$NI
NISOURCE INC. Stock $ni

$ni Overview Financials Valuation SEC Filings Company Website

2020 Q4 Form 10-K Financial Statement

#000111171121000010 Filed on February 17, 2021

Income Statement

Concept	2020 Q4	2020 Q3	2020 Q2
Revenue	$1.211B	$902.5M	$962.7M
YoY Change	-13.33%	-3.11%	-4.72%
Cost Of Revenue	$315.4M	$143.1M	$188.4M
YoY Change	-21.99%	-27.25%	-25.68%
Gross Profit	$1.211B	$902.5M	$962.7M
YoY Change	-13.33%	-3.11%	-4.72%
Gross Profit Margin	100.0%	100.0%	100.0%
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$183.5M	$180.6M	$177.5M
YoY Change	0.71%	-0.88%	-0.22%
% of Gross Profit	15.15%	20.01%	18.44%
Operating Expenses	$666.7M	$630.7M	$598.8M
YoY Change	8.18%	-24.96%	9.49%
Operating Profit	$218.1M	$92.80M	$91.70M
YoY Change	-673.95%	1.98%	-80.22%
Interest Expense	-$84.50M	$95.20M	$97.00M
YoY Change	-7.14%	-0.73%	3.08%
% of Operating Profit	-38.74%	102.59%	105.78%
Other Income/Expense, Net	$11.10M	-$330.6M	-$90.50M
YoY Change	-242.31%	249.47%	-4.13%
Pretax Income	$144.6M	-$237.8M	$1.200M
YoY Change	-205.7%	6505.56%	-99.67%
Income Tax	$56.80M	-$64.90M	$5.900M
% Of Pretax Income	39.28%		491.67%
Net Earnings	$84.40M	-$172.9M	-$4.700M
YoY Change	-160.59%	-2719.7%	-101.58%
Net Earnings / Revenue	6.97%	-19.16%	-0.49%
Basic Earnings Per Share	$0.18	-$0.49	-$0.05
Diluted Earnings Per Share	$0.18	-$0.49	-$0.05
COMMON SHARES
Basic Shares Outstanding	383.2M shares	383.8M shares	383.5M shares
Diluted Shares Outstanding		383.8M shares	383.5M shares

Balance Sheet

Concept	2020 Q4	2020 Q3	2020 Q2
SHORT-TERM ASSETS
Cash & Short-Term Investments	$117.0M	$59.00M	$142.0M
YoY Change	-15.83%	110.71%	491.67%
Cash & Equivalents	$116.5M	$58.60M	$142.2M
Short-Term Investments
Other Short-Term Assets	$86.00M	$112.6M	$142.6M
YoY Change	22.51%	31.85%	38.31%
Inventory	$401.0M	$397.0M	$312.0M
Prepaid Expenses
Receivables	$791.3M	$521.4M	$545.7M
Other Receivables	$34.00M	$25.00M	$18.00M
Total Short-Term Assets	$1.659B	$2.821B	$2.860B
YoY Change	-10.49%	104.66%	81.22%
LONG-TERM ASSETS
Property, Plant & Equipment	$16.62B	$16.08B	$15.77B
YoY Change	-1.73%	-2.8%	-2.6%
Goodwill	$1.486B	$1.486B	$1.486B
YoY Change	0.0%	-12.11%	-12.11%
Intangibles	$0.00
YoY Change
Long-Term Investments	$252.0M	$238.0M	$229.0M
YoY Change	9.57%	8.18%	5.05%
Other Assets	$3.510B	$3.564B	$3.575B
YoY Change	-4.2%	-12.08%	-11.61%
Total Long-Term Assets	$20.38B	$19.88B	$19.58B
YoY Change	-2.04%	-4.21%	-4.02%
TOTAL ASSETS
Total Short-Term Assets	$1.659B	$2.821B	$2.860B
Total Long-Term Assets	$20.38B	$19.88B	$19.58B
Total Assets	$22.04B	$22.70B	$22.44B
YoY Change	-2.73%	2.57%	2.1%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$589.0M	$410.3M	$402.5M
YoY Change	-11.56%	-17.09%	-27.11%
Accrued Expenses	$389.0M	$383.0M	$389.0M
YoY Change	-31.15%	-29.85%	-28.75%
Deferred Revenue	$243.3M	$229.2M	$163.1M
YoY Change	-5.11%
Short-Term Debt	$503.0M	$1.388B	$1.164B
YoY Change	-71.63%	-14.05%	-44.09%
Long-Term Debt Due	$23.00M	$21.00M	$16.00M
YoY Change	76.92%	90.91%	45.45%
Total Short-Term Liabilities	$2.279B	$3.447B	$3.228B
YoY Change	-39.15%	3.21%	-15.37%
LONG-TERM LIABILITIES
Long-Term Debt	$9.220B	$9.209B	$8.810B
YoY Change	17.36%	17.25%	23.91%
Other Long-Term Liabilities	$515.5M	$214.7M	$198.8M
YoY Change	125.9%	-4.45%	-10.77%
Total Long-Term Liabilities	$4.704B	$4.621B	$4.737B
YoY Change	-7.25%	-9.22%	-6.66%
TOTAL LIABILITIES
Total Short-Term Liabilities	$2.279B	$3.447B	$3.228B
Total Long-Term Liabilities	$4.704B	$4.621B	$4.737B
Total Liabilities	$6.983B	$8.068B	$7.965B
YoY Change	-20.8%	-4.3%	-10.39%
SHAREHOLDERS EQUITY
Retained Earnings	-$1.765B	-$1.850B	-$1.577B
YoY Change	28.77%	50.18%	37.82%
Common Stock	$6.894B	$6.688B	$6.680B
YoY Change	3.36%	4.01%	4.04%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$99.90M	$99.90M	$99.90M
YoY Change	0.0%	0.0%	0.0%
Treasury Stock Shares
Shareholders Equity	$5.752B	$5.425B	$5.662B
YoY Change
Total Liabilities & Shareholders Equity	$22.04B	$22.70B	$22.44B
YoY Change	-2.73%	2.57%	2.1%

Cashflow Statement

Concept	2020 Q4	2020 Q3	2020 Q2
OPERATING ACTIVITIES
Net Income	$84.40M	-$172.9M	-$4.700M
YoY Change	-160.59%	-2719.7%	-101.58%
Depreciation, Depletion And Amortization	$183.5M	$180.6M	$177.5M
YoY Change	0.71%	-0.88%	-0.22%
Cash From Operating Activities	$245.4M	$150.9M	$337.8M
YoY Change	-30.18%	-50.62%	-35.91%
INVESTING ACTIVITIES
Capital Expenditures	-$502.0M	-$508.3M	-$399.4M
YoY Change	-3.67%	2.62%	-23.22%
Acquisitions
YoY Change
Other Investing Activities	$1.023B	-$5.000M	-$2.600M
YoY Change	-13737.33%	900.0%	8.33%
Cash From Investing Activities	$520.8M	-$513.3M	-$402.0M
YoY Change	-198.52%	3.53%	-23.08%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	-708.2M	276.4M	4.800M
YoY Change	-345.48%	41.89%	-103.61%
NET CHANGE
Cash From Operating Activities	245.4M	150.9M	337.8M
Cash From Investing Activities	520.8M	-513.3M	-402.0M
Cash From Financing Activities	-708.2M	276.4M	4.800M
Net Change In Cash	58.00M	-86.00M	-59.40M
YoY Change	-47.94%	-1969.57%	-53.74%
FREE CASH FLOW
Cash From Operating Activities	$245.4M	$150.9M	$337.8M
Capital Expenditures	-$502.0M	-$508.3M	-$399.4M
Free Cash Flow	$747.4M	$659.2M	$737.2M
YoY Change	-14.35%	-17.69%	-29.61%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2020	dei	Entity Central Index Key EntityCentralIndexKey	0001111711
CY2020	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2020
CY2020	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2020	dei	Amendment Flag AmendmentFlag	false
CY2020	us-gaap	Debt Instrument Convertible Conversion Ratio1 DebtInstrumentConvertibleConversionRatio1	0.625	Rate
CY2019Q4	us-gaap	Operating Lease Right Of Use Asset Statement Of Financial Position Extensible List OperatingLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList	us-gaap:DeferredChargesAndOther
CY2020Q4	us-gaap	Operating Lease Right Of Use Asset Statement Of Financial Position Extensible List OperatingLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList	us-gaap:DeferredChargesAndOther
CY2019Q4	us-gaap	Operating Lease Liability Current Statement Of Financial Position Extensible List OperatingLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList	us-gaap:OtherAccruals
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CY2020Q4	us-gaap	Operating Lease Liability Noncurrent Statement Of Financial Position Extensible List OperatingLeaseLiabilityNoncurrentStatementOfFinancialPositionExtensibleList	us-gaap:OtherNoncurrentLiabilities
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CY2019Q4	us-gaap	Finance Lease Liability Current Statement Of Financial Position Extensible List FinanceLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList	us-gaap:Currentportionoflong-termdebt
CY2020Q4	us-gaap	Finance Lease Liability Current Statement Of Financial Position Extensible List FinanceLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList	us-gaap:Currentportionoflong-termdebt
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CY2020	dei	Document Type DocumentType	10-K
CY2020	dei	Document Annual Report DocumentAnnualReport	true
CY2020	dei	Document Period End Date DocumentPeriodEndDate	2020-12-31
CY2020	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2020	dei	Document Transition Report DocumentTransitionReport	false
CY2020	dei	Entity File Number EntityFileNumber	001-16189
CY2020	dei	Entity Registrant Name EntityRegistrantName	NiSource Inc.
