XML 89 R77.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Multiemployer Pension Plans - Multiemployer Pension Plan Description and Contributions (Parenthetical) (Details) | 6 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2024 Agreement $ / shares | Jun. 30, 2024 $ / shares | Dec. 31, 2024 Agreement $ / shares
Multiemployer Pension Plan Disclosure [Line Items] |  |  |
Green zone funding percentage |  |  | 80.00%
USW Plan |  |  |
Multiemployer Pension Plan Disclosure [Line Items] |  |  |
Number of collective-bargaining agreements | Agreement | 3 |  | 3
USW Plan | Newark and Trentwood Facilities |  |  |
Multiemployer Pension Plan Disclosure [Line Items] |  |  |
Percentage of employees covered by bargaining agreement |  |  | 87.00%
USW Plan | Newark and Trentwood Facilities | Starting in July Two Thousand Twenty |  |  |
Multiemployer Pension Plan Disclosure [Line Items] |  |  |
Monthly contributions per hour worked by each bargaining unit employee | $ 2.06 | $ 1.75 |
USW Plan | Richmond (Bellwood), Virginia Facility |  |  |
Multiemployer Pension Plan Disclosure [Line Items] |  |  |
Percentage of employees covered by bargaining agreement |  |  | 10.00%
Monthly contributions per hour worked by each bargaining unit employee |  |  | $ 1.50
USW Plan | Florence, Alabama Facility |  |  |
Multiemployer Pension Plan Disclosure [Line Items] |  |  |
Percentage of employees covered by bargaining agreement |  |  | 3.00%
Monthly contributions per hour worked by each bargaining unit employee |  |  | $ 1.35

X
- Definition Green zone funding percentage minimum. + References No definition available. + Details
Name: | kalu_GreenZoneFundingPercentageMinimum
Namespace Prefix: | kalu_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Monthly contributions per hour worked by each bargaining unit employee. + References No definition available. + Details
Name: | kalu_MonthlyContributionsPerHourWorkedByEachBargainingUnitEmployee
Namespace Prefix: | kalu_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Multiemployer Pension Plan Disclosure [Line Items] + References No definition available. + Details
Name: | kalu_MultiemployerPensionPlanDisclosureLineItems
Namespace Prefix: | kalu_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of collective-bargaining agreements + References No definition available. + Details
Name: | kalu_NumberOfCollectiveBargainingAgreements
Namespace Prefix: | kalu_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Percentage of entity's employees covered by collective-bargaining arrangement (CBA) to all entity's employees in multiemployer pension plan determined to be individually significant. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 80 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480576/715-80-50-5 + Details
Name: | us-gaap_MultiemployerPlanPensionSignificantEmployeesCoveredByCollectiveBargainingArrangementToAllEntitysEmployeesPercentage
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_RetirementPlanNameAxis=kalu_UswaPlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | kalu_ProductionFacilitiesAxis=kalu_NewarkOhioAndSpokaneWashingtonFacilitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | kalu_DatePeriodAxis=kalu_StartingInJulyTwoThousandTwentyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | kalu_ProductionFacilitiesAxis=kalu_BellwoodVirginiaFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | kalu_ProductionFacilitiesAxis=kalu_FlorenceAlabamaFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |