$KALU
KAISER ALUMINUM CORP Stock $kalu

$kalu Overview Financials Valuation SEC Filings Company Website

2018 Q4 Form 10-K Financial Statement

#000081159619000009 Filed on February 22, 2019

Income Statement

Concept	2018 Q4	2018 Q1	2018
Revenue	$389.4M	$388.0M	$1.586B
YoY Change	10.28%	9.2%	13.48%
Cost Of Revenue	$317.3M	$316.7M	$1.301B
YoY Change	14.47%	20.56%	19.78%
Gross Profit	$72.10M	$71.30M	$285.2M
YoY Change	-5.01%	-23.0%	-8.47%
Gross Profit Margin	18.52%	18.38%	17.98%
Selling, General & Admin	$22.40M	$23.60M	$86.50M
YoY Change	-1.75%	-0.42%	-1.14%
% of Gross Profit	31.07%	33.1%	30.33%
Research & Development			$9.800M
YoY Change			-2.0%
% of Gross Profit			3.44%
Depreciation & Amortization	$11.50M	$10.50M	$43.90M
YoY Change	10.58%	9.38%	10.58%
% of Gross Profit	15.95%	14.73%	15.39%
Operating Expenses	$35.20M	$34.20M	$9.800M
YoY Change	15.03%	2.7%	-2.0%
Operating Profit	$36.90M	$37.10M	$143.6M
YoY Change	-11.93%	-37.44%	-7.47%
Interest Expense	-$4.000M	$5.600M	-$16.30M
YoY Change	-78.26%	0.0%	-173.42%
% of Operating Profit	-10.84%	15.09%	-11.35%
Other Income/Expense, Net	-$2.900M	$100.0K	-$900.0K
YoY Change	-35.56%	-87.5%
Pretax Income	$30.00M	$31.60M	$114.6M
YoY Change	-15.73%	-42.02%	-10.4%
Income Tax	$6.300M	$5.900M	$28.30M
% Of Pretax Income	21.0%	18.67%	24.69%
Net Earnings	$23.60M	$25.70M	$91.70M
YoY Change	-255.26%	-28.61%	101.98%
Net Earnings / Revenue	6.06%	6.62%	5.78%
Basic Earnings Per Share	$1.44	$1.54	$5.53
Diluted Earnings Per Share	$1.41	$1.51	$5.43
COMMON SHARES
Basic Shares Outstanding	16.50M shares	16.71M shares	16.59M
Diluted Shares Outstanding		17.03M shares	16.87M

Balance Sheet

Concept	2018 Q4	2018 Q1	2018
SHORT-TERM ASSETS
Cash & Short-Term Investments	$162.3M	$218.8M	$162.3M
YoY Change	-30.88%	-4.83%	-30.88%
Cash & Equivalents	$125.6M	$135.0M
Short-Term Investments	$36.70M	$201.5M	$139.4M
Other Short-Term Assets	$18.90M	$25.70M	$18.90M
YoY Change	-43.41%	-24.41%	-43.41%
Inventory	$215.1M	$167.2M	$215.1M
Prepaid Expenses
Receivables	$179.8M	$185.3M	$234.7M
Other Receivables	$25.60M	$18.20M	$25.60M
Total Short-Term Assets	$656.6M	$671.5M	$656.6M
YoY Change	0.0%	5.55%	0.0%
LONG-TERM ASSETS
Property, Plant & Equipment	$611.8M	$578.7M	$610.2M
YoY Change	7.07%	8.01%	7.15%
Goodwill	$44.00M	$18.80M
YoY Change	134.04%	-49.46%
Intangibles
YoY Change
Long-Term Investments
YoY Change
Other Assets	$38.60M	$37.30M	$76.10M
YoY Change	-6.76%	0.54%	-34.0%
Total Long-Term Assets	$762.7M	$725.3M	$762.7M
YoY Change	4.68%	-6.64%	4.68%
TOTAL ASSETS
Total Short-Term Assets	$656.6M	$671.5M	$656.6M
Total Long-Term Assets	$762.7M	$725.3M	$762.7M
Total Assets	$1.419B	$1.397B	$1.419B
YoY Change	2.46%	-1.15%	2.46%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$121.4M	$120.2M	$121.4M
YoY Change	34.89%	42.42%	34.89%
Accrued Expenses	$77.60M	$53.50M	$77.60M
YoY Change	1.7%	-10.83%	1.7%
Deferred Revenue
YoY Change
Short-Term Debt	$0.00	$0.00	$0.00
YoY Change
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$205.5M	$174.6M	$205.5M
YoY Change	18.72%	13.45%	18.72%
LONG-TERM LIABILITIES
Long-Term Debt	$370.4M	$369.8M	$370.4M
YoY Change	0.22%	0.24%	0.22%
Other Long-Term Liabilities	$66.40M	$23.40M	$98.80M
YoY Change	10.67%	18.18%	7.51%
Total Long-Term Liabilities	$436.8M	$393.2M	$469.2M
YoY Change	1.68%	1.16%	1.67%
TOTAL LIABILITIES
Total Short-Term Liabilities	$205.5M	$174.6M	$205.5M
Total Long-Term Liabilities	$436.8M	$393.2M	$469.2M
Total Liabilities	$678.9M	$640.4M	$678.9M
YoY Change	6.26%	4.21%	6.26%
SHAREHOLDERS EQUITY
Retained Earnings	$150.2M	$95.60M
YoY Change	75.67%	-6.18%
Common Stock	$1.060B	$1.052B
YoY Change	0.32%	0.55%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$420.5M	$364.7M
YoY Change	17.26%	16.11%
Treasury Stock Shares	6.237M shares	5.678M shares
Shareholders Equity	$740.4M	$753.6M	$740.4M
YoY Change
Total Liabilities & Shareholders Equity	$1.419B	$1.397B	$1.419B
YoY Change	2.46%	-1.15%	2.46%

Cashflow Statement

Concept	2018 Q4	2018 Q1	2018
OPERATING ACTIVITIES
Net Income	$23.60M	$25.70M	$91.70M
YoY Change	-255.26%	-28.61%	101.98%
Depreciation, Depletion And Amortization	$11.50M	$10.50M	$43.90M
YoY Change	10.58%	9.38%	10.58%
Cash From Operating Activities	$37.70M	$26.10M	$150.2M
YoY Change	277.0%	536.59%	6.15%
INVESTING ACTIVITIES
Capital Expenditures	-$20.90M	-$19.70M	-$117.3M
YoY Change	7.73%	33.11%	55.36%
Acquisitions			$43.20M
YoY Change
Other Investing Activities	$51.90M	$100.3M	$148.4M
YoY Change	532.93%	177.07%	196.8%
Cash From Investing Activities	$31.00M	$80.60M	$31.10M
YoY Change	-376.79%	276.64%	-221.96%
FINANCING ACTIVITIES
Cash Dividend Paid		$10.00M	$37.70M
YoY Change		7.53%
Common Stock Issuance & Retirement, Net		$5.700M	$60.70M
YoY Change		-82.52%	-23.65%
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	-38.20M	-$22.80M	-106.0M
YoY Change	76.85%	-50.97%	-11.22%
NET CHANGE
Cash From Operating Activities	37.70M	$26.10M	150.2M
Cash From Investing Activities	31.00M	$80.60M	31.10M
Cash From Financing Activities	-38.20M	-$22.80M	-106.0M
Net Change In Cash	30.50M	$83.90M	75.30M
YoY Change	-233.77%	-499.52%	-2314.71%
FREE CASH FLOW
Cash From Operating Activities	$37.70M	$26.10M	$150.2M
Capital Expenditures	-$20.90M	-$19.70M	-$117.3M
Free Cash Flow	$58.60M	$45.80M	$267.5M
YoY Change	99.32%	142.33%	23.27%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2018	dei	Amendment Flag AmendmentFlag	false
CY2018	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2018	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2018	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2018
CY2018	dei	Document Period End Date DocumentPeriodEndDate	2018-12-31
CY2018	dei	Document Type DocumentType	10-K
CY2018	dei	Entity Central Index Key EntityCentralIndexKey	0000811596
CY2019Q1	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	16093993	shares
CY2018	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2018	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
CY2018	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2018Q2	dei	Entity Public Float EntityPublicFloat	1700000000	USD
CY2018	dei	Entity Registrant Name EntityRegistrantName	Kaiser Aluminum Corp
CY2018	dei	Entity Shell Company EntityShellCompany	false
CY2018	dei	Entity Small Business EntitySmallBusiness	false
CY2018	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2018	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
CY2017Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.01
CY2018Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.01
CY2017Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	90000000	shares
CY2018Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	90000000	shares
CY2017Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	22393537	shares
CY2018Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	22471705	shares
CY2017Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	16773586	shares
CY2018Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	16234603	shares
CY2017Q4	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	5000000	shares
CY2018Q4	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	5000000	shares
CY2017Q4	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2018Q4	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2017Q4	us-gaap	Preferred Stock Shares Outstanding PreferredStockSharesOutstanding	0	shares
CY2018Q4	us-gaap	Preferred Stock Shares Outstanding PreferredStockSharesOutstanding	0	shares
CY2017Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	5619951	shares
CY2018Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	6237102	shares
CY2017	us-gaap	Weighted Average Discount Rate Percent WeightedAverageDiscountRatePercent	0.087
CY2018Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	125600000	USD
CY2017Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	51100000	USD
CY2018Q4	us-gaap	Available For Sale Securities Current AvailableForSaleSecuritiesCurrent	36700000	USD
CY2017Q4	us-gaap	Available For Sale Securities Current AvailableForSaleSecuritiesCurrent	183700000	USD
CY2018Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	179800000	USD
CY2017Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	165000000.0	USD
CY2018Q4	us-gaap	Other Receivables OtherReceivables	25600000	USD
CY2017Q4	us-gaap	Other Receivables OtherReceivables	15500000	USD
CY2018Q4	us-gaap	Contract With Customer Asset Net Current ContractWithCustomerAssetNetCurrent	54900000	USD
CY2017Q4	us-gaap	Contract With Customer Asset Net Current ContractWithCustomerAssetNetCurrent	0	USD
CY2018Q4	us-gaap	Inventory Net InventoryNet	215100000	USD
CY2017Q4	us-gaap	Inventory Net InventoryNet	207900000	USD
CY2018Q4	us-gaap	Prepaid Expense And Other Assets Current PrepaidExpenseAndOtherAssetsCurrent	18900000	USD
CY2017Q4	us-gaap	Prepaid Expense And Other Assets Current PrepaidExpenseAndOtherAssetsCurrent	33400000	USD
CY2018Q4	us-gaap	Assets Current AssetsCurrent	656600000	USD
CY2017Q4	us-gaap	Assets Current AssetsCurrent	656600000	USD
CY2018Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	611800000	USD
CY2017Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	571400000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Net Noncurrent DeferredTaxAssetsNetNoncurrent	35900000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Net Noncurrent DeferredTaxAssetsNetNoncurrent	72000000.0	USD
CY2018Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	32400000	USD
CY2017Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	25000000.0	USD
CY2018Q4	us-gaap	Goodwill Goodwill	44000000.0	USD
CY2017Q4	us-gaap	Goodwill Goodwill	18800000	USD
CY2018Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	38600000	USD
CY2017Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	41400000	USD
CY2018Q4	us-gaap	Assets Assets	1419300000	USD
CY2017Q4	us-gaap	Assets Assets	1385200000	USD
CY2018Q4	us-gaap	Accounts Payable Current AccountsPayableCurrent	121400000	USD
CY2016	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	1000800000	USD
CY2017Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
CY2018Q4	us-gaap	Preferred Stock Value PreferredStockValue	0	USD
CY2017Q4	us-gaap	Preferred Stock Value PreferredStockValue	0	USD
CY2018Q4	us-gaap	Common Stock Value CommonStockValue	200000	USD
CY2017Q4	us-gaap	Common Stock Value CommonStockValue	200000	USD
CY2018Q4	us-gaap	Additional Paid In Capital Common Stock AdditionalPaidInCapitalCommonStock	1059300000	USD
CY2017Q4	us-gaap	Accounts Payable Current AccountsPayableCurrent	90000000.0	USD
CY2018Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	40100000	USD
CY2017Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	42600000	USD
CY2018Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	44000000.0	USD
CY2017Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	40500000	USD
CY2018Q4	us-gaap	Liabilities Current LiabilitiesCurrent	205500000	USD
CY2017Q4	us-gaap	Liabilities Current LiabilitiesCurrent	173100000	USD
CY2018Q4	kalu	Net Liability In Respect Of Veba NetLiabilityInRespectOfVeba	32400000	USD
CY2017Q4	kalu	Net Liability In Respect Of Veba NetLiabilityInRespectOfVeba	31900000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Gross Noncurrent DeferredTaxLiabilitiesGrossNoncurrent	4200000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Gross Noncurrent DeferredTaxLiabilitiesGrossNoncurrent	4300000	USD
CY2018Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	66400000	USD
CY2017Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	60000000.0	USD
CY2018Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	370400000	USD
CY2017Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	369600000	USD
CY2018Q4	us-gaap	Liabilities Liabilities	678900000	USD
CY2017Q4	us-gaap	Liabilities Liabilities	638900000	USD
CY2018Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
CY2017Q4	us-gaap	Additional Paid In Capital Common Stock AdditionalPaidInCapitalCommonStock	1055900000	USD
CY2018Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	150200000	USD
CY2017Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	85500000	USD
CY2018Q4	us-gaap	Treasury Stock Value TreasuryStockValue	420500000	USD
CY2017Q4	us-gaap	Treasury Stock Value TreasuryStockValue	358600000	USD
CY2018Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-48800000	USD
CY2017Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-36700000	USD
CY2018Q4	us-gaap	Stockholders Equity StockholdersEquity	740400000	USD
CY2017Q4	us-gaap	Stockholders Equity StockholdersEquity	746300000	USD
CY2018Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	1419300000	USD
CY2017Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	1385200000	USD
CY2018	us-gaap	Revenues Revenues	1585900000	USD
CY2017	us-gaap	Revenues Revenues	1397500000	USD
CY2016	us-gaap	Revenues Revenues	1330600000	USD
CY2018	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	1300700000	USD
CY2017	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	1085900000	USD
CY2017	us-gaap	Operating Income Loss OperatingIncomeLoss	155200000	USD
CY2016	us-gaap	Operating Income Loss OperatingIncomeLoss	181100000	USD
CY2018	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	-22700000	USD
CY2017	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	-22200000	USD
CY2018	us-gaap	Inventory Write Down InventoryWriteDown	0	USD
CY2017	us-gaap	Inventory Write Down InventoryWriteDown	0	USD
CY2016	us-gaap	Inventory Write Down InventoryWriteDown	4900000	USD
CY2018	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	43900000	USD
CY2017	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	39700000	USD
CY2016	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	36000000.0	USD
CY2018	kalu	Selling Administrative Research And Development And General Expenses SellingAdministrativeResearchAndDevelopmentAndGeneralExpenses	96300000	USD
CY2017	kalu	Selling Administrative Research And Development And General Expenses SellingAdministrativeResearchAndDevelopmentAndGeneralExpenses	97500000	USD
CY2016	kalu	Selling Administrative Research And Development And General Expenses SellingAdministrativeResearchAndDevelopmentAndGeneralExpenses	105000000.0	USD
CY2018	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	0	USD
CY2017	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	18400000	USD
CY2016	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	0	USD
CY2018	us-gaap	Other Operating Income Expense Net OtherOperatingIncomeExpenseNet	-1400000	USD
CY2017	us-gaap	Other Operating Income Expense Net OtherOperatingIncomeExpenseNet	-800000	USD
CY2016	us-gaap	Other Operating Income Expense Net OtherOperatingIncomeExpenseNet	-2800000	USD
CY2018	us-gaap	Costs And Expenses CostsAndExpenses	1442300000	USD
CY2017	us-gaap	Costs And Expenses CostsAndExpenses	1242300000	USD
CY2016	us-gaap	Costs And Expenses CostsAndExpenses	1149500000	USD
CY2018	us-gaap	Operating Income Loss OperatingIncomeLoss	143600000	USD
CY2016	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	-20300000	USD
CY2018	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	-900000	USD
CY2017	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	0	USD
CY2016	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	-13600000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	120000000.0	USD
CY2017	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	133000000.0	USD
CY2016	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	147200000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	28300000	USD
CY2017	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	87600000	USD
CY2016	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	55500000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	91700000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	45400000	USD
CY2016	us-gaap	Net Income Loss NetIncomeLoss	91700000	USD
CY2018	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	5.53
CY2017	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.67
CY2016	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	5.15
CY2018	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	5.43
CY2017	us-gaap	Stock Issued During Period Value Issued For Services StockIssuedDuringPeriodValueIssuedForServices	200000	USD
CY2016	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	900000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Net Of Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax	-13900000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Net Of Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax	700000	USD
CY2016	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Net Of Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax	0	USD
CY2018	kalu	Other Comprehensive Income Loss Other OtherComprehensiveIncomeLossOther	-100000	USD
CY2017	kalu	Other Comprehensive Income Loss Other OtherComprehensiveIncomeLossOther	200000	USD
CY2016	kalu	Other Comprehensive Income Loss Other OtherComprehensiveIncomeLossOther	-100000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-11700000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	0	USD
CY2016	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-5000000.0	USD
CY2018	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	80000000.0	USD
CY2017	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	45400000	USD
CY2016	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	86700000	USD
CY2017	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.63
CY2016	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	5.09
CY2018	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	16585000	shares
CY2017	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	16996000	shares
CY2016	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	17813000	shares
CY2018	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	16874000	shares
CY2017	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	17259000	shares
CY2016	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	18033000	shares
CY2018	us-gaap	Net Income Loss NetIncomeLoss	91700000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	45400000	USD
CY2016	us-gaap	Net Income Loss NetIncomeLoss	91700000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-2900000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	1400000	USD
CY2016	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	5800000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	-600000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	500000	USD
CY2016Q1	us-gaap	Cumulative Effect Of New Accounting Principle In Period Of Adoption CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	700000	USD
CY2016	us-gaap	Net Income Loss NetIncomeLoss	91700000	USD
CY2016	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-5000000.0	USD
CY2016	us-gaap	Stock Issued During Period Value Issued For Services StockIssuedDuringPeriodValueIssuedForServices	100000	USD
CY2016	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	1200000	USD
CY2016	us-gaap	Stock Repurchased And Retired During Period Value StockRepurchasedAndRetiredDuringPeriodValue	2900000	USD
CY2016	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	34900000	USD
CY2016	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	32400000	USD
CY2016	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	11700000	USD
CY2016	us-gaap	Restricted Stock Award Forfeitures Dividends RestrictedStockAwardForfeituresDividends	100000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	45400000	USD
CY2017	us-gaap	Stock Repurchased And Retired During Period Value StockRepurchasedAndRetiredDuringPeriodValue	4500000	USD
CY2017Q4	us-gaap	Cumulative Effect Of New Accounting Principle In Period Of Adoption CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	300000	USD
CY2017	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	77800000	USD
CY2017	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	35000000.0	USD
CY2017	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	13000000.0	USD
CY2017Q4	us-gaap	Stockholders Equity StockholdersEquity	746300000	USD
CY2018Q1	us-gaap	Cumulative Effect Of New Accounting Principle In Period Of Adoption CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	10300000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	91700000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-11700000	USD
CY2018	us-gaap	Stock Issued During Period Value Issued For Services StockIssuedDuringPeriodValueIssuedForServices	200000	USD
CY2018	us-gaap	Stock Repurchased And Retired During Period Value StockRepurchasedAndRetiredDuringPeriodValue	6900000	USD
CY2018	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	61900000	USD
CY2018	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	37700000	USD
CY2018	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	10100000	USD
CY2018Q4	us-gaap	Stockholders Equity StockholdersEquity	740400000	USD
CY2018	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	2.20
CY2017	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	2.00
CY2016	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.80
CY2018	us-gaap	Net Income Loss NetIncomeLoss	91700000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	45400000	USD
CY2016	us-gaap	Net Income Loss NetIncomeLoss	91700000	USD
CY2018	us-gaap	Depreciation Depreciation	42100000	USD
CY2017	us-gaap	Depreciation Depreciation	38300000	USD
CY2016	us-gaap	Depreciation Depreciation	34500000	USD
CY2018	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	1800000	USD
CY2017	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	1400000	USD
CY2016	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	1500000	USD
CY2018	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	1000000.0	USD
CY2017	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	1200000	USD
CY2016	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	1100000	USD
CY2018	us-gaap	Deferred Income Taxes And Tax Credits DeferredIncomeTaxesAndTaxCredits	36700000	USD
CY2017	us-gaap	Deferred Income Taxes And Tax Credits DeferredIncomeTaxesAndTaxCredits	89000000.0	USD
CY2016	us-gaap	Deferred Income Taxes And Tax Credits DeferredIncomeTaxesAndTaxCredits	57400000	USD
CY2018	us-gaap	Share Based Compensation ShareBasedCompensation	10300000	USD
CY2017	us-gaap	Share Based Compensation ShareBasedCompensation	13300000	USD
CY2016	us-gaap	Share Based Compensation ShareBasedCompensation	11800000	USD
CY2018	us-gaap	Inventory Write Down InventoryWriteDown	0	USD
CY2017	us-gaap	Inventory Write Down InventoryWriteDown	0	USD
CY2016	us-gaap	Inventory Write Down InventoryWriteDown	4900000	USD
CY2018	us-gaap	Asset Impairment Charges AssetImpairmentCharges	1400000	USD
CY2017	us-gaap	Asset Impairment Charges AssetImpairmentCharges	19200000	USD
CY2016	us-gaap	Asset Impairment Charges AssetImpairmentCharges	2800000	USD
CY2018	us-gaap	Gain Loss On Repurchase Of Debt Instrument GainLossOnRepurchaseOfDebtInstrument	0	USD
CY2017	us-gaap	Gain Loss On Repurchase Of Debt Instrument GainLossOnRepurchaseOfDebtInstrument	0	USD
CY2016	us-gaap	Gain Loss On Repurchase Of Debt Instrument GainLossOnRepurchaseOfDebtInstrument	-11100000	USD
CY2018	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	200000	USD
CY2017	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	500000	USD
CY2016	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	-200000	USD
CY2018	us-gaap	Gain Loss On Sale Of Investments GainLossOnSaleOfInvestments	2900000	USD
CY2017	us-gaap	Gain Loss On Sale Of Investments GainLossOnSaleOfInvestments	2300000	USD
CY2016	us-gaap	Gain Loss On Sale Of Investments GainLossOnSaleOfInvestments	0	USD
CY2018	us-gaap	Defined Benefit Plan Net Periodic Benefit Cost DefinedBenefitPlanNetPeriodicBenefitCost	6600000	USD
CY2017	us-gaap	Defined Benefit Plan Net Periodic Benefit Cost DefinedBenefitPlanNetPeriodicBenefitCost	4800000	USD
CY2016	us-gaap	Defined Benefit Plan Net Periodic Benefit Cost DefinedBenefitPlanNetPeriodicBenefitCost	3700000	USD
CY2018	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	-21900000	USD
CY2017	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	15500000	USD
CY2016	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	17500000	USD
CY2018	us-gaap	Increase Decrease In Accounts And Other Receivables IncreaseDecreaseInAccountsAndOtherReceivables	22300000	USD
CY2017	us-gaap	Increase Decrease In Accounts And Other Receivables IncreaseDecreaseInAccountsAndOtherReceivables	30900000	USD
CY2016	us-gaap	Increase Decrease In Accounts And Other Receivables IncreaseDecreaseInAccountsAndOtherReceivables	26800000	USD
CY2018	us-gaap	Increase Decrease In Contract Receivables Net IncreaseDecreaseInContractReceivablesNet	-700000	USD
CY2017	us-gaap	Increase Decrease In Contract Receivables Net IncreaseDecreaseInContractReceivablesNet	0	USD
CY2016	us-gaap	Increase Decrease In Contract Receivables Net IncreaseDecreaseInContractReceivablesNet	0	USD
CY2018	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	45000000.0	USD
CY2017	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	6300000	USD
CY2016	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	-13100000	USD
CY2018	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	400000	USD
CY2017	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	1700000	USD
CY2016	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	8000000.0	USD
CY2018	us-gaap	Increase Decrease In Accounts Payable Trade IncreaseDecreaseInAccountsPayableTrade	29200000	USD
CY2017	us-gaap	Increase Decrease In Accounts Payable Trade IncreaseDecreaseInAccountsPayableTrade	13000000.0	USD
CY2016	us-gaap	Increase Decrease In Accounts Payable Trade IncreaseDecreaseInAccountsPayableTrade	3400000	USD
CY2018	us-gaap	Increase Decrease In Other Accrued Liabilities IncreaseDecreaseInOtherAccruedLiabilities	-2600000	USD
CY2017	us-gaap	Increase Decrease In Other Accrued Liabilities IncreaseDecreaseInOtherAccruedLiabilities	-4700000	USD
CY2016	us-gaap	Increase Decrease In Other Accrued Liabilities IncreaseDecreaseInOtherAccruedLiabilities	26200000	USD
CY2018	us-gaap	Other Postretirement Benefits Payments OtherPostretirementBenefitsPayments	15700000	USD
CY2017	us-gaap	Other Postretirement Benefits Payments OtherPostretirementBenefitsPayments	20000000.0	USD
CY2016	us-gaap	Other Postretirement Benefits Payments OtherPostretirementBenefitsPayments	19500000	USD
CY2018	us-gaap	Increase Decrease In Other Noncurrent Assets And Liabilities Net IncreaseDecreaseInOtherNoncurrentAssetsAndLiabilitiesNet	4100000	USD
CY2017	us-gaap	Increase Decrease In Other Noncurrent Assets And Liabilities Net IncreaseDecreaseInOtherNoncurrentAssetsAndLiabilitiesNet	2200000	USD
CY2016	us-gaap	Increase Decrease In Other Noncurrent Assets And Liabilities Net IncreaseDecreaseInOtherNoncurrentAssetsAndLiabilitiesNet	26000000.0	USD
CY2017	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-25500000	USD
CY2016	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-276400000	USD
CY2018	us-gaap	Repayments Of Unsecured Debt RepaymentsOfUnsecuredDebt	0	USD
CY2017	us-gaap	Repayments Of Unsecured Debt RepaymentsOfUnsecuredDebt	0	USD
CY2016	us-gaap	Repayments Of Unsecured Debt RepaymentsOfUnsecuredDebt	206000000.0	USD
CY2018	us-gaap	Proceeds From Issuance Of Unsecured Debt ProceedsFromIssuanceOfUnsecuredDebt	0	USD
CY2018	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	150200000	USD
CY2017	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	141500000	USD
CY2016	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	165600000	USD
CY2018	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	74100000	USD
CY2017	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	75500000	USD
CY2016	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	76100000	USD
CY2018	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	135200000	USD
CY2017	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	247500000	USD
CY2016	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	255300000	USD
CY2018	us-gaap	Payments To Acquire Available For Sale Securities Equity PaymentsToAcquireAvailableForSaleSecuritiesEquity	900000	USD
CY2017	us-gaap	Payments To Acquire Available For Sale Securities Equity PaymentsToAcquireAvailableForSaleSecuritiesEquity	0	USD
CY2016	us-gaap	Payments To Acquire Available For Sale Securities Equity PaymentsToAcquireAvailableForSaleSecuritiesEquity	0	USD
CY2018	us-gaap	Proceeds From Sale And Maturity Of Available For Sale Securities ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities	283900000	USD
CY2017	us-gaap	Proceeds From Sale And Maturity Of Available For Sale Securities ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities	296900000	USD
CY2016	us-gaap	Proceeds From Sale And Maturity Of Available For Sale Securities ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities	55000000.0	USD
CY2018	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	43200000	USD
CY2017	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	0	USD
CY2016	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	0	USD
CY2018	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	600000	USD
CY2017	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	600000	USD
CY2016	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	0	USD
CY2018	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	31100000	USD
CY2017	us-gaap	Proceeds From Issuance Of Unsecured Debt ProceedsFromIssuanceOfUnsecuredDebt	0	USD
CY2016	us-gaap	Proceeds From Issuance Of Unsecured Debt ProceedsFromIssuanceOfUnsecuredDebt	375000000.0	USD
CY2018	us-gaap	Payments Of Financing Costs PaymentsOfFinancingCosts	0	USD
CY2017	us-gaap	Payments Of Financing Costs PaymentsOfFinancingCosts	0	USD
CY2016	us-gaap	Payments Of Financing Costs PaymentsOfFinancingCosts	6800000	USD
CY2018	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	0	USD
CY2017	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	0	USD
CY2016	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	1200000	USD
CY2018	us-gaap	Repayments Of Long Term Capital Lease Obligations RepaymentsOfLongTermCapitalLeaseObligations	700000	USD
CY2017	us-gaap	Repayments Of Long Term Capital Lease Obligations RepaymentsOfLongTermCapitalLeaseObligations	400000	USD
CY2016	us-gaap	Repayments Of Long Term Capital Lease Obligations RepaymentsOfLongTermCapitalLeaseObligations	0	USD
CY2018	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	6900000	USD
CY2017	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	4500000	USD
CY2016	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	2900000	USD
CY2018	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	60700000	USD
CY2017	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	79500000	USD
CY2016	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	33300000	USD
CY2018	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	37700000	USD
CY2017	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	35000000.0	USD
CY2016	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	32400000	USD
CY2018	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-106000000.0	USD
CY2017	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-119400000	USD
CY2016	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	94800000	USD
CY2018	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	75300000	USD
CY2017	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	-3400000	USD
CY2016	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	-16000000.0	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	64300000	USD
CY2016Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	67700000	USD
CY2015Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	83700000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	139600000	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	64300000	USD
CY2016Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	67700000	USD
CY2018	us-gaap	Number Of Operating Segments NumberOfOperatingSegments	1	segment
CY2018	us-gaap	Use Of Estimates UseOfEstimates	Use of Estimates in the Preparation of Financial Statements. The preparation of financial statements in accordance with GAAP requires the use of estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities known to exist as of the date the financial statements are published and the reported amounts of revenues and expenses during the reporting period. Uncertainties with respect to such estimates and assumptions are inherent in the preparation of our consolidated financial statements; accordingly, it is possible that the actual results could differ from these estimates and assumptions, which could have a material effect on the reported amounts of our consolidated financial position and results of operations.
CY2016	us-gaap	Inventory Write Down InventoryWriteDown	4900000	USD
CY2018Q4	us-gaap	Inventory Lifo Reserve InventoryLIFOReserve	31700000	USD
CY2017Q4	us-gaap	Inventory Lifo Reserve InventoryLIFOReserve	24300000	USD
CY2018	us-gaap	Interest Costs Incurred Capitalized InterestCostsIncurredCapitalized	1700000	USD
CY2017	us-gaap	Interest Costs Incurred Capitalized InterestCostsIncurredCapitalized	2200000	USD
CY2016	us-gaap	Interest Costs Incurred Capitalized InterestCostsIncurredCapitalized	2900000	USD
CY2017Q4	us-gaap	Accrued Employee Benefits Current And Noncurrent AccruedEmployeeBenefitsCurrentAndNoncurrent	3500000	USD
CY2018	us-gaap	Loss Contingency Undiscounted Amount Of Insurance Related Assessment Liability LossContingencyUndiscountedAmountOfInsuranceRelatedAssessmentLiability	27600000	USD
CY2017	us-gaap	Loss Contingency Undiscounted Amount Of Insurance Related Assessment Liability LossContingencyUndiscountedAmountOfInsuranceRelatedAssessmentLiability	24800000	USD
CY2018	us-gaap	Workers Compensation Discount Percent WorkersCompensationDiscountPercent	0.0300
CY2017	us-gaap	Workers Compensation Discount Percent WorkersCompensationDiscountPercent	0.0225
CY2018Q4	us-gaap	Accrued Employee Benefits Current And Noncurrent AccruedEmployeeBenefitsCurrentAndNoncurrent	3600000	USD
CY2018	us-gaap	Advertising Expense AdvertisingExpense	300000	USD
CY2017	us-gaap	Advertising Expense AdvertisingExpense	700000	USD
CY2016	us-gaap	Advertising Expense AdvertisingExpense	400000	USD
CY2018	us-gaap	Research And Development Expense ResearchAndDevelopmentExpense	9800000	USD
CY2017	us-gaap	Research And Development Expense ResearchAndDevelopmentExpense	10000000.0	USD
CY2016	us-gaap	Research And Development Expense ResearchAndDevelopmentExpense	10200000	USD
CY2018Q4	us-gaap	Cash Cash	22900000	USD
CY2017Q4	us-gaap	Cash Cash	23500000	USD
CY2018Q4	us-gaap	Commercial Paper At Carrying Value CommercialPaperAtCarryingValue	102700000	USD
CY2017Q4	us-gaap	Commercial Paper At Carrying Value CommercialPaperAtCarryingValue	27600000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents And Short Term Investments CashCashEquivalentsAndShortTermInvestments	125600000	USD
CY2017Q4	us-gaap	Cash Cash Equivalents And Short Term Investments CashCashEquivalentsAndShortTermInvestments	51100000	USD
CY2018Q4	us-gaap	Billed Contract Receivables BilledContractReceivables	179500000	USD
CY2017Q4	us-gaap	Billed Contract Receivables BilledContractReceivables	165900000	USD
CY2018Q4	us-gaap	Unbilled Contracts Receivable UnbilledContractsReceivable	1100000	USD
CY2017Q4	us-gaap	Unbilled Contracts Receivable UnbilledContractsReceivable	300000	USD
CY2018Q4	us-gaap	Accounts Receivable Gross Current AccountsReceivableGrossCurrent	180600000	USD
CY2017Q4	us-gaap	Accounts Receivable Gross Current AccountsReceivableGrossCurrent	166200000	USD
CY2018Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	800000	USD
CY2017Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	1200000	USD
CY2018Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	179800000	USD
CY2017Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	165000000.0	USD
CY2018Q4	us-gaap	Inventory Finished Goods InventoryFinishedGoods	48000000.0	USD
CY2017Q4	us-gaap	Inventory Finished Goods InventoryFinishedGoods	63800000	USD
CY2018Q4	us-gaap	Inventory Work In Process InventoryWorkInProcess	85600000	USD
CY2017Q4	us-gaap	Inventory Work In Process InventoryWorkInProcess	78300000	USD
CY2018Q4	us-gaap	Inventory Raw Materials InventoryRawMaterials	75000000.0	USD
CY2017Q4	us-gaap	Inventory Raw Materials InventoryRawMaterials	61300000	USD
CY2018Q4	us-gaap	Other Inventory Supplies OtherInventorySupplies	6500000	USD
CY2017Q4	us-gaap	Other Inventory Supplies OtherInventorySupplies	4500000	USD
CY2018Q4	us-gaap	Inventory Net InventoryNet	215100000	USD
CY2017Q4	us-gaap	Inventory Net InventoryNet	207900000	USD
CY2018Q4	us-gaap	Land Land	21400000	USD
CY2017Q4	us-gaap	Land Land	21100000	USD
CY2018Q4	us-gaap	Buildings And Improvements Gross BuildingsAndImprovementsGross	97000000.0	USD
CY2017Q4	us-gaap	Buildings And Improvements Gross BuildingsAndImprovementsGross	92100000	USD
CY2018Q4	us-gaap	Machinery And Equipment Gross MachineryAndEquipmentGross	755600000	USD
CY2017Q4	us-gaap	Machinery And Equipment Gross MachineryAndEquipmentGross	689100000	USD
CY2018Q4	us-gaap	Construction In Progress Gross ConstructionInProgressGross	43600000	USD
CY2017Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	60000000.0	USD
CY2017Q4	us-gaap	Other Sundry Liabilities Noncurrent OtherSundryLiabilitiesNoncurrent	21600000	USD
CY2018Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	66400000	USD
CY2017Q4	us-gaap	Construction In Progress Gross ConstructionInProgressGross	35100000	USD
CY2018Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	917600000	USD
CY2017Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	837400000	USD
CY2018Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	307400000	USD
CY2017Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	267900000	USD
CY2018Q4	us-gaap	Assets Held For Sale Not Part Of Disposal Group AssetsHeldForSaleNotPartOfDisposalGroup	1600000	USD
CY2017Q4	us-gaap	Assets Held For Sale Not Part Of Disposal Group AssetsHeldForSaleNotPartOfDisposalGroup	1900000	USD
CY2018Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	611800000	USD
CY2017Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	571400000	USD
CY2018Q4	us-gaap	Bank Overdrafts BankOverdrafts	4800000	USD
CY2017Q4	us-gaap	Bank Overdrafts BankOverdrafts	7300000	USD
CY2018Q4	us-gaap	Taxes Payable Current TaxesPayableCurrent	6500000	USD
CY2017Q4	us-gaap	Taxes Payable Current TaxesPayableCurrent	6800000	USD
CY2018Q4	kalu	Accrued Annual Veba Contribution AccruedAnnualVebaContribution	2100000	USD
CY2017Q4	kalu	Accrued Annual Veba Contribution AccruedAnnualVebaContribution	15700000	USD
CY2018Q4	us-gaap	Interest Payable Current InterestPayableCurrent	2900000	USD
CY2017Q4	us-gaap	Interest Payable Current InterestPayableCurrent	2900000	USD
CY2018Q4	us-gaap	Accrued Liabilities And Other Liabilities AccruedLiabilitiesAndOtherLiabilities	27700000	USD
CY2017Q4	us-gaap	Accrued Liabilities And Other Liabilities AccruedLiabilitiesAndOtherLiabilities	7800000	USD
CY2018Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	44000000.0	USD
CY2017Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	40500000	USD
CY2018Q4	us-gaap	Self Insurance Reserve Noncurrent SelfInsuranceReserveNoncurrent	24600000	USD
CY2017Q4	us-gaap	Self Insurance Reserve Noncurrent SelfInsuranceReserveNoncurrent	22600000	USD
CY2018Q4	us-gaap	Accrued Environmental Loss Contingencies Noncurrent AccruedEnvironmentalLossContingenciesNoncurrent	14300000	USD
CY2017Q4	us-gaap	Accrued Environmental Loss Contingencies Noncurrent AccruedEnvironmentalLossContingenciesNoncurrent	15800000	USD
CY2018Q4	us-gaap	Other Sundry Liabilities Noncurrent OtherSundryLiabilitiesNoncurrent	27500000	USD
CY2017Q4	us-gaap	Goodwill Gross GoodwillGross	37200000	USD
CY2018	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	25200000	USD
CY2018Q4	us-gaap	Goodwill Gross GoodwillGross	62400000	USD
CY2017Q4	us-gaap	Goodwill Impaired Accumulated Impairment Loss GoodwillImpairedAccumulatedImpairmentLoss	18400000	USD
CY2018	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	0	USD
CY2018Q4	us-gaap	Goodwill Impaired Accumulated Impairment Loss GoodwillImpairedAccumulatedImpairmentLoss	18400000	USD
CY2017Q4	us-gaap	Goodwill Goodwill	18800000	USD
CY2018	us-gaap	Goodwill Period Increase Decrease GoodwillPeriodIncreaseDecrease	25200000	USD
CY2018Q4	us-gaap	Goodwill Goodwill	44000000.0	USD
CY2018	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	25200000	USD
CY2018	kalu	Period Over Which Goodwill Deductiblefor Tax PeriodOverWhichGoodwillDeductibleforTax	P15Y
CY2017Q2	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	18400000	USD
CY2018Q4	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	43900000	USD
CY2018Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	11500000	USD
CY2018Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	32400000	USD
CY2017Q4	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	34700000	USD
CY2017Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	9700000	USD
CY2017Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	25000000.0	USD
CY2016Q3	us-gaap	Impairment Of Intangible Assets Finitelived ImpairmentOfIntangibleAssetsFinitelived	2600000	USD
CY2018	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	1800000	USD
CY2017	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	1400000	USD
CY2016	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	1500000	USD
CY2018Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Next Twelve Months FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	2800000	USD
CY2018Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Two FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	2800000	USD
CY2018Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Three FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	2800000	USD
CY2018Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Four FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	2800000	USD
CY2018Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Five FiniteLivedIntangibleAssetsAmortizationExpenseYearFive	2600000	USD
CY2018Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense After Year Five FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive	18600000	USD
CY2018Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	32400000	USD
CY2018	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	-1000000.0	USD
CY2018Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Next Twelve Months DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths	8300000	USD
CY2018Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Year Two DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo	8100000	USD
CY2018Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Year Three DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree	7800000	USD
CY2018Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Year Four DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour	7500000	USD
CY2018Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Year Five DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive	7200000	USD
CY2018Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Five Fiscal Years Thereafter DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter	31700000	USD
CY2016	us-gaap	Multiemployer Plan Contributions By Employer MultiemployerPlanContributionsByEmployer	4700000	USD
CY2018	us-gaap	Defined Benefit Plan Benefit Obligation Increase Decrease For Remeasurement Due To Settlement DefinedBenefitPlanBenefitObligationIncreaseDecreaseForRemeasurementDueToSettlement	0	USD
CY2017	us-gaap	Defined Benefit Plan Benefit Obligation Increase Decrease For Remeasurement Due To Settlement DefinedBenefitPlanBenefitObligationIncreaseDecreaseForRemeasurementDueToSettlement	0	USD
CY2016	us-gaap	Defined Benefit Plan Benefit Obligation Increase Decrease For Remeasurement Due To Settlement DefinedBenefitPlanBenefitObligationIncreaseDecreaseForRemeasurementDueToSettlement	-100000	USD
CY2018Q4	kalu	Multiemployer Plans Collective Bargaining Arrangement Percentage Of Employers Participants To All Employees MultiemployerPlansCollectiveBargainingArrangementPercentageOfEmployersParticipantsToAllEmployees	0.51
CY2018	us-gaap	Multiemployer Plan Contributions By Employer MultiemployerPlanContributionsByEmployer	4700000	USD
CY2017	us-gaap	Multiemployer Plan Contributions By Employer MultiemployerPlanContributionsByEmployer	4600000	USD
CY2018Q4	us-gaap	Defined Benefit Plan Fair Value Of Plan Assets DefinedBenefitPlanFairValueOfPlanAssets	68100000	USD
CY2017Q4	us-gaap	Defined Benefit Plan Fair Value Of Plan Assets DefinedBenefitPlanFairValueOfPlanAssets	72300000	USD
CY2018	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	8800000	USD
CY2017	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	8900000	USD
CY2016	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	8900000	USD
CY2018	us-gaap	Deferred Compensation Arrangement With Individual Compensation Expense DeferredCompensationArrangementWithIndividualCompensationExpense	1000000.0	USD
CY2017	us-gaap	Deferred Compensation Arrangement With Individual Compensation Expense DeferredCompensationArrangementWithIndividualCompensationExpense	1800000	USD
CY2016	us-gaap	Deferred Compensation Arrangement With Individual Compensation Expense DeferredCompensationArrangementWithIndividualCompensationExpense	900000	USD
CY2018	us-gaap	Multiemployer Plan Contributions By Employer MultiemployerPlanContributionsByEmployer	4700000	USD
CY2017	us-gaap	Multiemployer Plan Contributions By Employer MultiemployerPlanContributionsByEmployer	4600000	USD
CY2016	us-gaap	Multiemployer Plan Contributions By Employer MultiemployerPlanContributionsByEmployer	4700000	USD
CY2018	us-gaap	Multiemployer Plan Collective Bargaining Arrangement Required Percentage Of Contributions MultiemployerPlanCollectiveBargainingArrangementRequiredPercentageOfContributions	0.05
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant	577014	shares
CY2018Q4	us-gaap	Derivative Net Liability Position Aggregate Fair Value DerivativeNetLiabilityPositionAggregateFairValue	12600000	USD
CY2017Q4	us-gaap	Derivative Net Liability Position Aggregate Fair Value DerivativeNetLiabilityPositionAggregateFairValue	100000	USD
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	74.04
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	80.99
CY2018	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1	P2Y9M18D
CY2018	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	10100000	USD
CY2017	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	13100000	USD
CY2016	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	11700000	USD
CY2018	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	2500000	USD
CY2017	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	4900000	USD
CY2016	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	4400000	USD
CY2018Q4	us-gaap	Margin Deposit Assets MarginDepositAssets	0	USD
CY2018Q4	us-gaap	Customer Deposits Current CustomerDepositsCurrent	200000	USD
CY2018	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	1300700000	USD
CY2017	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	1085900000	USD
CY2016	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	1000800000	USD
CY2016Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber	1543	shares
CY2016Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	80.01
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	0	shares
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber	0	shares
CY2018	us-gaap	Shares Paid For Tax Withholding For Share Based Compensation SharesPaidForTaxWithholdingForShareBasedCompensation	68195	shares
CY2017	us-gaap	Shares Paid For Tax Withholding For Share Based Compensation SharesPaidForTaxWithholdingForShareBasedCompensation	56495	shares
CY2016	us-gaap	Shares Paid For Tax Withholding For Share Based Compensation SharesPaidForTaxWithholdingForShareBasedCompensation	36055	shares
CY2018	us-gaap	Debt Instrument Term DebtInstrumentTerm	P12M
CY2018	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	8200000	USD
CY2017	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	7900000	USD
CY2016	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	8500000	USD
CY2017	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	0	USD
CY2018	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	0	USD
CY2018Q4	us-gaap	Capital Leases Future Minimum Payments Due Current CapitalLeasesFutureMinimumPaymentsDueCurrent	1700000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due Current OperatingLeasesFutureMinimumPaymentsDueCurrent	6100000	USD
CY2018Q4	us-gaap	Capital Leases Future Minimum Payments Due In Two Years CapitalLeasesFutureMinimumPaymentsDueInTwoYears	1400000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due In Two Years OperatingLeasesFutureMinimumPaymentsDueInTwoYears	3700000	USD
CY2018Q4	us-gaap	Capital Leases Future Minimum Payments Due In Three Years CapitalLeasesFutureMinimumPaymentsDueInThreeYears	1200000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due In Three Years OperatingLeasesFutureMinimumPaymentsDueInThreeYears	2800000	USD
CY2018Q4	us-gaap	Capital Leases Future Minimum Payments Due In Four Years CapitalLeasesFutureMinimumPaymentsDueInFourYears	1100000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due In Four Years OperatingLeasesFutureMinimumPaymentsDueInFourYears	2400000	USD
CY2018Q4	us-gaap	Capital Leases Future Minimum Payments Due In Five Years CapitalLeasesFutureMinimumPaymentsDueInFiveYears	1000000.0	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due In Five Years OperatingLeasesFutureMinimumPaymentsDueInFiveYears	2200000	USD
CY2018Q4	us-gaap	Capital Leases Future Minimum Payments Due Thereafter CapitalLeasesFutureMinimumPaymentsDueThereafter	1800000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due Thereafter OperatingLeasesFutureMinimumPaymentsDueThereafter	20800000	USD
CY2018Q4	us-gaap	Capital Leases Future Minimum Payments Due CapitalLeasesFutureMinimumPaymentsDue	8200000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due OperatingLeasesFutureMinimumPaymentsDue	38000000.0	USD
CY2018	us-gaap	Interest Expense Lessee Assets Under Capital Lease InterestExpenseLesseeAssetsUnderCapitalLease	1200000	USD
CY2018Q4	us-gaap	Capital Lease Obligations CapitalLeaseObligations	7000000.0	USD
CY2018Q4	us-gaap	Capital Lease Obligations CapitalLeaseObligations	7000000.0	USD
CY2018Q4	us-gaap	Capital Leased Assets Gross CapitalLeasedAssetsGross	8300000	USD
CY2018Q4	us-gaap	Capital Leases Lessee Balance Sheet Assets By Major Class Accumulated Deprecation CapitalLeasesLesseeBalanceSheetAssetsByMajorClassAccumulatedDeprecation	1300000	USD