CY2020	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	DE
CY2020	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	35-2108964
CY2020	dei	Entity Address Address Line1 EntityAddressAddressLine1	801 East 86th Avenue
CY2020	dei	Entity Address City Or Town EntityAddressCityOrTown	Merrillville,
CY2020	dei	Entity Address State Or Province EntityAddressStateOrProvince	IN
CY2020	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	46410
CY2020	dei	City Area Code CityAreaCode	(877)
CY2020	dei	Local Phone Number LocalPhoneNumber	647-5990
CY2020	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
CY2020	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2020	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2020	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
CY2020	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2020	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
CY2020	dei	Entity Small Business EntitySmallBusiness	false
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CY2020	dei	Entity Shell Company EntityShellCompany	false
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CY2020Q4	us-gaap	Public Utilities Property Plant And Equipment Plant In Service PublicUtilitiesPropertyPlantAndEquipmentPlantInService	24179900000	USD
CY2019Q4	us-gaap	Public Utilities Property Plant And Equipment Plant In Service PublicUtilitiesPropertyPlantAndEquipmentPlantInService	24541900000	USD
CY2020Q4	us-gaap	Public Utilities Property Plant And Equipment Accumulated Depreciation PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation	7560400000	USD
CY2019Q4	us-gaap	Public Utilities Property Plant And Equipment Accumulated Depreciation PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation	7629700000	USD
CY2020Q4	us-gaap	Public Utilities Property Plant And Equipment Net PublicUtilitiesPropertyPlantAndEquipmentNet	16619500000	USD
CY2019Q4	us-gaap	Public Utilities Property Plant And Equipment Net PublicUtilitiesPropertyPlantAndEquipmentNet	16912200000	USD
CY2020Q4	us-gaap	Investments In Affiliates Subsidiaries Associates And Joint Ventures InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures	0	USD
CY2019Q4	us-gaap	Investments In Affiliates Subsidiaries Associates And Joint Ventures InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures	1300000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	163900000	USD
CY2019Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	150100000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss DebtSecuritiesAvailableForSaleAllowanceForCreditLoss	-500000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss DebtSecuritiesAvailableForSaleAllowanceForCreditLoss	0	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Securities Noncurrent AvailableForSaleSecuritiesDebtSecuritiesNoncurrent	170900000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Securities Noncurrent AvailableForSaleSecuritiesDebtSecuritiesNoncurrent	154200000	USD
CY2020Q4	us-gaap	Other Long Term Investments OtherLongTermInvestments	81100000	USD
CY2019Q4	us-gaap	Other Long Term Investments OtherLongTermInvestments	74700000	USD
CY2020Q4	us-gaap	Investments And Other Noncurrent Assets InvestmentsAndOtherNoncurrentAssets	252000000.0	USD
CY2019Q4	us-gaap	Investments And Other Noncurrent Assets InvestmentsAndOtherNoncurrentAssets	230200000	USD
CY2020Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	116500000	USD
CY2019Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	139300000	USD
CY2020Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	9100000	USD
CY2019Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	9100000	USD
CY2020Q4	us-gaap	Accounts Receivable Gross Current AccountsReceivableGrossCurrent	843600000	USD
CY2019Q4	us-gaap	Accounts Receivable Gross Current AccountsReceivableGrossCurrent	876100000	USD
CY2020Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	52300000	USD
CY2019Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	19200000	USD
CY2020Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	791300000	USD
CY2019Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	856900000	USD
CY2020Q4	us-gaap	Energy Related Inventory Natural Gas In Storage EnergyRelatedInventoryNaturalGasInStorage	191200000	USD
CY2019Q4	us-gaap	Energy Related Inventory Natural Gas In Storage EnergyRelatedInventoryNaturalGasInStorage	250900000	USD
CY2020Q4	us-gaap	Inventory Raw Materials And Supplies InventoryRawMaterialsAndSupplies	141500000	USD
CY2019Q4	us-gaap	Inventory Raw Materials And Supplies InventoryRawMaterialsAndSupplies	120200000	USD
CY2020Q4	us-gaap	Energy Related Inventory Coal EnergyRelatedInventoryCoal	68400000	USD
CY2019Q4	us-gaap	Energy Related Inventory Coal EnergyRelatedInventoryCoal	53600000	USD
CY2020Q4	nix	Exchange Gas Receivable ExchangeGasReceivable	34100000	USD
CY2019Q4	nix	Exchange Gas Receivable ExchangeGasReceivable	48500000	USD
CY2020Q4	us-gaap	Regulatory Assets Current RegulatoryAssetsCurrent	135700000	USD
CY2019Q4	us-gaap	Regulatory Assets Current RegulatoryAssetsCurrent	225700000	USD
CY2020Q4	us-gaap	Deferred Costs Current DeferredCostsCurrent	85600000	USD
CY2019Q4	us-gaap	Deferred Costs Current DeferredCostsCurrent	79500000	USD
CY2020Q4	us-gaap	Other Assets Current OtherAssetsCurrent	86000000.0	USD
CY2019Q4	us-gaap	Other Assets Current OtherAssetsCurrent	70200000	USD
CY2020Q4	us-gaap	Assets Current AssetsCurrent	1659400000	USD
CY2019Q4	us-gaap	Assets Current AssetsCurrent	1853900000	USD
CY2020Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	1794800000	USD
CY2019Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	2013900000	USD
CY2020Q4	us-gaap	Goodwill Goodwill	1485900000	USD
CY2019Q4	us-gaap	Goodwill Goodwill	1485900000	USD
CY2020Q4	nix	Deferred Charges And Other DeferredChargesAndOther	228900000	USD
CY2019Q4	nix	Deferred Charges And Other DeferredChargesAndOther	163700000	USD
CY2020Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	3509600000	USD
CY2019Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	3663500000	USD
CY2020Q4	us-gaap	Assets Assets	22040500000	USD
CY2019Q4	us-gaap	Assets Assets	22659800000	USD
CY2019Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.01
CY2020Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.01
CY2019Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	600000000	shares
CY2020Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	600000000	shares
CY2020Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	391760051	shares
CY2019Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	382135680	shares
CY2020Q4	us-gaap	Common Stock Value CommonStockValue	3900000	USD
CY2019Q4	us-gaap	Common Stock Value CommonStockValue	3800000	USD
CY2019Q4	us-gaap	Preferred Stock Par Or Stated Value Per Share PreferredStockParOrStatedValuePerShare	0.01
CY2020Q4	us-gaap	Preferred Stock Par Or Stated Value Per Share PreferredStockParOrStatedValuePerShare	0.01
CY2019Q4	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	20000000	shares
CY2020Q4	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	20000000	shares
CY2020Q4	us-gaap	Preferred Stock Shares Outstanding PreferredStockSharesOutstanding	440000	shares
CY2019Q4	us-gaap	Preferred Stock Shares Outstanding PreferredStockSharesOutstanding	440000	shares
CY2020Q4	us-gaap	Preferred Stock Value Outstanding PreferredStockValueOutstanding	880000000.0	USD
CY2019Q4	us-gaap	Preferred Stock Value Outstanding PreferredStockValueOutstanding	880000000.0	USD
CY2020Q4	us-gaap	Treasury Stock Value TreasuryStockValue	99900000	USD
CY2019Q4	us-gaap	Treasury Stock Value TreasuryStockValue	99900000	USD
CY2020Q4	us-gaap	Additional Paid In Capital Common Stock AdditionalPaidInCapitalCommonStock	6890100000	USD
CY2019Q4	us-gaap	Additional Paid In Capital Common Stock AdditionalPaidInCapitalCommonStock	6666200000	USD
CY2020Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	-1765200000	USD
CY2019Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	-1370800000	USD
CY2020Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-156700000	USD
CY2019Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-92600000	USD
CY2020Q4	us-gaap	Stockholders Equity StockholdersEquity	5752200000	USD
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	5986700000	USD
CY2020Q4	us-gaap	Minority Interest MinorityInterest	85600000	USD
CY2019Q4	us-gaap	Minority Interest MinorityInterest	0	USD
CY2020Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	5837800000	USD
CY2019Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	5986700000	USD
CY2020Q4	us-gaap	Long Term Debt And Capital Lease Obligations LongTermDebtAndCapitalLeaseObligations	9219800000	USD
CY2019Q4	us-gaap	Long Term Debt And Capital Lease Obligations LongTermDebtAndCapitalLeaseObligations	7856200000	USD
CY2020Q4	us-gaap	Capitalization Longterm Debt And Equity CapitalizationLongtermDebtAndEquity	15057600000	USD
CY2019Q4	us-gaap	Capitalization Longterm Debt And Equity CapitalizationLongtermDebtAndEquity	13842900000	USD
CY2020Q4	us-gaap	Long Term Debt And Capital Lease Obligations Current LongTermDebtAndCapitalLeaseObligationsCurrent	23300000	USD
CY2019Q4	us-gaap	Long Term Debt And Capital Lease Obligations Current LongTermDebtAndCapitalLeaseObligationsCurrent	13400000	USD
CY2020Q4	us-gaap	Short Term Borrowings ShortTermBorrowings	503000000.0	USD
CY2019Q4	us-gaap	Short Term Borrowings ShortTermBorrowings	1773200000	USD
CY2020Q4	us-gaap	Accounts Payable Current AccountsPayableCurrent	589000000.0	USD
CY2019Q4	us-gaap	Accounts Payable Current AccountsPayableCurrent	666000000.0	USD
CY2020Q4	us-gaap	Contract With Customer Liability Current ContractWithCustomerLiabilityCurrent	243300000	USD
CY2019Q4	us-gaap	Contract With Customer Liability Current ContractWithCustomerLiabilityCurrent	256400000	USD
CY2020Q4	us-gaap	Taxes Payable Current TaxesPayableCurrent	244100000	USD
CY2019Q4	us-gaap	Taxes Payable Current TaxesPayableCurrent	231600000	USD
CY2020Q4	us-gaap	Interest Payable Current InterestPayableCurrent	104700000	USD
CY2019Q4	us-gaap	Interest Payable Current InterestPayableCurrent	99400000	USD
CY2020Q4	us-gaap	Derivative Instruments And Hedges Liabilities DerivativeInstrumentsAndHedgesLiabilities	78200000	USD
CY2019Q4	us-gaap	Derivative Instruments And Hedges Liabilities DerivativeInstrumentsAndHedgesLiabilities	12600000	USD
CY2020Q4	nix	Exchange Gas Payable ExchangeGasPayable	48500000	USD
CY2019Q4	nix	Exchange Gas Payable ExchangeGasPayable	59700000	USD
CY2020Q4	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	161300000	USD
CY2019Q4	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	160200000	USD
CY2020Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	141800000	USD
CY2019Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	156300000	USD
CY2020Q4	nix	Accrued Insurance Claims Current AccruedInsuranceClaimsCurrent	28600000	USD
CY2019Q4	nix	Accrued Insurance Claims Current AccruedInsuranceClaimsCurrent	165400000	USD
CY2020Q4	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	113600000	USD
CY2019Q4	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	151600000	USD
CY2020Q4	us-gaap	Liabilities Current LiabilitiesCurrent	2279400000	USD
CY2019Q4	us-gaap	Liabilities Current LiabilitiesCurrent	3745800000	USD
CY2020Q4	us-gaap	Derivative Instruments And Hedges Liabilities Noncurrent DerivativeInstrumentsAndHedgesLiabilitiesNoncurrent	144600000	USD
CY2019Q4	us-gaap	Derivative Instruments And Hedges Liabilities Noncurrent DerivativeInstrumentsAndHedgesLiabilitiesNoncurrent	134000000.0	USD
CY2020Q4	us-gaap	Deferred Income Tax Liabilities Net DeferredIncomeTaxLiabilitiesNet	1470600000	USD
CY2019Q4	us-gaap	Deferred Income Tax Liabilities Net DeferredIncomeTaxLiabilitiesNet	1485300000	USD
CY2020Q4	us-gaap	Accrued Insurance Noncurrent AccruedInsuranceNoncurrent	84800000	USD
CY2019Q4	us-gaap	Accrued Insurance Noncurrent AccruedInsuranceNoncurrent	81500000	USD
CY2020Q4	us-gaap	Pension And Other Postretirement And Postemployment Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementAndPostemploymentBenefitPlansLiabilitiesNoncurrent	336100000	USD
CY2019Q4	us-gaap	Pension And Other Postretirement And Postemployment Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementAndPostemploymentBenefitPlansLiabilitiesNoncurrent	373200000	USD
CY2020Q4	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	1904200000	USD
CY2019Q4	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	2352000000.0	USD
CY2020Q4	us-gaap	Asset Retirement Obligations Noncurrent AssetRetirementObligationsNoncurrent	477100000	USD
CY2019Q4	us-gaap	Asset Retirement Obligations Noncurrent AssetRetirementObligationsNoncurrent	416900000	USD
CY2020Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	286100000	USD
CY2019Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	228200000	USD
CY2020Q4	us-gaap	Liabilities Noncurrent LiabilitiesNoncurrent	4703500000	USD
CY2019Q4	us-gaap	Liabilities Noncurrent LiabilitiesNoncurrent	5071100000	USD
CY2020Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	22040500000	USD
CY2019Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	22659800000	USD
CY2020	us-gaap	Profit Loss ProfitLoss	-14200000	USD
CY2019	us-gaap	Profit Loss ProfitLoss	383100000	USD
CY2018	us-gaap	Profit Loss ProfitLoss	-50600000	USD
CY2020	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-243500000	USD
CY2019	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	USD
CY2018	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-45500000	USD
CY2020	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	725900000	USD
CY2019	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	717400000	USD
CY2018	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	599600000	USD
CY2020	us-gaap	Deferred Income Taxes And Tax Credits DeferredIncomeTaxesAndTaxCredits	-29000000.0	USD
CY2019	us-gaap	Deferred Income Taxes And Tax Credits DeferredIncomeTaxesAndTaxCredits	118200000	USD
CY2018	us-gaap	Deferred Income Taxes And Tax Credits DeferredIncomeTaxesAndTaxCredits	-188200000	USD
CY2020	us-gaap	Share Based Compensation ShareBasedCompensation	17400000	USD
CY2019	us-gaap	Share Based Compensation ShareBasedCompensation	25900000	USD
CY2018	us-gaap	Share Based Compensation ShareBasedCompensation	28600000	USD
CY2020	us-gaap	Asset Impairment Charges AssetImpairmentCharges	0	USD
CY2019	us-gaap	Asset Impairment Charges AssetImpairmentCharges	414500000	USD
CY2018	us-gaap	Asset Impairment Charges AssetImpairmentCharges	0	USD
CY2020	us-gaap	Gain Loss On Disposition Of Assets1 GainLossOnDispositionOfAssets1	-409800000	USD
CY2019	us-gaap	Gain Loss On Disposition Of Assets1 GainLossOnDispositionOfAssets1	600000	USD
CY2018	us-gaap	Gain Loss On Disposition Of Assets1 GainLossOnDispositionOfAssets1	-1300000	USD
CY2020	us-gaap	Amortization Of Debt Discount Premium AmortizationOfDebtDiscountPremium	9400000	USD
CY2019	us-gaap	Amortization Of Debt Discount Premium AmortizationOfDebtDiscountPremium	8200000	USD
CY2018	us-gaap	Amortization Of Debt Discount Premium AmortizationOfDebtDiscountPremium	7500000	USD
CY2020	us-gaap	Public Utilities Allowance For Funds Used During Construction Additions PublicUtilitiesAllowanceForFundsUsedDuringConstructionAdditions	9900000	USD
CY2019	us-gaap	Public Utilities Allowance For Funds Used During Construction Additions PublicUtilitiesAllowanceForFundsUsedDuringConstructionAdditions	8000000.0	USD
