$ES
EVERSOURCE ENERGY Stock $es

$es Overview Financials Valuation SEC Filings Company Website

2017 Q4 Form 10-K Financial Statement

#000007274118000028 Filed on February 26, 2018

Income Statement

Concept	2017 Q4	2017 Q2	2017 Q1
Revenue	$1.896B	$1.763B	$2.105B
YoY Change	6.7%	-0.25%	2.41%
Cost Of Revenue
YoY Change
Gross Profit
YoY Change
Gross Profit Margin
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$202.6M	$182.1M	$210.8M
YoY Change	10.29%	8.52%	8.1%
% of Gross Profit
Operating Expenses	$1.452B	$1.315B	$1.604B
YoY Change	8.45%	-2.17%	2.36%
Operating Profit	$443.7M	$448.2M	$501.0M
YoY Change	1.28%	5.86%	2.56%
Interest Expense	-$102.3M	$107.3M	$103.4M
YoY Change	-0.1%	6.8%	5.31%
% of Operating Profit	-23.06%	23.95%	20.64%
Other Income/Expense, Net	$28.70M	$29.00M	$21.60M
YoY Change	29.28%	260.79%	974.09%
Pretax Income	$370.3M	$369.9M	$419.2M
YoY Change	3.46%	11.76%	6.84%
Income Tax	$131.0M	$137.3M	$157.8M
% Of Pretax Income	35.38%	37.11%	37.65%
Net Earnings	$239.4M	$232.6M	$261.3M
YoY Change	3.59%	13.19%	6.22%
Net Earnings / Revenue	12.63%	13.19%	12.41%
Basic Earnings Per Share	$0.75	$0.73	$0.82
Diluted Earnings Per Share	$0.75	$0.73	$0.82
COMMON SHARES
Basic Shares Outstanding	316.9M shares	317.4M shares	317.5M shares
Diluted Shares Outstanding		317.9M shares	318.1M shares

Balance Sheet

Concept	2017 Q4	2017 Q2	2017 Q1
SHORT-TERM ASSETS
Cash & Short-Term Investments	$38.00M	$25.00M	$46.00M
YoY Change	26.67%	-35.9%	-9.8%
Cash & Equivalents	$85.89M	$78.73M	$126.3M
Short-Term Investments
Other Short-Term Assets	$138.0M	$157.4M	$182.7M
YoY Change	-35.89%	-86.6%	-85.33%
Inventory	$223.0M	$286.0M	$362.0M
Prepaid Expenses
Receivables	$925.1M	$833.9M	$879.5M
Other Receivables	$19.00M	$0.00	$0.00
Total Short-Term Assets	$2.487B	$2.331B	$2.511B
YoY Change	0.38%	-3.49%	-3.07%
LONG-TERM ASSETS
Property, Plant & Equipment	$23.62B	$22.07B	$21.64B
YoY Change	10.62%	7.94%	7.69%
Goodwill	$4.427B	$3.519B	$3.519B
YoY Change	25.8%
Intangibles
YoY Change
Long-Term Investments	$277.6M	$565.0M	$562.0M
YoY Change	17.18%	8.86%	11.73%
Other Assets	$605.7M	$590.7M	$556.2M
YoY Change	15.98%	-85.16%	-86.11%
Total Long-Term Assets	$10.12B	$8.257B	$8.202B
YoY Change	22.99%	-71.0%	-70.83%
TOTAL ASSETS
Total Short-Term Assets	$2.487B	$2.331B	$2.511B
Total Long-Term Assets	$10.12B	$8.257B	$8.202B
Total Assets	$36.22B	$32.66B	$32.36B
YoY Change	13.0%	5.75%	5.35%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$1.085B	$587.2M	$745.9M
YoY Change	22.67%	-23.35%	-4.62%
Accrued Expenses
YoY Change
Deferred Revenue
YoY Change
Short-Term Debt	$1.088B	$938.0M	$976.0M
YoY Change	-5.31%	22.29%	26.75%
Long-Term Debt Due	$549.6M	$1.484B	$773.9M
YoY Change	-28.98%	728.98%	104.19%
Total Short-Term Liabilities	$3.589B	$3.786B	$3.334B
YoY Change	-1.36%	64.33%	28.52%
LONG-TERM LIABILITIES
Long-Term Debt	$11.78B	$8.899B	$9.268B
YoY Change	33.37%	-5.69%	1.34%
Other Long-Term Liabilities	$1.074B	$860.6M	$848.8M
YoY Change	25.81%	-1.68%	-72.58%
Total Long-Term Liabilities	$9.614B	$8.933B	$8.794B
YoY Change	10.27%	5.37%	-28.16%
TOTAL LIABILITIES
Total Short-Term Liabilities	$3.589B	$3.786B	$3.334B
Total Long-Term Liabilities	$9.614B	$8.933B	$8.794B
Total Liabilities	$13.20B	$12.72B	$12.13B
YoY Change	6.85%	17.97%	-39.72%
SHAREHOLDERS EQUITY
Retained Earnings	$3.561B	$3.364B	$3.284B
YoY Change	12.15%	13.55%
Common Stock	$1.669B	$1.669B	$1.669B
YoY Change	0.0%	0.0%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$317.8M	$317.8M	$317.8M
YoY Change	0.0%	-202.51%
Treasury Stock Shares	16.99M shares	16.99M shares	16.99M shares
Shareholders Equity	$11.09B	$10.89B	$10.80B
YoY Change
Total Liabilities & Shareholders Equity	$36.22B	$32.66B	$32.36B
YoY Change	13.0%	5.75%	5.35%

Cashflow Statement

Concept	2017 Q4	2017 Q2	2017 Q1
OPERATING ACTIVITIES
Net Income	$239.4M	$232.6M	$261.3M
YoY Change	3.59%	13.19%	6.22%
Depreciation, Depletion And Amortization	$202.6M	$182.1M	$210.8M
YoY Change	10.29%	8.52%	8.1%
Cash From Operating Activities	$520.4M	$449.7M	$445.3M
YoY Change	-6.7%	-6.0%	-10.92%
INVESTING ACTIVITIES
Capital Expenditures	-$705.8M	-$623.4M	$523.6M
YoY Change	14.26%	42.43%	21.35%
Acquisitions
YoY Change
Other Investing Activities	-$872.6M	-$30.00M	$16.11M
YoY Change	406.74%	552.17%	-393.14%
Cash From Investing Activities	-$1.578B	-$653.3M	-$534.6M
YoY Change	99.82%	47.74%	25.9%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net			$150.0M
YoY Change
Cash From Financing Activities	972.0M	156.1M	$108.8M
YoY Change	281.63%	-421.86%	-324.98%
NET CHANGE
Cash From Operating Activities	520.4M	449.7M	$445.3M
Cash From Investing Activities	-1.578B	-653.3M	-$534.6M
Cash From Financing Activities	972.0M	156.1M	$108.8M
Net Change In Cash	-86.00M	-47.50M	$19.54M
YoY Change	-480.53%	286.18%	-27.7%
FREE CASH FLOW
Cash From Operating Activities	$520.4M	$449.7M	$445.3M
Capital Expenditures	-$705.8M	-$623.4M	$523.6M
Free Cash Flow	$1.226B	$1.073B	-$78.25M
YoY Change	4.31%	17.14%	-214.25%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2017	es	Numberof Electricand Natural Gas Customers NumberofElectricandNaturalGasCustomers	4000000	customer
CY2017	dei	Entity Registrant Name EntityRegistrantName	EVERSOURCE ENERGY
CY2017	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2018Q1	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	316885808	shares
CY2017	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2017	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2017Q2	dei	Entity Public Float EntityPublicFloat	19210596737	USD
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	0000072741
CY2017	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
CY2017	es	Amount Capitalizedin Transmission Line Installation AmountCapitalizedinTransmissionLineInstallation	277000000	USD
CY2017	es	Amountof Capacity Provided Under Capacity Contract AmountofCapacityProvidedUnderCapacityContract	787	MW
CY2016	es	Amountof Natural Gas To Be Purchased Under Futures Contracts AmountofNaturalGasToBePurchasedUnderFuturesContracts	9200000	MMBTU
CY2017	es	Amountof Natural Gas To Be Purchased Under Futures Contracts AmountofNaturalGasToBePurchasedUnderFuturesContracts	9500000	MMBTU
CY2017	es	Amountof Natural Gas Transmission Purchased From Enbridgeby Yankee Gasand Nstar Gas AmountofNaturalGasTransmissionPurchasedFromEnbridgebyYankeeGasandNSTARGas	62500000	USD
CY2016Q3	es	Capacity Required For Installationof Distribution Cable CapacityRequiredForInstallationofDistributionCable	0.115	MW
CY2017	es	Capacity Requiredfor Transmission Line CapacityRequiredforTransmissionLine	1090	MW
CY2015Q4	es	Deferred Compensation Cash Based Arrangements Expense Pertaining To Deferred Benefits DeferredCompensationCashBasedArrangementsExpensePertainingToDeferredBenefits	3900000	USD
CY2016Q4	es	Deferred Compensation Cash Based Arrangements Expense Pertaining To Deferred Benefits DeferredCompensationCashBasedArrangementsExpensePertainingToDeferredBenefits	2900000	USD
CY2017Q4	es	Deferred Compensation Cash Based Arrangements Expense Pertaining To Deferred Benefits DeferredCompensationCashBasedArrangementsExpensePertainingToDeferredBenefits	2800000	USD
CY2016Q4	es	Deferred Tax Assets Tax Effect Tax Regulatory Liabilities DeferredTaxAssetsTaxEffectTaxRegulatoryLiabilities	11800000	USD
CY2017Q4	es	Deferred Tax Assets Tax Effect Tax Regulatory Liabilities DeferredTaxAssetsTaxEffectTaxRegulatoryLiabilities	832600000	USD
CY2016Q4	es	Deferred Tax Liabilities Goodwill Regulatory Asset DeferredTaxLiabilitiesGoodwillRegulatoryAsset	186700000	USD
CY2017Q4	es	Deferred Tax Liabilities Goodwill Regulatory Asset DeferredTaxLiabilitiesGoodwillRegulatoryAsset	99800000	USD
CY2016Q4	es	Deferred Tax Liabilities Regulatory Assets Derivative Assets DeferredTaxLiabilitiesRegulatoryAssetsDerivativeAssets	29500000	USD
CY2017Q4	es	Loss Contingency Periodof Recovery Approvedin Previously Expensed Merger Related Costs LossContingencyPeriodofRecoveryApprovedinPreviouslyExpensedMergerRelatedCosts	P10Y
CY2017Q4	es	Deferred Tax Liabilities Regulatory Assets Derivative Assets DeferredTaxLiabilitiesRegulatoryAssetsDerivativeAssets	17400000	USD
CY2016Q4	es	Deferred Tax Liabilities Regulatory Assets Other Regulatory Deferrals DeferredTaxLiabilitiesRegulatoryAssetsOtherRegulatoryDeferrals	1321800000	USD
CY2017Q4	es	Deferred Tax Liabilities Regulatory Assets Other Regulatory Deferrals DeferredTaxLiabilitiesRegulatoryAssetsOtherRegulatoryDeferrals	924900000	USD
CY2016Q4	es	Deferred Tax Liabilities Regulatory Assets Tax Effect Tax Regulatory Assets DeferredTaxLiabilitiesRegulatoryAssetsTaxEffectTaxRegulatoryAssets	252600000	USD
CY2017Q4	es	Deferred Tax Liabilities Regulatory Assets Tax Effect Tax Regulatory Assets DeferredTaxLiabilitiesRegulatoryAssetsTaxEffectTaxRegulatoryAssets	243100000	USD
CY2016Q4	es	Deferred Tax Liabilities Resulting From Property Tax Accruals And Other DeferredTaxLiabilitiesResultingFromPropertyTaxAccrualsAndOther	81900000	USD
CY2017Q4	es	Deferred Tax Liabilities Resulting From Property Tax Accruals And Other DeferredTaxLiabilitiesResultingFromPropertyTaxAccrualsAndOther	56700000	USD
CY2017Q4	es	Defined Benefit Plan Decreasein Discount Rate Resultingin Increasein Liability DefinedBenefitPlanDecreaseinDiscountRateResultinginIncreaseinLiability	64000000	USD
CY2017	es	Defined Benefit Plan Impacton Liabilityasa Resultof Changein Discount Rate DefinedBenefitPlanImpactonLiabilityasaResultofChangeinDiscountRate	390000000	USD
CY2015	es	Derivative Instruments Gain Loss Recognized In Regulatory Asset Liability DerivativeInstrumentsGainLossRecognizedInRegulatoryAssetLiability	60200000	USD
CY2016	es	Derivative Instruments Gain Loss Recognized In Regulatory Asset Liability DerivativeInstrumentsGainLossRecognizedInRegulatoryAssetLiability	-125500000	USD
CY2017	es	Derivative Instruments Gain Loss Recognized In Regulatory Asset Liability DerivativeInstrumentsGainLossRecognizedInRegulatoryAssetLiability	-29000000	USD
CY2017	es	Distribution Assets Average Useful Life DistributionAssetsAverageUsefulLife	P34Y7M6D
CY2015	es	Effective Income Tax Rate Reconciliation Excess Stock Benefit EffectiveIncomeTaxRateReconciliationExcessStockBenefit	0	USD
CY2016	es	Effective Income Tax Rate Reconciliation Excess Stock Benefit EffectiveIncomeTaxRateReconciliationExcessStockBenefit	19100000	USD
CY2017	es	Effective Income Tax Rate Reconciliation Excess Stock Benefit EffectiveIncomeTaxRateReconciliationExcessStockBenefit	2900000	USD
CY2016	es	Effective Income Tax Rate Reconciliation Sharebased Compensation Excess Tax Benefit Amount EffectiveIncomeTaxRateReconciliationSharebasedCompensationExcessTaxBenefitAmount	19100000	USD
CY2017	es	Effective Income Tax Rate Reconciliation Sharebased Compensation Excess Tax Benefit Amount EffectiveIncomeTaxRateReconciliationSharebasedCompensationExcessTaxBenefitAmount	2900000	USD
CY2017	es	Effective Tax Rate Reconciliation Percent Tax Effecton Share Based Payments EffectiveTaxRateReconciliationPercentTaxEffectonShareBasedPayments	0.40
CY2015	es	Energy Efficiency Programs EnergyEfficiencyPrograms	495701000	USD
CY2016	es	Energy Efficiency Programs EnergyEfficiencyPrograms	533659000	USD
CY2017	es	Energy Efficiency Programs EnergyEfficiencyPrograms	480835000	USD
CY2016	es	Environmental Site Quantity EnvironmentalSiteQuantity	61	site
CY2017	es	Environmental Site Quantity EnvironmentalSiteQuantity	59	site
CY2015	es	Fuel Costs Incurred FuelCostsIncurred	95900000	USD
CY2016	es	Fuel Costs Incurred FuelCostsIncurred	55700000	USD
CY2017	es	Fuel Costs Incurred FuelCostsIncurred	47700000	USD
CY2015	es	Fuel Power Costs FuelPowerCosts	516700000	USD
CY2016	es	Fuel Power Costs FuelPowerCosts	372200000	USD
CY2017	es	Fuel Power Costs FuelPowerCosts	432500000	USD
CY2017	es	Generation Assets Average Useful Life GenerationAssetsAverageUsefulLife	P25Y0M0D
CY2016Q4	es	Interest Included In Payment To Settle Spent Nuclear Fuel Obligation InterestIncludedInPaymentToSettleSpentNuclearFuelObligation	131200000	USD
CY2017Q4	es	Interest Included In Payment To Settle Spent Nuclear Fuel Obligation InterestIncludedInPaymentToSettleSpentNuclearFuelObligation	132600000	USD
CY2017Q4	es	Longtermdebtmaturitiesrepaymentsofprincipaltotal Longtermdebtmaturitiesrepaymentsofprincipaltotal	11812900000	USD
CY2017Q4	es	Loss Contingency Annual Distribution Rate Increase LossContingencyAnnualDistributionRateIncrease	37000000	USD
CY2017Q4	es	Loss Contingency Decrease Resultingfrom Revenue Requirement Reduction LossContingencyDecreaseResultingfromRevenueRequirementReduction	19000000	USD
CY2017Q4	es	Loss Contingency Percentageof Authorized Regulatory Roe LossContingencyPercentageofAuthorizedRegulatoryROE	0.1
CY2017	es	Loss Contingency Percentageof Authorized Regulatory Roe LossContingencyPercentageofAuthorizedRegulatoryROE	0.0925
CY2017Q4	es	Loss Contingency Periodof Stay Out Requirement LossContingencyPeriodofStayOutRequirement	P5Y
CY2017	es	Loss Contingency Pre Tax Benefitfor Approved Regulatory Deferral Costsand Expensed Coststhathavebeen Disallowed LossContingencyPreTaxBenefitforApprovedRegulatoryDeferralCostsandExpensedCoststhathavebeenDisallowed	44100000	USD
CY2017Q4	es	Loss Contingency Revenue Requirement Reduction LossContingencyRevenueRequirementReduction	56000000	USD
CY2015	es	Natural Gas Procurement Costs Incurred NaturalGasProcurementCostsIncurred	428600000	USD
CY2016	es	Natural Gas Procurement Costs Incurred NaturalGasProcurementCostsIncurred	323900000	USD
CY2017	es	Natural Gas Procurement Costs Incurred NaturalGasProcurementCostsIncurred	377000000	USD
CY2017	es	Numberof Companies That Transmit Electricity Imported From Hydro Quebec System NumberofCompaniesThatTransmitElectricityImportedFromHydroQuebecSystem	2	company
CY2017	es	Numberof Companies That Transmit Hydro Electricity Imported From The Hydro Quebec Systemin Canada NumberofCompaniesThatTransmitHydroElectricityImportedFromTheHydroQuebecSysteminCanada	2	company
CY2017	es	Numberof Environmental Sites Designatedas Superfund Sites NumberofEnvironmentalSitesDesignatedasSuperfundSites	9	site
CY2017	es	Numberof Nuclear Generation Companies NumberofNuclearGenerationCompanies	3	company
CY2017	es	Other Assets Average Useful Life OtherAssetsAverageUsefulLife	P12Y8M12D
CY2015	es	Otherchangesinshareholdersequity Otherchangesinshareholdersequity	3653000	USD
CY2016	es	Otherchangesinshareholdersequity Otherchangesinshareholdersequity	-449000	USD
CY2017	es	Otherchangesinshareholdersequity Otherchangesinshareholdersequity	550000	USD
CY2015	es	Payments Refunds Relatedto Spent Nuclear Fuel PaymentsRefundsRelatedtoSpentNuclearFuel	-297253000	USD
CY2016	es	Payments Refunds Relatedto Spent Nuclear Fuel PaymentsRefundsRelatedtoSpentNuclearFuel	59804000	USD
CY2017	es	Payments Refunds Relatedto Spent Nuclear Fuel PaymentsRefundsRelatedtoSpentNuclearFuel	0	USD
CY2015	es	Peaker Cfd Expense Incurred PeakerCfdExpenseIncurred	42700000	USD
CY2016	es	Peaker Cfd Expense Incurred PeakerCfdExpenseIncurred	47700000	USD
CY2017	es	Peaker Cfd Expense Incurred PeakerCfdExpenseIncurred	38700000	USD
CY2017	es	Pension Serp And Pbop Gain Loss To Be Reclassified Within Twelve Months PensionSerpAndPbopGainLossToBeReclassifiedWithinTwelveMonths	-6600000	USD
CY2017	es	Percentageof Costsand Benefits Borne Under Unrecorded Unconditional Purchase Obligationby United Illuminated Company PercentageofCostsandBenefitsBorneUnderUnrecordedUnconditionalPurchaseObligationbyUnitedIlluminatedCompany	0.2
CY2017	es	Percentageof Costsor Benefits Borne Under Capacity Related Contractsby United Illuminated Company PercentageofCostsorBenefitsBorneUnderCapacityRelatedContractsbyUnitedIlluminatedCompany	0.2
CY2016Q4	es	Property Plant And Equipment Net Excluding Construction Work In Progress PropertyPlantAndEquipmentNetExcludingConstructionWorkInProgress	20338100000	USD
CY2017Q4	es	Property Plant And Equipment Net Excluding Construction Work In Progress PropertyPlantAndEquipmentNetExcludingConstructionWorkInProgress	22080100000	USD
CY2015	es	Public Utilities Allowance For Funds Used During Construction Capitalized Total PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedTotal	26000000	USD
CY2016	es	Public Utilities Allowance For Funds Used During Construction Capitalized Total PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedTotal	37000000	USD
CY2017	es	Public Utilities Allowance For Funds Used During Construction Capitalized Total PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedTotal	46900000	USD
CY2016Q4	es	Public Utilities Property Plant And Equipment Distribution Natural Gas PublicUtilitiesPropertyPlantAndEquipmentDistributionNaturalGas	3010400000	USD
CY2017Q4	es	Public Utilities Property Plant And Equipment Distribution Natural Gas PublicUtilitiesPropertyPlantAndEquipmentDistributionNaturalGas	3244200000	USD
CY2016Q4	es	Public Utilities Property Plant And Equipment Distribution Water PublicUtilitiesPropertyPlantAndEquipmentDistributionWater	0	USD
CY2017Q4	es	Public Utilities Property Plant And Equipment Distribution Water PublicUtilitiesPropertyPlantAndEquipmentDistributionWater	1558400000	USD
CY2016Q4	es	Public Utilities Property Plant And Equipment Electric Natural Gasand Water Utility Total PublicUtilitiesPropertyPlantAndEquipmentElectricNaturalGasandWaterUtilityTotal	26468900000	USD
CY2017Q4	es	Public Utilities Property Plant And Equipment Electric Natural Gasand Water Utility Total PublicUtilitiesPropertyPlantAndEquipmentElectricNaturalGasandWaterUtilityTotal	28520200000	USD
CY2016Q4	es	Public Utilities Property Plantand Equipment Accumulated Depreciation Electric Natural Gasand Water Utility PublicUtilitiesPropertyPlantandEquipmentAccumulatedDepreciationElectricNaturalGasandWaterUtility	6480400000	USD
CY2017Q4	es	Public Utilities Property Plantand Equipment Accumulated Depreciation Electric Natural Gasand Water Utility PublicUtilitiesPropertyPlantandEquipmentAccumulatedDepreciationElectricNaturalGasandWaterUtility	6846900000	USD
CY2016Q4	es	Public Utilities Property Plantand Equipment Accumulated Depreciation Other PublicUtilitiesPropertyPlantandEquipmentAccumulatedDepreciationOther	242000000	USD
CY2017Q4	es	Public Utilities Property Plantand Equipment Accumulated Depreciation Other PublicUtilitiesPropertyPlantandEquipmentAccumulatedDepreciationOther	286900000	USD
CY2016Q4	es	Purchase Accounting Deferred Tax Asset PurchaseAccountingDeferredTaxAsset	112200000	USD
CY2017Q4	es	Purchase Accounting Deferred Tax Asset PurchaseAccountingDeferredTaxAsset	69900000	USD
CY2015	es	Renewable Energy Costs Incurred RenewableEnergyCostsIncurred	144300000	USD
CY2016	es	Renewable Energy Costs Incurred RenewableEnergyCostsIncurred	210900000	USD
CY2017	es	Renewable Energy Costs Incurred RenewableEnergyCostsIncurred	235500000	USD
CY2015	es	Supply And Stranded Costs Obligations Incurred SupplyAndStrandedCostsObligationsIncurred	147600000	USD
CY2016	es	Supply And Stranded Costs Obligations Incurred SupplyAndStrandedCostsObligationsIncurred	152500000	USD
CY2017	es	Supply And Stranded Costs Obligations Incurred SupplyAndStrandedCostsObligationsIncurred	103900000	USD
CY2017	es	Tax Cutsand Jobs Actof2017 Incomplete Accounting Changein Tax Rate Deferred Tax Liability Percentageof Provisional Regulated Excess Tax TaxCutsandJobsActof2017IncompleteAccountingChangeinTaxRateDeferredTaxLiabilityPercentageofProvisionalRegulatedExcessTax	0.85
CY2017	es	Tax Cutsand Jobs Actof2017 Incomplete Accounting Changein Tax Rate Deferred Tax Liability Provisional Income Tax Expense Benefit TaxCutsandJobsActof2017IncompleteAccountingChangeinTaxRateDeferredTaxLiabilityProvisionalIncomeTaxExpenseBenefit	2900000000	USD
CY2017	es	Transmission Assets Average Useful Life TransmissionAssetsAverageUsefulLife	P40Y10M25D
CY2015	es	Transmission Support Commitment Costs Incurred TransmissionSupportCommitmentCostsIncurred	25300000	USD
CY2016	es	Transmission Support Commitment Costs Incurred TransmissionSupportCommitmentCostsIncurred	15900000	USD
CY2017	es	Transmission Support Commitment Costs Incurred TransmissionSupportCommitmentCostsIncurred	19800000	USD
CY2016Q4	es	Uncollectible Hardship Accounts Receivable Reserve UncollectibleHardshipAccountsReceivableReserve	119900000	USD
CY2017Q4	es	Uncollectible Hardship Accounts Receivable Reserve UncollectibleHardshipAccountsReceivableReserve	122500000	USD
CY2017	es	Unrecorded Unconditional Purchase Obligation Amountof Capacity Contractsfor Differences Between Cl Pand United Illuminated Company UnrecordedUnconditionalPurchaseObligationAmountofCapacityContractsforDifferencesBetweenCLPandUnitedIlluminatedCompany	787	MW
CY2017	es	Unrecorded Unconditional Purchase Obligation Numberof Capacity Contractsfor Differences Between Cl Pand United Illuminated Company UnrecordedUnconditionalPurchaseObligationNumberofCapacityContractsforDifferencesBetweenCLPandUnitedIlluminatedCompany	4	contract
CY2017	es	Unrecorded Unconditional Purchase Obligation Numberof Demand Response Projects Between Cl Pand United Illuminated Company UnrecordedUnconditionalPurchaseObligationNumberofDemandResponseProjectsBetweenCLPandUnitedIlluminatedCompany	1	project
CY2017	es	Unrecorded Unconditional Purchase Obligation Numberof Generation Projects Between Cl Pand United Illuminated Company UnrecordedUnconditionalPurchaseObligationNumberofGenerationProjectsBetweenCLPandUnitedIlluminatedCompany	3	project
CY2017	es	Water Assets Average Useful Life WaterAssetsAverageUsefulLife	P32Y0M0D
CY2016Q4	us-gaap	Accounts Payable Current AccountsPayableCurrent	884521000	USD
CY2017Q4	us-gaap	Accounts Payable Current AccountsPayableCurrent	1085034000	USD
CY2016Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	847301000	USD
CY2017Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	925083000	USD
CY2015Q4	us-gaap	Accrual For Environmental Loss Contingencies AccrualForEnvironmentalLossContingencies	51100000	USD
CY2016Q4	us-gaap	Accrual For Environmental Loss Contingencies AccrualForEnvironmentalLossContingencies	65800000	USD
CY2017Q4	us-gaap	Accrual For Environmental Loss Contingencies AccrualForEnvironmentalLossContingencies	54900000	USD
CY2016	us-gaap	Accrual For Environmental Loss Contingencies Charges To Expense For New Losses AccrualForEnvironmentalLossContingenciesChargesToExpenseForNewLosses	20600000	USD
CY2017	us-gaap	Accrual For Environmental Loss Contingencies Charges To Expense For New Losses AccrualForEnvironmentalLossContingenciesChargesToExpenseForNewLosses	6200000	USD
CY2016	us-gaap	Accrual For Environmental Loss Contingencies Payments1 AccrualForEnvironmentalLossContingenciesPayments1	5900000	USD
CY2017	us-gaap	Accrual For Environmental Loss Contingencies Payments1 AccrualForEnvironmentalLossContingenciesPayments1	17100000	USD
CY2017Q4	us-gaap	Accrual For Taxes Other Than Income Taxes Current And Noncurrent AccrualForTaxesOtherThanIncomeTaxesCurrentAndNoncurrent	25400000	USD
CY2016Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-65282000	USD
CY2017Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-66403000	USD
CY2016Q4	us-gaap	Additional Collateral Aggregate Fair Value AdditionalCollateralAggregateFairValue	3700000	USD
CY2016Q4	us-gaap	Additional Paid In Capital AdditionalPaidInCapital	6250224000	USD
CY2017Q4	us-gaap	Additional Paid In Capital AdditionalPaidInCapital	6239940000	USD
CY2015	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	23100000	USD
CY2016	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	23600000	USD
CY2017	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	19700000	USD
CY2016Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	200600000	USD
CY2017Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	195700000	USD
CY2015	us-gaap	Amortization Of Regulatory Asset AmortizationOfRegulatoryAsset	22339000	USD
CY2016	us-gaap	Amortization Of Regulatory Asset AmortizationOfRegulatoryAsset	71696000	USD
CY2017	us-gaap	Amortization Of Regulatory Asset AmortizationOfRegulatoryAsset	89986000	USD
CY2016Q4	us-gaap	Amount Of Regulatory Costs Not Yet Approved AmountOfRegulatoryCostsNotYetApproved	86300000	USD
CY2017Q4	us-gaap	Amount Of Regulatory Costs Not Yet Approved AmountOfRegulatoryCostsNotYetApproved	105800000	USD
CY2015	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	1474	shares
CY2016	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	0	shares
CY2017	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	0	shares
CY2015Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	430100000	USD
CY2016Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	426400000	USD
CY2017Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	419100000	USD
CY2016	us-gaap	Asset Retirement Obligation Accretion Expense AssetRetirementObligationAccretionExpense	22900000	USD
CY2017	us-gaap	Asset Retirement Obligation Accretion Expense AssetRetirementObligationAccretionExpense	26300000	USD
CY2017Q4	us-gaap	Capital Leases Future Minimum Payments Interest Included In Payments CapitalLeasesFutureMinimumPaymentsInterestIncludedInPayments	3100000	USD
CY2017Q4	us-gaap	Capital Leases Future Minimum Payments Present Value Of Net Minimum Payments CapitalLeasesFutureMinimumPaymentsPresentValueOfNetMinimumPayments	13000000	USD
CY2016Q4	us-gaap	Capitalization Longterm Debt And Equity CapitalizationLongtermDebtAndEquity	19696656000	USD
CY2017Q4	us-gaap	Capitalization Longterm Debt And Equity CapitalizationLongtermDebtAndEquity	23017701000	USD
CY2014Q4	us-gaap	Cash Cash	38703000	USD
CY2016	us-gaap	Asset Retirement Obligation Liabilities Incurred AssetRetirementObligationLiabilitiesIncurred	1300000	USD
CY2017	us-gaap	Asset Retirement Obligation Liabilities Incurred AssetRetirementObligationLiabilitiesIncurred	200000	USD
CY2016	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	19000000	USD
CY2017	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	19300000	USD
CY2016	us-gaap	Asset Retirement Obligation Revision Of Estimate AssetRetirementObligationRevisionOfEstimate	-8900000	USD
CY2017	us-gaap	Asset Retirement Obligation Revision Of Estimate AssetRetirementObligationRevisionOfEstimate	-14500000	USD
CY2016Q4	us-gaap	Assets Assets	32053173000	USD
CY2016Q4	us-gaap	Assets Assets	32053200000	USD
CY2017Q4	us-gaap	Assets Assets	36220400000	USD
CY2017Q4	us-gaap	Assets Assets	36220386000	USD
CY2016Q4	us-gaap	Assets Current AssetsCurrent	2477672000	USD
CY2017Q4	us-gaap	Assets Current AssetsCurrent	2487099000	USD
CY2016Q4	us-gaap	Assets Held For Sale Not Part Of Disposal Group Current AssetsHeldForSaleNotPartOfDisposalGroupCurrent	0	USD
CY2017Q4	us-gaap	Assets Held For Sale Not Part Of Disposal Group Current AssetsHeldForSaleNotPartOfDisposalGroupCurrent	219550000	USD
CY2016Q4	us-gaap	Assets Noncurrent AssetsNoncurrent	8224991000	USD
CY2017Q4	us-gaap	Assets Noncurrent AssetsNoncurrent	10115824000	USD
CY2017Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	284900000	USD
CY2017Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost	64700000	USD
CY2017Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	65600000	USD
CY2017Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost	46700000	USD
CY2017Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	47500000	USD
CY2017Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost	133300000	USD
CY2017Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue	133800000	USD
CY2017Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost	40200000	USD
CY2017Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue	40100000	USD
CY2017Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	287000000	USD
CY2015	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	216600000	USD
CY2016	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	301500000	USD
CY2017	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	379500000	USD
CY2017Q4	us-gaap	Capital Leases Future Minimum Payments Due CapitalLeasesFutureMinimumPaymentsDue	16100000	USD
CY2017Q4	us-gaap	Capital Leases Future Minimum Payments Due Current CapitalLeasesFutureMinimumPaymentsDueCurrent	2900000	USD
CY2017Q4	us-gaap	Capital Leases Future Minimum Payments Due In Five Years CapitalLeasesFutureMinimumPaymentsDueInFiveYears	1300000	USD
CY2017Q4	us-gaap	Capital Leases Future Minimum Payments Due In Four Years CapitalLeasesFutureMinimumPaymentsDueInFourYears	2800000	USD
CY2017Q4	us-gaap	Capital Leases Future Minimum Payments Due In Three Years CapitalLeasesFutureMinimumPaymentsDueInThreeYears	3300000	USD
CY2017Q4	us-gaap	Capital Leases Future Minimum Payments Due In Two Years CapitalLeasesFutureMinimumPaymentsDueInTwoYears	3300000	USD
CY2017Q4	us-gaap	Capital Leases Future Minimum Payments Due Thereafter CapitalLeasesFutureMinimumPaymentsDueThereafter	2500000	USD
CY2015Q4	us-gaap	Cash Cash	23947000	USD
CY2016Q4	us-gaap	Cash Cash	30251000	USD
CY2017Q4	us-gaap	Cash Cash	38165000	USD
CY2016	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	6304000	USD
CY2015	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	-14756000	USD
CY2016	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	1.78
CY2017	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	1.9
CY2015Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	5
CY2016Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	5
CY2017Q4	us-gaap	Costs In Excess Of Billings On Uncompleted Contracts Or Programs Expected To Be Collected Within One Year CostsInExcessOfBillingsOnUncompletedContractsOrProgramsExpectedToBeCollectedWithinOneYear	201361000	USD
CY2017	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	7914000	USD
CY2017	us-gaap	Cash Flow Hedge Gain Loss To Be Reclassified Within Twelve Months CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths	-2800000	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 Cash Paid CommonStockDividendsPerShareCashPaid	1.67
CY2017Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	5
CY2016Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	380000000	shares
CY2017Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	380000000	shares
CY2016Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	333878402	shares
CY2017Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	333878402	shares
CY2016Q4	us-gaap	Common Stock Value CommonStockValue	1669392000	USD
CY2017Q4	us-gaap	Common Stock Value CommonStockValue	1669392000	USD
CY2015	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	885650000	USD
CY2016	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	943864000	USD
CY2017	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	986875000	USD
CY2015	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	7519000	USD
CY2016	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	7519000	USD
CY2017	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	7519000	USD
CY2015	us-gaap	Cost Of Purchased Power CostOfPurchasedPower	3086905000	USD
CY2016	us-gaap	Cost Of Purchased Power CostOfPurchasedPower	2500828000	USD
CY2017	us-gaap	Cost Of Purchased Power CostOfPurchasedPower	2535271000	USD
CY2016Q4	us-gaap	Costs In Excess Of Billings On Uncompleted Contracts Or Programs Expected To Be Collected Within One Year CostsInExcessOfBillingsOnUncompletedContractsOrProgramsExpectedToBeCollectedWithinOneYear	168490000	USD
CY2015	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	6200000	USD
