XML 62 R52.htm IDEA: XBRL DOCUMENT
v3.25.3

Derivatives, Hedging Programs and Other Financial Instruments - Summary of (Gain) Loss Associated with Derivative Contracts (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024
Derivative Instruments Gain Loss [Line Items] |  |  |  |  |  |  |
Total of income and expense line items presented in our Statements of Consolidated Income in which the effects of cash flow hedges are recorded |  | $ 728.8 | $ 676.0 | [1] | $ 2,125.0 | $ 1,997.1 | [1]
Loss (gain) recognized in our Statements of Consolidated Income - Unrealized mark-to-market (gain) loss | [2],[3] |  |  |  |  | 2.2 |
Not Designated as Hedging Instrument |  |  |  |  |  |  |
Derivative Instruments Gain Loss [Line Items] |  |  |  |  |  |  |
Loss (gain) recognized in our Statements of Consolidated Income | [4] |  | 2.0 |  |  | 4.2 |
Not Designated as Hedging Instrument | Electricity |  |  |  |  |  |  |
Derivative Instruments Gain Loss [Line Items] |  |  |  |  |  |  |
Loss (gain) recognized in our Statements of Consolidated Income | [4] |  | 2.0 |  |  | 2.0 |
Loss (gain) recognized in our Statements of Consolidated Income - Unrealized mark-to-market (gain) loss | [4] |  |  |  |  | 2.0 |
Reclassification from AOCI due to forecasted transactions probable of not occurring | [4] |  |  |  |  | 0.2 |
Cash Flow Hedges |  |  |  |  |  |  |
Derivative Instruments Gain Loss [Line Items] |  |  |  |  |  |  |
Total of income and expense line items presented in our Statements of Consolidated Income in which the effects of cash flow hedges are recorded |  | 728.8 | 676.0 | [4] | 2,125.0 | 1,997.1 | [4]
Cash Flow Hedges | Designated as Hedging Instrument |  |  |  |  |  |  |
Derivative Instruments Gain Loss [Line Items] |  |  |  |  |  |  |
Loss (gain) recognized in our Statements of Consolidated Income |  | $ (10.0) | $ 1.5 | [4] | $ (18.0) | $ 1.6 | [4]
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] |  | Total of income and expense line items presented in our Statements of Consolidated Income in which the effects of cash flow hedges are recorded | Total of income and expense line items presented in our Statements of Consolidated Income in which the effects of cash flow hedges are recorded |  | Total of income and expense line items presented in our Statements of Consolidated Income in which the effects of cash flow hedges are recorded | Total of income and expense line items presented in our Statements of Consolidated Income in which the effects of cash flow hedges are recorded |
Cash Flow Hedges | Designated as Hedging Instrument | Aluminum |  |  |  |  |  |  |
Derivative Instruments Gain Loss [Line Items] |  |  |  |  |  |  |
Loss (gain) recognized in our Statements of Consolidated Income |  | $ (9.7) | $ 1.6 | [4] | $ (17.1) | $ 0.9 | [4]
Cash Flow Hedges | Designated as Hedging Instrument | Alloying Metals |  |  |  |  |  |  |
Derivative Instruments Gain Loss [Line Items] |  |  |  |  |  |  |
Loss (gain) recognized in our Statements of Consolidated Income |  | (0.5) | (0.3) | [4] | (1.4) | (0.8) | [4]
Cash Flow Hedges | Designated as Hedging Instrument | Foreign exchange contracts |  |  |  |  |  |  |
Derivative Instruments Gain Loss [Line Items] |  |  |  |  |  |  |
Loss (gain) recognized in our Statements of Consolidated Income |  | (0.2) | (0.1) | [4] | (0.2) | (0.1) | [4]
Cash Flow Hedges | Designated as Hedging Instrument | Natural Gas |  |  |  |  |  |  |
Derivative Instruments Gain Loss [Line Items] |  |  |  |  |  |  |
Loss (gain) recognized in our Statements of Consolidated Income |  | $ 0.4 | $ 0.3 | [4] | $ 0.7 | 1.0 | [4]
Cash Flow Hedges | Designated as Hedging Instrument | Electricity |  |  |  |  |  |  |
Derivative Instruments Gain Loss [Line Items] |  |  |  |  |  |  |
Loss (gain) recognized in our Statements of Consolidated Income | [4] |  |  |  |  | $ 0.6 |
[1] | Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 14 for further discussion.
[2] | Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 14 for further discussion.
[3] | See Note 12 for supplemental cash flow information.
[4] | Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 14 for further discussion.

