$ALE
ALLETE INC Stock $ale

$ale Overview Financials Valuation SEC Filings Company Website

2016 Q4 Form 10-K Financial Statement

#000006675618000029 Filed on February 15, 2018

Income Statement

Concept	2016 Q4	2016	2015 Q4
Revenue	$341.5M	$1.340B	$380.6M
YoY Change	-10.27%	-9.87%	30.93%
Cost Of Revenue	$31.60M	$137.4M	$69.00M
YoY Change	-54.2%	-53.33%
Gross Profit	$309.9M	$1.202B	$311.6M
YoY Change	-0.55%	0.86%
Gross Profit Margin	90.75%	89.74%	81.87%
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$51.00M	$195.8M	$45.80M
YoY Change	11.35%	15.18%	26.87%
% of Gross Profit	16.46%	16.29%	14.7%
Operating Expenses	$248.8M	$340.9M	$245.7M
YoY Change	1.26%	2.22%	2.72%
Operating Profit	$59.40M	$217.0M	$29.60M
YoY Change	100.68%	2.99%	-42.52%
Interest Expense	-$13.80M	$70.30M	-$13.20M
YoY Change	4.55%	8.32%	24.53%
% of Operating Profit	-23.23%	32.4%	-44.59%
Other Income/Expense, Net	$1.100M	-$41.40M	$700.0K
YoY Change	57.14%	-5.69%	-63.16%
Pretax Income	$48.40M	$175.6M	$17.10M
YoY Change	183.04%	5.28%	-60.05%
Income Tax	$4.100M	$19.80M	-$1.700M
% Of Pretax Income	8.47%	11.28%	-9.94%
Net Earnings	$44.30M	$155.3M	$18.30M
YoY Change	142.08%	10.06%	-44.38%
Net Earnings / Revenue	12.97%	11.59%	4.81%
Basic Earnings Per Share	$0.89	$3.15	$0.37
Diluted Earnings Per Share	$0.89	$3.14	$0.37
COMMON SHARES
Basic Shares Outstanding		49.30M shares
Diluted Shares Outstanding		49.50M shares

Balance Sheet

Concept	2016 Q4	2016	2015 Q4
SHORT-TERM ASSETS
Cash & Short-Term Investments	$27.50M	$27.50M	$97.00M
YoY Change	-71.65%	-71.65%	-33.47%
Cash & Equivalents	$27.50M	$27.50M	$97.00M
Short-Term Investments
Other Short-Term Assets	$40.30M	$40.30M	$35.70M
YoY Change	12.89%	12.89%	-56.46%
Inventory	$104.2M	$104.2M	$117.1M
Prepaid Expenses
Receivables	$122.5M	$122.5M	$121.2M
Other Receivables	$0.00	$0.00	$0.00
Total Short-Term Assets	$294.5M	$294.5M	$371.0M
YoY Change	-20.62%	-20.62%	-11.41%
LONG-TERM ASSETS
Property, Plant & Equipment	$3.741B	$3.773B	$3.669B
YoY Change	1.97%	1.44%	11.7%
Goodwill	$131.2M		$130.6M
YoY Change	0.46%		4403.45%
Intangibles	$82.20M		$84.60M
YoY Change	-2.84%		4352.63%
Long-Term Investments	$135.6M	$159.5M	$124.5M
YoY Change	8.92%	7.05%	2.81%
Other Assets	$106.5M	$436.6M	$68.10M
YoY Change	56.39%	-0.8%	14.26%
Total Long-Term Assets	$4.582B	$4.582B	$4.524B
YoY Change	1.3%	1.3%	14.75%
TOTAL ASSETS
Total Short-Term Assets	$294.5M	$294.5M	$371.0M
Total Long-Term Assets	$4.582B	$4.582B	$4.524B
Total Assets	$4.877B	$4.877B	$4.895B
YoY Change	-0.36%	-0.36%	12.24%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$74.00M	$74.00M	$88.80M
YoY Change	-16.67%	-16.67%	-33.78%
Accrued Expenses	$17.60M	$17.60M	$18.60M
YoY Change	-5.38%	-5.38%	3.33%
Deferred Revenue
YoY Change
Short-Term Debt	$0.00	$0.00	$1.600M
YoY Change	-100.0%	-100.0%	-56.76%
Long-Term Debt Due	$187.7M	$187.7M	$35.70M
YoY Change	425.77%	425.77%	-64.55%
Total Short-Term Liabilities	$399.5M	$399.5M	$274.8M
YoY Change	45.38%	45.38%	-33.94%
LONG-TERM LIABILITIES
Long-Term Debt	$1.370B	$1.370B	$1.557B
YoY Change	-11.97%	-11.97%	22.31%
Other Long-Term Liabilities	$322.7M	$659.4M	$349.0M
YoY Change	-7.54%	-0.21%	31.7%
Total Long-Term Liabilities	$1.693B	$2.030B	$1.906B
YoY Change	-11.16%	-8.46%	23.92%
TOTAL LIABILITIES
Total Short-Term Liabilities	$399.5M	$399.5M	$274.8M
Total Long-Term Liabilities	$1.693B	$2.030B	$1.906B
Total Liabilities	$2.984B	$2.984B	$3.072B
YoY Change	-2.87%	-2.94%	11.73%
SHAREHOLDERS EQUITY
Retained Earnings	$625.9M		$573.3M
YoY Change	9.17%		8.15%
Common Stock	$1.295B		$1.271B
YoY Change	1.88%		14.79%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$1.893B	$1.893B	$1.820B
YoY Change
Total Liabilities & Shareholders Equity	$4.877B	$4.877B	$4.895B
YoY Change	-0.36%	-0.36%	12.24%

Cashflow Statement

Concept	2016 Q4	2016	2015 Q4
OPERATING ACTIVITIES
Net Income	$44.30M	$155.3M	$18.30M
YoY Change	142.08%	10.06%	-44.38%
Depreciation, Depletion And Amortization	$51.00M	$195.8M	$45.80M
YoY Change	11.35%	15.18%	26.87%
Cash From Operating Activities	$94.20M	$334.9M	$85.50M
YoY Change	10.18%	-1.53%	48.18%
INVESTING ACTIVITIES
Capital Expenditures	-$146.1M	$265.6M	-$78.60M
YoY Change	85.88%	-7.39%	-25.14%
Acquisitions		$5.800M
YoY Change		-98.26%
Other Investing Activities	-$9.400M	-$5.100M	-$5.900M
YoY Change	59.32%	64.52%	-90.51%
Cash From Investing Activities	-$155.5M	-$272.1M	-$84.50M
YoY Change	84.02%	-56.03%	-49.46%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net		$30.90M
YoY Change		-80.83%
Debt Paid & Issued, Net		$57.70M
YoY Change		-63.98%
Cash From Financing Activities	-18.40M	-$135.2M	-7.000M
YoY Change	162.86%	-158.81%	-106.68%
NET CHANGE
Cash From Operating Activities	94.20M	$334.9M	85.50M
Cash From Investing Activities	-155.5M	-$272.1M	-84.50M
Cash From Financing Activities	-18.40M	-$135.2M	-7.000M
Net Change In Cash	-79.70M	-$72.40M	-6.000M
YoY Change	1228.33%	48.36%	27.66%
FREE CASH FLOW
Cash From Operating Activities	$94.20M	$334.9M	$85.50M
Capital Expenditures	-$146.1M	$265.6M	-$78.60M
Free Cash Flow	$240.3M	$69.30M	$164.1M
YoY Change	46.44%	30.02%	0.86%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2015	ale	Amortizationof Power Purchase Agreements AmortizationofPowerPurchaseAgreements	23200000	USD
CY2016	ale	Amortizationof Power Purchase Agreements AmortizationofPowerPurchaseAgreements	22300000	USD
CY2017	ale	Amortizationof Power Purchase Agreements AmortizationofPowerPurchaseAgreements	23600000	USD
CY2017Q4	ale	Availableforsale Securities Debt Maturities After Five Years Fair Value AvailableforsaleSecuritiesDebtMaturitiesAfterFiveYearsFairValue	1400000	USD
CY2017Q4	ale	Availableforsale Securities Debt Maturities After One Year Through Three Years Fair Value AvailableforsaleSecuritiesDebtMaturitiesAfterOneYearThroughThreeYearsFairValue	3200000	USD
CY2017Q4	ale	Availableforsale Securities Debt Maturities After Three Years Through Five Years Fair Value AvailableforsaleSecuritiesDebtMaturitiesAfterThreeYearsThroughFiveYearsFairValue	3600000	USD
CY2016Q4	ale	Contract Payment Non Current ContractPaymentNonCurrent	29600000	USD
CY2017Q4	ale	Contract Payment Non Current ContractPaymentNonCurrent	27500000	USD
CY2017Q4	ale	Debt Instrument Actual Indebtedness To Total Capital Ratio DebtInstrumentActualIndebtednessToTotalCapitalRatio	0.42
CY2017Q4	ale	Debt Instrument Required Indebtedness To Total Capital Ratio DebtInstrumentRequiredIndebtednessToTotalCapitalRatio	0.65
CY2015Q4	ale	Decreasein Investmentof Equity Method Investee DecreaseinInvestmentofEquityMethodInvestee	0	USD
CY2016Q4	ale	Decreasein Investmentof Equity Method Investee DecreaseinInvestmentofEquityMethodInvestee	0	USD
CY2017Q4	ale	Decreasein Investmentof Equity Method Investee DecreaseinInvestmentofEquityMethodInvestee	-27900000	USD
CY2015	ale	Decreaseto Deferred Income Taxes DecreasetoDeferredIncomeTaxes	0	USD
CY2016	ale	Decreaseto Deferred Income Taxes DecreasetoDeferredIncomeTaxes	0	USD
CY2017	ale	Decreaseto Deferred Income Taxes DecreasetoDeferredIncomeTaxes	-353600000	USD
CY2015	ale	Deferred Federal Income Tax Expense Benefit Remeasurementof Deferred Income Taxes DeferredFederalIncomeTaxExpenseBenefitRemeasurementofDeferredIncomeTaxes	0	USD
CY2016	ale	Deferred Federal Income Tax Expense Benefit Remeasurementof Deferred Income Taxes DeferredFederalIncomeTaxExpenseBenefitRemeasurementofDeferredIncomeTaxes	0	USD
CY2017	ale	Deferred Federal Income Tax Expense Benefit Remeasurementof Deferred Income Taxes DeferredFederalIncomeTaxExpenseBenefitRemeasurementofDeferredIncomeTaxes	13000000	USD
CY2016Q4	ale	Deferred Tax Assets Regulatory Liabilities DeferredTaxAssetsRegulatoryLiabilities	7300000	USD
CY2017Q4	ale	Deferred Tax Assets Regulatory Liabilities DeferredTaxAssetsRegulatoryLiabilities	117700000	USD
CY2016Q4	ale	Deferred Tax Liabilities Regulatory Assetsfor Benefit Obligations DeferredTaxLiabilitiesRegulatoryAssetsforBenefitObligations	91900000	USD
CY2017Q4	ale	Deferred Tax Liabilities Regulatory Assetsfor Benefit Obligations DeferredTaxLiabilitiesRegulatoryAssetsforBenefitObligations	61400000	USD
CY2016Q4	ale	Deferred Tax Liabilty Partnership Basis Differences DeferredTaxLiabiltyPartnershipBasisDifferences	50900000	USD
CY2017Q4	ale	Deferred Tax Liabilty Partnership Basis Differences DeferredTaxLiabiltyPartnershipBasisDifferences	34900000	USD
CY2015	ale	Effective Income Tax Rate Reconciliation Regulatory Differences EffectiveIncomeTaxRateReconciliationRegulatoryDifferences	-600000	USD
CY2016	ale	Effective Income Tax Rate Reconciliation Regulatory Differences EffectiveIncomeTaxRateReconciliationRegulatoryDifferences	-100000	USD
CY2017	ale	Effective Income Tax Rate Reconciliation Regulatory Differences EffectiveIncomeTaxRateReconciliationRegulatoryDifferences	0	USD
CY2015	ale	Effective Income Tax Rate Reconciliation Remeasurementof Deferred Income Taxes EffectiveIncomeTaxRateReconciliationRemeasurementofDeferredIncomeTaxes	0	USD
CY2016	ale	Effective Income Tax Rate Reconciliation Remeasurementof Deferred Income Taxes EffectiveIncomeTaxRateReconciliationRemeasurementofDeferredIncomeTaxes	0	USD
CY2017	ale	Effective Income Tax Rate Reconciliation Remeasurementof Deferred Income Taxes EffectiveIncomeTaxRateReconciliationRemeasurementofDeferredIncomeTaxes	-13000000	USD
CY2016	ale	Financing Receivable Term FinancingReceivableTerm	P5Y
CY2015	ale	Increaseto Regulatory Assets IncreasetoRegulatoryAssets	0	USD
CY2016	ale	Increaseto Regulatory Assets IncreasetoRegulatoryAssets	0	USD
CY2017	ale	Increaseto Regulatory Assets IncreasetoRegulatoryAssets	80900000	USD
CY2015	ale	Increaseto Regulatory Liabilities IncreasetoRegulatoryLiabilities	0	USD
CY2016	ale	Increaseto Regulatory Liabilities IncreasetoRegulatoryLiabilities	0	USD
CY2017	ale	Increaseto Regulatory Liabilities IncreasetoRegulatoryLiabilities	393600000	USD
CY2017	ale	Intangible Assets Acquired IntangibleAssetsAcquired	900000	USD
CY2016	ale	Morelikelythannotdefined Morelikelythannotdefined	0.50
CY2017	ale	Morelikelythannotdefined Morelikelythannotdefined	0.50
CY2016Q4	ale	Power Purchase Agreement Current Liability PowerPurchaseAgreementCurrentLiability	24600000	USD
CY2017Q4	ale	Power Purchase Agreement Current Liability PowerPurchaseAgreementCurrentLiability	24500000	USD
CY2016Q4	ale	Power Purchase Agreement Noncurrent Liability PowerPurchaseAgreementNoncurrentLiability	113800000	USD
CY2017Q4	ale	Power Purchase Agreement Noncurrent Liability PowerPurchaseAgreementNoncurrentLiability	89500000	USD
CY2016Q4	ale	Power Purchase Agreements Deferred Tax Asset PowerPurchaseAgreementsDeferredTaxAsset	59300000	USD
CY2017Q4	ale	Power Purchase Agreements Deferred Tax Asset PowerPurchaseAgreementsDeferredTaxAsset	35000000	USD
CY2015	ale	Provisionfor Interim Rate Refund ProvisionforInterimRateRefund	0	USD
CY2016	ale	Provisionfor Interim Rate Refund ProvisionforInterimRateRefund	0	USD
CY2017	ale	Provisionfor Interim Rate Refund ProvisionforInterimRateRefund	32300000	USD
CY2017Q4	ale	Solar Energy Standard Mandate Qualifying Capacityfor Small Scale Solar Mandate SolarEnergyStandardMandateQualifyingCapacityforSmallScaleSolarMandate	40
CY2017	dei	Amendment Flag AmendmentFlag	false
CY2017	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2017	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2017	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2017
CY2017	dei	Document Period End Date DocumentPeriodEndDate	2017-12-31
CY2017	dei	Document Type DocumentType	10-K
CY2017	dei	Entity Central Index Key EntityCentralIndexKey	0000066756
CY2018Q1	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	51143656	shares
CY2017	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2017	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2017Q2	dei	Entity Public Float EntityPublicFloat	3637956646	USD
CY2017	dei	Entity Registrant Name EntityRegistrantName	ALLETE INC
CY2017	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	410418150
CY2017	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2017	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
CY2016Q4	us-gaap	Accounts Payable Current AccountsPayableCurrent	74000000	USD
CY2017Q4	us-gaap	Accounts Payable Current AccountsPayableCurrent	136300000	USD
CY2016Q4	us-gaap	Accounts Receivable Gross Current AccountsReceivableGrossCurrent	106500000	USD
CY2017Q4	us-gaap	Accounts Receivable Gross Current AccountsReceivableGrossCurrent	112600000	USD
CY2016Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	122500000	USD
CY2017Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	135100000	USD
CY2016Q4	us-gaap	Accumulated Deferred Investment Tax Credit AccumulatedDeferredInvestmentTaxCredit	33300000	USD
CY2017Q4	us-gaap	Accumulated Deferred Investment Tax Credit AccumulatedDeferredInvestmentTaxCredit	32800000	USD
CY2014Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-21100000	USD
CY2015Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-24500000	USD
CY2016Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-28200000	USD
CY2017Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-22600000	USD
CY2015	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	2600000	USD
CY2016	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	2600000	USD
CY2017	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	3100000	USD
CY2016Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	3100000	USD
CY2017Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	2100000	USD
CY2015	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	4000000	USD
CY2016	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	5200000	USD
CY2017	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	5500000	USD
CY2015Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	131400000	USD
CY2016Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	136600000	USD
CY2017Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	122700000	USD
CY2016	us-gaap	Asset Retirement Obligation Accretion Expense AssetRetirementObligationAccretionExpense	8000000	USD
CY2017	us-gaap	Asset Retirement Obligation Accretion Expense AssetRetirementObligationAccretionExpense	7600000	USD
CY2016	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	6500000	USD
CY2017	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	5900000	USD
CY2015	us-gaap	Asset Retirement Obligation Revision Of Estimate AssetRetirementObligationRevisionOfEstimate	12400000	USD
CY2016	us-gaap	Asset Retirement Obligation Revision Of Estimate AssetRetirementObligationRevisionOfEstimate	3700000	USD
CY2017	us-gaap	Asset Retirement Obligation Revision Of Estimate AssetRetirementObligationRevisionOfEstimate	-15600000	USD
CY2016Q4	us-gaap	Asset Retirement Obligations Noncurrent AssetRetirementObligationsNoncurrent	136600000	USD
CY2017Q4	us-gaap	Asset Retirement Obligations Noncurrent AssetRetirementObligationsNoncurrent	122700000	USD
CY2016Q4	us-gaap	Assets Assets	4876900000	USD
CY2017Q4	us-gaap	Assets Assets	5080000000	USD
CY2016Q4	us-gaap	Assets Current AssetsCurrent	294500000	USD
CY2017Q4	us-gaap	Assets Current AssetsCurrent	367500000	USD
CY2017Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue	700000	USD
CY2016Q4	us-gaap	Available For Sale Securities Noncurrent AvailableForSaleSecuritiesNoncurrent	18800000	USD
CY2017Q4	us-gaap	Available For Sale Securities Noncurrent AvailableForSaleSecuritiesNoncurrent	19100000	USD
CY2016	us-gaap	Business Acquisition Pro Forma Information Description BusinessAcquisitionProFormaInformationDescription	not significant
CY2017	us-gaap	Business Acquisition Pro Forma Information Description BusinessAcquisitionProFormaInformationDescription	not significant
CY2015	us-gaap	Business Combination Contingent Consideration Arrangements Change In Amount Of Contingent Consideration Liability1 BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1	0	USD
CY2016	us-gaap	Business Combination Contingent Consideration Arrangements Change In Amount Of Contingent Consideration Liability1 BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1	-13600000	USD
CY2017	us-gaap	Business Combination Contingent Consideration Arrangements Change In Amount Of Contingent Consideration Liability1 BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1	-700000	USD
CY2016Q4	us-gaap	Business Combination Contingent Consideration Liability Noncurrent BusinessCombinationContingentConsiderationLiabilityNoncurrent	25000000	USD
CY2017Q4	us-gaap	Business Combination Contingent Consideration Liability Noncurrent BusinessCombinationContingentConsiderationLiabilityNoncurrent	5400000	USD
CY2015	us-gaap	Business Combination Reason For Business Combination BusinessCombinationReasonForBusinessCombination	The acquisitions below are consistent with ALLETE’s stated strategy of investing in energy infrastructure and related services businesses to complement its core regulated utility, balance exposure to business cycles and changing demand, and provide potential long-term earnings growth.
CY2016	us-gaap	Business Combination Reason For Business Combination BusinessCombinationReasonForBusinessCombination	The acquisitions below are consistent with ALLETE’s stated strategy of investing in energy infrastructure and related services businesses to complement its core regulated utility, balance exposure to business cycles and changing demand, and provide potential long-term earnings growth.
CY2017	us-gaap	Business Combination Reason For Business Combination BusinessCombinationReasonForBusinessCombination	The following acquisitions are 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.
CY2015	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	40600000	USD
CY2016	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	22000000	USD
CY2017	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	67200000	USD
CY2014Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	145800000	USD
CY2015Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	97000000	USD
CY2016Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	27500000	USD
CY2017Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	98900000	USD
CY2015	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	-48800000	USD
CY2016	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	-69500000	USD
CY2017	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	71400000	USD
CY2016Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
CY2017Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
CY2015	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	2.02
CY2016	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	2.08
CY2017	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	2.14
CY2016Q4	us-gaap	Common Stock No Par Value CommonStockNoParValue	0.00
CY2017Q4	us-gaap	Common Stock No Par Value CommonStockNoParValue	0.00
CY2016Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	80000000	shares
CY2017Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	80000000	shares
CY2016Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	49600000	shares
CY2017Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	51100000	shares
CY2016Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	49600000	shares
CY2017Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	51100000	shares
CY2016Q4	us-gaap	Common Stock Value CommonStockValue	1295300000	USD
CY2017Q4	us-gaap	Common Stock Value CommonStockValue	1401400000	USD
CY2015	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	137700000	USD
CY2016	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	151600000	USD
CY2017	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	177800000	USD
CY2015	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	400000	USD
CY2016	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	500000	USD
CY2017	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	0	USD
CY2015	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	138100000	USD
CY2016	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	152100000	USD
CY2017	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	177800000	USD
CY2015	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	294400000	USD
CY2016	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	137700000	USD
CY2017	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	147800000	USD
CY2015	us-gaap	Cost Of Purchased Power CostOfPurchasedPower	336000000	USD
CY2016	us-gaap	Cost Of Purchased Power CostOfPurchasedPower	339900000	USD
CY2017	us-gaap	Cost Of Purchased Power CostOfPurchasedPower	396900000	USD
CY2015	us-gaap	Cost Of Transmission CostOfTransmission	54100000	USD
CY2016	us-gaap	Cost Of Transmission CostOfTransmission	65200000	USD
CY2017	us-gaap	Cost Of Transmission CostOfTransmission	71200000	USD
CY2015	us-gaap	Costs And Expenses CostsAndExpenses	1275700000	USD
CY2016	us-gaap	Costs And Expenses CostsAndExpenses	1116200000	USD
CY2017	us-gaap	Costs And Expenses CostsAndExpenses	1189500000	USD
CY2015	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	0	USD
CY2016	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	0	USD
CY2017	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	0	USD
CY2015	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	200000	USD
CY2016	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	400000	USD
CY2017	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	300000	USD
CY2015	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	200000	USD
CY2016	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	400000	USD
CY2017	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	300000	USD
CY2016Q4	us-gaap	Debt Current DebtCurrent	187700000	USD
CY2017Q4	us-gaap	Debt Current DebtCurrent	64100000	USD
CY2016Q4	us-gaap	Debt Instrument Carrying Amount DebtInstrumentCarryingAmount	1569100000	USD
CY2017Q4	us-gaap	Debt Instrument Carrying Amount DebtInstrumentCarryingAmount	1513300000	USD
CY2017	us-gaap	Debt Instrument Covenant Compliance DebtInstrumentCovenantCompliance	ALLETE was in compliance with its financial covenants.
CY2015	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	19400000	USD
CY2016	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	12000000	USD
CY2017	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	12100000	USD
CY2017Q4	us-gaap	Deferred Finance Costs Current Net DeferredFinanceCostsCurrentNet	500000	USD
CY2016Q4	us-gaap	Deferred Finance Costs Net DeferredFinanceCostsNet	11000000	USD
CY2017Q4	us-gaap	Deferred Finance Costs Net DeferredFinanceCostsNet	10000000	USD
CY2017Q4	us-gaap	Deferred Finance Costs Noncurrent Net DeferredFinanceCostsNoncurrentNet	9500000	USD
CY2016Q4	us-gaap	Deferred Fuel Cost DeferredFuelCost	18600000	USD
CY2017Q4	us-gaap	Deferred Fuel Cost DeferredFuelCost	0	USD
CY2015	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	25100000	USD
CY2016	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	19400000	USD
CY2017	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	14400000	USD
CY2016Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	1253200000	USD
CY2017Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	920100000	USD
CY2015	us-gaap	Deferred Other Tax Expense Benefit DeferredOtherTaxExpenseBenefit	-800000	USD
CY2016	us-gaap	Deferred Other Tax Expense Benefit DeferredOtherTaxExpenseBenefit	-700000	USD
CY2017	us-gaap	Deferred Other Tax Expense Benefit DeferredOtherTaxExpenseBenefit	-500000	USD
CY2015	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	6500000	USD
CY2016	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	8100000	USD
CY2017	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	15800000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	741600000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	749600000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	698600000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	689600000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	185600000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	99100000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	46900000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	33300000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Property Plant And Equipment DeferredTaxAssetsPropertyPlantAndEquipment	110500000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Property Plant And Equipment DeferredTaxAssetsPropertyPlantAndEquipment	104300000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards DeferredTaxAssetsTaxCreditCarryforwards	227400000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards DeferredTaxAssetsTaxCreditCarryforwards	294300000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Compensation DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation	104600000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Compensation DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation	65900000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	43000000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	60000000	USD
CY2016Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	554600000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	230500000	USD
CY2016Q4	us-gaap	Deferred Tax Liabilities Noncurrent DeferredTaxLiabilitiesNoncurrent	554600000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Noncurrent DeferredTaxLiabilitiesNoncurrent	230500000	USD
CY2016Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	11900000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	700000	USD
CY2016Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	1039600000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	758300000	USD
CY2016Q4	us-gaap	Deferred Tax Liabilities Regulatory Assets DeferredTaxLiabilitiesRegulatoryAssets	25600000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Regulatory Assets DeferredTaxLiabilitiesRegulatoryAssets	32000000	USD
CY2015	us-gaap	Depreciation Depreciation	165900000	USD
CY2016	us-gaap	Depreciation Depreciation	190600000	USD
CY2017	us-gaap	Depreciation Depreciation	171900000	USD
CY2015	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	170000000	USD
CY2016	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	195800000	USD
CY2017	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	177500000	USD
CY2017	us-gaap	Description Of Effect On Previously Reported Segment Information For Change In Composition Of Reportable Segments DescriptionOfEffectOnPreviouslyReportedSegmentInformationForChangeInCompositionOfReportableSegments	We present three reportable segments: Regulated Operations, ALLETE Clean Energy, and U.S. Water Services. We measure performance of our operations through budgeting and monitoring of contributions to consolidated net income by each business segment.
CY2015	us-gaap	Dividends Common Stock DividendsCommonStock	97900000	USD
CY2016	us-gaap	Dividends Common Stock DividendsCommonStock	102700000	USD
CY2017	us-gaap	Dividends Common Stock DividendsCommonStock	108700000	USD
CY2015Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.85
CY2015Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.46
CY2015Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.24
CY2015Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.37
CY2015	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.92
CY2016Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.93
CY2016Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.50
CY2016Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.82
CY2016Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.89
CY2016	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.15
CY2017Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.97
CY2017Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.73
CY2017Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.88
CY2017Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.81
CY2017	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.39
CY2015Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.85
CY2015Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.46
CY2015Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.23
CY2015Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.37
CY2015	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.92
CY2016Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.93
CY2016Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.50
CY2016Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.81
CY2016Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.89
CY2016	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.14
CY2017Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.97
CY2017Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.72
CY2017Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.88
CY2017Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.81
CY2017	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.38
CY2015	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.152
CY2016	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.113
CY2017	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.079
CY2015	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.35
CY2016	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.35
CY2017	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.35
CY2015	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	0	USD
CY2016	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	0	USD
CY2017	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	0	USD
CY2015	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	1100000	USD
CY2016	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	1100000	USD
CY2017	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	900000	USD
CY2015	us-gaap	Employee Stock Ownership Plan Esop Compensation Expense EmployeeStockOwnershipPlanESOPCompensationExpense	9000000	USD
CY2016	us-gaap	Employee Stock Ownership Plan Esop Compensation Expense EmployeeStockOwnershipPlanESOPCompensationExpense	9200000	USD
CY2017	us-gaap	Employee Stock Ownership Plan Esop Compensation Expense EmployeeStockOwnershipPlanESOPCompensationExpense	11000000	USD
CY2017	us-gaap	Employee Stock Ownership Plan Esop Debt Structure Employer Loan Description EmployeeStockOwnershipPlanESOPDebtStructureEmployerLoanDescription	In 1990, the ESOP issued a $75.0 million note to use as consideration for 2.8 million shares (1.9 million shares adjusted for stock splits) of our common stock. The note matured in December 2015.
CY2015Q4	us-gaap	Employee Stock Ownership Plan Esop Deferred Shares Fair Value EmployeeStockOwnershipPlanESOPDeferredSharesFairValue	0	USD
CY2016Q4	us-gaap	Employee Stock Ownership Plan Esop Deferred Shares Fair Value EmployeeStockOwnershipPlanESOPDeferredSharesFairValue	0	USD
CY2017Q4	us-gaap	Employee Stock Ownership Plan Esop Deferred Shares Fair Value EmployeeStockOwnershipPlanESOPDeferredSharesFairValue	0	USD
CY2015Q4	us-gaap	Employee Stock Ownership Plan Esop Number Of Allocated Shares EmployeeStockOwnershipPlanESOPNumberOfAllocatedShares	1800000	shares
CY2016Q4	us-gaap	Employee Stock Ownership Plan Esop Number Of Allocated Shares EmployeeStockOwnershipPlanESOPNumberOfAllocatedShares	1600000	shares
CY2017Q4	us-gaap	Employee Stock Ownership Plan Esop Number Of Allocated Shares EmployeeStockOwnershipPlanESOPNumberOfAllocatedShares	1400000	shares
CY2015Q4	us-gaap	Employee Stock Ownership Plan Esop Number Of Suspense Shares EmployeeStockOwnershipPlanESOPNumberOfSuspenseShares	0	shares
CY2016Q4	us-gaap	Employee Stock Ownership Plan Esop Number Of Suspense Shares EmployeeStockOwnershipPlanESOPNumberOfSuspenseShares	0	shares
CY2017Q4	us-gaap	Employee Stock Ownership Plan Esop Number Of Suspense Shares EmployeeStockOwnershipPlanESOPNumberOfSuspenseShares	0	shares
CY2015Q4	us-gaap	Employee Stock Ownership Plan Esop Shares In Esop EmployeeStockOwnershipPlanESOPSharesInESOP	1800000	shares
CY2016Q4	us-gaap	Employee Stock Ownership Plan Esop Shares In Esop EmployeeStockOwnershipPlanESOPSharesInESOP	1600000	shares
CY2017Q4	us-gaap	Employee Stock Ownership Plan Esop Shares In Esop EmployeeStockOwnershipPlanESOPSharesInESOP	1400000	shares
CY2016Q4	us-gaap	Energy Related Inventory Coal EnergyRelatedInventoryCoal	43900000	USD
CY2017Q4	us-gaap	Energy Related Inventory Coal EnergyRelatedInventoryCoal	34800000	USD
CY2016Q4	us-gaap	Equity Method Investments EquityMethodInvestments	135600000	USD
CY2017Q4	us-gaap	Equity Method Investments EquityMethodInvestments	118700000	USD
CY2016Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	9300000	USD
CY2017Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	14800000	USD
CY2017Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense After Year Five FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive	37100000	USD
CY2017Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Next Twelve Months FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	5300000	USD
CY2017Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Five FiniteLivedIntangibleAssetsAmortizationExpenseYearFive	4300000	USD
CY2017Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Four FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	4600000	USD
CY2017Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Three FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	4700000	USD
CY2017Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Two FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	5000000	USD
CY2016Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	65600000	USD
CY2017Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	61000000	USD
CY2017	us-gaap	Finitelived Intangible Assets Acquired1 FinitelivedIntangibleAssetsAcquired1	900000	USD
CY2015	us-gaap	Gain Loss On Disposition Of Assets1 GainLossOnDispositionOfAssets1	-200000	USD
CY2016	us-gaap	Gain Loss On Disposition Of Assets1 GainLossOnDispositionOfAssets1	-6000000	USD
CY2017	us-gaap	Gain Loss On Disposition Of Assets1 GainLossOnDispositionOfAssets1	400000	USD
CY2015Q4	us-gaap	Goodwill Goodwill	130600000	USD
CY2016Q4	us-gaap	Goodwill Goodwill	131200000	USD
CY2017Q4	us-gaap	Goodwill Goodwill	148300000	USD
CY2016	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	3900000	USD
CY2017	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	16900000	USD
CY2015	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	0	USD
CY2016	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	3300000	USD
CY2017	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	0	USD
CY2017	us-gaap	Goodwill Purchase Accounting Adjustments GoodwillPurchaseAccountingAdjustments	200000	USD
CY2015	us-gaap	Impairment Of Intangible Assets Excluding Goodwill ImpairmentOfIntangibleAssetsExcludingGoodwill	0	USD
CY2016	us-gaap	Impairment Of Intangible Assets Excluding Goodwill ImpairmentOfIntangibleAssetsExcludingGoodwill	0	USD
CY2017	us-gaap	Impairment Of Intangible Assets Excluding Goodwill ImpairmentOfIntangibleAssetsExcludingGoodwill	0	USD
CY2015	us-gaap	Impairment Of Real Estate ImpairmentOfRealEstate	36300000	USD
CY2016	us-gaap	Impairment Of Real Estate ImpairmentOfRealEstate	0	USD
CY2017	us-gaap	Impairment Of Real Estate ImpairmentOfRealEstate	0	USD
CY2015	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	166800000	USD
CY2016	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	175600000	USD
CY2017	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	186900000	USD
CY2015	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	16300000	USD
CY2016	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	18500000	USD
CY2017	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	22500000	USD
CY2015	us-gaap	Income Loss From Equity Method Investments Net Of Dividends Or Distributions IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions	-1800000	USD
CY2016	us-gaap	Income Loss From Equity Method Investments Net Of Dividends Or Distributions IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions	-5700000	USD
CY2017	us-gaap	Income Loss From Equity Method Investments Net Of Dividends Or Distributions IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions	-3200000	USD
CY2015	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	25300000	USD
CY2016	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	19800000	USD
CY2017	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	14700000	USD
CY2015	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	58400000	USD
CY2016	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	61500000	USD
CY2017	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	65400000	USD
CY2015	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	0	USD
