$ALE
ALLETE INC Stock $ale

$ale Overview Financials Valuation SEC Filings Company Website

2019 Q4 Form 10-K Financial Statement

#000006675621000025 Filed on February 17, 2021

Income Statement

Concept	2019 Q4	2018 Q4	2018 Q3
Revenue	$304.6M	$448.3M	$348.0M
YoY Change	-32.05%	32.67%	-4.0%
Cost Of Revenue	$18.80M	$109.4M	$38.70M
YoY Change	-82.82%	162.35%	7.5%
Gross Profit	$285.8M	$338.9M	$309.3M
YoY Change	-15.67%	13.65%	-5.27%
Gross Profit Margin	93.83%	75.6%	88.88%
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$53.40M	$53.40M	$51.50M
YoY Change	0.0%	97.05%	1.18%
% of Gross Profit	18.68%	15.76%	16.65%
Operating Expenses	$236.0M	$274.9M	$80.30M
YoY Change	-14.15%	3.74%	-0.99%
Operating Profit	$49.80M	$64.00M	$43.30M
YoY Change	-22.19%	98.14%	-36.32%
Interest Expense	-$9.600M	-$11.80M	$17.60M
YoY Change	-18.64%	-2.48%	6.02%
% of Operating Profit	-19.28%	-18.44%	40.65%
Other Income/Expense, Net	$4.100M	$2.100M	-$12.20M
YoY Change	95.24%	425.0%	37.08%
Pretax Income	$47.30M	$54.30M	$31.10M
YoY Change	-12.89%	152.56%	-47.38%
Income Tax	-$2.300M	-$23.20M	$400.0K
% Of Pretax Income	-4.86%	-42.73%	1.29%
Net Earnings	$49.70M	$61.10M	$30.70M
YoY Change	-18.66%	47.58%	-31.63%
Net Earnings / Revenue	16.32%	13.63%	8.82%
Basic Earnings Per Share	$0.96	$1.19	$0.59
Diluted Earnings Per Share	$0.96	$1.18	$0.59
COMMON SHARES
Basic Shares Outstanding			51.40M shares
Diluted Shares Outstanding			51.60M shares

Balance Sheet

Concept	2019 Q4	2018 Q4	2018 Q3
SHORT-TERM ASSETS
Cash & Short-Term Investments	$69.30M	$69.10M	$128.0M
YoY Change	0.29%	-30.13%	22.61%
Cash & Equivalents	$69.30M	$69.10M	$128.0M
Short-Term Investments
Other Short-Term Assets	$31.00M	$34.10M	$27.20M
YoY Change	-9.09%	-9.31%	-38.46%
Inventory	$72.80M	$86.70M	$154.8M
Prepaid Expenses
Receivables	$96.40M	$144.4M	$129.4M
Other Receivables	$0.00	$0.00	$0.00
Total Short-Term Assets	$269.5M	$334.3M	$439.4M
YoY Change	-19.38%	-9.03%	13.28%
LONG-TERM ASSETS
Property, Plant & Equipment	$4.377B	$3.904B	$3.847B
YoY Change	12.1%	2.15%	2.67%
Goodwill	$0.00	$148.5M	$148.5M
YoY Change	-100.0%	0.13%	-0.93%
Intangibles	$1.000M	$74.80M	$76.20M
YoY Change	-98.66%	-3.61%	-3.54%
Long-Term Investments	$197.6M	$161.1M	$126.0M
YoY Change	22.66%	35.72%	-13.7%
Other Assets	$218.2M	$152.4M	$104.4M
YoY Change	43.18%	41.5%	1.36%
Total Long-Term Assets	$5.213B	$4.831B	$4.724B
YoY Change	7.92%	2.51%	2.9%
TOTAL ASSETS
Total Short-Term Assets	$269.5M	$334.3M	$439.4M
Total Long-Term Assets	$5.213B	$4.831B	$4.724B
Total Assets	$5.483B	$5.165B	$5.163B
YoY Change	6.15%	1.67%	3.71%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$165.2M	$149.8M	$131.8M
YoY Change	10.28%	9.9%	75.03%
Accrued Expenses	$25.00M	$17.90M	$15.50M
YoY Change	39.66%	1.7%	6.16%
Deferred Revenue	$0.00	$7.600M	$22.70M
YoY Change	-100.0%	-12.64%
Short-Term Debt	$0.00	$0.00	$0.00
YoY Change
Long-Term Debt Due	$212.9M	$57.50M	$56.60M
YoY Change	270.26%	-10.3%	-11.7%
Total Short-Term Liabilities	$507.4M	$405.1M	$402.7M
YoY Change	25.25%	15.35%	38.62%
LONG-TERM LIABILITIES
Long-Term Debt	$1.401B	$1.429B	$1.462B
YoY Change	-1.93%	-0.74%	1.18%
Other Long-Term Liabilities	$293.0M	$262.6M	$265.6M
YoY Change	11.58%	-1.68%	-11.79%
Total Long-Term Liabilities	$1.694B	$1.691B	$1.727B
YoY Change	0.17%	-0.89%	-1.05%
TOTAL LIABILITIES
Total Short-Term Liabilities	$507.4M	$405.1M	$402.7M
Total Long-Term Liabilities	$1.694B	$1.691B	$1.727B
Total Liabilities	$3.147B	$3.009B	$3.047B
YoY Change	4.59%	-0.09%	3.79%
SHAREHOLDERS EQUITY
Retained Earnings	$818.8M	$754.6M	$722.3M
YoY Change	8.51%	9.46%	6.96%
Common Stock	$1.437B	$1.429B	$1.421B
YoY Change	0.57%	1.93%	1.92%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$2.232B	$2.156B	$2.116B
YoY Change
Total Liabilities & Shareholders Equity	$5.483B	$5.165B	$5.163B
YoY Change	6.15%	1.67%	3.71%