CY2018	us-gaap	Public Utilities Allowance For Funds Used During Construction Additions PublicUtilitiesAllowanceForFundsUsedDuringConstructionAdditions	14200000	USD
CY2020	us-gaap	Other Operating Activities Cash Flow Statement OtherOperatingActivitiesCashFlowStatement	200000	USD
CY2019	us-gaap	Other Operating Activities Cash Flow Statement OtherOperatingActivitiesCashFlowStatement	-300000	USD
CY2018	us-gaap	Other Operating Activities Cash Flow Statement OtherOperatingActivitiesCashFlowStatement	400000	USD
CY2020	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	3900000	USD
CY2019	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	-187800000	USD
CY2018	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	186200000	USD
CY2020	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	1500000	USD
CY2019	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	2000000.0	USD
CY2018	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	-41400000	USD
CY2020	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	-29700000	USD
CY2019	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	-299900000	USD
CY2018	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	268400000	USD
CY2020	us-gaap	Increase Decrease In Contract With Customer Liability IncreaseDecreaseInContractWithCustomerLiability	10000000.0	USD
CY2019	us-gaap	Increase Decrease In Contract With Customer Liability IncreaseDecreaseInContractWithCustomerLiability	16900000	USD
CY2018	us-gaap	Increase Decrease In Contract With Customer Liability IncreaseDecreaseInContractWithCustomerLiability	-25400000	USD
CY2020	us-gaap	Increase Decrease In Property And Other Taxes Payable IncreaseDecreaseInPropertyAndOtherTaxesPayable	28400000	USD
CY2019	us-gaap	Increase Decrease In Property And Other Taxes Payable IncreaseDecreaseInPropertyAndOtherTaxesPayable	7300000	USD
CY2018	us-gaap	Increase Decrease In Property And Other Taxes Payable IncreaseDecreaseInPropertyAndOtherTaxesPayable	20200000	USD
CY2020	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	5300000	USD
CY2019	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	8800000	USD
CY2018	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	-21700000	USD
CY2020	nix	Increase Decrease In Exchange Gas Receivable Payable IncreaseDecreaseInExchangeGasReceivablePayable	6900000	USD
CY2019	nix	Increase Decrease In Exchange Gas Receivable Payable IncreaseDecreaseInExchangeGasReceivablePayable	-55500000	USD
CY2018	nix	Increase Decrease In Exchange Gas Receivable Payable IncreaseDecreaseInExchangeGasReceivablePayable	21500000	USD
CY2020	nix	Increase Decrease In Other Accruals IncreaseDecreaseInOtherAccruals	218800000	USD
CY2019	nix	Increase Decrease In Other Accruals IncreaseDecreaseInOtherAccruals	-105300000	USD
CY2020	us-gaap	Increase Decrease In Regulatory Assets And Liabilities IncreaseDecreaseInRegulatoryAssetsAndLiabilities	-70800000	USD
CY2019	us-gaap	Increase Decrease In Regulatory Assets And Liabilities IncreaseDecreaseInRegulatoryAssetsAndLiabilities	85600000	USD
CY2018	nix	Increase Decrease In Other Accruals IncreaseDecreaseInOtherAccruals	-43500000	USD
CY2020	nix	Increase Decrease In Prepayments And Other Current Assets IncreaseDecreaseInPrepaymentsAndOtherCurrentAssets	-5900000	USD
CY2019	nix	Increase Decrease In Prepayments And Other Current Assets IncreaseDecreaseInPrepaymentsAndOtherCurrentAssets	-33600000	USD
CY2018	nix	Increase Decrease In Prepayments And Other Current Assets IncreaseDecreaseInPrepaymentsAndOtherCurrentAssets	-14500000	USD
CY2018	us-gaap	Increase Decrease In Regulatory Assets And Liabilities IncreaseDecreaseInRegulatoryAssetsAndLiabilities	53200000	USD
CY2020	us-gaap	Increase Decrease In Employee Related Liabilities IncreaseDecreaseInEmployeeRelatedLiabilities	-103600000	USD
CY2019	us-gaap	Increase Decrease In Employee Related Liabilities IncreaseDecreaseInEmployeeRelatedLiabilities	-21100000	USD
CY2018	us-gaap	Increase Decrease In Employee Related Liabilities IncreaseDecreaseInEmployeeRelatedLiabilities	58200000	USD
CY2020	nix	Increase Decrease In Deferred Charges And Other Non Current Assets IncreaseDecreaseInDeferredChargesAndOtherNonCurrentAssets	-15000000.0	USD
CY2019	nix	Increase Decrease In Deferred Charges And Other Non Current Assets IncreaseDecreaseInDeferredChargesAndOtherNonCurrentAssets	-76100000	USD
CY2018	nix	Increase Decrease In Deferred Charges And Other Non Current Assets IncreaseDecreaseInDeferredChargesAndOtherNonCurrentAssets	3800000	USD
CY2020	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	21700000	USD
CY2019	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	61600000	USD
CY2018	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-2800000	USD
CY2020	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	1104000000.0	USD
CY2019	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	1583300000	USD
CY2018	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	540100000	USD
CY2020	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	1758100000	USD
CY2019	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	1802400000	USD
CY2018	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	1818200000	USD
CY2020	us-gaap	Payments For Removal Costs PaymentsForRemovalCosts	138200000	USD
CY2019	us-gaap	Payments For Removal Costs PaymentsForRemovalCosts	113200000	USD
CY2018	us-gaap	Payments For Removal Costs PaymentsForRemovalCosts	104300000	USD
CY2020	us-gaap	Proceeds From Sale Of Productive Assets ProceedsFromSaleOfProductiveAssets	1115900000	USD
CY2019	us-gaap	Proceeds From Sale Of Productive Assets ProceedsFromSaleOfProductiveAssets	400000	USD
CY2018	us-gaap	Proceeds From Sale Of Productive Assets ProceedsFromSaleOfProductiveAssets	1800000	USD
CY2020	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	144700000	USD
CY2019	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	140400000	USD
CY2018	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	90000000.0	USD
CY2020	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	131400000	USD
CY2019	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	132100000	USD
CY2018	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	82300000	USD
CY2020	nix	Payment To Renewable Generation Asset Developer PaymentToRenewableGenerationAssetDeveloper	85300000	USD
CY2019	nix	Payment To Renewable Generation Asset Developer PaymentToRenewableGenerationAssetDeveloper	0	USD
CY2018	nix	Payment To Renewable Generation Asset Developer PaymentToRenewableGenerationAssetDeveloper	0	USD
CY2020	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	100000	USD
CY2019	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-1100000	USD
CY2018	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-2300000	USD
CY2020	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-879100000	USD
CY2019	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-1922400000	USD
CY2018	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-1926100000	USD
CY2020	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	2974000000.0	USD
CY2019	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	750000000.0	USD
CY2018	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	350000000.0	USD
CY2020	us-gaap	Repayments Of Long Term Debt And Capital Securities RepaymentsOfLongTermDebtAndCapitalSecurities	1622000000.0	USD
CY2019	us-gaap	Repayments Of Long Term Debt And Capital Securities RepaymentsOfLongTermDebtAndCapitalSecurities	51600000	USD
CY2018	us-gaap	Repayments Of Long Term Debt And Capital Securities RepaymentsOfLongTermDebtAndCapitalSecurities	1046100000	USD
CY2020	us-gaap	Proceeds From Short Term Debt Maturing In More Than Three Months ProceedsFromShortTermDebtMaturingInMoreThanThreeMonths	1350000000.0	USD
CY2019	us-gaap	Proceeds From Short Term Debt Maturing In More Than Three Months ProceedsFromShortTermDebtMaturingInMoreThanThreeMonths	600000000.0	USD
CY2018	us-gaap	Proceeds From Short Term Debt Maturing In More Than Three Months ProceedsFromShortTermDebtMaturingInMoreThanThreeMonths	950000000.0	USD
CY2020	us-gaap	Repayments Of Short Term Debt Maturing In More Than Three Months RepaymentsOfShortTermDebtMaturingInMoreThanThreeMonths	2200000000.0	USD
CY2019	us-gaap	Repayments Of Short Term Debt Maturing In More Than Three Months RepaymentsOfShortTermDebtMaturingInMoreThanThreeMonths	700000000.0	USD
CY2018	us-gaap	Repayments Of Short Term Debt Maturing In More Than Three Months RepaymentsOfShortTermDebtMaturingInMoreThanThreeMonths	0	USD
CY2020	us-gaap	Proceeds From Repayments Of Short Term Debt Maturing In Three Months Or Less ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess	-420100000	USD
CY2019	us-gaap	Proceeds From Repayments Of Short Term Debt Maturing In Three Months Or Less ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess	-104000000.0	USD
CY2018	us-gaap	Proceeds From Repayments Of Short Term Debt Maturing In Three Months Or Less ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess	-178500000	USD
CY2020	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	211400000	USD
CY2019	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	244400000	USD
CY2018	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	848200000	USD
CY2020	us-gaap	Proceeds From Issuance Of Preferred Stock And Preference Stock ProceedsFromIssuanceOfPreferredStockAndPreferenceStock	0	USD
CY2019	us-gaap	Proceeds From Issuance Of Preferred Stock And Preference Stock ProceedsFromIssuanceOfPreferredStockAndPreferenceStock	0	USD
CY2018	us-gaap	Proceeds From Issuance Of Preferred Stock And Preference Stock ProceedsFromIssuanceOfPreferredStockAndPreferenceStock	880000000.0	USD
CY2020	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-246500000	USD
CY2019	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-17800000	USD
CY2018	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-46000000.0	USD
CY2020	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	0	USD
CY2019	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	0	USD
CY2018	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	4000000.0	USD
CY2020	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	82200000	USD
CY2019	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	0	USD
CY2018	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	0	USD
CY2020	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	321600000	USD
CY2019	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	298500000	USD
CY2018	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	273300000	USD
CY2020	us-gaap	Payments Of Dividends Preferred Stock And Preference Stock PaymentsOfDividendsPreferredStockAndPreferenceStock	55100000	USD
CY2019	us-gaap	Payments Of Dividends Preferred Stock And Preference Stock PaymentsOfDividendsPreferredStockAndPreferenceStock	56100000	USD
CY2018	us-gaap	Payments Of Dividends Preferred Stock And Preference Stock PaymentsOfDividendsPreferredStockAndPreferenceStock	11600000	USD
CY2020	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-247700000	USD
CY2019	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	366400000	USD
CY2018	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	1468700000	USD
CY2020	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	-22800000	USD
CY2019	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	27300000	USD
CY2018	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	82700000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	148400000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	121100000	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	38400000	USD
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	125600000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	148400000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	121100000	USD
CY2017Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	4320100000	USD
CY2018	us-gaap	Profit Loss ProfitLoss	-50600000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	15700000	USD
CY2018	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	15400000	USD
CY2018	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.78
CY2018	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	273500000	USD
CY2018	us-gaap	Preferred Stock Dividends Per Share Declared PreferredStockDividendsPerShareDeclared	28.88
CY2018	us-gaap	Dividends Preferred Stock Cash DividendsPreferredStockCash	11600000	USD
CY2018	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	4000000.0	USD
CY2018	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	599600000	USD
CY2018	nix	Stock Issued During Period Value New Preferred Issues StockIssuedDuringPeriodValueNewPreferredIssues	880000000.0	USD
CY2018	us-gaap	Stock Issued During Period Value Employee Stock Purchase Plan StockIssuedDuringPeriodValueEmployeeStockPurchasePlan	5500000	USD
CY2018	us-gaap	Stock Issued During Period Value Employee Benefit Plan StockIssuedDuringPeriodValueEmployeeBenefitPlan	21800000	USD
CY2018	us-gaap	Stock Issued During Period Value Other StockIssuedDuringPeriodValueOther	232500000	USD
CY2018Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	5750900000	USD
CY2019	us-gaap	Profit Loss ProfitLoss	383100000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-55400000	USD
CY2019	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.80
CY2019	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	298500000	USD
CY2019	us-gaap	Dividends Preferred Stock Cash DividendsPreferredStockCash	56100000	USD
CY2019	us-gaap	Stock Issued During Period Value Employee Stock Purchase Plan StockIssuedDuringPeriodValueEmployeeStockPurchasePlan	5600000	USD
CY2019	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	10400000	USD
CY2019	us-gaap	Stock Issued During Period Value Employee Benefit Plan StockIssuedDuringPeriodValueEmployeeBenefitPlan	17600000	USD
CY2019	us-gaap	Stock Issued During Period Value Other StockIssuedDuringPeriodValueOther	229100000	USD
CY2019Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	5986700000	USD
CY2020	us-gaap	Profit Loss ProfitLoss	-14200000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-64100000	USD
CY2020	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.84
CY2020	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	321700000	USD
CY2020	us-gaap	Dividends Preferred Stock Cash DividendsPreferredStockCash	55100000	USD
CY2020	us-gaap	Noncontrolling Interest Increase From Subsidiary Equity Issuance NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance	82200000	USD
CY2020	us-gaap	Stock Issued During Period Value Employee Stock Purchase Plan StockIssuedDuringPeriodValueEmployeeStockPurchasePlan	5700000	USD
CY2020	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	8400000	USD
CY2020	us-gaap	Stock Issued During Period Value Employee Benefit Plan StockIssuedDuringPeriodValueEmployeeBenefitPlan	13400000	USD
CY2020	us-gaap	Stock Issued During Period Value Other StockIssuedDuringPeriodValueOther	196500000	USD
CY2020Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	5837800000	USD
CY2017Q4	us-gaap	Shares Issued SharesIssued	337016000	shares
CY2018	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	166000	shares
CY2018	us-gaap	Stock Issued During Period Shares New Issues StockIssuedDuringPeriodSharesNewIssues	24964000	shares
CY2018	nix	Stock Issued Duringthe Period Shares Preferred StockIssuedDuringthePeriodSharesPreferred	0	shares
CY2018	us-gaap	Stock Issued During Period Shares Employee Stock Purchase Plans StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans	223000	shares
CY2018	us-gaap	Stock Issued During Period Shares Share Based Compensation StockIssuedDuringPeriodSharesShareBasedCompensation	561000	shares
CY2018	us-gaap	Stock Issued During Period Shares Employee Benefit Plan StockIssuedDuringPeriodSharesEmployeeBenefitPlan	882000	shares
CY2018	us-gaap	Stock Issued During Period Shares Other StockIssuedDuringPeriodSharesOther	8883000	shares
CY2018Q4	us-gaap	Shares Issued SharesIssued	372363000	shares
CY2019	nix	Stock Issued Duringthe Period Shares Preferred StockIssuedDuringthePeriodSharesPreferred	0	shares
CY2019	us-gaap	Stock Issued During Period Shares Employee Stock Purchase Plans StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans	201000	shares
CY2019	us-gaap	Stock Issued During Period Shares Share Based Compensation StockIssuedDuringPeriodSharesShareBasedCompensation	518000	shares
CY2019	us-gaap	Stock Issued During Period Shares Employee Benefit Plan StockIssuedDuringPeriodSharesEmployeeBenefitPlan	631000	shares
CY2019	us-gaap	Stock Issued During Period Shares Other StockIssuedDuringPeriodSharesOther	8423000	shares
CY2019Q4	us-gaap	Shares Issued SharesIssued	382136000	shares
CY2020	us-gaap	Stock Issued During Period Shares Employee Stock Purchase Plans StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans	236000	shares
CY2020	us-gaap	Stock Issued During Period Shares Share Based Compensation StockIssuedDuringPeriodSharesShareBasedCompensation	385000	shares
CY2020	us-gaap	Stock Issued During Period Shares Employee Benefit Plan StockIssuedDuringPeriodSharesEmployeeBenefitPlan	544000	shares
CY2020	us-gaap	Stock Issued During Period Shares Other StockIssuedDuringPeriodSharesOther	8459000	shares
CY2020Q4	us-gaap	Shares Issued SharesIssued	391760000	shares
CY2020	nix	Number Of Customers NumberOfCustomers	3700000
CY2020Q4	nix	Net Proceeds From Sale NetProceedsFromSale	1113000000	USD
CY2020Q1	nix	Purchase Price PurchasePrice	1100000000	USD
CY2020	us-gaap	Disposal Group Not Discontinued Operation Loss Gain On Write Down DisposalGroupNotDiscontinuedOperationLossGainOnWriteDown	412400000	USD
CY2020	us-gaap	Use Of Estimates UseOfEstimates	Use of Estimates. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
CY2020Q4	us-gaap	Unbilled Receivables Current UnbilledReceivablesCurrent	338300000	USD
CY2019Q4	us-gaap	Unbilled Receivables Current UnbilledReceivablesCurrent	350500000	USD
CY2018	us-gaap	Impairment Of Investments ImpairmentOfInvestments	0	USD
CY2019	us-gaap	Impairment Of Investments ImpairmentOfInvestments	0	USD
CY2020	us-gaap	Impairment Of Investments ImpairmentOfInvestments	0	USD
CY2020	nix	Pre Tax Rate For Allowance For Funds Used During Construction PreTaxRateForAllowanceForFundsUsedDuringConstruction	0.026
CY2019	nix	Pre Tax Rate For Allowance For Funds Used During Construction PreTaxRateForAllowanceForFundsUsedDuringConstruction	0.030
CY2018	nix	Pre Tax Rate For Allowance For Funds Used During Construction PreTaxRateForAllowanceForFundsUsedDuringConstruction	0.035
CY2020Q4	us-gaap	Lifo Inventory Amount LIFOInventoryAmount	42300000	USD
CY2019Q4	us-gaap	Lifo Inventory Amount LIFOInventoryAmount	47200000	USD
CY2020Q4	us-gaap	Excess Of Replacement Or Current Costs Over Stated Lifo Value ExcessOfReplacementOrCurrentCostsOverStatedLIFOValue	19600000	USD
CY2019Q4	us-gaap	Excess Of Replacement Or Current Costs Over Stated Lifo Value ExcessOfReplacementOrCurrentCostsOverStatedLIFOValue	25500000	USD
CY2020Q4	us-gaap	Weighted Average Cost Inventory Amount WeightedAverageCostInventoryAmount	148800000	USD
CY2019Q4	us-gaap	Weighted Average Cost Inventory Amount WeightedAverageCostInventoryAmount	203700000	USD
CY2020	us-gaap	Description Of New Accounting Pronouncements Not Yet Adopted DescriptionOfNewAccountingPronouncementsNotYetAdopted	<div style="margin-bottom:8pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Recently Issued Accounting Pronouncements</span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">We are currently evaluating the impact of certain ASUs on our Consolidated Financial Statements or Notes to Consolidated Financial Statements, which are described below:</span></div><div style="margin-bottom:6pt;text-align:justify"><table style="border-collapse:collapse;display:inline-table;vertical-align:top;width:99.269%"><tr><td style="width:1.0%"/><td style="width:17.898%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:28.502%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:18.340%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:30.860%"/><td style="width:0.1%"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Standard</span></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Description</span></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Effective Date</span></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Effect on the financial statements or other significant matters</span></td></tr><tr style="height:84pt"><td colspan="3" style="border-top:1pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">ASU 2020-04,</span></div><div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:100%">Reference Rate Reform</span></div><div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:100%">(Topic 848):</span></div><div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:100%">Facilitation of the</span></div><div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:100%">Effects of Reference</span></div><div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:100%">Rate Reform on</span></div><div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:100%">Financial Statement</span></div></td><td colspan="3" rowspan="2" style="border-bottom:1pt solid #000;border-top:1pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">This pronouncement provides<br/>temporary optional expedients<br/>and exceptions for applying<br/>GAAP principles to contract<br/>modifications and hedging<br/>relationships to ease the financial<br/>reporting burdens of the expected<br/>market transition from LIBOR<br/>and other interbank offered rates<br/>to alternative reference rates.</span></td><td colspan="3" rowspan="2" style="border-bottom:1pt solid #000;border-top:1pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Upon issuance on<br/>March 12, 2020, and<br/>will apply though<br/>December 31, 2022.</span></td><td colspan="3" rowspan="2" style="border-bottom:1pt solid #000;border-top:1pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">We continue to evaluate the temporary expedients and options available under this guidance, and the effects of these pronouncements on our Consolidated Financial Statements and Notes to Consolidated Financial Statements. We are currently identifying and evaluating contracts that may be impacted. As of December 31, 2020, we have not applied any expedients and options available under this ASU.</span></td></tr><tr style="height:45pt"><td colspan="3" style="background-color:#cceeff;border-bottom:1pt solid #000;border-top:1pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">ASU 2021-01,</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:100%"> Reference Rate Reform (Topic 848): Scope</span></div></td></tr></table></div><table style="border-collapse:collapse;display:inline-table;vertical-align:top;width:99.269%"><tr><td style="width:1.0%"/><td style="width:17.898%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:28.502%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:18.340%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:30.860%"/><td style="width:0.1%"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Standard</span></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Description</span></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Effective Date</span></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Effect on the financial statements or other significant matters</span></td></tr><tr><td colspan="3" style="background-color:#cceeff;border-bottom:1pt solid #000;border-top:1pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">ASU 2020-06,</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:100%"> Debt with Conversion and Other Options (Subtopic 470-20) and Derivative and Hedging - Contracts in Entity's Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity's Own Equity</span></div></td><td colspan="3" style="background-color:#cceeff;border-bottom:1pt solid #000;border-top:1pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">This pronouncement simplifies<br/>the accounting for certain<br/>financial instruments with<br/>characteristics of liabilities and<br/>equity, including convertible<br/>instruments and contracts on an<br/>entity's own equity. Specifically,<br/>the ASU "simplifies accounting<br/>for convertible instruments by<br/>removing major separation<br/>models required under current<br/>GAAP." In addition, the ASU<br/>"removes certain settlement<br/>conditions that are required for<br/>equity contracts to qualify for it"<br/>and "simplifies the diluted<br/>earnings per share (EPS)<br/>calculations in certain areas."</span></td><td colspan="3" style="background-color:#cceeff;border-bottom:1pt solid #000;border-top:1pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Annual period<br/>beginning after<br/>December 15, 2021.<br/>Early adoption is<br/>permitted for annual<br/>period beginning after<br/>December 15, 2020.</span></td><td colspan="3" style="background-color:#cceeff;border-bottom:1pt solid #000;border-top:1pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">This pronouncement does not impact any securities we currently have on our balance sheet. We will continue to<br/>evaluate the effects of this pronouncement on our Consolidated Financial Statements and Notes to Consolidated Financial Statements as it pertains to any relevant future activity. We expect to adopt this ASU on its effective date.</span></td></tr></table>
CY2020	nix	Service Area By County ServiceAreaByCounty	20
CY2020	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	4473200000	USD
CY2020	us-gaap	Regulated Operating Revenue Other RegulatedOperatingRevenueOther	208500000	USD
CY2020	us-gaap	Regulated Operating Revenue RegulatedOperatingRevenue	4681700000	USD
CY2019	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	5053400000	USD
CY2019	us-gaap	Regulated Operating Revenue Other RegulatedOperatingRevenueOther	155500000	USD
CY2019	us-gaap	Regulated Operating Revenue RegulatedOperatingRevenue	5208900000	USD
CY2018	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	4991100000	USD
CY2018	us-gaap	Regulated Operating Revenue Other RegulatedOperatingRevenueOther	123400000	USD
CY2018	us-gaap	Regulated Operating Revenue RegulatedOperatingRevenue	5114500000	USD
CY2019Q4	nix	Customer Accounts Receivable Billed Less Reserve CustomerAccountsReceivableBilledLessReserve	466600000	USD
CY2019Q4	nix	Customer Accounts Receivable Unbilled Less Reserve CustomerAccountsReceivableUnbilledLessReserve	346600000	USD
CY2020Q4	nix	Customer Accounts Receivable Billed Less Reserve CustomerAccountsReceivableBilledLessReserve	400000000.0	USD
CY2020Q4	nix	Customer Accounts Receivable Unbilled Less Reserve CustomerAccountsReceivableUnbilledLessReserve	327200000	USD
CY2020	nix	Increase Decreasein Customer Accounts Receivable Billed Less Reserve IncreaseDecreaseinCustomerAccountsReceivableBilledLessReserve	-66600000	USD
CY2020	nix	Increase Decreasein Customer Accounts Receivable Unbilled Less Reserve IncreaseDecreaseinCustomerAccountsReceivableUnbilledLessReserve	-19400000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	13000000.0	USD
CY2020	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	54600000	USD
CY2020	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	29700000	USD
CY2020	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	14400000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	52300000	USD
CY2020Q4	nix	Nameplate Capacity NameplateCapacity	102	MW
CY2020Q4	nix	Total Equity Membership Interest TotalEquityMembershipInterest	1
CY2020Q4	nix	Obligation To The Developer ObligationToTheDeveloper	69700000	USD
CY2020	nix	Payment To Renewable Generation Asset Developer PaymentToRenewableGenerationAssetDeveloper	85300000	USD
CY2020Q4	nix	Expected Future Obligation To The Developer ExpectedFutureObligationToTheDeveloper	6000000.0	USD
CY2020Q4	nix	Total Expected Contributions TotalExpectedContributions	170100000	USD
CY2020Q4	nix	Vie Net Assets VIENetAssets	156400000	USD
CY2020Q4	us-gaap	Minority Interest MinorityInterest	85600000	USD
CY2020	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	3400000	USD
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	384347000	shares
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	374650000	shares
CY2018	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	356491000	shares
CY2020	us-gaap	Incremental Common Shares Attributable To Contingently Issuable Shares IncrementalCommonSharesAttributableToContingentlyIssuableShares	0	shares
CY2019	us-gaap	Incremental Common Shares Attributable To Contingently Issuable Shares IncrementalCommonSharesAttributableToContingentlyIssuableShares	929000	shares
CY2018	us-gaap	Incremental Common Shares Attributable To Contingently Issuable Shares IncrementalCommonSharesAttributableToContingentlyIssuableShares	0	shares
CY2020	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	0	shares
CY2019	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	154000	shares
CY2018	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	0	shares
CY2020	us-gaap	Incremental Common Shares Attributable To Equity Forward Agreements IncrementalCommonSharesAttributableToEquityForwardAgreements	0	shares
CY2019	us-gaap	Incremental Common Shares Attributable To Equity Forward Agreements IncrementalCommonSharesAttributableToEquityForwardAgreements	253000	shares
CY2018	us-gaap	Incremental Common Shares Attributable To Equity Forward Agreements IncrementalCommonSharesAttributableToEquityForwardAgreements	0	shares
CY2020	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	384347000	shares
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	375986000	shares
CY2018	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	356491000	shares
CY2020Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	24179900000	USD
CY2019Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	24541900000	USD
CY2020Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	7560400000	USD
CY2019Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	7629700000	USD
CY2020Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	16619500000	USD
CY2019Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	16912200000	USD
CY2020Q4	nix	Plant And Equipment Associated With Schahfer Generating Station Retirement PlantAndEquipmentAssociatedWithSchahferGeneratingStationRetirement	903800000	USD
CY2020	us-gaap	Depreciation Depreciation	655600000	USD
CY2019	us-gaap	Depreciation Depreciation	612200000	USD
CY2018	us-gaap	Depreciation Depreciation	503400000	USD
CY2020	us-gaap	Capitalized Computer Software Amortization1 CapitalizedComputerSoftwareAmortization1	56700000	USD
CY2019	us-gaap	Capitalized Computer Software Amortization1 CapitalizedComputerSoftwareAmortization1	55500000	USD
CY2018	us-gaap	Capitalized Computer Software Amortization1 CapitalizedComputerSoftwareAmortization1	54100000	USD
CY2020Q4	us-gaap	Capitalized Computer Software Gross CapitalizedComputerSoftwareGross	136400000	USD