CY2016	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	-3800000	USD
CY2017	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	0	USD
CY2015	us-gaap	Income Tax Reconciliation Other Reconciling Items IncomeTaxReconciliationOtherReconcilingItems	100000	USD
CY2016	us-gaap	Income Tax Reconciliation Other Reconciling Items IncomeTaxReconciliationOtherReconcilingItems	-1900000	USD
CY2017	us-gaap	Income Tax Reconciliation Other Reconciling Items IncomeTaxReconciliationOtherReconcilingItems	-3100000	USD
CY2015	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	4400000	USD
CY2016	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	5600000	USD
CY2017	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	10500000	USD
CY2015	us-gaap	Income Tax Reconciliation Tax Credits Other IncomeTaxReconciliationTaxCreditsOther	37000000	USD
CY2016	us-gaap	Income Tax Reconciliation Tax Credits Other IncomeTaxReconciliationTaxCreditsOther	41500000	USD
CY2017	us-gaap	Income Tax Reconciliation Tax Credits Other IncomeTaxReconciliationTaxCreditsOther	45100000	USD
CY2015	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	400000	USD
CY2016	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	500000	USD
CY2017	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	400000	USD
CY2015	us-gaap	Increase Decrease In Accounts And Other Receivables IncreaseDecreaseInAccountsAndOtherReceivables	1100000	USD
CY2016	us-gaap	Increase Decrease In Accounts And Other Receivables IncreaseDecreaseInAccountsAndOtherReceivables	-4700000	USD
CY2017	us-gaap	Increase Decrease In Accounts And Other Receivables IncreaseDecreaseInAccountsAndOtherReceivables	-8000000	USD
CY2015	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	-19300000	USD
CY2016	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	6500000	USD
CY2017	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	-7500000	USD
CY2015	us-gaap	Increase Decrease In Allowance For Equity Funds Used During Construction IncreaseDecreaseInAllowanceForEquityFundsUsedDuringConstruction	3300000	USD
CY2016	us-gaap	Increase Decrease In Allowance For Equity Funds Used During Construction IncreaseDecreaseInAllowanceForEquityFundsUsedDuringConstruction	2100000	USD
CY2017	us-gaap	Increase Decrease In Allowance For Equity Funds Used During Construction IncreaseDecreaseInAllowanceForEquityFundsUsedDuringConstruction	1200000	USD
CY2015	us-gaap	Increase Decrease In Deferred Fuel Costs IncreaseDecreaseInDeferredFuelCosts	0	USD
CY2016	us-gaap	Increase Decrease In Deferred Fuel Costs IncreaseDecreaseInDeferredFuelCosts	0	USD
CY2017	us-gaap	Increase Decrease In Deferred Fuel Costs IncreaseDecreaseInDeferredFuelCosts	-19500000	USD
CY2015	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	-22100000	USD
CY2016	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	13300000	USD
CY2017	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	11900000	USD
CY2015	us-gaap	Increase Decrease In Other Current Liabilities IncreaseDecreaseInOtherCurrentLiabilities	5100000	USD
CY2016	us-gaap	Increase Decrease In Other Current Liabilities IncreaseDecreaseInOtherCurrentLiabilities	-13800000	USD
CY2017	us-gaap	Increase Decrease In Other Current Liabilities IncreaseDecreaseInOtherCurrentLiabilities	1800000	USD
CY2015	us-gaap	Increase Decrease In Other Noncurrent Assets IncreaseDecreaseInOtherNoncurrentAssets	600000	USD
CY2016	us-gaap	Increase Decrease In Other Noncurrent Assets IncreaseDecreaseInOtherNoncurrentAssets	-10700000	USD
CY2017	us-gaap	Increase Decrease In Other Noncurrent Assets IncreaseDecreaseInOtherNoncurrentAssets	33700000	USD
CY2015	us-gaap	Increase Decrease In Other Noncurrent Liabilities IncreaseDecreaseInOtherNoncurrentLiabilities	-3500000	USD
CY2016	us-gaap	Increase Decrease In Other Noncurrent Liabilities IncreaseDecreaseInOtherNoncurrentLiabilities	11100000	USD
CY2017	us-gaap	Increase Decrease In Other Noncurrent Liabilities IncreaseDecreaseInOtherNoncurrentLiabilities	-31700000	USD
CY2015	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	3700000	USD
CY2016	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	-6900000	USD
CY2017	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	-5300000	USD
CY2015	us-gaap	Increase Decrease In Restricted Cash IncreaseDecreaseInRestrictedCash	0	USD
CY2016	us-gaap	Increase Decrease In Restricted Cash IncreaseDecreaseInRestrictedCash	4000000	USD
CY2017	us-gaap	Increase Decrease In Restricted Cash IncreaseDecreaseInRestrictedCash	0	USD
CY2016Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	82200000	USD
CY2017Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	77600000	USD
CY2016Q4	us-gaap	Intangible Assets Net Including Goodwill IntangibleAssetsNetIncludingGoodwill	213400000	USD
CY2017Q4	us-gaap	Intangible Assets Net Including Goodwill IntangibleAssetsNetIncludingGoodwill	225900000	USD
CY2015	us-gaap	Interest Expense InterestExpense	64900000	USD
CY2016	us-gaap	Interest Expense InterestExpense	70300000	USD
CY2017	us-gaap	Interest Expense InterestExpense	67800000	USD
CY2015	us-gaap	Interest Paid Net InterestPaidNet	59000000	USD
CY2016	us-gaap	Interest Paid Net InterestPaidNet	68200000	USD
CY2017	us-gaap	Interest Paid Net InterestPaidNet	64500000	USD
CY2016Q4	us-gaap	Interest Payable Current InterestPayableCurrent	17600000	USD
CY2017Q4	us-gaap	Interest Payable Current InterestPayableCurrent	17600000	USD
CY2016Q4	us-gaap	Inventory Finished Goods InventoryFinishedGoods	8600000	USD
CY2017Q4	us-gaap	Inventory Finished Goods InventoryFinishedGoods	8300000	USD
CY2016Q4	us-gaap	Inventory Net InventoryNet	104200000	USD
CY2017Q4	us-gaap	Inventory Net InventoryNet	95900000	USD
CY2016Q4	us-gaap	Inventory Raw Materials InventoryRawMaterials	2900000	USD
CY2017Q4	us-gaap	Inventory Raw Materials InventoryRawMaterials	2800000	USD
CY2016Q4	us-gaap	Inventory Supplies Net Of Reserves InventorySuppliesNetOfReserves	48700000	USD
CY2017Q4	us-gaap	Inventory Supplies Net Of Reserves InventorySuppliesNetOfReserves	46500000	USD
CY2016Q4	us-gaap	Inventory Valuation Reserves InventoryValuationReserves	900000	USD
CY2017Q4	us-gaap	Inventory Valuation Reserves InventoryValuationReserves	700000	USD
CY2016Q4	us-gaap	Inventory Work In Process InventoryWorkInProcess	1000000	USD
CY2017Q4	us-gaap	Inventory Work In Process InventoryWorkInProcess	4200000	USD
CY2016Q4	us-gaap	Jointly Owned Utility Plant Gross Ownership Amount Of Plant In Service JointlyOwnedUtilityPlantGrossOwnershipAmountOfPlantInService	769300000	USD
CY2017Q4	us-gaap	Jointly Owned Utility Plant Gross Ownership Amount Of Plant In Service JointlyOwnedUtilityPlantGrossOwnershipAmountOfPlantInService	769200000	USD
CY2016Q4	us-gaap	Jointly Owned Utility Plant Ownership Amount Of Construction Work In Progress JointlyOwnedUtilityPlantOwnershipAmountOfConstructionWorkInProgress	8100000	USD
CY2017Q4	us-gaap	Jointly Owned Utility Plant Ownership Amount Of Construction Work In Progress JointlyOwnedUtilityPlantOwnershipAmountOfConstructionWorkInProgress	8200000	USD
CY2016Q4	us-gaap	Jointly Owned Utility Plant Ownership Amount Of Plant Accumulated Depreciation JointlyOwnedUtilityPlantOwnershipAmountOfPlantAccumulatedDepreciation	217100000	USD
CY2017Q4	us-gaap	Jointly Owned Utility Plant Ownership Amount Of Plant Accumulated Depreciation JointlyOwnedUtilityPlantOwnershipAmountOfPlantAccumulatedDepreciation	231200000	USD
CY2015	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	17300000	USD
CY2016	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	17100000	USD
CY2017	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	17500000	USD
CY2016Q4	us-gaap	Liabilities Liabilities	2983900000	USD
CY2017Q4	us-gaap	Liabilities Liabilities	3011800000	USD
CY2016Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	4876900000	USD
CY2017Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	5080000000	USD
CY2015	us-gaap	Liabilities Assumed1 LiabilitiesAssumed1	0	USD
CY2016	us-gaap	Liabilities Assumed1 LiabilitiesAssumed1	15000000	USD
CY2017	us-gaap	Liabilities Assumed1 LiabilitiesAssumed1	0	USD
CY2016Q4	us-gaap	Liabilities Current LiabilitiesCurrent	399500000	USD
CY2017Q4	us-gaap	Liabilities Current LiabilitiesCurrent	351200000	USD
CY2016Q4	us-gaap	Long Term Debt LongTermDebt	1558100000	USD
CY2017Q4	us-gaap	Long Term Debt LongTermDebt	1503300000	USD
CY2016Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	187700000	USD
CY2017Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	64100000	USD
CY2017Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal After Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive	1062300000	USD
CY2017Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Next Twelve Months LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths	64600000	USD
CY2017Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive	88000000	USD
CY2017Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	97800000	USD
CY2017Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	143000000	USD
CY2017Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo	57600000	USD
CY2016Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	1370400000	USD
CY2017Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	1439200000	USD
CY2016Q4	us-gaap	Long Term Investments LongTermInvestments	55600000	USD
CY2017Q4	us-gaap	Long Term Investments LongTermInvestments	53100000	USD
CY2016	us-gaap	Minority Interest Decrease From Redemptions MinorityInterestDecreaseFromRedemptions	6700000	USD
CY2015	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	229900000	USD
CY2016	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-125300000	USD
CY2017	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-102500000	USD
CY2015	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-618800000	USD
CY2016	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-276200000	USD
CY2017	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-229000000	USD
CY2015	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	340100000	USD
CY2016	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	332000000	USD
CY2017	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	402900000	USD
CY2015Q1	us-gaap	Net Income Loss NetIncomeLoss	39900000	USD
CY2015Q2	us-gaap	Net Income Loss NetIncomeLoss	22500000	USD
CY2015Q3	us-gaap	Net Income Loss NetIncomeLoss	60400000	USD
CY2015Q4	us-gaap	Net Income Loss NetIncomeLoss	18300000	USD
CY2015	us-gaap	Net Income Loss NetIncomeLoss	141100000	USD
CY2016Q1	us-gaap	Net Income Loss NetIncomeLoss	45900000	USD
CY2016Q2	us-gaap	Net Income Loss NetIncomeLoss	24800000	USD
CY2016Q3	us-gaap	Net Income Loss NetIncomeLoss	40300000	USD
CY2016Q4	us-gaap	Net Income Loss NetIncomeLoss	44300000	USD
CY2016	us-gaap	Net Income Loss NetIncomeLoss	155300000	USD
CY2017Q1	us-gaap	Net Income Loss NetIncomeLoss	49000000	USD
CY2017Q2	us-gaap	Net Income Loss NetIncomeLoss	36900000	USD
CY2017Q3	us-gaap	Net Income Loss NetIncomeLoss	44900000	USD
CY2017Q4	us-gaap	Net Income Loss NetIncomeLoss	41400000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	172200000	USD
CY2015	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	400000	USD
CY2016	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	500000	USD
CY2017	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	0	USD
CY2015	us-gaap	Net Income Loss Attributable To Parent Diluted NetIncomeLossAttributableToParentDiluted	141100000	USD
CY2016	us-gaap	Net Income Loss Attributable To Parent Diluted NetIncomeLossAttributableToParentDiluted	155300000	USD
CY2017	us-gaap	Net Income Loss Attributable To Parent Diluted NetIncomeLossAttributableToParentDiluted	172200000	USD
CY2015	us-gaap	Noncash Or Part Noncash Acquisition Value Of Liabilities Assumed1 NoncashOrPartNoncashAcquisitionValueOfLiabilitiesAssumed1	35700000	USD
CY2016	us-gaap	Noncash Or Part Noncash Acquisition Value Of Liabilities Assumed1 NoncashOrPartNoncashAcquisitionValueOfLiabilitiesAssumed1	0	USD
CY2017	us-gaap	Noncash Or Part Noncash Acquisition Value Of Liabilities Assumed1 NoncashOrPartNoncashAcquisitionValueOfLiabilitiesAssumed1	0	USD
CY2016	us-gaap	Noncash Or Part Noncash Divestiture Amount Of Consideration Received1 NoncashOrPartNoncashDivestitureAmountOfConsiderationReceived1	21000000	USD
CY2015	us-gaap	Nonoperating Income Expense NonoperatingIncomeExpense	-43900000	USD
CY2016	us-gaap	Nonoperating Income Expense NonoperatingIncomeExpense	-47900000	USD
CY2017	us-gaap	Nonoperating Income Expense NonoperatingIncomeExpense	-42900000	USD
CY2016Q4	us-gaap	Notes Receivable Gross NotesReceivableGross	11500000	USD
CY2017Q4	us-gaap	Notes Receivable Gross NotesReceivableGross	11000000	USD
CY2017	us-gaap	Number Of Reportable Segments NumberOfReportableSegments	3
CY2015	us-gaap	Operating Expenses OperatingExpenses	333500000	USD
CY2016	us-gaap	Operating Expenses OperatingExpenses	334100000	USD
CY2017	us-gaap	Operating Expenses OperatingExpenses	339900000	USD
CY2015Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	56400000	USD
CY2015Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	39500000	USD
CY2015Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	85200000	USD
CY2015Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	29600000	USD
CY2015	us-gaap	Operating Income Loss OperatingIncomeLoss	210700000	USD
CY2016Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	66800000	USD
CY2016Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	42200000	USD
CY2016Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	53400000	USD
CY2016Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	61100000	USD
CY2016	us-gaap	Operating Income Loss OperatingIncomeLoss	223500000	USD
CY2017Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	72600000	USD
CY2017Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	55000000	USD
CY2017Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	69000000	USD
CY2017Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	33200000	USD
CY2017	us-gaap	Operating Income Loss OperatingIncomeLoss	229800000	USD
CY2017Q4	us-gaap	Operating Leases Future Minimum Payments Due OperatingLeasesFutureMinimumPaymentsDue	79900000	USD
CY2016Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	49100000	USD
CY2017Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	58700000	USD
CY2016Q4	us-gaap	Other Accrued Liabilities Noncurrent OtherAccruedLiabilitiesNoncurrent	47300000	USD
CY2017Q4	us-gaap	Other Accrued Liabilities Noncurrent OtherAccruedLiabilitiesNoncurrent	49500000	USD
CY2016Q4	us-gaap	Other Assets Current OtherAssetsCurrent	40300000	USD
CY2017Q4	us-gaap	Other Assets Current OtherAssetsCurrent	37600000	USD
CY2016Q4	us-gaap	Other Assets Miscellaneous Current OtherAssetsMiscellaneousCurrent	19500000	USD
CY2017Q4	us-gaap	Other Assets Miscellaneous Current OtherAssetsMiscellaneousCurrent	35000000	USD
CY2016Q4	us-gaap	Other Assets Miscellaneous Noncurrent OtherAssetsMiscellaneousNoncurrent	56800000	USD
CY2017Q4	us-gaap	Other Assets Miscellaneous Noncurrent OtherAssetsMiscellaneousNoncurrent	60600000	USD
CY2016Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	106500000	USD
CY2017Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	107700000	USD
CY2015	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	-4600000	USD
CY2016	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	-4100000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	5000000	USD
CY2015	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-3400000	USD
CY2016	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-3700000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	5600000	USD
CY2015	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	3000000	USD
CY2016	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	3500000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-4700000	USD
CY2015	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	2200000	USD
CY2016	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	2400000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	-2200000	USD
CY2015	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax	100000	USD
CY2016	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax	0	USD
CY2017	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax	0	USD
CY2015	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	100000	USD
CY2016	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	0	USD
CY2017	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	0	USD
CY2015	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-500000	USD
CY2016	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-200000	USD
CY2017	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	900000	USD
CY2015	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	-300000	USD
CY2016	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	-200000	USD
CY2017	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	700000	USD
CY2015	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	36300000	USD
CY2016	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	10300000	USD
CY2017	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	700000	USD
CY2015	us-gaap	Other Depreciation And Amortization OtherDepreciationAndAmortization	5600000	USD
CY2016	us-gaap	Other Depreciation And Amortization OtherDepreciationAndAmortization	10300000	USD
CY2017	us-gaap	Other Depreciation And Amortization OtherDepreciationAndAmortization	10200000	USD
CY2016Q4	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	73700000	USD
CY2017Q4	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	83200000	USD
CY2016Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	322700000	USD
CY2017Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	267100000	USD
CY2016Q4	us-gaap	Other Long Term Investments OtherLongTermInvestments	3800000	USD
CY2017Q4	us-gaap	Other Long Term Investments OtherLongTermInvestments	3800000	USD
CY2015	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	4700000	USD
CY2016	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	3900000	USD
CY2017	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	2400000	USD
CY2015	us-gaap	Other Operating Income Expense Net OtherOperatingIncomeExpenseNet	-36300000	USD
CY2016	us-gaap	Other Operating Income Expense Net OtherOperatingIncomeExpenseNet	10300000	USD
CY2017	us-gaap	Other Operating Income Expense Net OtherOperatingIncomeExpenseNet	700000	USD
CY2016Q4	us-gaap	Other Restricted Assets Noncurrent OtherRestrictedAssetsNoncurrent	1300000	USD
CY2017Q4	us-gaap	Other Restricted Assets Noncurrent OtherRestrictedAssetsNoncurrent	3800000	USD
CY2015	us-gaap	Payment For Contingent Consideration Liability Financing Activities PaymentForContingentConsiderationLiabilityFinancingActivities	0	USD
CY2016	us-gaap	Payment For Contingent Consideration Liability Financing Activities PaymentForContingentConsiderationLiabilityFinancingActivities	900000	USD
CY2017	us-gaap	Payment For Contingent Consideration Liability Financing Activities PaymentForContingentConsiderationLiabilityFinancingActivities	19700000	USD
CY2015	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-3100000	USD
CY2016	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-4400000	USD
CY2017	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-3000000	USD
CY2015	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	97900000	USD
CY2016	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	102700000	USD
CY2017	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	108700000	USD
CY2015	us-gaap	Payments To Acquire Additional Interest In Subsidiaries PaymentsToAcquireAdditionalInterestInSubsidiaries	0	USD
CY2016	us-gaap	Payments To Acquire Additional Interest In Subsidiaries PaymentsToAcquireAdditionalInterestInSubsidiaries	8000000	USD
CY2017	us-gaap	Payments To Acquire Additional Interest In Subsidiaries PaymentsToAcquireAdditionalInterestInSubsidiaries	0	USD
CY2015	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	2300000	USD
CY2016	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	9400000	USD
CY2017	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	8600000	USD
CY2015	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	333300000	USD
CY2016	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	5900000	USD
CY2017	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	18500000	USD
CY2015	us-gaap	Payments To Acquire Equity Method Investments PaymentsToAcquireEquityMethodInvestments	1600000	USD
CY2016	us-gaap	Payments To Acquire Equity Method Investments PaymentsToAcquireEquityMethodInvestments	5400000	USD
CY2017	us-gaap	Payments To Acquire Equity Method Investments PaymentsToAcquireEquityMethodInvestments	7800000	USD
CY2015	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	286800000	USD
CY2016	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	265600000	USD
CY2017	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	208500000	USD
CY2015	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	15400000	USD
CY2016	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	4600000	USD
CY2017	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	10100000	USD
CY2016Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	210900000	USD
CY2017Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	191800000	USD
CY2015	us-gaap	Pension Contributions PensionContributions	0	USD
CY2016	us-gaap	Pension Contributions PensionContributions	6300000	USD
CY2017	us-gaap	Pension Contributions PensionContributions	1700000	USD
CY2015	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	161200000	USD
CY2016	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	30900000	USD
CY2017	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	86000000	USD
CY2015	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	324500000	USD
CY2016	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	4800000	USD
CY2017	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	131500000	USD
CY2015	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-4100000	USD
CY2016	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	0	USD
CY2017	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-1600000	USD
CY2015	us-gaap	Proceeds From Repayments Of Notes Payable ProceedsFromRepaymentsOfNotesPayable	-2100000	USD
CY2016	us-gaap	Proceeds From Repayments Of Notes Payable ProceedsFromRepaymentsOfNotesPayable	-1600000	USD
CY2017	us-gaap	Proceeds From Repayments Of Notes Payable ProceedsFromRepaymentsOfNotesPayable	0	USD
CY2015	us-gaap	Proceeds From Repayments Of Restricted Cash Financing Activities ProceedsFromRepaymentsOfRestrictedCashFinancingActivities	8500000	USD
CY2016	us-gaap	Proceeds From Repayments Of Restricted Cash Financing Activities ProceedsFromRepaymentsOfRestrictedCashFinancingActivities	7000000	USD
CY2017	us-gaap	Proceeds From Repayments Of Restricted Cash Financing Activities ProceedsFromRepaymentsOfRestrictedCashFinancingActivities	-400000	USD
CY2015	us-gaap	Proceeds From Sale Of Available For Sale Securities ProceedsFromSaleOfAvailableForSaleSecurities	1700000	USD
CY2016	us-gaap	Proceeds From Sale Of Available For Sale Securities ProceedsFromSaleOfAvailableForSaleSecurities	9000000	USD
CY2017	us-gaap	Proceeds From Sale Of Available For Sale Securities ProceedsFromSaleOfAvailableForSaleSecurities	10100000	USD
CY2015	us-gaap	Proceeds From Sale Of Productive Assets ProceedsFromSaleOfProductiveAssets	400000	USD
CY2016	us-gaap	Proceeds From Sale Of Productive Assets ProceedsFromSaleOfProductiveAssets	700000	USD
CY2017	us-gaap	Proceeds From Sale Of Productive Assets ProceedsFromSaleOfProductiveAssets	1300000	USD
CY2015	us-gaap	Profit Loss ProfitLoss	141500000	USD
CY2016	us-gaap	Profit Loss ProfitLoss	155800000	USD
CY2017	us-gaap	Profit Loss ProfitLoss	172200000	USD
CY2016	us-gaap	Property Plant And Equipment Additions PropertyPlantAndEquipmentAdditions	247800000	USD
CY2017	us-gaap	Property Plant And Equipment Additions PropertyPlantAndEquipmentAdditions	266500000	USD
CY2016Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	3741200000	USD
CY2017Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	3822400000	USD
CY2015	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	1600000	USD
CY2016	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	4100000	USD
CY2017	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	800000	USD
CY2016Q4	us-gaap	Real Estate Investments RealEstateInvestments	31700000	USD
CY2017Q4	us-gaap	Real Estate Investments RealEstateInvestments	26400000	USD
CY2015	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	-1200000	USD
CY2016	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	-400000	USD
CY2017	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	-600000	USD
CY2015	us-gaap	Regulated Operating Revenue RegulatedOperatingRevenue	991200000	USD
CY2016	us-gaap	Regulated Operating Revenue RegulatedOperatingRevenue	1000700000	USD
CY2017	us-gaap	Regulated Operating Revenue RegulatedOperatingRevenue	1063800000	USD
CY2016Q4	us-gaap	Regulatory Assets RegulatoryAssets	348700000	USD
CY2017Q4	us-gaap	Regulatory Assets RegulatoryAssets	384700000	USD
CY2016Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	330100000	USD
CY2017Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	384700000	USD
CY2016Q4	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	125800000	USD
CY2017Q4	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	532000000	USD
CY2015	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	160200000	USD
CY2016	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	54800000	USD
CY2017	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	189600000	USD
CY2016Q4	us-gaap	Restricted Cash And Cash Equivalents At Carrying Value RestrictedCashAndCashEquivalentsAtCarryingValue	2200000	USD
CY2017Q4	us-gaap	Restricted Cash And Cash Equivalents At Carrying Value RestrictedCashAndCashEquivalentsAtCarryingValue	2600000	USD
CY2016Q4	us-gaap	Restricted Cash And Cash Equivalents Noncurrent RestrictedCashAndCashEquivalentsNoncurrent	8600000	USD
CY2017Q4	us-gaap	Restricted Cash And Cash Equivalents Noncurrent RestrictedCashAndCashEquivalentsNoncurrent	8600000	USD
CY2016Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	625900000	USD
CY2017Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	689400000	USD
CY2015Q1	us-gaap	Revenues Revenues	320000000	USD
CY2015Q2	us-gaap	Revenues Revenues	323300000	USD
CY2015Q3	us-gaap	Revenues Revenues	462500000	USD
CY2015Q4	us-gaap	Revenues Revenues	380600000	USD
CY2015	us-gaap	Revenues Revenues	1486400000	USD
CY2016Q1	us-gaap	Revenues Revenues	333800000	USD
CY2016Q2	us-gaap	Revenues Revenues	314800000	USD
CY2016Q3	us-gaap	Revenues Revenues	349600000	USD
CY2016Q4	us-gaap	Revenues Revenues	341500000	USD
CY2016	us-gaap	Revenues Revenues	1339700000	USD
CY2017Q1	us-gaap	Revenues Revenues	365600000	USD
CY2017Q2	us-gaap	Revenues Revenues	353300000	USD
CY2017Q3	us-gaap	Revenues Revenues	362500000	USD
CY2017Q4	us-gaap	Revenues Revenues	337900000	USD
CY2017	us-gaap	Revenues Revenues	1419300000	USD
CY2015	us-gaap	Share Based Compensation ShareBasedCompensation	11600000	USD
CY2016	us-gaap	Share Based Compensation ShareBasedCompensation	5100000	USD
CY2017	us-gaap	Share Based Compensation ShareBasedCompensation	6600000	USD
CY2017Q4	us-gaap	Significant Change In Unrecognized Tax Benefits Is Reasonably Possible Amount Of Unrecorded Benefit SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleAmountOfUnrecordedBenefit	0	USD
CY2015	us-gaap	Stock Issued During Period Value Employee Benefit Plan StockIssuedDuringPeriodValueEmployeeBenefitPlan	0	USD
CY2016	us-gaap	Stock Issued During Period Value Employee Benefit Plan StockIssuedDuringPeriodValueEmployeeBenefitPlan	0	USD
CY2017	us-gaap	Stock Issued During Period Value Employee Benefit Plan StockIssuedDuringPeriodValueEmployeeBenefitPlan	13500000	USD
CY2015	us-gaap	Stock Issued During Period Value Employee Stock Ownership Plan StockIssuedDuringPeriodValueEmployeeStockOwnershipPlan	7200000	USD
CY2015	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	163800000	USD
CY2016	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	35900000	USD
CY2017	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	106100000	USD
CY2016	us-gaap	Stock Repurchased And Retired During Period Shares StockRepurchasedAndRetiredDuringPeriodShares	100000	shares
CY2016	us-gaap	Stock Repurchased And Retired During Period Value StockRepurchasedAndRetiredDuringPeriodValue	8000000	USD
CY2014Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	1611200000	USD
CY2015Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	1822400000	USD
CY2016Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	1893000000	USD
CY2017Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	2068200000	USD
CY2015	us-gaap	Taxes Other TaxesOther	51400000	USD
CY2016	us-gaap	Taxes Other TaxesOther	53800000	USD
CY2017	us-gaap	Taxes Other TaxesOther	56900000	USD
CY2016Q4	us-gaap	Taxes Payable Current TaxesPayableCurrent	46500000	USD
CY2017Q4	us-gaap	Taxes Payable Current TaxesPayableCurrent	50000000	USD
CY2017	us-gaap	Types Of Net Regulatory Assets Earning Returns TypesOfNetRegulatoryAssetsEarningReturns	No regulatory assets or liabilities are currently earning a return.
CY2016Q4	us-gaap	Unbilled Receivables Current UnbilledReceivablesCurrent	19100000	USD
CY2017Q4	us-gaap	Unbilled Receivables Current UnbilledReceivablesCurrent	24600000	USD
CY2014Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	2000000	USD
CY2015Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	2400000	USD
CY2016Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	2000000	USD
CY2017Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1700000	USD
CY2015	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	700000	USD
CY2016	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	300000	USD
CY2017	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	100000	USD
CY2015	us-gaap	Unrecognized Tax Benefits Income Tax Penalties Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesExpense	0	USD
CY2016	us-gaap	Unrecognized Tax Benefits Income Tax Penalties Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesExpense	0	USD
CY2017	us-gaap	Unrecognized Tax Benefits Income Tax Penalties Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesExpense	0	USD
CY2015	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	500000	USD
CY2016	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	100000	USD
CY2017	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	100000	USD
CY2015	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	700000	USD
CY2016	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	200000	USD
CY2017	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	100000	USD
CY2015Q4	us-gaap	Unrecognized Tax Benefits Interest On Income Taxes Accrued UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued	0	USD
CY2016Q4	us-gaap	Unrecognized Tax Benefits Interest On Income Taxes Accrued UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued	0	USD
CY2017Q4	us-gaap	Unrecognized Tax Benefits Interest On Income Taxes Accrued UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued	0	USD
CY2015	us-gaap	Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	100000	USD
CY2016	us-gaap	Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	400000	USD
CY2017	us-gaap	Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	400000	USD
CY2017Q4	us-gaap	Unrecognized Tax Benefits That Would Impact Effective Tax Rate UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate	800000	USD
CY2015	us-gaap	Unregulated Operating Revenue UnregulatedOperatingRevenue	495200000	USD
CY2016	us-gaap	Unregulated Operating Revenue UnregulatedOperatingRevenue	339000000	USD
CY2017	us-gaap	Unregulated Operating Revenue UnregulatedOperatingRevenue	355500000	USD
CY2015	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	100000	shares
CY2016	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	200000	shares
CY2017	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	200000	shares
CY2015	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	48400000	shares
CY2016	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	49500000	shares
CY2017	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	51000000	shares
CY2015	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	48300000	shares
CY2016	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	49300000	shares
CY2017	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	50800000	shares
CY2017	us-gaap	Property Plant And Equipment Impairment PropertyPlantAndEquipmentImpairment	<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;text-align:justify;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-style:italic;"></font><font style="font-family:inherit;font-size:10pt;">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.</font></div></div>

Files In Submission

Name	View Source	Status
0000066756-18-000029-index-headers.html	Edgar Link	pending
0000066756-18-000029-index.html	Edgar Link	pending
0000066756-18-000029.txt	Edgar Link	pending
0000066756-18-000029-xbrl.zip	Edgar Link	pending
ale-20171231.xml	Edgar Link	completed
ale-20171231.xsd	Edgar Link	pending
ale-20171231_cal.xml	Edgar Link	unprocessable
ale-20171231_def.xml	Edgar Link	unprocessable
ale-20171231_lab.xml	Edgar Link	unprocessable
ale-20171231_pre.xml	Edgar Link	unprocessable
ale12312017-10k.htm	Edgar Link	pending
ale1231201_chart-53916a02.jpg	Edgar Link	pending
exhibit10i712-31x2017.htm	Edgar Link	pending
exhibit10i812-31x2017.htm	Edgar Link	pending
exhibit1212-31x2017.htm	Edgar Link	pending
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FilingSummary.xml	Edgar Link	unprocessable
Financial_Report.xlsx	Edgar Link	pending
logoallete201510ka02.jpg	Edgar Link	pending
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report.css	Edgar Link	pending
Show.js	Edgar Link	pending

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$ALE
ALLETE INC Stock $ale

2016 Q4 Form 10-K Financial Statement

#000006675618000029 Filed on February 15, 2018

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$ALE ALLETE INC Stock $ale

2016 Q4 Form 10-K Financial Statement

#000006675618000029 Filed on February 15, 2018

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$ALE
ALLETE INC Stock $ale