CY2016	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	38900000	USD
CY2017	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	58900000	USD
CY2015	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	51900000	USD
CY2016	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	91900000	USD
CY2017	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	90500000	USD
CY2015	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	45700000	USD
CY2016	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	53000000	USD
CY2017	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	31600000	USD
CY2015Q4	us-gaap	Deferred Compensation Cashbased Arrangements Liability Classified Noncurrent DeferredCompensationCashbasedArrangementsLiabilityClassifiedNoncurrent	55200000	USD
CY2016Q4	us-gaap	Deferred Compensation Cashbased Arrangements Liability Classified Noncurrent DeferredCompensationCashbasedArrangementsLiabilityClassifiedNoncurrent	54200000	USD
CY2017Q4	us-gaap	Deferred Compensation Cashbased Arrangements Liability Classified Noncurrent DeferredCompensationCashbasedArrangementsLiabilityClassifiedNoncurrent	53400000	USD
CY2015	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	436100000	USD
CY2016	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	427900000	USD
CY2017	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	433000000	USD
CY2015	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	491700000	USD
CY2015	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	491736000	USD
CY2016	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	466463000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	1909400000	USD
CY2016Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	223600000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	288400000	USD
CY2017	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	491630000	USD
CY2017	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	491600000	USD
CY2015	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	55600000	USD
CY2016	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	38600000	USD
CY2016Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	5001200000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	3562000000	USD
CY2017	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	58600000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Derivative Instruments DeferredTaxAssetsDerivativeInstruments	192600000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Derivative Instruments DeferredTaxAssetsDerivativeInstruments	111800000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	1495200000	USD
CY2015	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	30400000	USD
CY2016	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	466500000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	1490100000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	1894800000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	0	USD
CY2017Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	47800000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	170500000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	149500000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Regulatory Assets And Liabilities DeferredTaxAssetsRegulatoryAssetsAndLiabilities	290900000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Regulatory Assets And Liabilities DeferredTaxAssetsRegulatoryAssetsAndLiabilities	205600000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits	640600000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits	442100000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Allowance For Doubtful Accounts DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts	76600000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Allowance For Doubtful Accounts DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts	50100000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	5100000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	14600000	USD
CY2016Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	7097300000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	5192300000	USD
CY2016Q4	us-gaap	Deferred Tax Liabilities Noncurrent DeferredTaxLiabilitiesNoncurrent	5607207000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Noncurrent DeferredTaxLiabilitiesNoncurrent	3297518000	USD
CY2016	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	31800000	USD
CY2017	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	34500000	USD
CY2015	us-gaap	Depreciation Depreciation	665856000	USD
CY2016	us-gaap	Depreciation Depreciation	715466000	USD
CY2017	us-gaap	Depreciation Depreciation	773802000	USD
CY2015	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	688200000	USD
CY2016	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	787100000	USD
CY2017	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	863800000	USD
CY2016Q4	us-gaap	Derivative Liabilities Noncurrent DerivativeLiabilitiesNoncurrent	413676000	USD
CY2017Q4	us-gaap	Derivative Liabilities Noncurrent DerivativeLiabilitiesNoncurrent	377257000	USD
CY2017Q4	us-gaap	Derivative Net Liability Position Aggregate Fair Value DerivativeNetLiabilityPositionAggregateFairValue	3400000	USD
CY2015	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.379
CY2016	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.369
CY2015	us-gaap	Dividends Common Stock DividendsCommonStock	529791000	USD
CY2016	us-gaap	Dividends Common Stock DividendsCommonStock	564486000	USD
CY2017	us-gaap	Dividends Common Stock DividendsCommonStock	602083000	USD
CY2015	us-gaap	Dividends Preferred Stock DividendsPreferredStock	7519000	USD
CY2016	us-gaap	Dividends Preferred Stock DividendsPreferredStock	7519000	USD
CY2017	us-gaap	Dividends Preferred Stock DividendsPreferredStock	7519000	USD
CY2015	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.77
CY2016Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.77
CY2016Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.64
CY2016Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.83
CY2016Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.72
CY2016	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.97
CY2017Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.82
CY2017Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.73
CY2017Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.82
CY2017Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.75
CY2017	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.11
CY2015	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.76
CY2016Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.77
CY2016Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.64
CY2016Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.83
CY2016Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.72
CY2016	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.96
CY2017Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.82
CY2017Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.73
CY2017Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.82
CY2017Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.75
CY2017	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.11
CY2017	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.368
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
CY2017Q4	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized	20100000	USD
CY2015	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	9400000	USD
CY2016	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	9600000	USD
CY2017	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	8000000	USD
CY2017	us-gaap	Employee Service Share Based Compensation Tax Benefit From Exercise Of Stock Options EmployeeServiceShareBasedCompensationTaxBenefitFromExerciseOfStockOptions	1800000	USD
CY2016Q4	us-gaap	Energy Related Inventory EnergyRelatedInventory	328721000	USD
CY2017Q4	us-gaap	Energy Related Inventory EnergyRelatedInventory	223063000	USD
CY2016Q4	us-gaap	Equity Method Investments EquityMethodInvestments	236900000	USD
CY2017Q4	us-gaap	Equity Method Investments EquityMethodInvestments	277600000	USD
CY2015	us-gaap	Excess Tax Benefit From Share Based Compensation Financing Activities ExcessTaxBenefitFromShareBasedCompensationFinancingActivities	9500000	USD
CY2015	us-gaap	Excise And Sales Taxes ExciseAndSalesTaxes	147200000	USD
CY2016	us-gaap	Excise And Sales Taxes ExciseAndSalesTaxes	162700000	USD
CY2017	us-gaap	Excise And Sales Taxes ExciseAndSalesTaxes	157400000	USD
CY2015	us-gaap	Income Tax Reconciliation Nondeductible Expense Depreciation IncomeTaxReconciliationNondeductibleExpenseDepreciation	-4600000	USD
CY2016	us-gaap	Income Tax Reconciliation Nondeductible Expense Depreciation IncomeTaxReconciliationNondeductibleExpenseDepreciation	-3400000	USD
CY2017	us-gaap	Income Tax Reconciliation Nondeductible Expense Depreciation IncomeTaxReconciliationNondeductibleExpenseDepreciation	-10800000	USD
CY2015	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	-4800000	USD
CY2016	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	6600000	USD
CY2017	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	-1500000	USD
CY2016Q4	us-gaap	Goodwill Goodwill	3519401000	USD
CY2017Q4	us-gaap	Goodwill Goodwill	4400000000	USD
CY2017Q4	us-gaap	Goodwill Goodwill	4427266000	USD
CY2017	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	900000000	USD
CY2017Q4	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	0	USD
CY2017	us-gaap	Goodwill Period Increase Decrease GoodwillPeriodIncreaseDecrease	3500000000	USD
CY2015	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	1425971000	USD
CY2016	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	1504800000	USD
CY2016	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	1504818000	USD
CY2017	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	1574407000	USD
CY2017	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	1574400000	USD
CY2015	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	539967000	USD
CY2015	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	540000000	USD
CY2016	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	555000000	USD
CY2016	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	554997000	USD
CY2017	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	578900000	USD
CY2017	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	578892000	USD
CY2015	us-gaap	Income Tax Rate Reconciliation Deductions Employee Stock Ownership Plan Dividends IncomeTaxRateReconciliationDeductionsEmployeeStockOwnershipPlanDividends	8100000	USD
CY2016	us-gaap	Income Tax Rate Reconciliation Deductions Employee Stock Ownership Plan Dividends IncomeTaxRateReconciliationDeductionsEmployeeStockOwnershipPlanDividends	8400000	USD
CY2017	us-gaap	Income Tax Rate Reconciliation Deductions Employee Stock Ownership Plan Dividends IncomeTaxRateReconciliationDeductionsEmployeeStockOwnershipPlanDividends	8400000	USD
CY2015	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	4700000	USD
CY2016	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	3300000	USD
CY2017	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	7000000	USD
CY2015	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	499100000	USD
CY2016	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	526700000	USD
CY2017	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	551000000	USD
CY2015	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	61100000	USD
CY2016	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	56200000	USD
CY2017	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	47700000	USD
CY2015	us-gaap	Income Tax Reconciliation Tax Credits Investment IncomeTaxReconciliationTaxCreditsInvestment	3600000	USD
CY2016	us-gaap	Income Tax Reconciliation Tax Credits Investment IncomeTaxReconciliationTaxCreditsInvestment	3400000	USD
CY2017	us-gaap	Income Tax Reconciliation Tax Credits Investment IncomeTaxReconciliationTaxCreditsInvestment	3200000	USD
CY2015	us-gaap	Income Tax Reconciliation Tax Credits Other IncomeTaxReconciliationTaxCreditsOther	3800000	USD
CY2016	us-gaap	Income Tax Reconciliation Tax Credits Other IncomeTaxReconciliationTaxCreditsOther	3500000	USD
CY2017	us-gaap	Income Tax Reconciliation Tax Credits Other IncomeTaxReconciliationTaxCreditsOther	0	USD
CY2015	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	10300000	USD
CY2016	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	-135500000	USD
CY2017	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	30800000	USD
CY2015	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	-91618000	USD
CY2016	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	-14126000	USD
CY2017	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	56067000	USD
CY2016Q4	us-gaap	Investments Fair Value Disclosure InvestmentsFairValueDisclosure	569200000	USD
CY2017Q4	us-gaap	Investments Fair Value Disclosure InvestmentsFairValueDisclosure	600800000	USD
CY2017	us-gaap	Investment Income Interest InvestmentIncomeInterest	8300000	USD
CY2015	us-gaap	Increase Decrease In Income Taxes Receivable IncreaseDecreaseInIncomeTaxesReceivable	-30282000	USD
CY2016	us-gaap	Increase Decrease In Income Taxes Receivable IncreaseDecreaseInIncomeTaxesReceivable	-234543000	USD
CY2017	us-gaap	Increase Decrease In Income Taxes Receivable IncreaseDecreaseInIncomeTaxesReceivable	-52284000	USD
CY2015	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	-34112000	USD
CY2016	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	-7755000	USD
CY2017	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	9223000	USD
CY2015	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	-44031000	USD
CY2016	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	-9112000	USD
CY2017	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	-88738000	USD
CY2015	us-gaap	Increase Decrease In Receivables IncreaseDecreaseInReceivables	39797000	USD
CY2016	us-gaap	Increase Decrease In Receivables IncreaseDecreaseInReceivables	142699000	USD
CY2017	us-gaap	Increase Decrease In Receivables IncreaseDecreaseInReceivables	117155000	USD
CY2015	us-gaap	Increase Decrease In Regulatory Assets And Liabilities IncreaseDecreaseInRegulatoryAssetsAndLiabilities	163287000	USD
CY2016	us-gaap	Increase Decrease In Regulatory Assets And Liabilities IncreaseDecreaseInRegulatoryAssetsAndLiabilities	-13340000	USD
CY2017	us-gaap	Increase Decrease In Regulatory Assets And Liabilities IncreaseDecreaseInRegulatoryAssetsAndLiabilities	47935000	USD
CY2015	us-gaap	Interest Expense InterestExpense	372400000	USD
CY2015	us-gaap	Interest Expense InterestExpense	372420000	USD
CY2016	us-gaap	Interest Expense InterestExpense	400961000	USD
CY2016	us-gaap	Interest Expense InterestExpense	401000000	USD
CY2017	us-gaap	Interest Expense InterestExpense	421755000	USD
CY2017	us-gaap	Interest Expense InterestExpense	421800000	USD
CY2015	us-gaap	Interest Paid Net InterestPaidNet	365900000	USD
CY2016	us-gaap	Interest Paid Net InterestPaidNet	398100000	USD
CY2017	us-gaap	Interest Paid Net InterestPaidNet	419100000	USD
CY2015	us-gaap	Investment Income Interest InvestmentIncomeInterest	6700000	USD
CY2016	us-gaap	Investment Income Interest InvestmentIncomeInterest	11000000	USD
CY2015	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	12100000	USD
CY2016	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	12100000	USD
CY2017	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	10500000	USD
CY2016Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	32053173000	USD
CY2017Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	36220386000	USD
CY2016Q4	us-gaap	Liabilities Current LiabilitiesCurrent	3638605000	USD
CY2017Q4	us-gaap	Liabilities Current LiabilitiesCurrent	3589045000	USD
CY2016Q4	us-gaap	Liabilities Noncurrent LiabilitiesNoncurrent	8717912000	USD
CY2017Q4	us-gaap	Liabilities Noncurrent LiabilitiesNoncurrent	9613640000	USD
CY2016Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	773883000	USD
CY2017Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	549631000	USD
CY2017Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal After Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive	7643100000	USD
CY2017Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Next Twelve Months LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths	961000000	USD
CY2017Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive	1188900000	USD
CY2017Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	922800000	USD
CY2017Q3	us-gaap	Net Income Loss NetIncomeLoss	262200000	USD
CY2017Q4	us-gaap	Net Income Loss NetIncomeLoss	239400000	USD
CY2017Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	296100000	USD
CY2017Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo	801000000	USD
CY2016Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	8829354000	USD
CY2017Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	11775889000	USD
CY2016Q1	us-gaap	Loss Contingency Damages Awarded Value LossContingencyDamagesAwardedValue	26100000	USD
CY2016Q4	us-gaap	Marketable Securities Noncurrent MarketableSecuritiesNoncurrent	544642000	USD
CY2017Q4	us-gaap	Marketable Securities Noncurrent MarketableSecuritiesNoncurrent	585419000	USD
CY2016Q4	us-gaap	Marketable Securities Restricted Noncurrent MarketableSecuritiesRestrictedNoncurrent	466700000	USD
CY2017Q4	us-gaap	Marketable Securities Restricted Noncurrent MarketableSecuritiesRestrictedNoncurrent	503600000	USD
CY2015	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	210643000	USD
CY2016	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-17940000	USD
CY2017	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	1213454000	USD
CY2015	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-1659150000	USD
CY2016	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-2150808000	USD
CY2017	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-3210474000	USD
CY2015	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	1433751000	USD
CY2016	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	2175052000	USD
CY2017	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	2004934000	USD
CY2015	us-gaap	Net Income Loss NetIncomeLoss	886000000	USD
CY2015	us-gaap	Net Income Loss NetIncomeLoss	886004000	USD
CY2016Q1	us-gaap	Net Income Loss NetIncomeLoss	246000000	USD
CY2016Q2	us-gaap	Net Income Loss NetIncomeLoss	205500000	USD
CY2016Q3	us-gaap	Net Income Loss NetIncomeLoss	267200000	USD
CY2016Q4	us-gaap	Net Income Loss NetIncomeLoss	231100000	USD
CY2016	us-gaap	Net Income Loss NetIncomeLoss	949821000	USD
CY2016	us-gaap	Net Income Loss NetIncomeLoss	949800000	USD
CY2017Q1	us-gaap	Net Income Loss NetIncomeLoss	261300000	USD
CY2017Q2	us-gaap	Net Income Loss NetIncomeLoss	232600000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	995500000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	995515000	USD
CY2015	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	7519000	USD
CY2015	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	7500000	USD
CY2016	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	7519000	USD
CY2016	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	7500000	USD
CY2017	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	7519000	USD
CY2017	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	7500000	USD
CY2015	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	878485000	USD
CY2015	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	878500000	USD
CY2016Q1	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	244200000	USD
CY2016Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	203600000	USD
CY2016Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	265300000	USD
CY2016Q4	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	229200000	USD
CY2017	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	987996000	USD
CY2017	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	988000000	USD
CY2016	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	942300000	USD
CY2016	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	942302000	USD
CY2017Q1	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	259500000	USD
CY2017Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	230700000	USD
CY2017Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	260400000	USD
CY2017Q4	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	237400000	USD
CY2015	us-gaap	Nonoperating Income Expense NonoperatingIncomeExpense	34227000	USD
CY2016	us-gaap	Nonoperating Income Expense NonoperatingIncomeExpense	45920000	USD
CY2017	us-gaap	Nonoperating Income Expense NonoperatingIncomeExpense	78008000	USD
CY2016Q4	us-gaap	Notes Payable NotesPayable	1148500000	USD
CY2017Q4	us-gaap	Notes Payable NotesPayable	1088087000	USD
CY2016	us-gaap	Oci Before Reclassifications Before Tax Attributable To Parent OciBeforeReclassificationsBeforeTaxAttributableToParent	-4500000	USD
CY2015	us-gaap	Operating Expenses OperatingExpenses	6190663000	USD
CY2016	us-gaap	Operating Expenses OperatingExpenses	5779270000	USD
CY2017	us-gaap	Operating Expenses OperatingExpenses	5833798000	USD
CY2015	us-gaap	Operating Income Loss OperatingIncomeLoss	1764164000	USD
CY2015	us-gaap	Operating Income Loss OperatingIncomeLoss	1764200000	USD
CY2016Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	488500000	USD
CY2016Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	423400000	USD
CY2016Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	509900000	USD
CY2016Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	438100000	USD
CY2016	us-gaap	Operating Income Loss OperatingIncomeLoss	1859900000	USD
CY2016	us-gaap	Operating Income Loss OperatingIncomeLoss	1859859000	USD
CY2017Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	509000000	USD
CY2017Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	455700000	USD
CY2017Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	502600000	USD
CY2017Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	450900000	USD
CY2017	us-gaap	Operating Income Loss OperatingIncomeLoss	1918154000	USD
CY2017	us-gaap	Operating Income Loss OperatingIncomeLoss	1918200000	USD
CY2017Q4	us-gaap	Operating Leases Future Minimum Payments Due OperatingLeasesFutureMinimumPaymentsDue	70600000	USD
CY2017Q4	us-gaap	Operating Leases Future Minimum Payments Due Current OperatingLeasesFutureMinimumPaymentsDueCurrent	13200000	USD
CY2017Q4	us-gaap	Operating Leases Future Minimum Payments Due In Five Years OperatingLeasesFutureMinimumPaymentsDueInFiveYears	7400000	USD
CY2017Q4	us-gaap	Operating Leases Future Minimum Payments Due In Four Years OperatingLeasesFutureMinimumPaymentsDueInFourYears	8900000	USD
CY2017Q4	us-gaap	Operating Leases Future Minimum Payments Due In Three Years OperatingLeasesFutureMinimumPaymentsDueInThreeYears	10000000	USD
CY2017Q4	us-gaap	Operating Leases Future Minimum Payments Due In Two Years OperatingLeasesFutureMinimumPaymentsDueInTwoYears	11400000	USD
CY2017Q4	us-gaap	Operating Leases Future Minimum Payments Due Thereafter OperatingLeasesFutureMinimumPaymentsDueThereafter	19700000	USD
CY2016Q4	us-gaap	Other Assets Current OtherAssetsCurrent	215284000	USD
CY2017Q4	us-gaap	Other Assets Current OtherAssetsCurrent	138009000	USD
CY2016Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	522260000	USD
CY2017Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	605692000	USD
CY2015	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	-2588000	USD
CY2016	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	2294000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	-350000	USD
CY2015	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Net Of Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax	2079000	USD
CY2016	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Net Of Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax	2137000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Net Of Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax	1974000	USD
CY2015	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	7165000	USD
CY2016	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	1562000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-1121000	USD
CY2016	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	1500000	USD
CY2015	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-7674000	USD
CY2016	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Before Reclassification Adjustments Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansBeforeReclassificationAdjustmentsTax	4000000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Before Reclassification Adjustments Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansBeforeReclassificationAdjustmentsTax	4100000	USD
CY2016	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	2869000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	2745000	USD
CY2015	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Before Reclassification Adjustments Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansBeforeReclassificationAdjustmentsTax	-2000000	USD
CY2016Q4	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	684914000	USD
CY2017Q4	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	738222000	USD
CY2016Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	853260000	USD
CY2017Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	1073501000	USD
CY2015	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	82219000	USD
CY2016	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	77294000	USD
CY2017	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	148429000	USD
CY2015	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	27500000	USD
CY2016	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	34900000	USD
CY2017	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	69700000	USD
CY2015	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-6291000	USD
CY2016	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-36951000	USD
CY2017	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-25521000	USD
CY2015	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	529791000	USD
CY2016	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	564486000	USD
CY2017	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	602083000	USD
CY2015	us-gaap	Payments Of Dividends Preferred Stock And Preference Stock PaymentsOfDividendsPreferredStockAndPreferenceStock	7519000	USD
CY2016	us-gaap	Payments Of Dividends Preferred Stock And Preference Stock PaymentsOfDividendsPreferredStockAndPreferenceStock	7519000	USD
CY2017	us-gaap	Payments Of Dividends Preferred Stock And Preference Stock PaymentsOfDividendsPreferredStockAndPreferenceStock	7519000	USD
CY2015	us-gaap	Payments To Acquire Businesses Gross PaymentsToAcquireBusinessesGross	0	USD
CY2016	us-gaap	Payments To Acquire Businesses Gross PaymentsToAcquireBusinessesGross	0	USD
CY2017	us-gaap	Payments To Acquire Businesses Gross PaymentsToAcquireBusinessesGross	877652000	USD
CY2015	us-gaap	Payments To Acquire Investments PaymentsToAcquireInvestments	23353000	USD
CY2016	us-gaap	Payments To Acquire Investments PaymentsToAcquireInvestments	188958000	USD
CY2017	us-gaap	Payments To Acquire Investments PaymentsToAcquireInvestments	32634000	USD
CY2015	us-gaap	Payments To Acquire Marketable Securities PaymentsToAcquireMarketableSecurities	717114000	USD
CY2016	us-gaap	Payments To Acquire Marketable Securities PaymentsToAcquireMarketableSecurities	681272000	USD
CY2017	us-gaap	Payments To Acquire Marketable Securities PaymentsToAcquireMarketableSecurities	810507000	USD
CY2015	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	1724139000	USD
CY2015	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	1724100000	USD
CY2016	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	1976867000	USD
CY2016	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	1976900000	USD
CY2017	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	2348100000	USD
CY2017	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	2348105000	USD
CY2015	us-gaap	Pension And Other Postretirement Benefit Contributions PensionAndOtherPostretirementBenefitContributions	162452000	USD
CY2016	us-gaap	Pension And Other Postretirement Benefit Contributions PensionAndOtherPostretirementBenefitContributions	158741000	USD
CY2017	us-gaap	Pension And Other Postretirement Benefit Contributions PensionAndOtherPostretirementBenefitContributions	242800000	USD
CY2015	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	96017000	USD
CY2016	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	39912000	USD
CY2017	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	22454000	USD
CY2016Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	1141514000	USD
CY2017Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	1228091000	USD
CY2016Q4	us-gaap	Preferred Stock Value Outstanding PreferredStockValueOutstanding	155600000	USD
CY2017Q4	us-gaap	Preferred Stock Value Outstanding PreferredStockValueOutstanding	155600000	USD
CY2015	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	1225000000	USD
CY2016	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	800000000	USD
CY2017	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	2500000000	USD
CY2015	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-18225000	USD
CY2016	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-33482000	USD
CY2017Q4	us-gaap	Ratio Of Indebtedness To Net Capital1 RatioOfIndebtednessToNetCapital1	0.65
CY2015	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	-6300000	USD
CY2017	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-4754000	USD
CY2015	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	-242122000	USD
CY2016	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	-6000000	USD
CY2017	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	-6500000	USD
CY2016Q4	us-gaap	Public Utilities Property Plant And Equipment Net PublicUtilitiesPropertyPlantAndEquipmentNet	21350500000	USD
CY2017Q4	us-gaap	Public Utilities Property Plant And Equipment Net PublicUtilitiesPropertyPlantAndEquipmentNet	23617500000	USD
CY2016	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	-12453000	USD
CY2017	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	72810000	USD
CY2017Q4	us-gaap	Public Utilities Property Plant And Equipment Net PublicUtilitiesPropertyPlantAndEquipmentNet	23617463000	USD
CY2016Q4	us-gaap	Public Utilities Property Plant And Equipment Other Property Plant And Equipment PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipment	591600000	USD
CY2017Q4	us-gaap	Public Utilities Property Plant And Equipment Other Property Plant And Equipment PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipment	693700000	USD
CY2016Q4	us-gaap	Public Utilities Property Plant And Equipment Plant In Service PublicUtilitiesPropertyPlantAndEquipmentPlantInService	27060500000	USD
CY2017Q4	us-gaap	Public Utilities Property Plant And Equipment Plant In Service PublicUtilitiesPropertyPlantAndEquipmentPlantInService	29213900000	USD
CY2016Q4	us-gaap	Public Utilities Property Plant And Equipment Transmission PublicUtilitiesPropertyPlantAndEquipmentTransmission	8517400000	USD
CY2017Q4	us-gaap	Public Utilities Property Plant And Equipment Transmission PublicUtilitiesPropertyPlantAndEquipmentTransmission	9270900000	USD
CY2015	us-gaap	Proceeds From Sale And Maturity Of Marketable Securities ProceedsFromSaleAndMaturityOfMarketableSecurities	799165000	USD
CY2016	us-gaap	Proceeds From Sale And Maturity Of Marketable Securities ProceedsFromSaleAndMaturityOfMarketableSecurities	659338000	USD
CY2017	us-gaap	Proceeds From Sale And Maturity Of Marketable Securities ProceedsFromSaleAndMaturityOfMarketableSecurities	832903000	USD
CY2017	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	3200000	USD
CY2015	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	18800000	USD
CY2016	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	26200000	USD
CY2017	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	34400000	USD
CY2015	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Interest PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedInterest	7200000	USD
CY2016	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Interest PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedInterest	10800000	USD
CY2017	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Interest PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedInterest	12500000	USD
CY2015	us-gaap	Public Utilities Allowance For Funds Used During Construction Rate PublicUtilitiesAllowanceForFundsUsedDuringConstructionRate	0.039
CY2016	us-gaap	Public Utilities Allowance For Funds Used During Construction Rate PublicUtilitiesAllowanceForFundsUsedDuringConstructionRate	0.044
CY2017	us-gaap	Public Utilities Allowance For Funds Used During Construction Rate PublicUtilitiesAllowanceForFundsUsedDuringConstructionRate	0.051
CY2016Q4	us-gaap	Public Utilities Property Plant And Equipment Accumulated Depreciation PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation	6722400000	USD
CY2017Q4	us-gaap	Public Utilities Property Plant And Equipment Accumulated Depreciation PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation	7133800000	USD
CY2016Q4	us-gaap	Public Utilities Property Plant And Equipment Construction Work In Progress PublicUtilitiesPropertyPlantAndEquipmentConstructionWorkInProgress	1012400000	USD
CY2017Q4	us-gaap	Public Utilities Property Plant And Equipment Construction Work In Progress PublicUtilitiesPropertyPlantAndEquipmentConstructionWorkInProgress	1537400000	USD
CY2015	us-gaap	Public Utilities Property Plant And Equipment Disclosure Of Composite Depreciation Rate For Plants In Service PublicUtilitiesPropertyPlantAndEquipmentDisclosureOfCompositeDepreciationRateForPlantsInService	0.029
CY2016	us-gaap	Public Utilities Property Plant And Equipment Disclosure Of Composite Depreciation Rate For Plants In Service PublicUtilitiesPropertyPlantAndEquipmentDisclosureOfCompositeDepreciationRateForPlantsInService	0.030
CY2017	us-gaap	Public Utilities Property Plant And Equipment Disclosure Of Composite Depreciation Rate For Plants In Service PublicUtilitiesPropertyPlantAndEquipmentDisclosureOfCompositeDepreciationRateForPlantsInService	0.030
CY2016Q4	us-gaap	Public Utilities Property Plant And Equipment Distribution PublicUtilitiesPropertyPlantAndEquipmentDistribution	13716900000	USD
CY2017Q4	us-gaap	Public Utilities Property Plant And Equipment Distribution PublicUtilitiesPropertyPlantAndEquipmentDistribution	14410500000	USD
CY2016Q4	us-gaap	Public Utilities Property Plant And Equipment Generation Or Processing PublicUtilitiesPropertyPlantAndEquipmentGenerationOrProcessing	1224200000	USD
CY2017Q4	us-gaap	Public Utilities Property Plant And Equipment Generation Or Processing PublicUtilitiesPropertyPlantAndEquipmentGenerationOrProcessing	36200000	USD
CY2016Q4	us-gaap	Public Utilities Property Plant And Equipment Net PublicUtilitiesPropertyPlantAndEquipmentNet	21350510000	USD
CY2016	us-gaap	Reclassification From Aoci Current Period Net Of Tax Attributable To Parent ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent	-6000000	USD
CY2016Q4	us-gaap	Redeemable Noncontrolling Interest Equity Preferred Carrying Amount RedeemableNoncontrollingInterestEquityPreferredCarryingAmount	155568000	USD
CY2017Q4	us-gaap	Redeemable Noncontrolling Interest Equity Preferred Carrying Amount RedeemableNoncontrollingInterestEquityPreferredCarryingAmount	155570000	USD
CY2016Q4	us-gaap	Regulatory Assets RegulatoryAssets	4526300000	USD
CY2017Q4	us-gaap	Regulatory Assets RegulatoryAssets	5239300000	USD
CY2016Q4	us-gaap	Regulatory Assets Current RegulatoryAssetsCurrent	887600000	USD
CY2017	us-gaap	Revenues Revenues	7751952000	USD
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	388269	shares
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue	52.75
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Authorized ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized	8000000	shares
CY2016Q4	us-gaap	Regulatory Assets Current RegulatoryAssetsCurrent	887625000	USD
CY2017Q4	us-gaap	Regulatory Assets Current RegulatoryAssetsCurrent	741900000	USD
CY2017Q4	us-gaap	Regulatory Assets Current RegulatoryAssetsCurrent	741868000	USD
CY2016Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	3638700000	USD
CY2016Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	3638688000	USD
CY2017Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	4497400000	USD
CY2017Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	4497447000	USD
CY2016Q4	us-gaap	Regulatory Liabilities RegulatoryLiabilities	849100000	USD
CY2017Q4	us-gaap	Regulatory Liabilities RegulatoryLiabilities	883400000	USD
CY2016Q4	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	146787000	USD
CY2016Q4	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	146800000	USD
CY2017Q4	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	128100000	USD
CY2017Q4	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	128071000	USD
CY2016Q4	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	702255000	USD
CY2017Q4	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	3637273000	USD
CY2015	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	216700000	USD
CY2016	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	200000000	USD
CY2017	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	745000000	USD
CY2016Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	3175171000	USD
CY2017Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	3561084000	USD
CY2017Q4	us-gaap	Retained Earnings Unappropriated RetainedEarningsUnappropriated	3600000000	USD
CY2015	us-gaap	Revenues Revenues	7954827000	USD
CY2015	us-gaap	Revenues Revenues	7954800000	USD
CY2016Q1	us-gaap	Revenues Revenues	2055600000	USD
CY2016Q2	us-gaap	Revenues Revenues	1767200000	USD
CY2016Q3	us-gaap	Revenues Revenues	2039700000	USD
CY2016Q4	us-gaap	Revenues Revenues	1776600000	USD
CY2016	us-gaap	Revenues Revenues	7639100000	USD
CY2016	us-gaap	Revenues Revenues	7639129000	USD
CY2017Q1	us-gaap	Revenues Revenues	2105100000	USD
CY2017Q2	us-gaap	Revenues Revenues	1762800000	USD
CY2017Q3	us-gaap	Revenues Revenues	1988500000	USD
CY2017Q4	us-gaap	Revenues Revenues	1895600000	USD
CY2017	us-gaap	Revenues Revenues	7752000000	USD
CY2016Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant	2692350	shares
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant	2445110	shares
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	4400000	USD
CY2016Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	3700000	USD
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	0	USD
CY2016Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	124640	shares
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	0	shares
CY2016Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	25.84
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	0.00
CY2017	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	25.84
CY2017	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	124640	shares
CY2015	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	9468000	USD
CY2016	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	-5560000	USD
CY2015	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	-6140000	USD
CY2016	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	-6056000	USD
CY2017	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	-10834000	USD
CY2015	us-gaap	Stock Issued During Period Value Treasury Stock Reissued StockIssuedDuringPeriodValueTreasuryStockReissued	12560000	USD
CY2016	us-gaap	Stock Issued During Period Value Treasury Stock Reissued StockIssuedDuringPeriodValueTreasuryStockReissued	-7794000	USD
CY2014Q4	us-gaap	Stockholders Equity StockholdersEquity	9976815000	USD
CY2015Q4	us-gaap	Stockholders Equity StockholdersEquity	10352215000	USD
CY2016Q4	us-gaap	Stockholders Equity StockholdersEquity	10711734000	USD
CY2017Q4	us-gaap	Stockholders Equity StockholdersEquity	11086242000	USD
CY2015	us-gaap	Taxes Excluding Income And Excise Taxes TaxesExcludingIncomeAndExciseTaxes	590573000	USD
CY2016	us-gaap	Taxes Excluding Income And Excise Taxes TaxesExcludingIncomeAndExciseTaxes	634072000	USD
CY2017	us-gaap	Taxes Excluding Income And Excise Taxes TaxesExcludingIncomeAndExciseTaxes	676757000	USD
CY2016	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	24.26
CY2017Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	16992594	shares
CY2016	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	321228	shares
CY2016Q4	us-gaap	Treasury Stock Value TreasuryStockValue	317771000	USD
CY2017Q4	us-gaap	Treasury Stock Value TreasuryStockValue	317771000	USD
CY2014Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	46200000	USD
CY2015Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	48000000	USD
CY2016Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	48400000	USD
CY2017Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	51700000	USD
CY2017	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	900000	USD
CY2015	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	9900000	USD
CY2016	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	9900000	USD
CY2017	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	11400000	USD
CY2015	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	100000	USD
CY2016	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	200000	USD
CY2016Q4	us-gaap	Unrecognized Tax Benefits Interest On Income Taxes Accrued UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued	1800000	USD
CY2017Q4	us-gaap	Unrecognized Tax Benefits Interest On Income Taxes Accrued UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued	1800000	USD
CY2015	us-gaap	Unrecognized Tax Benefits Interest On Income Taxes Expense UnrecognizedTaxBenefitsInterestOnIncomeTaxesExpense	100000	USD
CY2016	us-gaap	Unrecognized Tax Benefits Interest On Income Taxes Expense UnrecognizedTaxBenefitsInterestOnIncomeTaxesExpense	-200000	USD
CY2017	us-gaap	Unrecognized Tax Benefits Interest On Income Taxes Expense UnrecognizedTaxBenefitsInterestOnIncomeTaxesExpense	0	USD
CY2015	us-gaap	Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	8200000	USD
CY2016	us-gaap	Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	9700000	USD
CY2017	us-gaap	Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	7200000	USD
CY2017Q4	us-gaap	Unrecorded Unconditional Purchase Obligation Balance On Fifth Anniversary UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary	459500000	USD
CY2017Q4	us-gaap	Unrecorded Unconditional Purchase Obligation Balance On First Anniversary UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary	599000000	USD
CY2017Q4	us-gaap	Unrecorded Unconditional Purchase Obligation Balance On Fourth Anniversary UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary	497200000	USD
CY2017Q4	us-gaap	Unrecorded Unconditional Purchase Obligation Balance On Second Anniversary UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary	578200000	USD
CY2017Q4	us-gaap	Unrecorded Unconditional Purchase Obligation Balance On Third Anniversary UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary	542800000	USD
CY2017Q4	us-gaap	Unrecorded Unconditional Purchase Obligation Balance Sheet Amount UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount	5546100000	USD
CY2017Q4	us-gaap	Unrecorded Unconditional Purchase Obligation Due After Five Years UnrecordedUnconditionalPurchaseObligationDueAfterFiveYears	2869400000	USD
CY2015	us-gaap	Utilities Operating Expense Maintenance And Operations UtilitiesOperatingExpenseMaintenanceAndOperations	1329289000	USD
CY2016	us-gaap	Utilities Operating Expense Maintenance And Operations UtilitiesOperatingExpenseMaintenanceAndOperations	1323549000	USD
CY2017	us-gaap	Utilities Operating Expense Maintenance And Operations UtilitiesOperatingExpenseMaintenanceAndOperations	1277147000	USD
CY2015	us-gaap	Utilities Operating Expense Other UtilitiesOperatingExpenseOther	5502400000	USD
CY2016	us-gaap	Utilities Operating Expense Other UtilitiesOperatingExpenseOther	4992100000	USD
CY2017	us-gaap	Utilities Operating Expense Other UtilitiesOperatingExpenseOther	4970000000	USD
CY2015	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	1095806	shares
CY2016	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	804059	shares
CY2017	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	620483	shares
CY2015	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	318432687	shares
CY2016	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	318454239	shares
CY2017	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	318031580	shares
CY2015	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	317336881	shares
CY2016	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	317650180	shares
CY2017	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	317411097	shares
CY2017	us-gaap	Revenue Recognition Deferred Revenue RevenueRecognitionDeferredRevenue	<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">Revenues</font></div><div style="line-height:120%;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-style:italic;">Retail Revenues:  </font><font style="font-family:inherit;font-size:9pt;">Retail revenues are based on rates approved by respective state regulatory commissions.  In general, rates can only be changed through formal proceedings with the state regulatory commissions.  These rates are designed to recover the costs to provide service to customers, and include a return on investment.  Regulatory commission-approved tracking mechanisms are also used to recover certain costs on a fully-reconciling basis.  These tracking mechanisms require rates to be changed periodically to ensure recovery of actual costs incurred.  </font></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div><div style="line-height:120%;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">Certain Eversource electric, natural gas and water companies, including CL&P and NSTAR Electric (for a portion of its customers), have a regulatory commission approved revenue decoupling mechanism ("decoupled companies"). Distribution revenues are decoupled from customer sales volumes, where applicable, which breaks the relationship between sales volumes and revenues recognized. The decoupled companies reconcile their annual base distribution rate recovery to pre-established levels of baseline distribution delivery service revenues.  Any difference between the allowed level of distribution revenue and the actual amount realized is adjusted through rates in a subsequent period.  </font></div><div style="line-height:120%;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;"><br clear="none"/></font></div><div style="line-height:120%;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">A significant portion of the electric and natural gas companies' retail revenues relate to the recovery of costs incurred for the sale of electricity and natural gas purchased on behalf of customers.  These energy supply costs are recovered from customers in rates through cost tracking mechanisms.</font><font style="font-family:inherit;font-size:9pt;font-weight:bold;"> </font><font style="font-family:inherit;font-size:9pt;">Energy purchases are recorded in Purchased Power, Fuel and Transmission, and the sales of energy associated with these purchases are recorded in Operating Revenues on the statements of income. </font></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div><div style="line-height:120%;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-style:italic;">Unbilled Revenues:  </font><font style="font-family:inherit;font-size:9pt;">Because customers are billed throughout the month based on pre-determined cycles rather than on a calendar month basis, an estimate of electricity, natural gas or water delivered to customers for which the customers have not yet been billed is calculated as of the balance sheet date.  Unbilled revenues are included in Operating Revenues on the statements of income and in Current Assets on the balance sheets.  Actual amounts billed to customers when meter readings become available may vary from the estimated amount.</font></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div><div style="line-height:120%;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">Unbilled revenues are recognized by allocating estimated unbilled sales volumes to the respective customer classes, and then applying an estimated rate by customer class to those sales volumes.  Unbilled revenues can vary significantly from period to period as a result of seasonality, weather, customer usage patterns, customer rates in effect for customer classes, and the timing of customer billing. The estimate of unbilled revenues can significantly impact the amount of revenues recorded at the companies that do not have a revenue decoupling mechanism.  Companies that do have a decoupling mechanism record a regulatory deferral to reflect the actual allowed amount of revenue associated with their respective decoupled distribution rate design. </font></div><div style="line-height:120%;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;"><br clear="none"/></font></div><div style="line-height:120%;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-style:italic;">Transmission Revenues - Wholesale Rates:</font><font style="font-family:inherit;font-size:9pt;">  The Eversource electric transmission-owning companies have a combination of FERC-approved regional and local formula rates that work in tandem to recover all their transmission costs. These rates are part of the ISO-NE Tariff. Regional rates recover the costs of higher voltage transmission facilities that benefit the region, and are collected from all New England transmission customers, including the Eversource distribution businesses. Eversource and NSTAR Electric each have two sets of local rates that recover the companies' total transmission revenue requirements, less revenues received from regional rates and other sources, and are collected from Eversource's distribution businesses and other transmission customers. The distribution businesses of Eversource, in turn, recover the FERC- approved charges from retail customers through annual or semiannual tracking mechanisms. The transmission formula rates provide for the annual reconciliation and recovery or refund of estimated costs to actual costs.  The financial impacts of differences between actual and estimated costs are deferred for future recovery from, or refund to, transmission customers.  See Note 11E, "Commitments and Contingencies – FERC ROE Complaints," for complaints filed at the FERC relating to Eversource's ROE.</font></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div><div style="line-height:120%;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-style:italic;">Transmission Revenues - Retail Rates:</font><font style="font-family:inherit;font-size:9pt;">  A significant portion of the Eversource electric transmission segment revenue comes from ISO-NE charges to the distribution businesses of CL&P, NSTAR Electric, and PSNH, each of which recovers these costs through rates charged to their retail customers.  CL&P, NSTAR Electric and PSNH each have a retail transmission cost tracking mechanism as part of their rates, which allows the electric distribution companies to charge their retail customers for transmission costs on a timely basis.</font></div></div>
CY2017	es	Percentageof Costsand Benefits Borne Under Unrecorded Unconditional Purchase Obligationby United Illuminated Company PercentageofCostsandBenefitsBorneUnderUnrecordedUnconditionalPurchaseObligationbyUnitedIlluminatedCompany	0.2

Files In Submission

Name	View Source	Status
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2017 Q4 Form 10-K Financial Statement

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Income Statement

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Files In Submission

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