Cashflow Statement

Concept	2019 Q4	2018 Q4	2018 Q3
OPERATING ACTIVITIES
Net Income	$49.70M	$61.10M	$30.70M
YoY Change	-18.66%	47.58%	-31.63%
Depreciation, Depletion And Amortization	$53.40M	$53.40M	$51.50M
YoY Change	0.0%	97.05%	1.18%
Cash From Operating Activities	$73.10M	$135.0M	$103.7M
YoY Change	-45.85%	41.07%	-15.55%
INVESTING ACTIVITIES
Capital Expenditures	-$175.8M	-$111.4M	-$67.60M
YoY Change	57.81%	42.46%	37.4%
Acquisitions
YoY Change
Other Investing Activities	-$9.500M	-$29.80M	-$1.700M
YoY Change	-68.12%	-3411.11%	-90.45%
Cash From Investing Activities	-$185.3M	-$141.2M	-$69.30M
YoY Change	31.23%	82.66%	3.43%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	69.50M	-56.30M	-25.70M
YoY Change	-223.45%	135.56%	-27.81%
NET CHANGE
Cash From Operating Activities	73.10M	135.0M	103.7M
Cash From Investing Activities	-185.3M	-141.2M	-69.30M
Cash From Financing Activities	69.50M	-56.30M	-25.70M
Net Change In Cash	-42.70M	-62.50M	8.700M
YoY Change	-31.68%	1036.36%	-56.93%
FREE CASH FLOW
Cash From Operating Activities	$73.10M	$135.0M	$103.7M
Capital Expenditures	-$175.8M	-$111.4M	-$67.60M
Free Cash Flow	$248.9M	$246.4M	$171.3M
YoY Change	1.01%	41.69%	-0.41%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2020	dei	Entity Central Index Key EntityCentralIndexKey	0000066756
CY2020	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
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CY2020	dei	City Area Code CityAreaCode	218
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CY2019Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	51700000	shares
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CY2020	dei	Document Transition Report DocumentTransitionReport	false
CY2020	dei	Entity File Number EntityFileNumber	1-3548
CY2020	dei	Entity Registrant Name EntityRegistrantName	ALLETE, Inc.
CY2020	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	MN
CY2020	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	41-0418150
CY2020	dei	Entity Address Address Line1 EntityAddressAddressLine1	30 West Superior Street
CY2020	dei	Entity Address City Or Town EntityAddressCityOrTown	Duluth
CY2020	dei	Entity Address State Or Province EntityAddressStateOrProvince	MN
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CY2020	dei	Security12b Title Security12bTitle	Common Stock, without par value
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CY2020	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	-12600000	USD
CY2019	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	-100000	USD
CY2018	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	0	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	174200000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	185600000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	174100000	USD
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	51900000	shares
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	51600000	shares
CY2018	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	51300000	shares
CY2020	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	51900000	shares
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	51700000	shares
CY2018	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	51500000	shares
CY2020	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.36
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.59
CY2018	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.39
CY2020	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.35
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.59
CY2018	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.38
CY2020	us-gaap	Profit Loss ProfitLoss	161600000	USD
CY2019	us-gaap	Profit Loss ProfitLoss	185500000	USD
CY2018	us-gaap	Profit Loss ProfitLoss	174100000	USD
CY2020	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	100000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	200000	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-100000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	7600000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-3500000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-1000000.0	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-7500000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	3700000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	900000	USD
CY2020	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	154100000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	189200000	USD
CY2018	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	175000000.0	USD
CY2020	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	-12600000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	189300000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	-100000	USD
CY2018	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	0	USD
CY2020	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	166700000	USD
CY2018	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	175000000.0	USD
CY2020	us-gaap	Profit Loss ProfitLoss	161600000	USD
CY2019	us-gaap	Profit Loss ProfitLoss	185500000	USD
CY2018	us-gaap	Profit Loss ProfitLoss	174100000	USD
CY2020	us-gaap	Increase Decrease In Allowance For Equity Funds Used During Construction IncreaseDecreaseInAllowanceForEquityFundsUsedDuringConstruction	1900000	USD
CY2019	us-gaap	Increase Decrease In Allowance For Equity Funds Used During Construction IncreaseDecreaseInAllowanceForEquityFundsUsedDuringConstruction	2300000	USD
CY2018	us-gaap	Increase Decrease In Allowance For Equity Funds Used During Construction IncreaseDecreaseInAllowanceForEquityFundsUsedDuringConstruction	1200000	USD
CY2020	us-gaap	Income Loss From Equity Method Investments Net Of Dividends Or Distributions IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions	3200000	USD
CY2019	us-gaap	Income Loss From Equity Method Investments Net Of Dividends Or Distributions IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions	5600000	USD
CY2018	us-gaap	Income Loss From Equity Method Investments Net Of Dividends Or Distributions IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions	2300000	USD
CY2020	us-gaap	Business Combination Contingent Consideration Arrangements Change In Amount Of Contingent Consideration Liability1 BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1	0	USD
CY2019	us-gaap	Business Combination Contingent Consideration Arrangements Change In Amount Of Contingent Consideration Liability1 BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1	0	USD
CY2018	us-gaap	Business Combination Contingent Consideration Arrangements Change In Amount Of Contingent Consideration Liability1 BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1	-2000000.0	USD
CY2020	us-gaap	Gain Loss On Sale Of Other Assets GainLossOnSaleOfOtherAssets	1300000	USD
CY2019	us-gaap	Gain Loss On Sale Of Other Assets GainLossOnSaleOfOtherAssets	1600000	USD
CY2018	us-gaap	Gain Loss On Sale Of Other Assets GainLossOnSaleOfOtherAssets	-2700000	USD
CY2020	us-gaap	Depreciation Depreciation	217700000	USD
CY2019	us-gaap	Depreciation Depreciation	200600000	USD
CY2018	us-gaap	Depreciation Depreciation	200100000	USD
CY2020	ale	Amortizationof Power Purchase Agreements AmortizationofPowerPurchaseAgreements	11300000	USD
CY2019	ale	Amortizationof Power Purchase Agreements AmortizationofPowerPurchaseAgreements	11600000	USD
CY2018	ale	Amortizationof Power Purchase Agreements AmortizationofPowerPurchaseAgreements	23600000	USD
CY2020	us-gaap	Other Depreciation And Amortization OtherDepreciationAndAmortization	10400000	USD
CY2019	us-gaap	Other Depreciation And Amortization OtherDepreciationAndAmortization	11700000	USD
CY2018	us-gaap	Other Depreciation And Amortization OtherDepreciationAndAmortization	9600000	USD
CY2020	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-39500000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-6700000	USD
CY2018	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-15800000	USD
CY2020	us-gaap	Share Based Compensation ShareBasedCompensation	6100000	USD
CY2019	us-gaap	Share Based Compensation ShareBasedCompensation	6300000	USD
CY2018	us-gaap	Share Based Compensation ShareBasedCompensation	6800000	USD
CY2020	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	100000	USD
CY2019	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	1200000	USD
CY2018	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	8600000	USD
CY2020	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	2700000	USD
CY2019	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	-100000	USD
CY2018	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	1100000	USD
CY2020	ale	Provision Payments For Interim Rate Refund ProvisionPaymentsForInterimRateRefund	0	USD
CY2019	ale	Provision Payments For Interim Rate Refund ProvisionPaymentsForInterimRateRefund	-40000000.0	USD
CY2018	ale	Provision Payments For Interim Rate Refund ProvisionPaymentsForInterimRateRefund	16300000	USD
CY2020	ale	Provision Payments For Tax Reform Refund ProvisionPaymentsForTaxReformRefund	200000	USD
CY2019	ale	Provision Payments For Tax Reform Refund ProvisionPaymentsForTaxReformRefund	10400000	USD
CY2018	ale	Provision Payments For Tax Reform Refund ProvisionPaymentsForTaxReformRefund	-10700000	USD
	us-gaap	Gain Loss On Sale Of Business GainLossOnSaleOfBusiness	0	USD
CY2019	us-gaap	Gain Loss On Sale Of Business GainLossOnSaleOfBusiness	23600000	USD
CY2018	us-gaap	Gain Loss On Sale Of Business GainLossOnSaleOfBusiness	0	USD
CY2020	us-gaap	Increase Decrease In Accounts And Other Receivables IncreaseDecreaseInAccountsAndOtherReceivables	18200000	USD
CY2019	us-gaap	Increase Decrease In Accounts And Other Receivables IncreaseDecreaseInAccountsAndOtherReceivables	-22600000	USD
CY2018	us-gaap	Increase Decrease In Accounts And Other Receivables IncreaseDecreaseInAccountsAndOtherReceivables	10700000	USD
CY2020	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	1400000	USD
CY2019	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	4100000	USD
CY2018	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	-55500000	USD
CY2020	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	-900000	USD
CY2019	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	-300000	USD
CY2018	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	4000000.0	USD
CY2020	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	11800000	USD
CY2019	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	-8800000	USD
CY2018	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	13600000	USD
CY2020	us-gaap	Increase Decrease In Other Current Liabilities IncreaseDecreaseInOtherCurrentLiabilities	16700000	USD
CY2019	us-gaap	Increase Decrease In Other Current Liabilities IncreaseDecreaseInOtherCurrentLiabilities	-13700000	USD
CY2018	us-gaap	Increase Decrease In Other Current Liabilities IncreaseDecreaseInOtherCurrentLiabilities	6700000	USD
CY2020	us-gaap	Pension Contributions PensionContributions	10700000	USD
CY2019	us-gaap	Pension Contributions PensionContributions	10400000	USD
CY2018	us-gaap	Pension Contributions PensionContributions	15000000.0	USD
CY2020	us-gaap	Increase Decrease In Other Noncurrent Assets IncreaseDecreaseInOtherNoncurrentAssets	31000000.0	USD
CY2019	us-gaap	Increase Decrease In Other Noncurrent Assets IncreaseDecreaseInOtherNoncurrentAssets	25200000	USD
CY2018	us-gaap	Increase Decrease In Other Noncurrent Assets IncreaseDecreaseInOtherNoncurrentAssets	-5000000.0	USD
CY2020	us-gaap	Increase Decrease In Other Noncurrent Liabilities IncreaseDecreaseInOtherNoncurrentLiabilities	-9500000	USD
CY2019	us-gaap	Increase Decrease In Other Noncurrent Liabilities IncreaseDecreaseInOtherNoncurrentLiabilities	-17200000	USD
CY2018	us-gaap	Increase Decrease In Other Noncurrent Liabilities IncreaseDecreaseInOtherNoncurrentLiabilities	-4900000	USD
CY2020	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	299800000	USD
CY2019	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	246900000	USD
CY2018	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	431300000	USD
CY2020	us-gaap	Proceeds From Sale Of Available For Sale Securities ProceedsFromSaleOfAvailableForSaleSecurities	12800000	USD
CY2019	us-gaap	Proceeds From Sale Of Available For Sale Securities ProceedsFromSaleOfAvailableForSaleSecurities	12100000	USD
CY2018	us-gaap	Proceeds From Sale Of Available For Sale Securities ProceedsFromSaleOfAvailableForSaleSecurities	10200000	USD
CY2020	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	8700000	USD
CY2019	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	12200000	USD
CY2018	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	13300000	USD
CY2020	us-gaap	Payments To Acquire Equity Method Investments PaymentsToAcquireEquityMethodInvestments	99100000	USD
CY2019	us-gaap	Payments To Acquire Equity Method Investments PaymentsToAcquireEquityMethodInvestments	37900000	USD
CY2018	us-gaap	Payments To Acquire Equity Method Investments PaymentsToAcquireEquityMethodInvestments	39200000	USD
CY2020	us-gaap	Proceeds From Equity Method Investment Dividends Or Distributions Return Of Capital ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital	0	USD
CY2019	us-gaap	Proceeds From Equity Method Investment Dividends Or Distributions Return Of Capital ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital	8300000	USD
CY2018	us-gaap	Proceeds From Equity Method Investment Dividends Or Distributions Return Of Capital ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital	0	USD
CY2020	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	717800000	USD
CY2019	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	597100000	USD
CY2018	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	312400000	USD
CY2020	us-gaap	Proceeds From Sale Of Productive Assets ProceedsFromSaleOfProductiveAssets	0	USD
CY2019	us-gaap	Proceeds From Sale Of Productive Assets ProceedsFromSaleOfProductiveAssets	268600000	USD
CY2018	us-gaap	Proceeds From Sale Of Productive Assets ProceedsFromSaleOfProductiveAssets	0	USD
CY2020	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	0	USD
CY2019	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-15500000	USD
CY2018	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-7500000	USD
CY2020	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-812800000	USD
CY2019	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-342700000	USD
CY2018	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-347200000	USD
CY2020	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	18100000	USD
CY2019	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	1900000	USD
CY2018	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	20300000	USD
CY2020	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	672400000	USD
CY2019	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	201900000	USD
CY2018	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	75600000	USD
CY2020	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	488600000	USD
CY2019	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	72200000	USD
CY2018	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	95500000	USD
CY2020	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	414500000	USD
CY2019	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	103800000	USD
CY2018	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	0	USD
CY2020	us-gaap	Payment For Contingent Consideration Liability Financing Activities PaymentForContingentConsiderationLiabilityFinancingActivities	0	USD
CY2019	us-gaap	Payment For Contingent Consideration Liability Financing Activities PaymentForContingentConsiderationLiabilityFinancingActivities	3800000	USD
CY2018	us-gaap	Payment For Contingent Consideration Liability Financing Activities PaymentForContingentConsiderationLiabilityFinancingActivities	0	USD
CY2020	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	128200000	USD
CY2019	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	121400000	USD
CY2018	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	115000000.0	USD
CY2020	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-2500000	USD
CY2019	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-900000	USD
CY2018	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-600000	USD
CY2020	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	485700000	USD
CY2019	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	109300000	USD
CY2018	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-115200000	USD
CY2020	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	-27300000	USD
CY2019	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	13500000	USD
CY2018	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	-31100000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	92500000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	79000000.0	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	110100000	USD
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	65200000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	92500000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	79000000.0	USD
CY2020Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	2800200000	USD
CY2019Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	2335600000	USD
CY2018Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	2155800000	USD
CY2020	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	2.47
CY2019	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	2.35
CY2018	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	2.24
CY2020	us-gaap	Number Of Reportable Segments NumberOfReportableSegments	3
CY2020Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	44300000	USD
CY2019Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	69300000	USD
CY2018Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	69100000	USD
CY2020Q4	us-gaap	Restricted Cash Current RestrictedCashCurrent	800000	USD
CY2019Q4	us-gaap	Restricted Cash Current RestrictedCashCurrent	2800000	USD
CY2018Q4	us-gaap	Restricted Cash Current RestrictedCashCurrent	1300000	USD
CY2020Q4	us-gaap	Restricted Cash Noncurrent RestrictedCashNoncurrent	20100000	USD
CY2019Q4	us-gaap	Restricted Cash Noncurrent RestrictedCashNoncurrent	20400000	USD
CY2018Q4	us-gaap	Restricted Cash Noncurrent RestrictedCashNoncurrent	8600000	USD
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	65200000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	92500000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	79000000.0	USD
CY2020	us-gaap	Interest Paid Net InterestPaidNet	62000000.0	USD
CY2019	us-gaap	Interest Paid Net InterestPaidNet	63500000	USD
CY2018	us-gaap	Interest Paid Net InterestPaidNet	66000000.0	USD
CY2020	ale	Recognitionof Rightofuse Assetsand Lease Liabilities RecognitionofRightofuseAssetsandLeaseLiabilities	0	USD
CY2019	ale	Recognitionof Rightofuse Assetsand Lease Liabilities RecognitionofRightofuseAssetsandLeaseLiabilities	28700000	USD
CY2018	ale	Recognitionof Rightofuse Assetsand Lease Liabilities RecognitionofRightofuseAssetsandLeaseLiabilities	0	USD
CY2020	ale	Increase Decreasein Accounts Payablefor Capital Additionsto Property Plantand Equipment IncreaseDecreaseinAccountsPayableforCapitalAdditionstoPropertyPlantandEquipment	-67000000.0	USD
CY2019	ale	Increase Decreasein Accounts Payablefor Capital Additionsto Property Plantand Equipment IncreaseDecreaseinAccountsPayableforCapitalAdditionstoPropertyPlantandEquipment	33900000	USD
CY2018	ale	Increase Decreasein Accounts Payablefor Capital Additionsto Property Plantand Equipment IncreaseDecreaseinAccountsPayableforCapitalAdditionstoPropertyPlantandEquipment	-100000	USD
CY2020	ale	Reclassificationof Property Plantand Equipmentto Inventory ReclassificationofPropertyPlantandEquipmenttoInventory	0	USD
CY2019	ale	Reclassificationof Property Plantand Equipmentto Inventory ReclassificationofPropertyPlantandEquipmenttoInventory	0	USD
CY2018	ale	Reclassificationof Property Plantand Equipmentto Inventory ReclassificationofPropertyPlantandEquipmenttoInventory	46300000	USD
CY2020	ale	Costs Incurred Capitalized Asset Retirement Obligation Costs CostsIncurredCapitalizedAssetRetirementObligationCosts	4100000	USD
CY2019	ale	Costs Incurred Capitalized Asset Retirement Obligation Costs CostsIncurredCapitalizedAssetRetirementObligationCosts	20700000	USD
CY2018	ale	Costs Incurred Capitalized Asset Retirement Obligation Costs CostsIncurredCapitalizedAssetRetirementObligationCosts	14200000	USD
CY2020	us-gaap	Increase Decrease In Allowance For Equity Funds Used During Construction IncreaseDecreaseInAllowanceForEquityFundsUsedDuringConstruction	1900000	USD
CY2019	us-gaap	Increase Decrease In Allowance For Equity Funds Used During Construction IncreaseDecreaseInAllowanceForEquityFundsUsedDuringConstruction	2300000	USD
CY2018	us-gaap	Increase Decrease In Allowance For Equity Funds Used During Construction IncreaseDecreaseInAllowanceForEquityFundsUsedDuringConstruction	1200000	USD
CY2018	ale	Reclassificationof Property Plantand Equipmentto Inventory ReclassificationofPropertyPlantandEquipmenttoInventory	46300000	USD
CY2020Q4	us-gaap	Accounts Receivable Gross Current AccountsReceivableGrossCurrent	93500000	USD
CY2019Q4	us-gaap	Accounts Receivable Gross Current AccountsReceivableGrossCurrent	77200000	USD
CY2020Q4	us-gaap	Unbilled Receivables Current UnbilledReceivablesCurrent	20900000	USD
CY2019Q4	us-gaap	Unbilled Receivables Current UnbilledReceivablesCurrent	20100000	USD
CY2020Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	2500000	USD
CY2019Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	900000	USD
CY2020Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	111900000	USD
CY2019Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	96400000	USD
CY2020Q4	us-gaap	Energy Related Inventory Coal EnergyRelatedInventoryCoal	23100000	USD
CY2019Q4	us-gaap	Energy Related Inventory Coal EnergyRelatedInventoryCoal	25900000	USD
CY2020Q4	us-gaap	Inventory Supplies Net Of Reserves InventorySuppliesNetOfReserves	51100000	USD
CY2019Q4	us-gaap	Inventory Supplies Net Of Reserves InventorySuppliesNetOfReserves	46900000	USD
CY2020Q4	us-gaap	Inventory Net InventoryNet	74200000	USD
CY2019Q4	us-gaap	Inventory Net InventoryNet	72800000	USD
CY2020	us-gaap	Impairment Of Real Estate ImpairmentOfRealEstate	0	USD
CY2020Q4	us-gaap	Contract With Customer Asset Net Noncurrent ContractWithCustomerAssetNetNoncurrent	25500000	USD
CY2019Q4	us-gaap	Contract With Customer Asset Net Noncurrent ContractWithCustomerAssetNetNoncurrent	28000000.0	USD
CY2020Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	22400000	USD
CY2019Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	28600000	USD
CY2020Q4	us-gaap	Real Estate Investments RealEstateInvestments	18200000	USD
CY2019Q4	us-gaap	Real Estate Investments RealEstateInvestments	21900000	USD
CY2020Q4	us-gaap	Restricted Cash Noncurrent RestrictedCashNoncurrent	20100000	USD
CY2019Q4	us-gaap	Restricted Cash Noncurrent RestrictedCashNoncurrent	20400000	USD
CY2020Q4	ale	Other Postretirement Benefit Plans OtherPostretirementBenefitPlans	34200000	USD
CY2019Q4	ale	Other Postretirement Benefit Plans OtherPostretirementBenefitPlans	37500000	USD
CY2020Q4	us-gaap	Other Assets Miscellaneous Noncurrent OtherAssetsMiscellaneousNoncurrent	86400000	USD
CY2019Q4	us-gaap	Other Assets Miscellaneous Noncurrent OtherAssetsMiscellaneousNoncurrent	81800000	USD
CY2020Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	206800000	USD
CY2019Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	218200000	USD
CY2020Q4	ale	Power Purchase Agreement Current Liability PowerPurchaseAgreementCurrentLiability	12500000	USD
CY2019Q4	ale	Power Purchase Agreement Current Liability PowerPurchaseAgreementCurrentLiability	12300000	USD
CY2020Q4	ale	Public Utilities Fuel Adjustment Clause PublicUtilitiesFuelAdjustmentClause	3700000	USD
CY2019Q4	ale	Public Utilities Fuel Adjustment Clause PublicUtilitiesFuelAdjustmentClause	0	USD
CY2020Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	44600000	USD
CY2019Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	41200000	USD
CY2020Q4	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	66700000	USD
CY2019Q4	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	60400000	USD
CY2020Q4	us-gaap	Asset Retirement Obligations Noncurrent AssetRetirementObligationsNoncurrent	166600000	USD
CY2019Q4	us-gaap	Asset Retirement Obligations Noncurrent AssetRetirementObligationsNoncurrent	160300000	USD
CY2020Q4	ale	Power Purchase Agreement Noncurrent Liability PowerPurchaseAgreementNoncurrentLiability	52100000	USD
CY2019Q4	ale	Power Purchase Agreement Noncurrent Liability PowerPurchaseAgreementNoncurrentLiability	64600000	USD
CY2020Q4	us-gaap	Other Accrued Liabilities Noncurrent OtherAccruedLiabilitiesNoncurrent	50100000	USD
CY2019Q4	us-gaap	Other Accrued Liabilities Noncurrent OtherAccruedLiabilitiesNoncurrent	46300000	USD
CY2020Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	285300000	USD
CY2019Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	293000000.0	USD
CY2020	us-gaap	Lessee Operating Lease Residual Value Guarantee Description LesseeOperatingLeaseResidualValueGuaranteeDescription	Our largest operating lease is for the dragline at BNI Energy which includes a termination payment at the end of the lease term if we do not exercise our purchase option.
CY2020Q4	us-gaap	Residual Value Of Leased Asset ResidualValueOfLeasedAsset	3000000	USD
CY2020	us-gaap	Operating Lease Cost OperatingLeaseCost	8300000	USD
CY2019	us-gaap	Operating Lease Cost OperatingLeaseCost	9400000	USD
CY2020	us-gaap	Operating Lease Payments OperatingLeasePayments	8300000	USD
CY2019	us-gaap	Operating Lease Payments OperatingLeasePayments	9400000	USD
CY2020Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	22400000	USD
CY2019Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	28600000	USD
CY2020Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	22400000	USD
CY2019Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	28600000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	6000000.0	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	5000000.0	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	3200000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	2900000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	2900000	USD
CY2020Q4	us-gaap	Operating Leases Future Minimum Payments Due Thereafter OperatingLeasesFutureMinimumPaymentsDueThereafter	8600000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	28600000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	6200000	USD
CY2020Q4	ale	Large Power Customer Contracts LargePowerCustomerContracts	8
CY2020	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. 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.
CY2020Q4	us-gaap	Contract With Customer Asset Net Noncurrent ContractWithCustomerAssetNetNoncurrent	25500000	USD
CY2019Q4	us-gaap	Contract With Customer Asset Net Noncurrent ContractWithCustomerAssetNetNoncurrent	28000000.0	USD
CY2020	us-gaap	Capitalized Contract Cost Amortization CapitalizedContractCostAmortization	2600000	USD
CY2018	us-gaap	Business Combination Contingent Consideration Arrangements Change In Amount Of Contingent Consideration Liability1 BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1	-2000000.0	USD
CY2020	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	14700000	USD
CY2019	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	18700000	USD
CY2018	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	7800000	USD
CY2020	ale	Morelikelythannotdefined Morelikelythannotdefined	0.50
CY2020Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	4840800000	USD
CY2019Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	4377000000.0	USD
CY2018Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	138600000	USD
CY2019	us-gaap	Asset Retirement Obligation Accretion Expense AssetRetirementObligationAccretionExpense	7200000	USD
CY2019	us-gaap	Asset Retirement Obligation Liabilities Incurred AssetRetirementObligationLiabilitiesIncurred	1400000	USD
CY2019	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	4600000	USD
CY2019	us-gaap	Asset Retirement Obligation Revision Of Estimate AssetRetirementObligationRevisionOfEstimate	17700000	USD
CY2019Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	160300000	USD
CY2020	us-gaap	Asset Retirement Obligation Accretion Expense AssetRetirementObligationAccretionExpense	8300000	USD
CY2020	us-gaap	Asset Retirement Obligation Liabilities Incurred AssetRetirementObligationLiabilitiesIncurred	1400000	USD
CY2020	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	3600000	USD
CY2020	us-gaap	Asset Retirement Obligation Revision Of Estimate AssetRetirementObligationRevisionOfEstimate	200000	USD
CY2020Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	166600000	USD
CY2020Q4	us-gaap	Jointly Owned Utility Plant Gross Ownership Amount Of Plant In Service JointlyOwnedUtilityPlantGrossOwnershipAmountOfPlantInService	764800000	USD
CY2020Q4	us-gaap	Jointly Owned Utility Plant Ownership Amount Of Plant Accumulated Depreciation JointlyOwnedUtilityPlantOwnershipAmountOfPlantAccumulatedDepreciation	304800000	USD
CY2020Q4	us-gaap	Jointly Owned Utility Plant Ownership Amount Of Construction Work In Progress JointlyOwnedUtilityPlantOwnershipAmountOfConstructionWorkInProgress	15000000.0	USD
CY2019Q4	us-gaap	Jointly Owned Utility Plant Gross Ownership Amount Of Plant In Service JointlyOwnedUtilityPlantGrossOwnershipAmountOfPlantInService	763700000	USD
CY2019Q4	us-gaap	Jointly Owned Utility Plant Ownership Amount Of Plant Accumulated Depreciation JointlyOwnedUtilityPlantOwnershipAmountOfPlantAccumulatedDepreciation	272400000	USD
CY2019Q4	us-gaap	Jointly Owned Utility Plant Ownership Amount Of Construction Work In Progress JointlyOwnedUtilityPlantOwnershipAmountOfConstructionWorkInProgress	5700000	USD
CY2020Q4	ale	Conservation Improvement Program Goal Next Fiscal Year ConservationImprovementProgramGoalNextFiscalYear	10500000	USD
CY2020Q4	ale	Conservation Improvement Program Goal In2 Years ConservationImprovementProgramGoalIn2Years	10700000	USD
CY2020Q4	ale	Conservation Improvement Program Goal In3 Years ConservationImprovementProgramGoalIn3Years	10900000	USD
CY2020	us-gaap	Types Of Net Regulatory Assets Earning Returns TypesOfNetRegulatoryAssetsEarningReturns	With the exception of the regulatory asset for Boswell Units 1 and 2 net plant and equipment, no other regulatory assets are currently earning a return.
CY2020Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	480900000	USD
CY2019Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	420500000	USD
CY2020Q4	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	7600000	USD
CY2019Q4	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	1900000	USD
CY2020Q4	us-gaap	Debt Instrument Carrying Amount DebtInstrumentCarryingAmount	1806400000	USD
CY2020Q4	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	524800000	USD
CY2019Q4	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	560300000	USD
CY2020Q4	us-gaap	Regulatory Liabilities RegulatoryLiabilities	532400000	USD
CY2019Q4	us-gaap	Regulatory Liabilities RegulatoryLiabilities	562200000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue	1800000	USD
CY2020Q4	ale	Availableforsale Securities Debt Maturities After One Year Through Three Years Fair Value AvailableforsaleSecuritiesDebtMaturitiesAfterOneYearThroughThreeYearsFairValue	4300000	USD
CY2020Q4	ale	Availableforsale Securities Debt Maturities After Three Years Through Five Years Fair Value AvailableforsaleSecuritiesDebtMaturitiesAfterThreeYearsThroughFiveYearsFairValue	4000000.0	USD
CY2020Q4	ale	Availableforsale Securities Debt Maturities After Five Years Fair Value AvailableforsaleSecuritiesDebtMaturitiesAfterFiveYearsFairValue	300000	USD
CY2019Q4	us-gaap	Debt Instrument Carrying Amount DebtInstrumentCarryingAmount	1622600000	USD
CY2020Q4	us-gaap	Equity Method Investments EquityMethodInvestments	301200000	USD
CY2019Q4	us-gaap	Equity Method Investments EquityMethodInvestments	197600000	USD
CY2020	us-gaap	Property Plant And Equipment Impairment PropertyPlantAndEquipmentImpairment	The Company assesses the impairment of property, plant, and equipment whenever events or changes in circumstances indicate that the carrying amount of property, plant, and equipment assets may not be recoverable.
CY2020Q4	us-gaap	Debt Current DebtCurrent	203700000	USD
CY2019Q4	us-gaap	Debt Current DebtCurrent	212900000	USD
CY2020Q4	us-gaap	Deferred Finance Costs Current Net DeferredFinanceCostsCurrentNet	300000	USD
CY2020Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	1593200000	USD
CY2019Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	1400900000	USD
CY2020Q4	us-gaap	Deferred Finance Costs Noncurrent Net DeferredFinanceCostsNoncurrentNet	9200000	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Next Twelve Months LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths	204000000.0	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo	89200000	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	89100000	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	73900000	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive	241100000	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal After Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive	1109100000	USD
CY2020Q4	us-gaap	Deferred Finance Costs Net DeferredFinanceCostsNet	9500000	USD
CY2019Q4	us-gaap	Deferred Finance Costs Net DeferredFinanceCostsNet	8800000	USD
CY2020Q4	us-gaap	Long Term Debt LongTermDebt	1796900000	USD
CY2019Q4	us-gaap	Long Term Debt LongTermDebt	1613800000	USD
CY2020Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	203700000	USD
CY2019Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	212900000	USD
CY2020Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	1593200000	USD
CY2019Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	1400900000	USD
CY2020Q4	ale	Debt Instrument Actual Indebtedness To Total Capital Ratio DebtInstrumentActualIndebtednessToTotalCapitalRatio	0.40
CY2020	us-gaap	Net Income Loss NetIncomeLoss	174200000	USD
CY2020	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	174200000	USD
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	51900000	shares
CY2020	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	0	shares
CY2020	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	51900000	shares
CY2020	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.36
CY2020	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.35
CY2019	us-gaap	Net Income Loss NetIncomeLoss	185600000	USD
CY2019	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	185600000	USD
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	51600000	shares
CY2019	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	100000	shares
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	51700000	shares
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.59
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.59
CY2018	us-gaap	Net Income Loss NetIncomeLoss	174100000	USD
CY2018	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	174100000	USD
CY2018	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	51300000	shares
CY2018	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	200000	shares
CY2018	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	51500000	shares
CY2018	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.39
CY2018	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.38
CY2020	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	0	USD
CY2019	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	0	USD
CY2018	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	0	USD
CY2020	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	0	USD
CY2019	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	100000	USD
CY2018	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	300000	USD
CY2020	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	0	USD
CY2019	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	100000	USD
CY2018	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	300000	USD
CY2020	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-48800000	USD
CY2019	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-27800000	USD
CY2018	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-26200000	USD
CY2020	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	9800000	USD
CY2019	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	21700000	USD
CY2018	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	11000000.0	USD
CY2020	us-gaap	Deferred Other Tax Expense Benefit DeferredOtherTaxExpenseBenefit	-500000	USD
CY2019	us-gaap	Deferred Other Tax Expense Benefit DeferredOtherTaxExpenseBenefit	-600000	USD
CY2018	us-gaap	Deferred Other Tax Expense Benefit DeferredOtherTaxExpenseBenefit	-600000	USD
CY2020	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-39500000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-6700000	USD
CY2018	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-15800000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-39500000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-6600000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-15500000	USD
CY2020	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	122100000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	178900000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	158600000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.21
CY2019	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.21
CY2018	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.21
CY2020	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	25600000	USD
CY2019	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	37600000	USD
CY2018	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	33300000	USD
CY2020	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	7700000	USD
CY2019	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	17200000	USD
CY2018	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	8900000	USD
CY2020	us-gaap	Income Tax Reconciliation Tax Credits Other IncomeTaxReconciliationTaxCreditsOther	62700000	USD
CY2019	us-gaap	Income Tax Reconciliation Tax Credits Other IncomeTaxReconciliationTaxCreditsOther	50700000	USD
CY2018	us-gaap	Income Tax Reconciliation Tax Credits Other IncomeTaxReconciliationTaxCreditsOther	45000000.0	USD
CY2020	ale	Effective Income Tax Rate Reconciliation Regulatory Differences EffectiveIncomeTaxRateReconciliationRegulatoryDifferences	-9900000	USD
CY2019	ale	Effective Income Tax Rate Reconciliation Regulatory Differences EffectiveIncomeTaxRateReconciliationRegulatoryDifferences	-8800000	USD
CY2018	ale	Effective Income Tax Rate Reconciliation Regulatory Differences EffectiveIncomeTaxRateReconciliationRegulatoryDifferences	-8200000	USD
CY2020	ale	Effective Income Taxrate Reconciliation Stock Basis Difference EffectiveIncomeTaxrateReconciliationStockBasisDifference	0	USD
CY2019	ale	Effective Income Taxrate Reconciliation Stock Basis Difference EffectiveIncomeTaxrateReconciliationStockBasisDifference	1700000	USD
CY2018	ale	Effective Income Taxrate Reconciliation Stock Basis Difference EffectiveIncomeTaxrateReconciliationStockBasisDifference	0	USD
CY2020	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	0	USD
CY2019	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	0	USD
CY2018	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	-400000	USD
CY2020	us-gaap	Income Tax Reconciliation Minority Interest Income Expense IncomeTaxReconciliationMinorityInterestIncomeExpense	-2700000	USD
CY2019	us-gaap	Income Tax Reconciliation Minority Interest Income Expense IncomeTaxReconciliationMinorityInterestIncomeExpense	0	USD
CY2018	us-gaap	Income Tax Reconciliation Minority Interest Income Expense IncomeTaxReconciliationMinorityInterestIncomeExpense	0	USD
CY2020	us-gaap	Income Tax Reconciliation Other Reconciling Items IncomeTaxReconciliationOtherReconcilingItems	-2900000	USD
CY2019	us-gaap	Income Tax Reconciliation Other Reconciling Items IncomeTaxReconciliationOtherReconcilingItems	-3600000	USD
CY2018	us-gaap	Income Tax Reconciliation Other Reconciling Items IncomeTaxReconciliationOtherReconcilingItems	-4100000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-39500000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-6600000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-15500000	USD
CY2020	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.324
CY2019	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.037
CY2018	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.098
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Compensation DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation	67600000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Compensation DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation	49900000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Property Plant And Equipment DeferredTaxAssetsPropertyPlantAndEquipment	61400000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Property Plant And Equipment DeferredTaxAssetsPropertyPlantAndEquipment	76900000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	60700000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	63200000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards DeferredTaxAssetsTaxCreditCarryforwards	455700000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards DeferredTaxAssetsTaxCreditCarryforwards	395500000	USD
CY2020Q4	ale	Power Purchase Agreements Deferred Tax Asset PowerPurchaseAgreementsDeferredTaxAsset	20100000	USD
CY2020Q4	ale	Deferred Tax Liabilty Partnership Basis Differences DeferredTaxLiabiltyPartnershipBasisDifferences	86700000	USD
CY2019Q4	ale	Power Purchase Agreements Deferred Tax Asset PowerPurchaseAgreementsDeferredTaxAsset	23700000	USD
CY2020Q4	ale	Deferred Tax Assets Regulatory Liabilities DeferredTaxAssetsRegulatoryLiabilities	107700000	USD
CY2019Q4	ale	Deferred Tax Assets Regulatory Liabilities DeferredTaxAssetsRegulatoryLiabilities	116900000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	22400000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	23400000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	795600000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	749500000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	69900000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	70000000.0	USD
CY2020Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	725700000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	679500000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	691500000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	713400000	USD
CY2020Q4	ale	Deferred Tax Liabilities Regulatory Assetsfor Benefit Obligations DeferredTaxLiabilitiesRegulatoryAssetsforBenefitObligations	71500000	USD
CY2019Q4	ale	Deferred Tax Liabilities Regulatory Assetsfor Benefit Obligations DeferredTaxLiabilitiesRegulatoryAssetsforBenefitObligations	54500000	USD
CY2020Q4	us-gaap	Accumulated Deferred Investment Tax Credit AccumulatedDeferredInvestmentTaxCredit	31100000	USD
CY2019Q4	us-gaap	Accumulated Deferred Investment Tax Credit AccumulatedDeferredInvestmentTaxCredit	31600000	USD
CY2019Q4	ale	Deferred Tax Liabilty Partnership Basis Differences DeferredTaxLiabiltyPartnershipBasisDifferences	49400000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Regulatory Assets DeferredTaxLiabilitiesRegulatoryAssets	32600000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Regulatory Assets DeferredTaxLiabilitiesRegulatoryAssets	35400000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	8000000.0	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	8000000.0	USD
CY2020Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	921400000	USD
CY2019Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	892300000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	195700000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	212800000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1400000	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1600000	USD
CY2017Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1700000	USD
CY2020	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	100000	USD
CY2019	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	100000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	100000	USD
CY2020	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	0	USD
CY2019	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	100000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	100000	USD
CY2020	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	100000	USD
CY2019	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	400000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	200000	USD
CY2020	us-gaap	Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	0	USD
CY2019	us-gaap	Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	0	USD
CY2018	us-gaap	Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	100000	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1400000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1400000	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1600000	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits That Would Impact Effective Tax Rate UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate	600000	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits Interest On Income Taxes Accrued UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued	0	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits Interest On Income Taxes Accrued UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued	0	USD
CY2020	us-gaap	Unrecognized Tax Benefits Income Tax Penalties Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesExpense	0	USD
CY2020Q4	us-gaap	Significant Change In Unrecognized Tax Benefits Is Reasonably Possible Amount Of Unrecorded Benefit SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleAmountOfUnrecordedBenefit	0	USD
CY2020	us-gaap	Employee Stock Ownership Plan Esop Compensation Expense EmployeeStockOwnershipPlanESOPCompensationExpense	11200000	USD
CY2019	us-gaap	Employee Stock Ownership Plan Esop Compensation Expense EmployeeStockOwnershipPlanESOPCompensationExpense	10800000	USD
CY2018	us-gaap	Employee Stock Ownership Plan Esop Compensation Expense EmployeeStockOwnershipPlanESOPCompensationExpense	11400000	USD
CY2020	us-gaap	Employee Stock Ownership Plan Esop Compensation Expense EmployeeStockOwnershipPlanESOPCompensationExpense	11200000	USD
CY2019	us-gaap	Employee Stock Ownership Plan Esop Compensation Expense EmployeeStockOwnershipPlanESOPCompensationExpense	10800000	USD
CY2018	us-gaap	Employee Stock Ownership Plan Esop Compensation Expense EmployeeStockOwnershipPlanESOPCompensationExpense	11400000	USD
CY2020	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	3100000	USD
CY2019	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	3100000	USD
CY2018	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	3200000	USD
CY2020	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	900000	USD
CY2019	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	900000	USD
CY2018	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	900000	USD
CY2020	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	0	USD
CY2020	us-gaap	Revenues Revenues	1169100000	USD
CY2019	us-gaap	Revenues Revenues	1240500000	USD
CY2018	us-gaap	Revenues Revenues	1498600000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	174200000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	185600000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	174100000	USD
CY2020	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	217800000	USD
CY2019	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	202000000.0	USD
CY2018	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	205600000	USD
CY2020	us-gaap	Interest Expense InterestExpense	65600000	USD
CY2019	us-gaap	Interest Expense InterestExpense	64900000	USD
CY2018	us-gaap	Interest Expense InterestExpense	67900000	USD
CY2020	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	22100000	USD
CY2019	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	21700000	USD
CY2018	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	17500000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-39500000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-6600000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-15500000	USD
CY2020	ale	Income Tax Expense Benefit Dueto Saleof Subsidiary IncomeTaxExpenseBenefitDuetoSaleofSubsidiary	10400000	USD
CY2020Q4	us-gaap	Assets Assets	6084600000	USD
CY2019Q4	us-gaap	Assets Assets	5482800000	USD
CY2020	us-gaap	Property Plant And Equipment Additions PropertyPlantAndEquipmentAdditions	657200000	USD
CY2019	us-gaap	Property Plant And Equipment Additions PropertyPlantAndEquipmentAdditions	626600000	USD
CY2020Q1	us-gaap	Revenues Revenues	311600000	USD
CY2020Q2	us-gaap	Revenues Revenues	243200000	USD
CY2020Q3	us-gaap	Revenues Revenues	293900000	USD
CY2020Q4	us-gaap	Revenues Revenues	320400000	USD
CY2020Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	60200000	USD
CY2020Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	12700000	USD
CY2020Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	41600000	USD
CY2020Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	36400000	USD
CY2020Q1	us-gaap	Net Income Loss NetIncomeLoss	66300000	USD
CY2020Q2	us-gaap	Net Income Loss NetIncomeLoss	20100000	USD
CY2020Q3	us-gaap	Net Income Loss NetIncomeLoss	40700000	USD
CY2020Q4	us-gaap	Net Income Loss NetIncomeLoss	47100000	USD
CY2020Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.28
CY2020Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.39
CY2020Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.78
CY2020Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.91
CY2020Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.28
CY2020Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.39
CY2020Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.78
CY2020Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.90
CY2019Q1	us-gaap	Revenues Revenues	357200000	USD
CY2019Q2	us-gaap	Revenues Revenues	290400000	USD
CY2019Q3	us-gaap	Revenues Revenues	288300000	USD
CY2019Q4	us-gaap	Revenues Revenues	304600000	USD
CY2019Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	56800000	USD
CY2019Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	36200000	USD
CY2019Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	37000000.0	USD
CY2019Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	49800000	USD
CY2019Q1	us-gaap	Net Income Loss NetIncomeLoss	70500000	USD
CY2019Q2	us-gaap	Net Income Loss NetIncomeLoss	34200000	USD
CY2019Q3	us-gaap	Net Income Loss NetIncomeLoss	31200000	USD
CY2019Q4	us-gaap	Net Income Loss NetIncomeLoss	49700000	USD
CY2019Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.37
CY2019Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.66
CY2019Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.60
CY2019Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.96
CY2019Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.37
CY2019Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.66
CY2019Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.60
CY2019Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.96
CY2018Q1	us-gaap	Revenues Revenues	358200000	USD
CY2018Q2	us-gaap	Revenues Revenues	344100000	USD
CY2018Q3	us-gaap	Revenues Revenues	348000000.0	USD
CY2018Q4	us-gaap	Revenues Revenues	448300000	USD
CY2018Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	57400000	USD
CY2018Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	36500000	USD
CY2018Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	43300000	USD
CY2018Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	64000000.0	USD
CY2018Q1	us-gaap	Net Income Loss NetIncomeLoss	51000000.0	USD
CY2018Q2	us-gaap	Net Income Loss NetIncomeLoss	31300000	USD
CY2018Q3	us-gaap	Net Income Loss NetIncomeLoss	30700000	USD
CY2018Q4	us-gaap	Net Income Loss NetIncomeLoss	61100000	USD
CY2018Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.00
CY2018Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.61
CY2018Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.59
CY2018Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.19
CY2018Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.99
CY2018Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.61
CY2018Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.59
CY2018Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.18

Files In Submission

Name	View Source	Status
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0000066756-21-000025-index.html	Edgar Link	pending
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report.css	Edgar Link	pending
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$ALE
ALLETE INC Stock $ale

2019 Q4 Form 10-K Financial Statement

#000006675621000025 Filed on February 17, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$ALE ALLETE INC Stock $ale

2019 Q4 Form 10-K Financial Statement

#000006675621000025 Filed on February 17, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$ALE
ALLETE INC Stock $ale