X
- Definition The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4A -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4A Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 220 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 11 -Publisher FASB -URI https://asc.fasb.org/1943274/2147476153/220-40-55-11 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Topic 220 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org/1943274/2147476153/220-40-55-4 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(2)(d)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(2)(a)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 924 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 11.L) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479941/924-10-S99-1 Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 220 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147476148/220-40-50-6 + Details
Name: | us-gaap_CostOfGoodsAndServicesSold
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of increase (decrease) in the fair value of derivatives recognized in the income statement. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4A -Subparagraph (b)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4A Reference 2: http://www.xbrl.org/2003/role/exampleRef -Name Accounting Standards Codification -Section 55 -Paragraph 10 -SubTopic 10 -Topic 825 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482881/825-10-55-10 + Details
Name: | us-gaap_DerivativeGainLossOnDerivativeNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Indicates line item in statement of income or comprehensive income that includes gain (loss) from derivative. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4A -Subparagraph (b)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4A + Details
Name: | us-gaap_DerivativeGainLossStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration
Namespace Prefix: | us-gaap_
Data Type: | enum2:enumerationSetItemType
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 Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4C -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4C Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 182 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480401/815-10-55-182 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4D -Subparagraph (a)(5) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4D Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4D -Subparagraph (a)(4) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4D Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4D -Subparagraph (a)(3) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4D Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4D -Subparagraph (a)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4D Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4A -Subparagraph (b)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4A Reference 8: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4D -Subparagraph (a)(6) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4D Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4D -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4D Reference 10: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4A -Subparagraph (b)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4A Reference 11: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4C -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4C Reference 12: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4CCC -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4CCC Reference 13: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4CCC -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4CCC Reference 14: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4CCC -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4CCC Reference 15: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4CC -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4CC Reference 16: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4C -Subparagraph (g) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4C Reference 17: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4C -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4C Reference 18: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4C -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4C Reference 19: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4C -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4C Reference 20: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4C -Subparagraph (bb) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4C Reference 21: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4D -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4D Reference 22: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4E -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4E + Details
Name: | us-gaap_DerivativeInstrumentsGainLossLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of loss reclassified into earnings in the period when cash flow hedge is discontinued because it is probable that the original forecasted transactions will not occur by the end of the original period or an additional two month time period. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4C -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4C + Details
Name: | us-gaap_LossOnDiscontinuationOfCashFlowHedgeDueToForecastedTransactionProbableOfNotOccurring
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 28 -Subparagraph (b) -SubTopic 10 -Topic 230 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482740/230-10-45-28 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-07(7)(c)(3)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-07(7)(c)(5)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-07(7)(c)(6)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-07(7)(c)(7)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 320 -Name Accounting Standards Codification -Section S99 -Paragraph 5A -Subparagraph (SX 210.12-13A(Column F)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147477271/946-320-S99-5A + Details
Name: | us-gaap_UnrealizedGainLossOnDerivatives
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_HedgingDesignationAxis=us-gaap_NondesignatedMember
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: |

X
- Details
Name: | us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=us-gaap_CashFlowHedgingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_HedgingDesignationAxis=us-gaap_DesignatedAsHedgingInstrumentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

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

X
- Details
Name: | srt_ReserveQuantitiesByTypeOfReserveAxis=srt_NaturalGasReservesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |