XML 74 R61.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Employee Benefits, Defined Contribution Plans Narrative (Details) | 12 Months Ended
--- | ---
Dec. 31, 2018 USD ($) productionfacilities
Defined Contribution Plan Disclosure [Line Items] |
Equity Securities, FV-NI, Unrealized Gain (Loss) | $ | $ (1,000,000.0)
Defined Contribution Plan | Hourly bargaining unit employees |
Defined Contribution Plan Disclosure [Line Items] |
Number of production facilities | 9
Defined Contribution Plan | Hourly bargaining unit employees | Fixed rate contributions |
Defined Contribution Plan Disclosure [Line Items] |
Number of production facilities | 3
Defined Contribution Plan | Hourly bargaining unit employees | Concurrent match |
Defined Contribution Plan Disclosure [Line Items] |
Number of production facilities | 1
Defined Contribution Plan | Hourly bargaining unit employees | Fixed rate and concurrent match |
Defined Contribution Plan Disclosure [Line Items] |
Number of production facilities | 3
Defined Contribution Plan | Hourly bargaining unit employees | No contributions required |
Defined Contribution Plan Disclosure [Line Items] |
Number of production facilities | 2
Defined Contribution Plan | Salaried and certain hourly employee | Concurrent match |
Defined Contribution Plan Disclosure [Line Items] |
Defined contribution plan employer concurrent match percentage | 4.00%
Defined Contribution Plan | Hired on or after January 1, 2004 | Hourly bargaining unit employees | Fixed rate contributions |
Defined Contribution Plan Disclosure [Line Items] |
Defined contribution plan annual employer contribution percentage | 2.00%
Defined Contribution Plan | Hired on or after January 1, 2004 | Salaried and certain hourly employee | Fixed rate contributions |
Defined Contribution Plan Disclosure [Line Items] |
Defined contribution plan annual employer contribution percentage | 2.00%
Defined Contribution Plan | Minimum | Hourly bargaining unit employees | Fixed rate contributions |
Defined Contribution Plan Disclosure [Line Items] |
Defined Contribution Plan, Employer Discretionary Contribution Amount | $ | $ 800
Defined Contribution Plan | Minimum | Hired prior to January 1, 2004 | Hourly bargaining unit employees | Fixed rate contributions |
Defined Contribution Plan Disclosure [Line Items] |
Defined contribution plan annual employer contribution percentage | 2.00%
Defined Contribution Plan | Minimum | Hired prior to January 1, 2004 | Salaried and certain hourly employee | Fixed rate contributions |
Defined Contribution Plan Disclosure [Line Items] |
Defined contribution plan annual employer contribution percentage | 2.00%
Defined Contribution Plan | Maximum | Hourly bargaining unit employees | Fixed rate contributions |
Defined Contribution Plan Disclosure [Line Items] |
Defined Contribution Plan, Employer Discretionary Contribution Amount | $ | $ 2,400
Defined Contribution Plan | Maximum | Salaried and certain hourly employee |
Defined Contribution Plan Disclosure [Line Items] |
Estimated annual contribution to pension and other postretirement benefit plans | $ | $ 2,900,000
Defined Contribution Plan | Maximum | Hired prior to January 1, 2004 | Hourly bargaining unit employees | Fixed rate contributions |
Defined Contribution Plan Disclosure [Line Items] |
Defined contribution plan annual employer contribution percentage | 10.00%
Defined Contribution Plan | Maximum | Hired prior to January 1, 2004 | Salaried and certain hourly employee | Fixed rate contributions |
Defined Contribution Plan Disclosure [Line Items] |
Defined contribution plan annual employer contribution percentage | 10.00%

X
- Definition Defined Contribution Plan Employer Contribution Percentage + References No definition available. + Details
Name: | kalu_DefinedContributionPlanEmployerContributionPercentage
Namespace Prefix: | kalu_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Estimated annual contribution to pension and other postretirement benefit plans. + References No definition available. + Details
Name: | kalu_EstimatedAnnualContributionToPensionAndOtherPostretirementBenefitPlans
Namespace Prefix: | kalu_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Number of Production Facilities. + References No definition available. + Details
Name: | kalu_NumberOfProductionFacilities
Namespace Prefix: | kalu_
Data Type: | xbrli:integerItemType
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_DefinedContributionPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of discretionary contributions made by an employer to a defined contribution plan. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of unrealized gain (loss) on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 321 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=84241550&loc=SL75117546-209714 + Details
Name: | us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | kalu_EmployeeAxis=kalu_HourlyBargainingUnitEmployeesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | kalu_TypesOfContributionsAxis=kalu_FixedRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | kalu_TypesOfContributionsAxis=kalu_ConcurrentMatchMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | kalu_TypesOfContributionsAxis=kalu_FixedRateAndConcurrentMatchMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | kalu_TypesOfContributionsAxis=kalu_NoContributionsRequiredMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | kalu_EmployeeAxis=kalu_SalariedAndCertainHourlyEmployeeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | kalu_DatePeriodAxis=kalu_HiredOnOrAfterJanuaryOneTwoThousandFourMember
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: | kalu_DatePeriodAxis=kalu_HiredPriorToJanuaryOneTwoThousandFourMember
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: |