CY2017Q4	us-gaap	Capital Leased Assets Gross CapitalLeasedAssetsGross	2200000	USD
CY2017Q4	us-gaap	Capital Leases Lessee Balance Sheet Assets By Major Class Accumulated Deprecation CapitalLeasesLesseeBalanceSheetAssetsByMajorClassAccumulatedDeprecation	900000	USD
CY2017Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	5900000	USD
CY2016Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	5500000	USD
CY2015Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	4900000	USD
CY2016	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	100000	USD
CY2018	us-gaap	Asset Retirement Obligation Accretion Expense AssetRetirementObligationAccretionExpense	400000	USD
CY2017	us-gaap	Asset Retirement Obligation Accretion Expense AssetRetirementObligationAccretionExpense	400000	USD
CY2016	us-gaap	Asset Retirement Obligation Accretion Expense AssetRetirementObligationAccretionExpense	500000	USD
CY2018	us-gaap	Asset Retirement Obligation Revision Of Estimate AssetRetirementObligationRevisionOfEstimate	0	USD
CY2017	us-gaap	Asset Retirement Obligation Revision Of Estimate AssetRetirementObligationRevisionOfEstimate	0	USD
CY2016	us-gaap	Asset Retirement Obligation Revision Of Estimate AssetRetirementObligationRevisionOfEstimate	200000	USD
CY2018Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	6300000	USD
CY2017Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	5900000	USD
CY2016Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	5500000	USD
CY2018	us-gaap	Weighted Average Discount Rate Percent WeightedAverageDiscountRatePercent	0.087
CY2018	kalu	Period For Final Feasibility Study PeriodForFinalFeasibilityStudy	P12M
CY2017Q4	us-gaap	Accrual For Environmental Loss Contingencies AccrualForEnvironmentalLossContingencies	16600000	USD
CY2016Q4	us-gaap	Accrual For Environmental Loss Contingencies AccrualForEnvironmentalLossContingencies	17200000	USD
CY2015Q4	us-gaap	Accrual For Environmental Loss Contingencies AccrualForEnvironmentalLossContingencies	18600000	USD
CY2018	us-gaap	Accrual For Environmental Loss Contingencies Increase Decrease For Revision In Estimates AccrualForEnvironmentalLossContingenciesIncreaseDecreaseForRevisionInEstimates	1700000	USD
CY2017	us-gaap	Accrual For Environmental Loss Contingencies Increase Decrease For Revision In Estimates AccrualForEnvironmentalLossContingenciesIncreaseDecreaseForRevisionInEstimates	300000	USD
CY2016	us-gaap	Accrual For Environmental Loss Contingencies Increase Decrease For Revision In Estimates AccrualForEnvironmentalLossContingenciesIncreaseDecreaseForRevisionInEstimates	100000	USD
CY2018	us-gaap	Accrual For Environmental Loss Contingencies Payments1 AccrualForEnvironmentalLossContingenciesPayments1	1400000	USD
CY2017	us-gaap	Accrual For Environmental Loss Contingencies Payments1 AccrualForEnvironmentalLossContingenciesPayments1	900000	USD
CY2016	us-gaap	Accrual For Environmental Loss Contingencies Payments1 AccrualForEnvironmentalLossContingenciesPayments1	1500000	USD
CY2018Q4	us-gaap	Accrual For Environmental Loss Contingencies AccrualForEnvironmentalLossContingencies	16900000	USD
CY2017Q4	us-gaap	Accrual For Environmental Loss Contingencies AccrualForEnvironmentalLossContingencies	16600000	USD
CY2016Q4	us-gaap	Accrual For Environmental Loss Contingencies AccrualForEnvironmentalLossContingencies	17200000	USD
CY2018Q4	us-gaap	Accrual For Environmental Loss Contingencies AccrualForEnvironmentalLossContingencies	16900000	USD
CY2018	kalu	Expected Period Related To Remediation Expenditures For Environmental Contingencies ExpectedPeriodRelatedToRemediationExpendituresForEnvironmentalContingencies	P30Y
CY2018Q4	us-gaap	Loss Contingency Range Of Possible Loss Portion Not Accrued LossContingencyRangeOfPossibleLossPortionNotAccrued	11600000	USD
CY2018	kalu	Time Period Within Which Companys Recorded Estimate Of Its Obligation May Change TimePeriodWithinWhichCompanysRecordedEstimateOfItsObligationMayChange	P12M
CY2018Q4	us-gaap	Gain Contingency Unrecorded Amount GainContingencyUnrecordedAmount	2400000	USD
CY2018	us-gaap	Cash Flow Hedge Gain Loss To Be Reclassified Within Twelve Months CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths	-15600000	USD
CY2018Q1	us-gaap	Contract With Customer Asset Net Current ContractWithCustomerAssetNetCurrent	55600000	USD
CY2018Q1	us-gaap	Inventory Net InventoryNet	167200000	USD
CY2018Q1	us-gaap	Assets Current AssetsCurrent	671500000	USD
CY2018Q1	us-gaap	Deferred Tax Assets Net Noncurrent DeferredTaxAssetsNetNoncurrent	68700000	USD
CY2018Q1	us-gaap	Assets Assets	1396800000	USD
CY2018Q1	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	42000000.0	USD
CY2018Q1	us-gaap	Liabilities Current LiabilitiesCurrent	174600000	USD
CY2018Q1	us-gaap	Liabilities Liabilities	640400000	USD
CY2018Q1	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	95600000	USD
CY2018Q1	us-gaap	Stockholders Equity StockholdersEquity	756400000	USD
CY2018Q1	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	1396800000	USD
CY2018Q1	us-gaap	Effect Of Lifo Inventory Liquidation On Income EffectOfLIFOInventoryLiquidationOnIncome	5000000.0	USD
CY2018Q4	us-gaap	Contract With Customer Asset Net Current ContractWithCustomerAssetNetCurrent	54900000	USD
CY2018Q4	us-gaap	Inventory Net InventoryNet	215100000	USD
CY2018Q4	us-gaap	Assets Current AssetsCurrent	656600000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Net Noncurrent DeferredTaxAssetsNetNoncurrent	35900000	USD
CY2018Q4	us-gaap	Assets Assets	1419300000	USD
CY2018Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	44000000.0	USD
CY2018Q4	us-gaap	Liabilities Current LiabilitiesCurrent	205500000	USD
CY2018Q4	us-gaap	Liabilities Liabilities	678900000	USD
CY2018Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	150200000	USD
CY2018Q4	us-gaap	Stockholders Equity StockholdersEquity	740400000	USD
CY2018Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	1419300000	USD
CY2018	us-gaap	Revenues Revenues	1585900000	USD
CY2018	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	1300700000	USD
CY2018	us-gaap	Operating Income Loss OperatingIncomeLoss	143600000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	120000000.0	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	28300000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	91700000	USD
CY2018	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	5.53
CY2018	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	5.43
CY2018	us-gaap	Net Income Loss NetIncomeLoss	91700000	USD
CY2018	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	80000000.0	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	91700000	USD
CY2018	us-gaap	Increase Decrease In Contract Receivables Net IncreaseDecreaseInContractReceivablesNet	-700000	USD
CY2018	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	45000000.0	USD
CY2018	us-gaap	Increase Decrease In Other Accrued Liabilities IncreaseDecreaseInOtherAccruedLiabilities	-2600000	USD
CY2018	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	150200000	USD
CY2018	us-gaap	Investment Income Interest InvestmentIncomeInterest	300000	USD
CY2017	us-gaap	Investment Income Interest InvestmentIncomeInterest	200000	USD
CY2016	us-gaap	Investment Income Interest InvestmentIncomeInterest	100000	USD
CY2018	kalu	Defined Benefit Plan Net Periodic Cost Benefit Veb As DefinedBenefitPlanNetPeriodicCostBenefitVEBAs	6100000	USD
CY2017	kalu	Defined Benefit Plan Net Periodic Cost Benefit Veb As DefinedBenefitPlanNetPeriodicCostBenefitVEBAs	4500000	USD
CY2016	kalu	Defined Benefit Plan Net Periodic Cost Benefit Veb As DefinedBenefitPlanNetPeriodicCostBenefitVEBAs	3400000	USD
CY2018	us-gaap	Defined Benefit Plan Recognized Net Gain Loss Due To Curtailments DefinedBenefitPlanRecognizedNetGainLossDueToCurtailments	0	USD
CY2017	us-gaap	Defined Benefit Plan Recognized Net Gain Loss Due To Curtailments DefinedBenefitPlanRecognizedNetGainLossDueToCurtailments	0	USD
CY2016	us-gaap	Defined Benefit Plan Recognized Net Gain Loss Due To Curtailments DefinedBenefitPlanRecognizedNetGainLossDueToCurtailments	100000	USD
CY2018	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	6100000	USD
CY2017	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	3400000	USD
CY2016	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	800000	USD
CY2018	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	USD
CY2017	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	USD
CY2016	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-11100000	USD
CY2018	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	1200000	USD
CY2017	us-gaap	Other Nonoperating Income OtherNonoperatingIncome	900000	USD
CY2016	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	100000	USD
CY2018	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	-900000	USD
CY2017	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	0	USD
CY2016	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	-13600000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	114600000	USD
CY2017	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	127900000	USD
CY2016	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	143600000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	5400000	USD
CY2017	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	5100000	USD
CY2016	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	3600000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	120000000.0	USD
CY2017	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	133000000.0	USD
CY2016	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	147200000	USD
CY2017	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	82000000.0	USD
CY2017	us-gaap	Deferred Foreign Income Tax Expense Benefit DeferredForeignIncomeTaxExpenseBenefit	1000000.0	USD
CY2017	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	5700000	USD
CY2017	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	88700000	USD
CY2017	kalu	Federal Income Tax Provision Benefit Other FederalIncomeTaxProvisionBenefitOther	100000	USD
CY2017	kalu	Foreign Income Tax Provision Benefit Other ForeignIncomeTaxProvisionBenefitOther	100000	USD
CY2017	kalu	State Income Tax Provision Benefit Other StateIncomeTaxProvisionBenefitOther	0	USD
CY2018	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	-11900000	USD
CY2018	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	1900000	USD
CY2018	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	1500000	USD
CY2018	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	-8500000	USD
CY2018	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	34700000	USD
CY2018	us-gaap	Deferred Foreign Income Tax Expense Benefit DeferredForeignIncomeTaxExpenseBenefit	-100000	USD
CY2018	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	1400000	USD
CY2018	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	36000000.0	USD
CY2018	kalu	Federal Income Tax Provision Benefit Other FederalIncomeTaxProvisionBenefitOther	700000	USD
CY2018	kalu	Foreign Income Tax Provision Benefit Other ForeignIncomeTaxProvisionBenefitOther	0	USD
CY2018	kalu	State Income Tax Provision Benefit Other StateIncomeTaxProvisionBenefitOther	100000	USD
CY2018	us-gaap	Other Income Tax Expense Benefit Continuing Operations OtherIncomeTaxExpenseBenefitContinuingOperations	800000	USD
CY2018	us-gaap	Federal Income Tax Expense Benefit Continuing Operations FederalIncomeTaxExpenseBenefitContinuingOperations	23500000	USD
CY2018	us-gaap	Foreign Income Tax Expense Benefit Continuing Operations ForeignIncomeTaxExpenseBenefitContinuingOperations	1800000	USD
CY2018	us-gaap	State And Local Income Tax Expense Benefit Continuing Operations StateAndLocalIncomeTaxExpenseBenefitContinuingOperations	3000000.0	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	28300000	USD
CY2017	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	-3100000	USD
CY2017	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	800000	USD
CY2017	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	1000000.0	USD
CY2017	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	-1300000	USD
CY2017	us-gaap	Other Income Tax Expense Benefit Continuing Operations OtherIncomeTaxExpenseBenefitContinuingOperations	200000	USD
CY2017	us-gaap	Federal Income Tax Expense Benefit Continuing Operations FederalIncomeTaxExpenseBenefitContinuingOperations	79000000.0	USD
CY2017	us-gaap	Foreign Income Tax Expense Benefit Continuing Operations ForeignIncomeTaxExpenseBenefitContinuingOperations	1900000	USD
CY2017	us-gaap	State And Local Income Tax Expense Benefit Continuing Operations StateAndLocalIncomeTaxExpenseBenefitContinuingOperations	6700000	USD
CY2017	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	87600000	USD
CY2016	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	-2700000	USD
CY2016	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	-600000	USD
CY2016	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	1500000	USD
CY2016	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	-1800000	USD
CY2016	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	47800000	USD
CY2016	us-gaap	Deferred Foreign Income Tax Expense Benefit DeferredForeignIncomeTaxExpenseBenefit	1200000	USD
CY2016	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	4700000	USD
CY2016	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	53700000	USD
CY2016	kalu	Federal Income Tax Provision Benefit Other FederalIncomeTaxProvisionBenefitOther	3200000	USD
CY2016	kalu	Foreign Income Tax Provision Benefit Other ForeignIncomeTaxProvisionBenefitOther	100000	USD
CY2016	kalu	State Income Tax Provision Benefit Other StateIncomeTaxProvisionBenefitOther	300000	USD
CY2016	us-gaap	Other Income Tax Expense Benefit Continuing Operations OtherIncomeTaxExpenseBenefitContinuingOperations	3600000	USD
CY2016	us-gaap	Federal Income Tax Expense Benefit Continuing Operations FederalIncomeTaxExpenseBenefitContinuingOperations	48300000	USD
CY2016	us-gaap	Foreign Income Tax Expense Benefit Continuing Operations ForeignIncomeTaxExpenseBenefitContinuingOperations	700000	USD
CY2016	us-gaap	State And Local Income Tax Expense Benefit Continuing Operations StateAndLocalIncomeTaxExpenseBenefitContinuingOperations	6500000	USD
CY2016	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	55500000	USD
CY2018	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	25200000	USD
CY2017	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	46500000	USD
CY2016	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	51500000	USD
CY2018	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	-1700000	USD
CY2017	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	-500000	USD
CY2016	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	300000	USD
CY2018	us-gaap	Income Tax Reconciliation Nondeductible Expense Share Based Compensation Cost IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost	600000	USD
CY2017	us-gaap	Income Tax Reconciliation Nondeductible Expense Share Based Compensation Cost IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost	2300000	USD
CY2016	us-gaap	Income Tax Reconciliation Nondeductible Expense Share Based Compensation Cost IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost	-300000	USD
CY2018	us-gaap	Income Tax Reconciliation Nondeductible Expense Other IncomeTaxReconciliationNondeductibleExpenseOther	1500000	USD
CY2017	us-gaap	Income Tax Reconciliation Nondeductible Expense Other IncomeTaxReconciliationNondeductibleExpenseOther	0	USD
CY2016	us-gaap	Income Tax Reconciliation Nondeductible Expense Other IncomeTaxReconciliationNondeductibleExpenseOther	300000	USD
CY2018	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	2500000	USD
CY2017	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	4300000	USD
CY2016	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	4200000	USD
CY2018	us-gaap	Income Tax Reconciliation Foreign Income Tax Rate Differential IncomeTaxReconciliationForeignIncomeTaxRateDifferential	500000	USD
CY2017	us-gaap	Income Tax Reconciliation Foreign Income Tax Rate Differential IncomeTaxReconciliationForeignIncomeTaxRateDifferential	100000	USD
CY2016	us-gaap	Income Tax Reconciliation Foreign Income Tax Rate Differential IncomeTaxReconciliationForeignIncomeTaxRateDifferential	-500000	USD
CY2018	us-gaap	Income Tax Reconciliation Repatriation Of Foreign Earnings IncomeTaxReconciliationRepatriationOfForeignEarnings	-400000	USD
CY2017	us-gaap	Income Tax Reconciliation Repatriation Of Foreign Earnings IncomeTaxReconciliationRepatriationOfForeignEarnings	5900000	USD
CY2016	us-gaap	Income Tax Reconciliation Repatriation Of Foreign Earnings IncomeTaxReconciliationRepatriationOfForeignEarnings	0	USD
CY2018	us-gaap	Income Tax Reconciliation Tax Settlements Foreign IncomeTaxReconciliationTaxSettlementsForeign	100000	USD
CY2017	us-gaap	Income Tax Reconciliation Tax Settlements Foreign IncomeTaxReconciliationTaxSettlementsForeign	29000000.0	USD
CY2016	us-gaap	Income Tax Reconciliation Tax Settlements Foreign IncomeTaxReconciliationTaxSettlementsForeign	0	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	28300000	USD
CY2017	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	87600000	USD
CY2016	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	55500000	USD
CY2018Q4	kalu	Deferred Tax Assets Operating Loss Carryforwards And Tax Credits DeferredTaxAssetsOperatingLossCarryforwardsAndTaxCredits	48700000	USD
CY2017Q4	kalu	Deferred Tax Assets Operating Loss Carryforwards And Tax Credits DeferredTaxAssetsOperatingLossCarryforwardsAndTaxCredits	98700000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Pensions DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPensions	8000000.0	USD
CY2018Q4	us-gaap	Tax Credit Carryforward Amount TaxCreditCarryforwardAmount	11400000	USD
CY2018	us-gaap	Valuation Allowance Deferred Tax Asset Change In Amount ValuationAllowanceDeferredTaxAssetChangeInAmount	-4600000	USD
CY2017	us-gaap	Valuation Allowance Deferred Tax Asset Change In Amount ValuationAllowanceDeferredTaxAssetChangeInAmount	-2700000	USD
CY2016	us-gaap	Valuation Allowance Deferred Tax Asset Change In Amount ValuationAllowanceDeferredTaxAssetChangeInAmount	-5500000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Pensions DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPensions	11600000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	27200000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	21000000.0	USD
CY2018Q4	us-gaap	Deferred Tax Assets Inventory DeferredTaxAssetsInventory	20000000.0	USD
CY2017Q4	us-gaap	Deferred Tax Assets Inventory DeferredTaxAssetsInventory	9300000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	8400000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	13000000.0	USD
CY2018Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	95500000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	127600000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	62000000.0	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	57700000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Capitalized Inventory Costs DeferredTaxLiabilitiesDeferredExpenseCapitalizedInventoryCosts	1800000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Capitalized Inventory Costs DeferredTaxLiabilitiesDeferredExpenseCapitalizedInventoryCosts	2200000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	63800000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	59900000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	31700000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	67700000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	31700000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Liabilities Net Noncurrent DeferredTaxAssetsLiabilitiesNetNoncurrent	35900000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Noncurrent DeferredTaxLiabilitiesNoncurrent	4200000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	67700000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Liabilities Net Noncurrent DeferredTaxAssetsLiabilitiesNetNoncurrent	72000000.0	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Noncurrent DeferredTaxLiabilitiesNoncurrent	4300000	USD
CY2018Q4	us-gaap	Operating Loss Carryforwards OperatingLossCarryforwards	117700000	USD
CY2017Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1500000	USD
CY2016Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1800000	USD
CY2015Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1700000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	0	USD
CY2017	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	0	USD
CY2016	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	100000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions		USD
CY2017	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	300000	USD
CY2016	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	0	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1500000	USD
CY2017Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1500000	USD
CY2016Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1800000	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1500000	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits That Would Impact Effective Tax Rate UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate	400000	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	200000	USD
CY2017Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	100000	USD
CY2018Q4	kalu	Accrued Interest And Penalty On Unrecognized Tax Benefits Current AccruedInterestAndPenaltyOnUnrecognizedTaxBenefitsCurrent	0	USD
CY2018Q4	us-gaap	Income Tax Examination Increase Decrease In Liability From Prior Year IncomeTaxExaminationIncreaseDecreaseInLiabilityFromPriorYear	-100000	USD
CY2018Q4	us-gaap	Income Tax Examination Increase Decrease In Liability From Prior Year IncomeTaxExaminationIncreaseDecreaseInLiabilityFromPriorYear	-100000	USD
CY2016Q4	us-gaap	Income Tax Examination Increase Decrease In Liability From Prior Year IncomeTaxExaminationIncreaseDecreaseInLiabilityFromPriorYear	0	USD
CY2017	kalu	Tax Cutsand Jobs Actof2017 Incomplete Accounting Changein Tax Rate Deferred Tax Asset Provisional Income Tax Expense Benefit TaxCutsandJobsActof2017IncompleteAccountingChangeinTaxRateDeferredTaxAssetProvisionalIncomeTaxExpenseBenefit	29000000.0	USD
CY2018Q4	kalu	Tax Cutsand Jobs Actof2017 Incomplete Accounting Transition Taxfor Accumulated Foreign Earnings Provisional Income Tax Expense Benefit TaxCutsandJobsActof2017IncompleteAccountingTransitionTaxforAccumulatedForeignEarningsProvisionalIncomeTaxExpenseBenefit	3500000	USD
CY2018Q4	kalu	Tax Cutsand Jobs Actof2017 Incomplete Accounting Transition Taxfor Accumulated Foreign Earnings Provisional Liability Noncurrent TaxCutsandJobsActof2017IncompleteAccountingTransitionTaxforAccumulatedForeignEarningsProvisionalLiabilityNoncurrent	1600000	USD
CY2018Q4	kalu	Tax Cutsand Jobs Actof2017 Incomplete Accounting Tradeor Business Expense Provisional Liability TaxCutsandJobsActof2017IncompleteAccountingTradeorBusinessExpenseProvisionalLiability	2300000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	91700000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	45400000	USD
CY2016	us-gaap	Net Income Loss NetIncomeLoss	91700000	USD
CY2018	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	16585000	shares
CY2017	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	16996000	shares
CY2016	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	17813000	shares
CY2018	us-gaap	Incremental Common Shares Attributable To Nonvested Shares With Forfeitable Dividends IncrementalCommonSharesAttributableToNonvestedSharesWithForfeitableDividends	289000	shares
CY2017	us-gaap	Incremental Common Shares Attributable To Nonvested Shares With Forfeitable Dividends IncrementalCommonSharesAttributableToNonvestedSharesWithForfeitableDividends	263000	shares
CY2016	us-gaap	Incremental Common Shares Attributable To Nonvested Shares With Forfeitable Dividends IncrementalCommonSharesAttributableToNonvestedSharesWithForfeitableDividends	220000	shares
CY2018	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	16874000	shares
CY2017	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	17259000	shares
CY2018	us-gaap	Other Significant Noncash Transaction Value Of Consideration Given1 OtherSignificantNoncashTransactionValueOfConsiderationGiven1	1300000	USD
CY2016	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	18033000	shares
CY2018	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	5.53
CY2017	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.67
CY2016	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	5.15
CY2018	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	5.43
CY2017	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.63
CY2016	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	5.09
CY2017	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	52000	shares
CY2016	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	50000	shares
CY2018	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	37700000	USD
CY2018	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	2.20
CY2017	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	35000000.0	USD
CY2017	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	2.00
CY2016	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	32400000	USD
CY2016	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	1.80
CY2018	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	617151	shares
CY2017	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	938680	shares
CY2016	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	443838	shares
CY2018	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	100.28
CY2017	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	82.97
CY2016	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	78.59
CY2018	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	61900000	USD
CY2017	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	77800000	USD
CY2016	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	34900000	USD
CY2018Q4	us-gaap	Stock Repurchase Program Remaining Authorized Repurchase Amount1 StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1	148700000	USD
CY2017Q4	us-gaap	Stock Repurchase Program Remaining Authorized Repurchase Amount1 StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1	110500000	USD
CY2018	us-gaap	Interest Paid InterestPaid	21600000	USD
CY2017	us-gaap	Interest Paid InterestPaid	21100000	USD
CY2016	us-gaap	Interest Paid InterestPaid	17700000	USD
CY2018	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	7000000.0	USD
CY2017	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	7400000	USD
CY2016	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	4600000	USD
CY2017	us-gaap	Other Significant Noncash Transaction Value Of Consideration Given1 OtherSignificantNoncashTransactionValueOfConsiderationGiven1	100000	USD
CY2016	us-gaap	Other Significant Noncash Transaction Value Of Consideration Given1 OtherSignificantNoncashTransactionValueOfConsiderationGiven1	1800000	USD
CY2018	us-gaap	Capital Lease Obligations Incurred CapitalLeaseObligationsIncurred	6500000	USD
CY2017	us-gaap	Capital Lease Obligations Incurred CapitalLeaseObligationsIncurred	1200000	USD
CY2016	us-gaap	Capital Lease Obligations Incurred CapitalLeaseObligationsIncurred	200000	USD
CY2018Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	125600000	USD
CY2017Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	51100000	USD
CY2016Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	55200000	USD
CY2018Q4	us-gaap	Restricted Cash And Cash Equivalents At Carrying Value RestrictedCashAndCashEquivalentsAtCarryingValue	300000	USD
CY2017Q4	us-gaap	Restricted Cash And Cash Equivalents At Carrying Value RestrictedCashAndCashEquivalentsAtCarryingValue	300000	USD
CY2016Q4	us-gaap	Restricted Cash And Cash Equivalents At Carrying Value RestrictedCashAndCashEquivalentsAtCarryingValue	300000	USD
CY2018Q4	us-gaap	Restricted Cash And Cash Equivalents Noncurrent RestrictedCashAndCashEquivalentsNoncurrent	13700000	USD
CY2017Q4	us-gaap	Restricted Cash And Cash Equivalents Noncurrent RestrictedCashAndCashEquivalentsNoncurrent	12900000	USD
CY2016Q4	us-gaap	Restricted Cash And Cash Equivalents Noncurrent RestrictedCashAndCashEquivalentsNoncurrent	12200000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	139600000	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	64300000	USD
CY2016Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	67700000	USD
CY2018Q4	kalu	Percentageof Employees Coveredby Collective Bargaining Agreements PercentageofEmployeesCoveredbyCollectiveBargainingAgreements	0.62
CY2018Q4	kalu	Percentageof Employees Coveredby Collective Bargaining Agreements Expiring Within One Year PercentageofEmployeesCoveredbyCollectiveBargainingAgreementsExpiringWithinOneYear	0
CY2018	us-gaap	Revenues Revenues	1585900000	USD
CY2017	us-gaap	Revenues Revenues	1397500000	USD
CY2016	us-gaap	Revenues Revenues	1330600000	USD
CY2018	us-gaap	Revenues Revenues	1585900000	USD
CY2018	us-gaap	Revenues Revenues	1585900000	USD
CY2017	us-gaap	Revenues Revenues	1397500000	USD
CY2016	us-gaap	Revenues Revenues	1330600000	USD
CY2018	us-gaap	Income Taxes Paid IncomeTaxesPaid	3600000	USD
CY2017	us-gaap	Income Taxes Paid IncomeTaxesPaid	1300000	USD
CY2016	us-gaap	Income Taxes Paid IncomeTaxesPaid	1200000	USD
CY2018Q4	us-gaap	Noncurrent Assets NoncurrentAssets	611800000	USD
CY2017Q4	us-gaap	Noncurrent Assets NoncurrentAssets	571400000	USD
CY2018Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	38600000	USD
CY2018Q4	us-gaap	Assets Assets	1419300000	USD
CY2018Q4	us-gaap	Accounts Payable Current AccountsPayableCurrent	121400000	USD
CY2018Q4	kalu	Intercompany Payable Current IntercompanyPayableCurrent	0	USD
CY2018Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	40100000	USD
CY2018Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	44000000.0	USD
CY2016Q4	us-gaap	Noncurrent Assets NoncurrentAssets	530900000	USD
CY2018Q4	kalu	Ownership Interest In Subsidiaries OwnershipInterestInSubsidiaries	1
CY2018Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	125600000	USD
CY2018Q4	us-gaap	Available For Sale Securities Current AvailableForSaleSecuritiesCurrent	36700000	USD
CY2018Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	179800000	USD
CY2018Q4	kalu	Intercompany Receivables Current IntercompanyReceivablesCurrent	0	USD
CY2018Q4	us-gaap	Other Receivables OtherReceivables	25600000	USD
CY2018Q4	us-gaap	Contract With Customer Asset Net Current ContractWithCustomerAssetNetCurrent	54900000	USD
CY2018Q4	us-gaap	Inventory Net InventoryNet	215100000	USD
CY2018Q4	us-gaap	Prepaid Expense And Other Assets Current PrepaidExpenseAndOtherAssetsCurrent	18900000	USD
CY2018Q4	us-gaap	Assets Current AssetsCurrent	656600000	USD
CY2018Q4	us-gaap	Investments In And Advances To Affiliates At Fair Value InvestmentsInAndAdvancesToAffiliatesAtFairValue	0	USD
CY2018Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	611800000	USD
CY2018Q4	kalu	Intercompany Receivables Noncurrent IntercompanyReceivablesNoncurrent	0	USD
CY2018Q4	us-gaap	Deferred Tax Assets Net Noncurrent DeferredTaxAssetsNetNoncurrent	35900000	USD
CY2018Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	32400000	USD
CY2018Q4	us-gaap	Goodwill Goodwill	44000000.0	USD
CY2018Q4	us-gaap	Liabilities Current LiabilitiesCurrent	205500000	USD
CY2018Q4	kalu	Net Liability In Respect Of Veba NetLiabilityInRespectOfVeba	32400000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Gross Noncurrent DeferredTaxLiabilitiesGrossNoncurrent	4200000	USD
CY2018Q4	kalu	Intercompany Payable Noncurrent IntercompanyPayableNoncurrent	0	USD
CY2018Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	66400000	USD
CY2018Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	370400000	USD
CY2018Q4	us-gaap	Liabilities Liabilities	678900000	USD
CY2018Q4	us-gaap	Stockholders Equity StockholdersEquity	740400000	USD
CY2017Q4	us-gaap	Liabilities Liabilities	638900000	USD
CY2017Q4	us-gaap	Stockholders Equity StockholdersEquity	746300000	USD
CY2017Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	1385200000	USD
CY2018	us-gaap	Revenues Revenues	1585900000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Gross Noncurrent DeferredTaxLiabilitiesGrossNoncurrent	4300000	USD
CY2017Q4	kalu	Intercompany Payable Noncurrent IntercompanyPayableNoncurrent	0	USD
CY2017Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	60000000.0	USD
CY2017Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	369600000	USD
CY2017Q4	kalu	Intercompany Payable Current IntercompanyPayableCurrent	0	USD
CY2017Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	42600000	USD
CY2017Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	40500000	USD
CY2017Q4	us-gaap	Liabilities Current LiabilitiesCurrent	173100000	USD
CY2017Q4	kalu	Net Liability In Respect Of Veba NetLiabilityInRespectOfVeba	31900000	USD
CY2018Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	1419300000	USD
CY2017Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	51100000	USD
CY2017Q4	us-gaap	Available For Sale Securities Current AvailableForSaleSecuritiesCurrent	183700000	USD
CY2017Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	165000000.0	USD
CY2017Q4	kalu	Intercompany Receivables Current IntercompanyReceivablesCurrent	0	USD
CY2017Q4	us-gaap	Other Receivables OtherReceivables	15500000	USD
CY2017Q4	us-gaap	Inventory Net InventoryNet	207900000	USD
CY2017Q4	us-gaap	Prepaid Expense And Other Assets Current PrepaidExpenseAndOtherAssetsCurrent	33400000	USD
CY2017Q4	us-gaap	Assets Current AssetsCurrent	656600000	USD
CY2017Q4	us-gaap	Investments In And Advances To Affiliates At Fair Value InvestmentsInAndAdvancesToAffiliatesAtFairValue	0	USD
CY2017Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	571400000	USD
CY2017Q4	kalu	Intercompany Receivables Noncurrent IntercompanyReceivablesNoncurrent	0	USD
CY2017Q4	us-gaap	Deferred Tax Assets Net Noncurrent DeferredTaxAssetsNetNoncurrent	72000000.0	USD
CY2017Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	25000000.0	USD
CY2017Q4	us-gaap	Goodwill Goodwill	18800000	USD
CY2017Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	41400000	USD
CY2017Q4	us-gaap	Assets Assets	1385200000	USD
CY2017Q4	us-gaap	Accounts Payable Current AccountsPayableCurrent	90000000.0	USD
CY2018	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	1300700000	USD
CY2018	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	43900000	USD
CY2018	kalu	Selling Administrative Research And Development And General Expenses SellingAdministrativeResearchAndDevelopmentAndGeneralExpenses	96300000	USD
CY2018	us-gaap	Other Operating Income Expense Net OtherOperatingIncomeExpenseNet	-1400000	USD
CY2018	us-gaap	Costs And Expenses CostsAndExpenses	1442300000	USD
CY2018	us-gaap	Operating Income Loss OperatingIncomeLoss	143600000	USD
CY2018	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	-22700000	USD
CY2018	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	-900000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	120000000.0	USD
CY2018	us-gaap	Repayments Of Long Term Capital Lease Obligations RepaymentsOfLongTermCapitalLeaseObligations	700000	USD
CY2018	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	6900000	USD
CY2018	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	60700000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	28300000	USD
CY2018	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	0	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	91700000	USD
CY2018	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	80000000.0	USD
CY2017	us-gaap	Revenues Revenues	1397500000	USD
CY2017	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	1085900000	USD
CY2017	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	39700000	USD
CY2017	kalu	Selling Administrative Research And Development And General Expenses SellingAdministrativeResearchAndDevelopmentAndGeneralExpenses	97500000	USD
CY2017	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	18400000	USD
CY2017	us-gaap	Other Operating Income Expense Net OtherOperatingIncomeExpenseNet	-800000	USD
CY2017	us-gaap	Costs And Expenses CostsAndExpenses	1242300000	USD
CY2017	us-gaap	Operating Income Loss OperatingIncomeLoss	155200000	USD
CY2017	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	-22200000	USD
CY2017	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	0	USD
CY2017	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	133000000.0	USD
CY2017	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	87600000	USD
CY2017	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	0	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	45400000	USD
CY2017	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	45400000	USD
CY2016	us-gaap	Revenues Revenues	1330600000	USD
CY2016	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	1000800000	USD
CY2016	us-gaap	Inventory Write Down InventoryWriteDown	4900000	USD
CY2016	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	36000000.0	USD
CY2016	kalu	Selling Administrative Research And Development And General Expenses SellingAdministrativeResearchAndDevelopmentAndGeneralExpenses	105000000.0	USD
CY2016	us-gaap	Other Operating Income Expense Net OtherOperatingIncomeExpenseNet	-2800000	USD
CY2016	us-gaap	Costs And Expenses CostsAndExpenses	1149500000	USD
CY2016	us-gaap	Operating Income Loss OperatingIncomeLoss	181100000	USD
CY2016	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	-20300000	USD
CY2016	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	-13600000	USD
CY2016	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	147200000	USD
CY2016	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	55500000	USD
CY2016	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	0	USD
CY2016	us-gaap	Net Income Loss NetIncomeLoss	91700000	USD
CY2016	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	86700000	USD
CY2018	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	150200000	USD
CY2018	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	74100000	USD
CY2018	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	135200000	USD
CY2018	us-gaap	Payments To Acquire Available For Sale Securities Equity PaymentsToAcquireAvailableForSaleSecuritiesEquity	900000	USD
CY2018	us-gaap	Proceeds From Sale And Maturity Of Available For Sale Securities ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities	283900000	USD
CY2018	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	43200000	USD
CY2018	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	600000	USD
CY2018	kalu	Changein Intercompany Loans Receivable ChangeinIntercompanyLoansReceivable	0	USD
CY2018	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	31100000	USD
CY2018	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	37700000	USD
CY2018	us-gaap	Cash Dividends Paid To Parent Company By Consolidated Subsidiaries CashDividendsPaidToParentCompanyByConsolidatedSubsidiaries	0	USD
CY2018	kalu	Repayments Of Proceeds From Intercompanyloan RepaymentsOfProceedsFromIntercompanyloan	0	USD
CY2018	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-106000000.0	USD
CY2018	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	75300000	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	64300000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	139600000	USD
CY2017	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	141500000	USD
CY2017	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	75500000	USD
CY2017	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	247500000	USD
CY2017	us-gaap	Proceeds From Sale And Maturity Of Available For Sale Securities ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities	296900000	USD
CY2017	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	600000	USD
CY2017	kalu	Changein Intercompany Loans Receivable ChangeinIntercompanyLoansReceivable	0	USD
CY2017	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-25500000	USD
CY2017	us-gaap	Repayments Of Long Term Capital Lease Obligations RepaymentsOfLongTermCapitalLeaseObligations	400000	USD
CY2017	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	4500000	USD
CY2017	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	79500000	USD
CY2017	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	35000000.0	USD
CY2017	kalu	Repayments Of Proceeds From Intercompanyloan RepaymentsOfProceedsFromIntercompanyloan	0	USD
CY2017	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-119400000	USD
CY2017	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	-3400000	USD
CY2016Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	67700000	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	64300000	USD
CY2016	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	165600000	USD
CY2016	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	76100000	USD
CY2016	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	255300000	USD
CY2016	us-gaap	Proceeds From Sale And Maturity Of Available For Sale Securities ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities	55000000.0	USD
CY2016	kalu	Changein Intercompany Loans Receivable ChangeinIntercompanyLoansReceivable	0	USD
CY2016	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-276400000	USD
CY2016	us-gaap	Repayments Of Unsecured Debt RepaymentsOfUnsecuredDebt	206000000.0	USD
CY2016	us-gaap	Proceeds From Issuance Of Unsecured Debt ProceedsFromIssuanceOfUnsecuredDebt	375000000.0	USD
CY2016	us-gaap	Payments Of Financing Costs PaymentsOfFinancingCosts	6800000	USD
CY2016	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	1200000	USD
CY2016	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	2900000	USD
CY2016	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	33300000	USD
CY2016	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	32400000	USD
CY2016	kalu	Repayments Of Proceeds From Intercompanyloan RepaymentsOfProceedsFromIntercompanyloan	0	USD
CY2016	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	94800000	USD
CY2016	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	-16000000.0	USD
CY2015Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	83700000	USD
CY2016Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	67700000	USD
CY2018Q1	us-gaap	Revenues Revenues	388000000.0	USD
CY2018Q2	us-gaap	Revenues Revenues	415400000	USD
CY2018Q3	us-gaap	Revenues Revenues	393100000	USD
CY2018Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.44
CY2018Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.51
CY2018Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.22
CY2018Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.29
CY2018Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.41
CY2018Q1	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.55
CY2018Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.55
CY2018Q4	us-gaap	Revenues Revenues	389400000	USD
CY2018Q1	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	316700000	USD
CY2018Q2	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	343400000	USD
CY2018Q3	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	323300000	USD
CY2018Q4	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	317300000	USD
CY2018Q1	us-gaap	Gross Profit GrossProfit	71300000	USD
CY2018Q2	us-gaap	Gross Profit GrossProfit	72000000.0	USD
CY2018Q3	us-gaap	Gross Profit GrossProfit	69800000	USD
CY2018Q4	us-gaap	Gross Profit GrossProfit	72100000	USD
CY2018Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	37100000	USD
CY2018Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	34700000	USD
CY2018Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	34900000	USD
CY2018Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	36900000	USD
CY2018Q1	us-gaap	Net Income Loss NetIncomeLoss	25700000	USD
CY2018Q2	us-gaap	Net Income Loss NetIncomeLoss	20700000	USD
CY2018Q3	us-gaap	Net Income Loss NetIncomeLoss	21700000	USD
CY2018Q4	us-gaap	Net Income Loss NetIncomeLoss	23600000	USD
CY2018Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.54
CY2018Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.24
CY2018Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.31
CY2018Q3	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.55
CY2018Q4	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.55
CY2017Q1	us-gaap	Revenues Revenues	355300000	USD
CY2017Q2	us-gaap	Revenues Revenues	356300000	USD
CY2017Q3	us-gaap	Revenues Revenues	332800000	USD
CY2017Q4	us-gaap	Revenues Revenues	353100000	USD
CY2017Q1	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	262700000	USD
CY2017Q2	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	289600000	USD
CY2017Q3	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	256400000	USD
CY2017Q4	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	277200000	USD
CY2017Q1	us-gaap	Gross Profit GrossProfit	92600000	USD
CY2017Q2	us-gaap	Gross Profit GrossProfit	66700000	USD
CY2017Q3	us-gaap	Gross Profit GrossProfit	76400000	USD
CY2017Q4	us-gaap	Gross Profit GrossProfit	75900000	USD
CY2017Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	59300000	USD
CY2017Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	12500000	USD
CY2017Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	41500000	USD
CY2017Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	41900000	USD
CY2017Q1	us-gaap	Net Income Loss NetIncomeLoss	36000000.0	USD
CY2017Q2	us-gaap	Net Income Loss NetIncomeLoss	4700000	USD
CY2017Q3	us-gaap	Net Income Loss NetIncomeLoss	19900000	USD
CY2017Q4	us-gaap	Net Income Loss NetIncomeLoss	-15200000	USD
CY2017Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.07
CY2017Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.28
CY2017Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.18
CY2017Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.90
CY2017Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.04
CY2017Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.27
CY2017Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.16
CY2017Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.90
CY2017Q1	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.50
CY2017Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.50
CY2017Q3	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.50
CY2017Q4	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.50
CY2017Q2	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	18400000	USD
CY2017Q4	kalu	Tax Cutsand Jobs Actof2017 Incomplete Accounting Provisional Income Tax Expense Benefit TaxCutsandJobsActof2017IncompleteAccountingProvisionalIncomeTaxExpenseBenefit	-37200000	USD

Files In Submission

Name	View Source	Status
0000811596-19-000009-index-headers.html	Edgar Link	pending
0000811596-19-000009-index.html	Edgar Link	pending
0000811596-19-000009.txt	Edgar Link	pending
0000811596-19-000009-xbrl.zip	Edgar Link	pending
ex231-kalux12311810k.htm	Edgar Link	pending
ex311-kalux12311810k.htm	Edgar Link	pending
ex312-kalux12311810k.htm	Edgar Link	pending
ex321-kalux12311810k.htm	Edgar Link	pending
ex322-kalux12311810k.htm	Edgar Link	pending
FilingSummary.xml	Edgar Link	unprocessable
Financial_Report.xlsx	Edgar Link	pending
kalu-12312018x10k.htm	Edgar Link	pending
kalu-12312018x10k_htm.xml	Edgar Link	completed
kalu-20181231.xsd	Edgar Link	pending
kalu-20181231_cal.xml	Edgar Link	unprocessable
kalu-20181231_def.xml	Edgar Link	unprocessable
kalu-20181231_lab.xml	Edgar Link	unprocessable
kalu-20181231_pre.xml	Edgar Link	unprocessable
MetaLinks.json	Edgar Link	pending
R1.htm	Edgar Link	pending
R10.htm	Edgar Link	pending
R100.htm	Edgar Link	pending
R101.htm	Edgar Link	pending
R102.htm	Edgar Link	pending
R103.htm	Edgar Link	pending
R104.htm	Edgar Link	pending
R11.htm	Edgar Link	pending
R12.htm	Edgar Link	pending
R13.htm	Edgar Link	pending
R14.htm	Edgar Link	pending
R15.htm	Edgar Link	pending
R16.htm	Edgar Link	pending
R17.htm	Edgar Link	pending
R18.htm	Edgar Link	pending
R19.htm	Edgar Link	pending
R2.htm	Edgar Link	pending
R20.htm	Edgar Link	pending
R21.htm	Edgar Link	pending
R22.htm	Edgar Link	pending
R23.htm	Edgar Link	pending
R24.htm	Edgar Link	pending
R25.htm	Edgar Link	pending
R26.htm	Edgar Link	pending
R27.htm	Edgar Link	pending
R28.htm	Edgar Link	pending
R29.htm	Edgar Link	pending
R3.htm	Edgar Link	pending
R30.htm	Edgar Link	pending
R31.htm	Edgar Link	pending
R32.htm	Edgar Link	pending
R33.htm	Edgar Link	pending
R34.htm	Edgar Link	pending
R35.htm	Edgar Link	pending
R36.htm	Edgar Link	pending
R37.htm	Edgar Link	pending
R38.htm	Edgar Link	pending
R39.htm	Edgar Link	pending
R4.htm	Edgar Link	pending
R40.htm	Edgar Link	pending
R41.htm	Edgar Link	pending
R42.htm	Edgar Link	pending
R43.htm	Edgar Link	pending
R44.htm	Edgar Link	pending
R45.htm	Edgar Link	pending
R46.htm	Edgar Link	pending
R47.htm	Edgar Link	pending
R48.htm	Edgar Link	pending
R49.htm	Edgar Link	pending
R5.htm	Edgar Link	pending
R50.htm	Edgar Link	pending
R51.htm	Edgar Link	pending
R52.htm	Edgar Link	pending
R53.htm	Edgar Link	pending
R54.htm	Edgar Link	pending
R55.htm	Edgar Link	pending
R56.htm	Edgar Link	pending
R57.htm	Edgar Link	pending
R58.htm	Edgar Link	pending
R59.htm	Edgar Link	pending
R6.htm	Edgar Link	pending
R60.htm	Edgar Link	pending
R61.htm	Edgar Link	pending
R62.htm	Edgar Link	pending
R63.htm	Edgar Link	pending
R64.htm	Edgar Link	pending
R65.htm	Edgar Link	pending
R66.htm	Edgar Link	pending
R67.htm	Edgar Link	pending
R68.htm	Edgar Link	pending
R69.htm	Edgar Link	pending
R7.htm	Edgar Link	pending
R70.htm	Edgar Link	pending
R71.htm	Edgar Link	pending
R72.htm	Edgar Link	pending
R73.htm	Edgar Link	pending
R74.htm	Edgar Link	pending
R75.htm	Edgar Link	pending
R76.htm	Edgar Link	pending
R77.htm	Edgar Link	pending
R78.htm	Edgar Link	pending
R79.htm	Edgar Link	pending
R8.htm	Edgar Link	pending
R80.htm	Edgar Link	pending
R81.htm	Edgar Link	pending
R82.htm	Edgar Link	pending
R83.htm	Edgar Link	pending
R84.htm	Edgar Link	pending
R85.htm	Edgar Link	pending
R86.htm	Edgar Link	pending
R87.htm	Edgar Link	pending
R88.htm	Edgar Link	pending
R89.htm	Edgar Link	pending
R9.htm	Edgar Link	pending
R90.htm	Edgar Link	pending
R91.htm	Edgar Link	pending
R92.htm	Edgar Link	pending
R93.htm	Edgar Link	pending
R94.htm	Edgar Link	pending
R95.htm	Edgar Link	pending
R96.htm	Edgar Link	pending
R97.htm	Edgar Link	pending
R98.htm	Edgar Link	pending
R99.htm	Edgar Link	pending
R9999.htm	Edgar Link	pending
report.css	Edgar Link	pending
Show.js	Edgar Link	pending
stockperformancegraph1231184.jpg	Edgar Link	pending

Create your account

Find Stocks Worth Researching

Deeply Understand Businesses

Value Businesses Intelligently

$KALU
KAISER ALUMINUM CORP Stock $kalu

2018 Q4 Form 10-K Financial Statement

#000081159619000009 Filed on February 22, 2019

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$KALU KAISER ALUMINUM CORP Stock $kalu

2018 Q4 Form 10-K Financial Statement

#000081159619000009 Filed on February 22, 2019

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$KALU
KAISER ALUMINUM CORP Stock $kalu