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Derivative Financial Instruments and Related Hedging Programs, Hedging Discussion (Details) (USD $) In Millions, unless otherwise specified | 3 Months Ended |
--- | --- | ---
Mar. 31, 2015 mmlbs | Mar. 31, 2014 mmlbs | Dec. 31, 2014
Derivative Financial Instruments and Related Hedging Programs (Textuals) [Abstract] |  |  |
Aggregate fair value of derivative instruments that contain credit-risk-related contingency features that were in a net liability position | $ 13.7 us-gaap_DerivativeNetLiabilityPositionAggregateFairValue |  | $ 11.4 us-gaap_DerivativeNetLiabilityPositionAggregateFairValue
Total fabricated products shipments containing fixed price terms | 41.1 kalu_FabricatedProductsShipmentsContainingFixedPriceTerms | 34.4 kalu_FabricatedProductsShipmentsContainingFixedPriceTerms |
Remainder of 2015 |  |  |
Derivative [Line Items] |  |  |
Percentage of Electricity Purchases For Which Company Exposure To Fluctuations In Electricity Prices Have Been Reduced | 55.00%kalu_PercentageofElectricityPurchasesForWhichCompanyExposureToFluctuationsInElectricityPricesHaveBeenReduced / kalu_DatePeriodAxis = kalu_RemainderOfCurrentYearMember |  |
Derivative Financial Instruments and Related Hedging Programs (Textuals) [Abstract] |  |  |
Firm price customer sales contracts containing price risk on anticipated purchases of primary aluminum | 96.3 kalu_FirmPriceCustomerSalesContractsContainingPriceRiskOnAnticipatedPurchasesOfPrimaryAluminum / kalu_DatePeriodAxis = kalu_RemainderOfCurrentYearMember |  |
2016 |  |  |
Derivative [Line Items] |  |  |
Percentage of Electricity Purchases For Which Company Exposure To Fluctuations In Electricity Prices Have Been Reduced | 54.00%kalu_PercentageofElectricityPurchasesForWhichCompanyExposureToFluctuationsInElectricityPricesHaveBeenReduced / kalu_DatePeriodAxis = kalu_YearOneMember |  |
Derivative Financial Instruments and Related Hedging Programs (Textuals) [Abstract] |  |  |
Firm price customer sales contracts containing price risk on anticipated purchases of primary aluminum | 1.9 kalu_FirmPriceCustomerSalesContractsContainingPriceRiskOnAnticipatedPurchasesOfPrimaryAluminum / kalu_DatePeriodAxis = kalu_YearOneMember |  |
2017 |  |  |
Derivative [Line Items] |  |  |
Percentage of Electricity Purchases For Which Company Exposure To Fluctuations In Electricity Prices Have Been Reduced | 27.00%kalu_PercentageofElectricityPurchasesForWhichCompanyExposureToFluctuationsInElectricityPricesHaveBeenReduced / kalu_DatePeriodAxis = kalu_YearTwoMember |  |

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- Definition Firm price customer sales contracts containing price risk on anticipated purchases of primary aluminum. + References No definition available. + Details
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- Definition Percentage of Electricity Purchases For Which The Company's Exposure To Fluctuations In Electricity Prices Have Been Reduced + References No definition available. + Details
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- Definition The aggregate fair value amounts of derivative instruments that contain credit-risk-related contingent features that are in a net liability position at the end of the reporting period. For nonderivative instruments that are designated and qualify as hedging instruments, the fair value amounts are the carrying value of the nonderivative hedging instrument, including the adjustment for the foreign currency transaction gain (loss) on that instrument. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4H -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624258-113959 + Details
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