22.0.1

Derivatives, Hedging Programs and Other Financial Instruments - Summary of Percentage of Expected Variable Priced Purchases of Metals Alloys and Energy (Details) - Scenario, Forecast | Dec. 31, 2026 | Dec. 31, 2025 | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
--- | --- | --- | --- | --- | ---
Zinc |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage |  |  |  |  | 61.00%
Copper |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage |  |  |  |  | 64.00%
Magnesium |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage |  |  |  |  | 100.00%
Silicon |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage |  |  |  |  | 100.00%
Natural Gas |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage | 20.00% | 25.00% | 45.00% | 47.00% | 48.00%
Electricity |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage |  |  |  | 43.00% | 74.00%

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 The percentage of expected requirements covered by the aggregate notional amount of derivative contracts expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract as a percentage of expected need. + References No definition available. + Details
Name: | us-gaap_DerivativeNonmonetaryNotionalAmountPercentOfRequiredNeedCoverage
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

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

X
- Details
Name: | srt_StatementScenarioAxis=srt_ScenarioForecastMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

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