v2.3.0.15

Employee Benefits, Net Periodic Benefit Costs Segment Allocation (Details) (USD $) In Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2011 | Sep. 30, 2010 | Sep. 30, 2011 | Sep. 30, 2010
Allocation of Defined Benefit Plan Net Periodic Benefit Cost And Charges Relating To Other Benefit Plans, by Segment |  |  |  |
Defined benefit plan net periodic benefit (income ) cost and (benefits) charges relating to other benefit plans | $ (0.4) | $ 2.4 | $ 1.6 | $ 10.0
Fabricated Products [Member] |  |  |  |
Allocation of Defined Benefit Plan Net Periodic Benefit Cost And Charges Relating To Other Benefit Plans, by Segment |  |  |  |
Defined benefit plan net periodic benefit (income ) cost and (benefits) charges relating to other benefit plans | 1.7 | 1.8 | 7.4 | 7.0
All Other [Member] |  |  |  |
Allocation of Defined Benefit Plan Net Periodic Benefit Cost And Charges Relating To Other Benefit Plans, by Segment |  |  |  |
Defined benefit plan net periodic benefit (income ) cost and (benefits) charges relating to other benefit plans | $ (2.1) | $ 0.6 | $ (5.8) | $ 3.0

X
- Definition Allocation of Defined Benefit Plan Net Periodic Benefit Cost And Charges Relating To Other Benefit Plans, by Segment. + Details
Name: | kalu_AllocationOfDefinedBenefitPlanNetPeriodicBenefitCostAndChargesRelatingToOtherBenefitPlansBySegmentAbstract
Namespace Prefix: | kalu
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Defined benefit plan net periodic benefit cost and charges relating to other benefit plans. + Details
Name: | kalu_DefinedBenefitPlanNetPeriodicBenefitCostAndChargesRelatingToOtherBenefitPlans
Namespace Prefix: | kalu
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration