$ALE
ALLETE INC Stock $ale

$ale Overview Financials Valuation SEC Filings Company Website

2018 Q3 Form 10-Q Financial Statement

#000006675618000088 Filed on November 01, 2018

Income Statement

Concept	2018 Q3	2017 Q4	2017 Q3
Revenue	$348.0M	$337.9M	$362.5M
YoY Change	-4.0%	-1.05%	3.69%
Cost Of Revenue	$38.70M	$41.70M	$36.00M
YoY Change	7.5%	31.96%	-21.23%
Gross Profit	$309.3M	$298.2M	$326.5M
YoY Change	-5.27%	-3.78%	7.44%
Gross Profit Margin	88.88%	88.25%	90.07%
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$51.50M	$27.10M	$50.90M
YoY Change	1.18%	-46.86%	4.09%
% of Gross Profit	16.65%	9.09%	15.59%
Operating Expenses	$80.30M	$265.0M	$81.10M
YoY Change	-0.99%	6.51%	0.37%
Operating Profit	$43.30M	$32.30M	$68.00M
YoY Change	-36.32%	-45.62%	31.27%
Interest Expense	$17.60M	-$12.10M	$16.60M
YoY Change	6.02%	-12.32%	-11.23%
% of Operating Profit	40.65%	-37.46%	24.41%
Other Income/Expense, Net	-$12.20M	$400.0K	-$8.900M
YoY Change	37.08%	-63.64%	-21.93%
Pretax Income	$31.10M	$21.50M	$59.10M
YoY Change	-47.38%	-55.58%	40.71%
Income Tax	$400.0K	-$6.900M	$14.20M
% Of Pretax Income	1.29%	-32.09%	24.03%
Net Earnings	$30.70M	$41.40M	$44.90M
YoY Change	-31.63%	-6.55%	11.41%
Net Earnings / Revenue	8.82%	12.25%	12.39%
Basic Earnings Per Share	$0.59	$0.81	$0.88
Diluted Earnings Per Share	$0.59	$0.81	$0.88
COMMON SHARES
Basic Shares Outstanding	51.40M shares		51.00M shares
Diluted Shares Outstanding	51.60M shares		51.20M shares

Balance Sheet

Concept	2018 Q3	2017 Q4	2017 Q3
SHORT-TERM ASSETS
Cash & Short-Term Investments	$128.0M	$98.90M	$104.4M
YoY Change	22.61%	259.64%	-2.61%
Cash & Equivalents	$128.0M	$98.90M	$104.4M
Short-Term Investments
Other Short-Term Assets	$27.20M	$37.60M	$44.20M
YoY Change	-38.46%	-6.7%	13.62%
Inventory	$154.8M	$95.90M	$102.6M
Prepaid Expenses
Receivables	$129.4M	$135.1M	$136.7M
Other Receivables	$0.00	$0.00	$0.00
Total Short-Term Assets	$439.4M	$367.5M	$387.9M
YoY Change	13.28%	24.79%	7.27%
LONG-TERM ASSETS
Property, Plant & Equipment	$3.847B	$3.822B	$3.746B
YoY Change	2.67%	2.17%	2.79%
Goodwill	$148.5M	$148.3M	$149.9M
YoY Change	-0.93%	13.03%	14.78%
Intangibles	$76.20M	$77.60M	$79.00M
YoY Change	-3.54%	-5.6%	-2.23%
Long-Term Investments	$126.0M	$118.7M	$146.0M
YoY Change	-13.7%	-12.46%	9.12%
Other Assets	$104.4M	$107.7M	$103.0M
YoY Change	1.36%	1.13%	-3.29%
Total Long-Term Assets	$4.724B	$4.713B	$4.591B
YoY Change	2.9%	2.84%	1.71%
TOTAL ASSETS
Total Short-Term Assets	$439.4M	$367.5M	$387.9M
Total Long-Term Assets	$4.724B	$4.713B	$4.591B
Total Assets	$5.163B	$5.080B	$4.979B
YoY Change	3.71%	4.16%	2.13%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$131.8M	$136.3M	$75.30M
YoY Change	75.03%	84.19%	3.72%
Accrued Expenses	$15.50M	$17.60M	$14.60M
YoY Change	6.16%	0.0%	-1.35%
Deferred Revenue	$22.70M	$8.700M
YoY Change
Short-Term Debt	$0.00	$0.00	$0.00
YoY Change
Long-Term Debt Due	$56.60M	$64.10M	$64.10M
YoY Change	-11.7%	-65.85%	-65.65%
Total Short-Term Liabilities	$402.7M	$351.2M	$290.5M
YoY Change	38.62%	-12.09%	-28.15%
LONG-TERM LIABILITIES
Long-Term Debt	$1.462B	$1.439B	$1.445B
YoY Change	1.18%	5.02%	6.31%
Other Long-Term Liabilities	$265.6M	$267.1M	$301.1M
YoY Change	-11.79%	-17.23%	-10.36%
Total Long-Term Liabilities	$1.727B	$1.706B	$1.746B
YoY Change	-1.05%	0.78%	3.0%
TOTAL LIABILITIES
Total Short-Term Liabilities	$402.7M	$351.2M	$290.5M
Total Long-Term Liabilities	$1.727B	$1.706B	$1.746B
Total Liabilities	$3.047B	$3.012B	$2.936B
YoY Change	3.79%	0.94%	-2.2%
SHAREHOLDERS EQUITY
Retained Earnings	$722.3M	$689.4M	$675.3M
YoY Change	6.96%	10.15%	11.2%
Common Stock	$1.421B	$1.401B	$1.394B
YoY Change	1.92%	8.19%	8.14%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$2.116B	$2.068B	$2.043B
YoY Change
Total Liabilities & Shareholders Equity	$5.163B	$5.080B	$4.979B
YoY Change	3.71%	4.16%	2.13%

Cashflow Statement

Concept	2018 Q3	2017 Q4	2017 Q3
OPERATING ACTIVITIES
Net Income	$30.70M	$41.40M	$44.90M
YoY Change	-31.63%	-6.55%	11.41%
Depreciation, Depletion And Amortization	$51.50M	$27.10M	$50.90M
YoY Change	1.18%	-46.86%	4.09%
Cash From Operating Activities	$103.7M	$95.70M	$122.8M
YoY Change	-15.55%	1.59%	34.06%
INVESTING ACTIVITIES
Capital Expenditures	-$67.60M	-$78.20M	-$49.20M
YoY Change	37.4%	-46.48%	10.07%
Acquisitions
YoY Change
Other Investing Activities	-$1.700M	$900.0K	-$17.80M
YoY Change	-90.45%	-109.57%	747.62%
Cash From Investing Activities	-$69.30M	-$77.30M	-$67.00M
YoY Change	3.43%	-50.29%	43.16%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	-25.70M	-23.90M	-35.60M
YoY Change	-27.81%	29.89%	20.68%
NET CHANGE
Cash From Operating Activities	103.7M	95.70M	122.8M
Cash From Investing Activities	-69.30M	-77.30M	-67.00M
Cash From Financing Activities	-25.70M	-23.90M	-35.60M
Net Change In Cash	8.700M	-5.500M	20.20M
YoY Change	-56.93%	-93.1%	32.03%
FREE CASH FLOW
Cash From Operating Activities	$103.7M	$95.70M	$122.8M
Capital Expenditures	-$67.60M	-$78.20M	-$49.20M
Free Cash Flow	$171.3M	$173.9M	$172.0M
YoY Change	-0.41%	-27.63%	26.19%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
	dei	Amendment Flag AmendmentFlag	false
	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	Q3
	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2018
	dei	Entity Central Index Key EntityCentralIndexKey	0000066756
	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
	dei	Entity Small Business EntitySmallBusiness	false
	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	410418150
CY2017Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	2100000	USD
CY2018Q3	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	2600000	USD
	us-gaap	Business Combination Reason For Business Combination BusinessCombinationReasonForBusinessCombination	The following acquisition is consistent with ALLETE?s stated strategy of investing in energy infrastructure and related services businesses to complement its regulated businesses, balance exposure to business cycles and changing demand, and provide potential long-term earnings growth.
	us-gaap	Capitalized Contract Cost Amortization CapitalizedContractCostAmortization	1900000	USD
CY2017Q4	us-gaap	Common Stock No Par Value CommonStockNoParValue	0.00
CY2018Q3	us-gaap	Common Stock No Par Value CommonStockNoParValue	0.00
CY2017Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	80000000	shares
CY2018Q3	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	80000000	shares
CY2017Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	51100000	shares
CY2018Q3	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	51400000	shares
CY2017Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	51100000	shares
CY2018Q3	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	51400000	shares
	us-gaap	Number Of Reportable Segments NumberOfReportableSegments	3	Segments
CY2017Q3	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	-100000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	-400000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	-100000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	-300000	USD
CY2017Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	100000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	600000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	0	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	0	USD
	dei	Document Type DocumentType	10-Q
	dei	Document Period End Date DocumentPeriodEndDate	2018-09-30
	dei	Entity Registrant Name EntityRegistrantName	ALLETE INC
	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2018Q3	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	51424535	shares
CY2018Q3	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	128000000.0	USD
CY2017Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	98900000	USD
CY2018Q3	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	129400000	USD
CY2017Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	135100000	USD
CY2018Q3	us-gaap	Inventory Net InventoryNet	154800000	USD
CY2017Q4	us-gaap	Inventory Net InventoryNet	95900000	USD
CY2018Q3	us-gaap	Other Assets Current OtherAssetsCurrent	27200000	USD
CY2017Q4	us-gaap	Other Assets Current OtherAssetsCurrent	37600000	USD
CY2018Q3	us-gaap	Assets Current AssetsCurrent	439400000	USD
CY2017Q4	us-gaap	Assets Current AssetsCurrent	367500000	USD
CY2018Q3	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	3846500000	USD
CY2017Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	3822400000	USD
CY2018Q3	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	370600000	USD
CY2017Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	384700000	USD
CY2018Q3	us-gaap	Equity Method Investments EquityMethodInvestments	126000000.0	USD
CY2017Q4	us-gaap	Equity Method Investments EquityMethodInvestments	118700000	USD
CY2018Q3	us-gaap	Long Term Investments LongTermInvestments	51700000	USD
CY2017Q4	us-gaap	Long Term Investments LongTermInvestments	53100000	USD
CY2018Q3	us-gaap	Intangible Assets Net Including Goodwill IntangibleAssetsNetIncludingGoodwill	224700000	USD
CY2017Q4	us-gaap	Intangible Assets Net Including Goodwill IntangibleAssetsNetIncludingGoodwill	225900000	USD
CY2018Q3	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	104400000	USD
CY2017Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	107700000	USD
CY2018Q3	us-gaap	Assets Assets	5163300000	USD
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CY2018Q3	us-gaap	Accounts Payable Current AccountsPayableCurrent	131800000	USD
CY2017Q4	us-gaap	Accounts Payable Current AccountsPayableCurrent	136300000	USD
CY2018Q3	us-gaap	Taxes Payable Current TaxesPayableCurrent	53900000	USD
CY2017Q4	us-gaap	Taxes Payable Current TaxesPayableCurrent	50000000.0	USD
CY2018Q3	us-gaap	Interest Payable Current InterestPayableCurrent	15500000	USD
CY2017Q4	us-gaap	Interest Payable Current InterestPayableCurrent	17600000	USD
CY2018Q3	us-gaap	Long Term Debt Current LongTermDebtCurrent	56600000	USD
CY2017Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	64100000	USD
CY2018Q3	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	144900000	USD
CY2017Q4	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	83200000	USD
CY2018Q3	us-gaap	Liabilities Current LiabilitiesCurrent	402700000	USD
CY2017Q4	us-gaap	Liabilities Current LiabilitiesCurrent	351200000	USD
CY2018Q3	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	1461700000	USD
CY2017Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	1439200000	USD
CY2018Q3	us-gaap	Deferred Tax Liabilities Noncurrent DeferredTaxLiabilitiesNoncurrent	231300000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Noncurrent DeferredTaxLiabilitiesNoncurrent	230500000	USD
CY2018Q3	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	512300000	USD
CY2017Q4	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	532000000.0	USD
CY2018Q3	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	173600000	USD
CY2017Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	191800000	USD
CY2018Q3	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	265600000	USD
CY2017Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	267100000	USD
CY2018Q3	us-gaap	Liabilities Liabilities	3047200000	USD
CY2017Q4	us-gaap	Liabilities Liabilities	3011800000	USD
CY2018Q3	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
CY2017Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
CY2018Q3	us-gaap	Common Stock Value CommonStockValue	1421100000	USD
CY2017Q4	us-gaap	Common Stock Value CommonStockValue	1401400000	USD
CY2018Q3	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-27300000	USD
CY2017Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-22600000	USD
CY2018Q3	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	722300000	USD
CY2017Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	689400000	USD
CY2018Q3	us-gaap	Stockholders Equity StockholdersEquity	2116100000	USD
CY2017Q4	us-gaap	Stockholders Equity StockholdersEquity	2068200000	USD
CY2018Q3	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	5163300000	USD
CY2017Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	5080000000.0	USD
CY2018Q3	us-gaap	Regulated Operating Revenue RegulatedOperatingRevenue	261300000	USD
CY2017Q3	us-gaap	Regulated Operating Revenue RegulatedOperatingRevenue	277600000	USD
	us-gaap	Regulated Operating Revenue RegulatedOperatingRevenue	789300000	USD
	us-gaap	Regulated Operating Revenue RegulatedOperatingRevenue	824100000	USD
CY2018Q3	us-gaap	Unregulated Operating Revenue UnregulatedOperatingRevenue	80700000	USD
CY2017Q3	us-gaap	Unregulated Operating Revenue UnregulatedOperatingRevenue	79000000.0	USD
	us-gaap	Unregulated Operating Revenue UnregulatedOperatingRevenue	243100000	USD
	us-gaap	Unregulated Operating Revenue UnregulatedOperatingRevenue	239600000	USD
CY2018Q3	ale	Amortizationof Power Purchase Agreements AmortizationofPowerPurchaseAgreements	6000000.0	USD
CY2017Q3	ale	Amortizationof Power Purchase Agreements AmortizationofPowerPurchaseAgreements	5900000	USD
	ale	Amortizationof Power Purchase Agreements AmortizationofPowerPurchaseAgreements	17900000	USD
	ale	Amortizationof Power Purchase Agreements AmortizationofPowerPurchaseAgreements	17700000	USD
CY2018Q3	us-gaap	Revenues Revenues	348000000.0	USD
CY2017Q3	us-gaap	Revenues Revenues	362500000	USD
	us-gaap	Revenues Revenues	1050300000	USD
	us-gaap	Revenues Revenues	1081400000	USD
CY2018Q3	ale	Fuel Purchased Powerand Gas Utility FuelPurchasedPowerandGasUtility	103200000	USD
CY2017Q3	ale	Fuel Purchased Powerand Gas Utility FuelPurchasedPowerandGasUtility	93500000	USD
	ale	Fuel Purchased Powerand Gas Utility FuelPurchasedPowerandGasUtility	300600000	USD
	ale	Fuel Purchased Powerand Gas Utility FuelPurchasedPowerandGasUtility	283200000	USD
CY2018Q3	ale	Transmission Services Utility TransmissionServicesUtility	17900000	USD
CY2017Q3	ale	Transmission Services Utility TransmissionServicesUtility	18900000	USD
	ale	Transmission Services Utility TransmissionServicesUtility	53100000	USD
	ale	Transmission Services Utility TransmissionServicesUtility	53100000	USD
CY2018Q3	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	38700000	USD
CY2017Q3	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	36000000.0	USD
	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	108600000	USD
	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	105900000	USD
CY2018Q3	us-gaap	Operating Expenses OperatingExpenses	80300000	USD
CY2017Q3	us-gaap	Operating Expenses OperatingExpenses	81100000	USD
	us-gaap	Operating Expenses OperatingExpenses	253600000	USD
	us-gaap	Operating Expenses OperatingExpenses	251400000	USD
CY2018Q3	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	51500000	USD
CY2017Q3	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	50900000	USD
	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	153400000	USD
	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	151500000	USD
CY2018Q3	us-gaap	Taxes Other TaxesOther	13100000	USD
CY2017Q3	us-gaap	Taxes Other TaxesOther	14100000	USD
	us-gaap	Taxes Other TaxesOther	43800000	USD
	us-gaap	Taxes Other TaxesOther	42700000	USD
CY2018Q3	us-gaap	Costs And Expenses CostsAndExpenses	304700000	USD
CY2017Q3	us-gaap	Costs And Expenses CostsAndExpenses	294500000	USD
	us-gaap	Costs And Expenses CostsAndExpenses	913100000	USD
	us-gaap	Costs And Expenses CostsAndExpenses	887800000	USD
CY2018Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	43300000	USD
CY2017Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	68000000.0	USD
	us-gaap	Operating Income Loss OperatingIncomeLoss	137200000	USD
	us-gaap	Operating Income Loss OperatingIncomeLoss	193600000	USD
CY2018Q3	us-gaap	Interest Expense InterestExpense	17600000	USD
CY2017Q3	us-gaap	Interest Expense InterestExpense	16600000	USD
	us-gaap	Interest Expense InterestExpense	51600000	USD
	us-gaap	Interest Expense InterestExpense	50500000	USD
CY2018Q3	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	4000000.0	USD
CY2017Q3	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	5900000	USD
	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	13000000.0	USD
	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	17300000	USD
CY2018Q3	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	1400000	USD
CY2017Q3	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	1800000	USD
	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	5700000	USD
	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	5000000.0	USD
CY2018Q3	us-gaap	Nonoperating Income Expense NonoperatingIncomeExpense	-12200000	USD
CY2017Q3	us-gaap	Nonoperating Income Expense NonoperatingIncomeExpense	-8900000	USD
	us-gaap	Nonoperating Income Expense NonoperatingIncomeExpense	-32900000	USD
	us-gaap	Nonoperating Income Expense NonoperatingIncomeExpense	-28200000	USD
CY2018Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	31100000	USD
CY2017Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	59100000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	104300000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	165400000	USD
CY2018Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	400000	USD
CY2017Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	14200000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-8700000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	34600000	USD
CY2018Q3	us-gaap	Net Income Loss NetIncomeLoss	30700000	USD
CY2017Q3	us-gaap	Net Income Loss NetIncomeLoss	44900000	USD
	us-gaap	Net Income Loss NetIncomeLoss	113000000.0	USD
	us-gaap	Net Income Loss NetIncomeLoss	130800000	USD
CY2018Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	51400000	shares
CY2017Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	51000000.0	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	51300000	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	50700000	shares
CY2018Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	51600000	shares
CY2017Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	51200000	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	51500000	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	50900000	shares
CY2018Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.59
CY2017Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.88
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.20
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.58
CY2018Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.59
CY2017Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.88
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.19
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.57
CY2018Q3	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.56
CY2017Q3	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.535
	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.68
	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.605
CY2018Q3	us-gaap	Net Income Loss NetIncomeLoss	30700000	USD
CY2017Q3	us-gaap	Net Income Loss NetIncomeLoss	44900000	USD
	us-gaap	Net Income Loss NetIncomeLoss	113000000.0	USD
	us-gaap	Net Income Loss NetIncomeLoss	130800000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax	0	USD
CY2017Q3	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax	100000	USD
	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax	0	USD
	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax	-100000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	0	USD
CY2017Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	100000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-100000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	800000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-300000	USD
CY2017Q3	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-200000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-1000000.0	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-600000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	300000	USD
CY2017Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	400000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	900000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	1300000	USD
CY2018Q3	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	31000000.0	USD
CY2017Q3	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	45300000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	113900000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	132100000	USD
	us-gaap	Net Income Loss NetIncomeLoss	113000000.0	USD
	us-gaap	Net Income Loss NetIncomeLoss	130800000	USD
	us-gaap	Increase Decrease In Allowance For Equity Funds Used During Construction IncreaseDecreaseInAllowanceForEquityFundsUsedDuringConstruction	900000	USD
	us-gaap	Increase Decrease In Allowance For Equity Funds Used During Construction IncreaseDecreaseInAllowanceForEquityFundsUsedDuringConstruction	700000	USD
	us-gaap	Income Loss From Equity Method Investments Net Of Dividends Or Distributions IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions	-1300000	USD
	us-gaap	Income Loss From Equity Method Investments Net Of Dividends Or Distributions IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions	-3800000	USD
	us-gaap	Depreciation Depreciation	149300000	USD
	us-gaap	Depreciation Depreciation	147400000	USD
	ale	Amortizationof Power Purchase Agreements AmortizationofPowerPurchaseAgreements	17900000	USD
	ale	Amortizationof Power Purchase Agreements AmortizationofPowerPurchaseAgreements	17700000	USD
	us-gaap	Other Depreciation And Amortization OtherDepreciationAndAmortization	7800000	USD
	us-gaap	Other Depreciation And Amortization OtherDepreciationAndAmortization	7600000	USD
	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-9100000	USD
	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	34300000	USD
	us-gaap	Share Based Compensation ShareBasedCompensation	5100000	USD
	us-gaap	Share Based Compensation ShareBasedCompensation	5000000.0	USD
	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	6400000	USD
	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	7600000	USD
	ale	Provisionfor Interim Rate Refund ProvisionforInterimRateRefund	13000000.0	USD
	ale	Provisionfor Interim Rate Refund ProvisionforInterimRateRefund	0	USD
	ale	Provisionfor Tax Reform Refund ProvisionforTaxReformRefund	9200000	USD
	ale	Provisionfor Tax Reform Refund ProvisionforTaxReformRefund	0	USD
	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	1500000	USD
	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	500000	USD
	us-gaap	Increase Decrease In Accounts And Other Receivables IncreaseDecreaseInAccountsAndOtherReceivables	3900000	USD
	us-gaap	Increase Decrease In Accounts And Other Receivables IncreaseDecreaseInAccountsAndOtherReceivables	-9600000	USD
	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	-12600000	USD
	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	5300000	USD
	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	5700000	USD
	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	2100000	USD
	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	9900000	USD
	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	-2600000	USD
	us-gaap	Increase Decrease In Other Current Liabilities IncreaseDecreaseInOtherCurrentLiabilities	21200000	USD
	us-gaap	Increase Decrease In Other Current Liabilities IncreaseDecreaseInOtherCurrentLiabilities	2700000	USD
	us-gaap	Pension Contributions PensionContributions	15000000.0	USD
	us-gaap	Pension Contributions PensionContributions	1700000	USD
	us-gaap	Increase Decrease In Other Noncurrent Assets IncreaseDecreaseInOtherNoncurrentAssets	7200000	USD
	us-gaap	Increase Decrease In Other Noncurrent Assets IncreaseDecreaseInOtherNoncurrentAssets	23900000	USD
	us-gaap	Increase Decrease In Other Noncurrent Liabilities IncreaseDecreaseInOtherNoncurrentLiabilities	1700000	USD
	us-gaap	Increase Decrease In Other Noncurrent Liabilities IncreaseDecreaseInOtherNoncurrentLiabilities	-23900000	USD
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	298100000	USD
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	307200000	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities ProceedsFromSaleOfAvailableForSaleSecurities	9300000	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities ProceedsFromSaleOfAvailableForSaleSecurities	5200000	USD
	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	12500000	USD
	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	5900000	USD
	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	0	USD
	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	17400000	USD
	us-gaap	Payments To Acquire Equity Method Investments PaymentsToAcquireEquityMethodInvestments	5000000.0	USD
	us-gaap	Payments To Acquire Equity Method Investments PaymentsToAcquireEquityMethodInvestments	6600000	USD
	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	201000000.0	USD
	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	130300000	USD
	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-1400000	USD
	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-3300000	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-207800000	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-151700000	USD
	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	14600000	USD
	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	80500000	USD
	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	72700000	USD
	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	131500000	USD
	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	59500000	USD
	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	183600000	USD
	us-gaap	Payment For Contingent Consideration Liability Financing Activities PaymentForContingentConsiderationLiabilityFinancingActivities	0	USD
	us-gaap	Payment For Contingent Consideration Liability Financing Activities PaymentForContingentConsiderationLiabilityFinancingActivities	19700000	USD
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	86200000	USD
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	81400000	USD
	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-500000	USD
	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-1600000	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-58900000	USD
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	31400000	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-74300000	USD
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	81200000	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	110100000	USD
CY2016Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	38300000	USD
CY2018Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	141500000	USD
CY2017Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	119500000	USD
CY2017Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	2068200000	USD
CY2017Q4	us-gaap	Cumulative Effect Of New Accounting Principle In Period Of Adoption CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	500000	USD
CY2017Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest Adjusted Balance1 StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAdjustedBalance1	2068700000	USD
	us-gaap	Net Income Loss NetIncomeLoss	113000000.0	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-100000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-1000000.0	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	113900000	USD
	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	19700000	USD
	us-gaap	Dividends Common Stock DividendsCommonStock	86200000	USD
CY2018Q3	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	2116100000	USD
CY2018Q3	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	128000000.0	USD
CY2017Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	98900000	USD
CY2017Q3	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	104400000	USD
CY2016Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	27500000	USD
CY2018Q3	us-gaap	Restricted Cash Current RestrictedCashCurrent	4800000	USD
CY2017Q4	us-gaap	Restricted Cash Current RestrictedCashCurrent	2600000	USD
CY2017Q3	us-gaap	Restricted Cash Current RestrictedCashCurrent	6500000	USD
CY2016Q4	us-gaap	Restricted Cash Current RestrictedCashCurrent	2200000	USD
CY2018Q3	us-gaap	Restricted Cash Noncurrent RestrictedCashNoncurrent	8700000	USD
CY2017Q4	us-gaap	Restricted Cash Noncurrent RestrictedCashNoncurrent	8600000	USD
CY2017Q3	us-gaap	Restricted Cash Noncurrent RestrictedCashNoncurrent	8600000	USD
CY2016Q4	us-gaap	Restricted Cash Noncurrent RestrictedCashNoncurrent	8600000	USD
CY2018Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	141500000	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	110100000	USD
CY2017Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	119500000	USD
CY2016Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	38300000	USD
CY2018Q3	us-gaap	Energy Related Inventory Coal EnergyRelatedInventoryCoal	27300000	USD
CY2017Q4	us-gaap	Energy Related Inventory Coal EnergyRelatedInventoryCoal	34800000	USD
CY2018Q3	us-gaap	Inventory Supplies Net Of Reserves InventorySuppliesNetOfReserves	44000000.0	USD
CY2017Q4	us-gaap	Inventory Supplies Net Of Reserves InventorySuppliesNetOfReserves	46500000	USD
CY2018Q3	us-gaap	Other Inventory OtherInventory	66700000	USD
CY2017Q4	us-gaap	Other Inventory OtherInventory	0	USD
CY2018Q3	us-gaap	Inventory Raw Materials InventoryRawMaterials	3100000	USD
CY2017Q4	us-gaap	Inventory Raw Materials InventoryRawMaterials	2800000	USD
CY2018Q3	us-gaap	Inventory Work In Process InventoryWorkInProcess	5500000	USD
CY2017Q4	us-gaap	Inventory Work In Process InventoryWorkInProcess	4200000	USD
CY2018Q3	us-gaap	Inventory Finished Goods InventoryFinishedGoods	9000000.0	USD
CY2017Q4	us-gaap	Inventory Finished Goods InventoryFinishedGoods	8300000	USD
CY2018Q3	us-gaap	Inventory Valuation Reserves InventoryValuationReserves	800000	USD
CY2017Q4	us-gaap	Inventory Valuation Reserves InventoryValuationReserves	700000	USD
CY2018Q3	us-gaap	Inventory Net InventoryNet	154800000	USD
CY2017Q4	us-gaap	Inventory Net InventoryNet	95900000	USD
CY2018Q3	us-gaap	Contract With Customer Asset Net Noncurrent ContractWithCustomerAssetNetNoncurrent	31100000	USD
CY2017Q4	us-gaap	Contract With Customer Asset Net Noncurrent ContractWithCustomerAssetNetNoncurrent	31600000	USD
CY2018Q3	us-gaap	Notes Receivable Gross NotesReceivableGross	10400000	USD
CY2017Q4	us-gaap	Notes Receivable Gross NotesReceivableGross	11000000.0	USD
CY2018Q3	us-gaap	Other Assets Miscellaneous Noncurrent OtherAssetsMiscellaneousNoncurrent	62900000	USD
CY2017Q4	us-gaap	Other Assets Miscellaneous Noncurrent OtherAssetsMiscellaneousNoncurrent	65100000	USD
CY2018Q3	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	104400000	USD
CY2017Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	107700000	USD
CY2018Q3	ale	Provisionfor Interim Rate Refunds ProvisionforInterimRateRefunds	36700000	USD
CY2017Q4	ale	Provisionfor Interim Rate Refunds ProvisionforInterimRateRefunds	0	USD
CY2018Q3	us-gaap	Contract With Customer Liability Current ContractWithCustomerLiabilityCurrent	22700000	USD
CY2017Q4	us-gaap	Contract With Customer Liability Current ContractWithCustomerLiabilityCurrent	8700000	USD
CY2018Q3	ale	Power Purchase Agreement Current Liability PowerPurchaseAgreementCurrentLiability	15400000	USD
CY2017Q4	ale	Power Purchase Agreement Current Liability PowerPurchaseAgreementCurrentLiability	24500000	USD
CY2018Q3	ale	Provisionfor Tax Reform Refunds ProvisionforTaxReformRefunds	9200000	USD
CY2017Q4	ale	Provisionfor Tax Reform Refunds ProvisionforTaxReformRefunds	0	USD
CY2018Q3	us-gaap	Business Combination Contingent Consideration Liability Current BusinessCombinationContingentConsiderationLiabilityCurrent	5700000	USD
CY2017Q4	us-gaap	Business Combination Contingent Consideration Liability Current BusinessCombinationContingentConsiderationLiabilityCurrent	0	USD
CY2018Q3	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	55200000	USD
CY2017Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	50000000.0	USD
CY2018Q3	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	144900000	USD
CY2017Q4	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	83200000	USD
CY2018Q3	us-gaap	Asset Retirement Obligations Noncurrent AssetRetirementObligationsNoncurrent	138300000	USD
CY2017Q4	us-gaap	Asset Retirement Obligations Noncurrent AssetRetirementObligationsNoncurrent	122700000	USD
CY2018Q3	ale	Power Purchase Agreement Noncurrent Liability PowerPurchaseAgreementNoncurrentLiability	80000000.0	USD
CY2017Q4	ale	Power Purchase Agreement Noncurrent Liability PowerPurchaseAgreementNoncurrentLiability	89500000	USD
CY2018Q3	us-gaap	Business Combination Contingent Consideration Liability Noncurrent BusinessCombinationContingentConsiderationLiabilityNoncurrent	0	USD
CY2017Q4	us-gaap	Business Combination Contingent Consideration Liability Noncurrent BusinessCombinationContingentConsiderationLiabilityNoncurrent	5400000	USD
CY2018Q3	us-gaap	Other Accrued Liabilities Noncurrent OtherAccruedLiabilitiesNoncurrent	47300000	USD
CY2017Q4	us-gaap	Other Accrued Liabilities Noncurrent OtherAccruedLiabilitiesNoncurrent	49500000	USD
CY2018Q3	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	265600000	USD
CY2017Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	267100000	USD
	us-gaap	Interest Paid Net InterestPaidNet	52900000	USD
	us-gaap	Interest Paid Net InterestPaidNet	51400000	USD
	ale	Increase Decreasein Accounts Payablefor Capital Additionsto Property Plantand Equipment IncreaseDecreaseinAccountsPayableforCapitalAdditionstoPropertyPlantandEquipment	14400000	USD
	ale	Increase Decreasein Accounts Payablefor Capital Additionsto Property Plantand Equipment IncreaseDecreaseinAccountsPayableforCapitalAdditionstoPropertyPlantandEquipment	-1200000	USD
	ale	Reclassificationof Property Plantand Equipmentto Inventory ReclassificationofPropertyPlantandEquipmenttoInventory	46300000	USD
	ale	Reclassificationof Property Plantand Equipmentto Inventory ReclassificationofPropertyPlantandEquipmenttoInventory	0	USD
	us-gaap	Increase Decrease In Asset Retirement Obligations IncreaseDecreaseInAssetRetirementObligations	15400000	USD
	us-gaap	Increase Decrease In Asset Retirement Obligations IncreaseDecreaseInAssetRetirementObligations	19700000	USD
	us-gaap	Increase Decrease In Allowance For Equity Funds Used During Construction IncreaseDecreaseInAllowanceForEquityFundsUsedDuringConstruction	900000	USD
	us-gaap	Increase Decrease In Allowance For Equity Funds Used During Construction IncreaseDecreaseInAllowanceForEquityFundsUsedDuringConstruction	700000	USD
	us-gaap	Stock Issued During Period Value Employee Benefit Plan StockIssuedDuringPeriodValueEmployeeBenefitPlan	0	USD
	us-gaap	Stock Issued During Period Value Employee Benefit Plan StockIssuedDuringPeriodValueEmployeeBenefitPlan	13500000	USD
	us-gaap	Revenue Performance Obligation Description Of Payment Terms RevenuePerformanceObligationDescriptionOfPaymentTerms	Payment terms and conditions vary across our businesses. Aside from taconite-producing Large Power Customers, payment terms generally require payment to be made within 15 to 30 days from the end of the period that the service has been rendered or goods provided. In the case of its taconite-producing Large Power Customers, as permitted by the MPUC, Minnesota Power requires weekly payments for electric usage based on monthly energy usage estimates.
CY2018Q3	us-gaap	Contract With Customer Asset Net Noncurrent ContractWithCustomerAssetNetNoncurrent	31100000	USD
CY2017Q4	us-gaap	Contract With Customer Asset Net Noncurrent ContractWithCustomerAssetNetNoncurrent	31600000	USD
	us-gaap	Capitalized Contract Cost Amortization CapitalizedContractCostAmortization	1900000	USD
CY2018Q3	us-gaap	Operating Leases Future Minimum Payments Due OperatingLeasesFutureMinimumPaymentsDue	65000000	USD
CY2018Q3	us-gaap	Real Estate Investments RealEstateInvestments	25400000	USD
CY2017Q4	us-gaap	Real Estate Investments RealEstateInvestments	26400000	USD
CY2018Q3	us-gaap	Available For Sale Securities Noncurrent AvailableForSaleSecuritiesNoncurrent	21000000.0	USD
CY2017Q4	us-gaap	Available For Sale Securities Noncurrent AvailableForSaleSecuritiesNoncurrent	19100000	USD
CY2018Q3	us-gaap	Other Restricted Assets Noncurrent OtherRestrictedAssetsNoncurrent	1500000	USD
CY2017Q4	us-gaap	Other Restricted Assets Noncurrent OtherRestrictedAssetsNoncurrent	3800000	USD
CY2018Q3	us-gaap	Other Long Term Investments OtherLongTermInvestments	3800000	USD
CY2017Q4	us-gaap	Other Long Term Investments OtherLongTermInvestments	3800000	USD
CY2018Q3	us-gaap	Long Term Investments LongTermInvestments	51700000	USD
CY2017Q4	us-gaap	Long Term Investments LongTermInvestments	53100000	USD
CY2018Q3	us-gaap	Available For Sale Securities Debt Maturities Within One Year Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue	1800000	USD
CY2018Q3	ale	Availableforsale Securities Debt Maturities After One Year Through Three Years Fair Value AvailableforsaleSecuritiesDebtMaturitiesAfterOneYearThroughThreeYearsFairValue	3500000	USD
CY2018Q3	ale	Availableforsale Securities Debt Maturities After Three Years Through Five Years Fair Value AvailableforsaleSecuritiesDebtMaturitiesAfterThreeYearsThroughFiveYearsFairValue	1900000	USD
CY2018Q3	ale	Availableforsale Securities Debt Maturities After Five Years Fair Value AvailableforsaleSecuritiesDebtMaturitiesAfterFiveYearsFairValue	1100000	USD
	us-gaap	Business Combination Reason For Business Combination BusinessCombinationReasonForBusinessCombination	The following acquisition is consistent with ALLETE’s stated strategy of investing in energy infrastructure and related services businesses to complement its regulated businesses, balance exposure to business cycles and changing demand, and provide potential long-term earnings growth.
CY2018Q3	us-gaap	Goodwill Goodwill	148500000	USD
CY2017Q4	us-gaap	Goodwill Goodwill	148300000	USD
CY2017Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	61000000.0	USD
	us-gaap	Finite Lived Intangible Assets Period Increase Decrease FiniteLivedIntangibleAssetsPeriodIncreaseDecrease	2700000	USD
	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	4100000	USD
CY2018Q3	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	59600000	USD
CY2017Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	77600000	USD
	ale	Intangible Assets Increase Decrease IntangibleAssetsIncreaseDecrease	2700000	USD
	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	4100000	USD
CY2018Q3	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	76200000	USD
CY2018Q3	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	1400000	USD
	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	4100000	USD
CY2017Q3	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	1300000	USD
	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	4100000	USD
CY2018Q3	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	18900000	USD
CY2017Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	14800000	USD
CY2018Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Remainder Of Fiscal Year FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear	1500000	USD
CY2018Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Two FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	5300000	USD
CY2018Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Three FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	4900000	USD
CY2018Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Four FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	4900000	USD
CY2018Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Five FiniteLivedIntangibleAssetsAmortizationExpenseYearFive	4600000	USD
CY2018Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense After Year Five FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive	38400000	USD
CY2018Q3	us-gaap	Long Term Debt LongTermDebt	1527900000	USD
CY2017Q4	us-gaap	Long Term Debt LongTermDebt	1513300000	USD
	us-gaap	Types Of Net Regulatory Assets Earning Returns TypesOfNetRegulatoryAssetsEarningReturns	No regulatory assets or liabilities are currently earning a return.
CY2018Q3	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	370600000	USD
CY2017Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	384700000	USD
CY2018Q3	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	50300000	USD
CY2017Q4	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	0	USD
CY2018Q3	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	512300000	USD
CY2017Q4	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	532000000.0	USD
CY2018Q3	us-gaap	Regulatory Liabilities RegulatoryLiabilities	562600000	USD
CY2017Q4	us-gaap	Regulatory Liabilities RegulatoryLiabilities	532000000.0	USD
CY2018Q3	ale	Debt Current Gross DebtCurrentGross	57000000.0	USD
CY2018Q3	ale	Unamortized Debt Issuance Expense Debt Current UnamortizedDebtIssuanceExpenseDebtCurrent	400000	USD
CY2018Q3	us-gaap	Debt Current DebtCurrent	56600000	USD
CY2018Q3	us-gaap	Debt Instrument Carrying Amount DebtInstrumentCarryingAmount	1470900000	USD
CY2018Q3	ale	Unamortized Debt Issuance Expense Long Term Debt Excluding Current Maturities UnamortizedDebtIssuanceExpenseLongTermDebtExcludingCurrentMaturities	9200000	USD
CY2018Q3	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	1461700000	USD
CY2018Q3	ale	Debt Long Termand Short Term Combined Amount Gross DebtLongTermandShortTermCombinedAmountGross	1527900000	USD
CY2018Q3	us-gaap	Unamortized Debt Issuance Expense UnamortizedDebtIssuanceExpense	9600000	USD
CY2018Q3	us-gaap	Debt Longterm And Shortterm Combined Amount DebtLongtermAndShorttermCombinedAmount	1518300000	USD
CY2017Q4	ale	Debt Current Gross DebtCurrentGross	64600000	USD
CY2017Q4	ale	Unamortized Debt Issuance Expense Debt Current UnamortizedDebtIssuanceExpenseDebtCurrent	500000	USD
CY2017Q4	us-gaap	Debt Current DebtCurrent	64100000	USD
CY2017Q4	us-gaap	Debt Instrument Carrying Amount DebtInstrumentCarryingAmount	1448700000	USD
CY2017Q4	ale	Unamortized Debt Issuance Expense Long Term Debt Excluding Current Maturities UnamortizedDebtIssuanceExpenseLongTermDebtExcludingCurrentMaturities	9500000	USD
CY2017Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	1439200000	USD
CY2017Q4	ale	Debt Long Termand Short Term Combined Amount Gross DebtLongTermandShortTermCombinedAmountGross	1513300000	USD
CY2017Q4	us-gaap	Unamortized Debt Issuance Expense UnamortizedDebtIssuanceExpense	10000000.0	USD
CY2017Q4	us-gaap	Debt Longterm And Shortterm Combined Amount DebtLongtermAndShorttermCombinedAmount	1503300000	USD
CY2018Q3	ale	Debt Instrument Actual Indebtedness To Total Capital Ratio DebtInstrumentActualIndebtednessToTotalCapitalRatio	0.42
CY2018Q3	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	0	USD
CY2017Q3	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	0	USD
	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	0	USD
	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	0	USD
CY2018Q3	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	0	USD
CY2017Q3	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	100000	USD
	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	400000	USD
	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	300000	USD
CY2018Q3	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	0	USD
CY2017Q3	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	100000	USD
	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	400000	USD
	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	300000	USD
CY2018Q3	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-2200000	USD
CY2017Q3	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	9200000	USD
	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-16400000	USD
	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	20300000	USD
CY2018Q3	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	2800000	USD
CY2017Q3	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	5000000.0	USD
	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	7800000	USD
	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	14500000	USD
CY2018Q3	us-gaap	Deferred Other Tax Expense Benefit DeferredOtherTaxExpenseBenefit	-200000	USD
CY2017Q3	us-gaap	Deferred Other Tax Expense Benefit DeferredOtherTaxExpenseBenefit	-100000	USD
	us-gaap	Deferred Other Tax Expense Benefit DeferredOtherTaxExpenseBenefit	-500000	USD
	us-gaap	Deferred Other Tax Expense Benefit DeferredOtherTaxExpenseBenefit	-500000	USD
CY2018Q3	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	400000	USD
CY2017Q3	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	14100000	USD
	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-9100000	USD
	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	34300000	USD
CY2018Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	400000	USD
CY2017Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	14200000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-8700000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	34600000	USD
CY2017	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.35
	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.21
CY2018Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	31100000	USD
CY2017Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	59100000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	104300000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	165400000	USD
CY2018Q3	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.21
CY2017Q3	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.35
	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.21
	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.35
CY2018Q3	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	6500000	USD
CY2017Q3	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	20700000	USD
	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	21900000	USD
	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	57900000	USD
CY2018Q3	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	2200000	USD
CY2017Q3	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	3300000	USD
	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	6400000	USD
	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	9600000	USD
CY2018Q3	us-gaap	Income Tax Reconciliation Tax Credits Other IncomeTaxReconciliationTaxCreditsOther	9400000	USD
CY2017Q3	us-gaap	Income Tax Reconciliation Tax Credits Other IncomeTaxReconciliationTaxCreditsOther	10400000	USD
	us-gaap	Income Tax Reconciliation Tax Credits Other IncomeTaxReconciliationTaxCreditsOther	35000000.0	USD
	us-gaap	Income Tax Reconciliation Tax Credits Other IncomeTaxReconciliationTaxCreditsOther	33400000	USD
CY2018Q3	ale	Effective Income Tax Rate Reconciliation Regulatory Differences EffectiveIncomeTaxRateReconciliationRegulatoryDifferences	-1100000	USD
CY2017Q3	ale	Effective Income Tax Rate Reconciliation Regulatory Differences EffectiveIncomeTaxRateReconciliationRegulatoryDifferences	300000	USD
	ale	Effective Income Tax Rate Reconciliation Regulatory Differences EffectiveIncomeTaxRateReconciliationRegulatoryDifferences	-5500000	USD
	ale	Effective Income Tax Rate Reconciliation Regulatory Differences EffectiveIncomeTaxRateReconciliationRegulatoryDifferences	1000000.0	USD
CY2018Q3	us-gaap	Income Tax Reconciliation Other Reconciling Items IncomeTaxReconciliationOtherReconcilingItems	2200000	USD
CY2017Q3	us-gaap	Income Tax Reconciliation Other Reconciling Items IncomeTaxReconciliationOtherReconcilingItems	300000	USD
	us-gaap	Income Tax Reconciliation Other Reconciling Items IncomeTaxReconciliationOtherReconcilingItems	3500000	USD
	us-gaap	Income Tax Reconciliation Other Reconciling Items IncomeTaxReconciliationOtherReconcilingItems	-500000	USD
CY2018Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	400000	USD
CY2017Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	14200000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-8700000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	34600000	USD
	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.083
	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.209
CY2017	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.35
	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.21
CY2018Q3	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1700000	USD
CY2017Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1700000	USD
CY2018Q3	us-gaap	Unrecognized Tax Benefits That Would Impact Effective Tax Rate UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate	800000	USD
CY2018Q3	us-gaap	Net Income Loss NetIncomeLoss	30700000	USD
CY2018Q3	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	30700000	USD
CY2017Q3	us-gaap	Net Income Loss NetIncomeLoss	44900000	USD
CY2017Q3	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	44900000	USD
CY2018Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	51400000	shares
CY2018Q3	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	200000	shares
CY2018Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	51600000	shares
CY2017Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	51000000.0	shares
CY2017Q3	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	200000	shares
CY2017Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	51200000	shares
CY2018Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.59
CY2018Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.59
CY2017Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.88
CY2017Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.88
	us-gaap	Net Income Loss NetIncomeLoss	113000000.0	USD
	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	113000000.0	USD
	us-gaap	Net Income Loss NetIncomeLoss	130800000	USD
	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	130800000	USD
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	51300000	shares
	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	200000	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	51500000	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	50700000	shares
	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	200000	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	50900000	shares
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.20
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.19
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.58
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.57
CY2018Q3	us-gaap	Operating Leases Future Minimum Payments Remainder Of Fiscal Year OperatingLeasesFutureMinimumPaymentsRemainderOfFiscalYear	3600000	USD
CY2018Q3	us-gaap	Operating Leases Future Minimum Payments Due In Two Years OperatingLeasesFutureMinimumPaymentsDueInTwoYears	12800000	USD
CY2018Q3	us-gaap	Operating Leases Future Minimum Payments Due In Three Years OperatingLeasesFutureMinimumPaymentsDueInThreeYears	9500000	USD
CY2018Q3	us-gaap	Operating Leases Future Minimum Payments Due In Four Years OperatingLeasesFutureMinimumPaymentsDueInFourYears	7300000	USD
CY2018Q3	us-gaap	Operating Leases Future Minimum Payments Due In Five Years OperatingLeasesFutureMinimumPaymentsDueInFiveYears	6100000	USD
CY2018Q3	us-gaap	Operating Leases Future Minimum Payments Due Thereafter OperatingLeasesFutureMinimumPaymentsDueThereafter	30000000.0	USD
CY2018Q3	us-gaap	Revenues Revenues	348000000.0	USD
CY2017Q3	us-gaap	Revenues Revenues	362500000	USD
	us-gaap	Revenues Revenues	1050300000	USD
	us-gaap	Revenues Revenues	1081400000	USD
CY2018Q3	us-gaap	Net Income Loss NetIncomeLoss	30700000	USD
CY2017Q3	us-gaap	Net Income Loss NetIncomeLoss	44900000	USD
	us-gaap	Net Income Loss NetIncomeLoss	113000000.0	USD
	us-gaap	Net Income Loss NetIncomeLoss	130800000	USD
CY2018Q3	us-gaap	Assets Assets	5163300000	USD
CY2017Q4	us-gaap	Assets Assets	5080000000.0	USD

Files In Submission

Name	View Source	Status
0000066756-18-000088-index-headers.html	Edgar Link	pending
0000066756-18-000088-index.html	Edgar Link	pending
0000066756-18-000088.txt	Edgar Link	pending
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ale-20180930.xsd	Edgar Link	pending
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ale-20180930_lab.xml	Edgar Link	unprocessable
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$ALE
ALLETE INC Stock $ale

2018 Q3 Form 10-Q Financial Statement

#000006675618000088 Filed on November 01, 2018

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$ALE ALLETE INC Stock $ale

2018 Q3 Form 10-Q Financial Statement

#000006675618000088 Filed on November 01, 2018

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$ALE
ALLETE INC Stock $ale