XML 77 R66.htm IDEA: XBRL DOCUMENT
v3.21.1

Commitments and Contingencies - Additional Information (Details) | 3 Months Ended
--- | ---
Mar. 31, 2021 USD ($)
Environmental Contingency |
Environmental accrual | $ 18,000,000.0
Expected period related to remediation expenditures for environmental contingencies period | 30 years
Potential increase in environmental costs | $ 11,600,000
Time period within which recorded estimate of its obligation may change | 12 months
Liability for conditional asset retirement obligations | $ 0
Minimum |
Environmental Contingency |
Period for final feasibility study | 7 months
Maximum |
Environmental Contingency |
Period for final feasibility study | 13 months

X
- Definition ExpectedPeriodRelatedToRemediationExpendituresForEnvironmentalContingencies + References No definition available. + Details
Name: | kalu_ExpectedPeriodRelatedToRemediationExpendituresForEnvironmentalContingenciesPeriod
Namespace Prefix: | kalu_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Period For Final Feasibility Study + References No definition available. + Details
Name: | kalu_PeriodForFinalFeasibilityStudy
Namespace Prefix: | kalu_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Time period within which recorded estimate of its obligation may change. + References No definition available. + Details
Name: | kalu_TimePeriodWithinWhichRecordedEstimateOfItsObligationMayChange
Namespace Prefix: | kalu_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Total costs accrued as of the balance sheet date for environmental loss contingencies. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 25 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6395460&loc=d3e13647-108346 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 30 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859 + Details
Name: | us-gaap_AccrualForEnvironmentalLossContingencies
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
Name: | us-gaap_AssetRetirementObligation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The difference between the maximum amount of estimated loss and the amount recorded as of the balance sheet date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 05 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=99385795&loc=d3e12631-108344 + Details
Name: | us-gaap_LossContingencyRangeOfPossibleLossPortionNotAccrued
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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_SiteContingencyLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
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: |