CY2019Q4	us-gaap	Capitalized Computer Software Gross CapitalizedComputerSoftwareGross	169600000	USD
CY2020	nix	Capitalized Cloud Computing Amortization CapitalizedCloudComputingAmortization	3400000	USD
CY2019	nix	Capitalized Cloud Computing Amortization CapitalizedCloudComputingAmortization	1600000	USD
CY2018	nix	Capitalized Cloud Computing Amortization CapitalizedCloudComputingAmortization	100000	USD
CY2020	nix	Capitalized Cloud Computing Gross CapitalizedCloudComputingGross	12700000	USD
CY2019	nix	Capitalized Cloud Computing Gross CapitalizedCloudComputingGross	14200000	USD
CY2020Q4	us-gaap	Goodwill Goodwill	1485900000	USD
CY2019Q4	us-gaap	Goodwill Goodwill	1485900000	USD
CY2019Q4	us-gaap	Intangible Assets Net Including Goodwill IntangibleAssetsNetIncludingGoodwill	0	USD
CY2020Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	0	USD
CY2019Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	0	USD
CY2020	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	0	USD
CY2018	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	11000000.0	USD
CY2019	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	11000000.0	USD
CY2019Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	416900000	USD
CY2018Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	352000000.0	USD
CY2020	nix	Accretion Recorded As Regulatory Asset Or Liability AccretionRecordedAsRegulatoryAssetOrLiability	17300000	USD
CY2019	nix	Accretion Recorded As Regulatory Asset Or Liability AccretionRecordedAsRegulatoryAssetOrLiability	15700000	USD
CY2020	us-gaap	Asset Retirement Obligation Liabilities Incurred AssetRetirementObligationLiabilitiesIncurred	5500000	USD
CY2019	us-gaap	Asset Retirement Obligation Liabilities Incurred AssetRetirementObligationLiabilitiesIncurred	0	USD
CY2020	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	13900000	USD
CY2019	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	5400000	USD
CY2020	us-gaap	Asset Retirement Obligation Revision Of Estimate AssetRetirementObligationRevisionOfEstimate	86000000.0	USD
CY2019	us-gaap	Asset Retirement Obligation Revision Of Estimate AssetRetirementObligationRevisionOfEstimate	54600000	USD
CY2020	nix	Asset Retirement Obligation Other AssetRetirementObligationOther	-16200000	USD
CY2019	nix	Asset Retirement Obligation Other AssetRetirementObligationOther	0	USD
CY2020Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	495600000	USD
CY2019Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	416900000	USD
CY2020Q4	us-gaap	Regulatory Assets RegulatoryAssets	1930500000	USD
CY2019Q4	us-gaap	Regulatory Assets RegulatoryAssets	2239600000	USD
CY2020Q4	us-gaap	Regulatory Assets Current RegulatoryAssetsCurrent	135700000	USD
CY2019Q4	us-gaap	Regulatory Assets Current RegulatoryAssetsCurrent	225700000	USD
CY2020Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	1794800000	USD
CY2019Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	2013900000	USD
CY2020Q4	us-gaap	Regulatory Liabilities RegulatoryLiabilities	2065500000	USD
CY2019Q4	us-gaap	Regulatory Liabilities RegulatoryLiabilities	2512200000	USD
CY2020Q4	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	161300000	USD
CY2019Q4	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	160200000	USD
CY2020Q4	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	1904200000	USD
CY2019Q4	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	2352000000.0	USD
CY2020Q4	us-gaap	Remaining Amounts Of Regulatory Assets For Which No Return On Investment During Recovery Period Is Provided RemainingAmountsOfRegulatoryAssetsForWhichNoReturnOnInvestmentDuringRecoveryPeriodIsProvided	1260600000	USD
CY2019Q4	us-gaap	Remaining Amounts Of Regulatory Assets For Which No Return On Investment During Recovery Period Is Provided RemainingAmountsOfRegulatoryAssetsForWhichNoReturnOnInvestmentDuringRecoveryPeriodIsProvided	1524300000	USD
CY2020	us-gaap	Remaining Recovery Period Of Regulatory Assets For Which No Return On Investment During Recovery Period Is Provided1 RemainingRecoveryPeriodOfRegulatoryAssetsForWhichNoReturnOnInvestmentDuringRecoveryPeriodIsProvided1	P41Y
CY2020Q4	nix	Limitof Gca Volumes LimitofGCAVolumes	0.20
CY2018	us-gaap	Derivative Instruments Gain Loss Recognized In Income Ineffective Portion And Amount Excluded From Effectiveness Testing Net DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet	0	USD
CY2020	us-gaap	Derivative Instruments Gain Loss Recognized In Income Ineffective Portion And Amount Excluded From Effectiveness Testing Net DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet	0	USD
CY2019	us-gaap	Derivative Instruments Gain Loss Recognized In Income Ineffective Portion And Amount Excluded From Effectiveness Testing Net DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet	0	USD
CY2020	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	200000	USD
CY2019	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	0	USD
CY2018	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	0	USD
CY2020	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	11700000	USD
CY2019	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	5200000	USD
CY2018	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	8200000	USD
CY2020	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	11900000	USD
CY2019	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	5200000	USD
CY2018	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	8200000	USD
CY2020	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-400000	USD
CY2019	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	110700000	USD
CY2018	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-209400000	USD
CY2020	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	-27400000	USD
CY2019	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	9000000.0	USD
CY2018	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	22200000	USD
CY2020	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-27800000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	119700000	USD
CY2018	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-187200000	USD
CY2020	us-gaap	Deferred Other Tax Expense Benefit DeferredOtherTaxExpenseBenefit	-1200000	USD
CY2019	us-gaap	Deferred Other Tax Expense Benefit DeferredOtherTaxExpenseBenefit	-1400000	USD
CY2018	us-gaap	Deferred Other Tax Expense Benefit DeferredOtherTaxExpenseBenefit	-1000000.0	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-17100000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	123500000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-180000000.0	USD
CY2020	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	-31300000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	506600000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	-230600000	USD
CY2020	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	-6600000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2019	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	106500000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2018	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	-48400000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2020	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	-11700000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.374
CY2019	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	10100000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.020
CY2018	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	24700000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	-0.107
CY2020	us-gaap	Income Tax Reconciliation Nondeductible Expense Depreciation IncomeTaxReconciliationNondeductibleExpenseDepreciation	-38400000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense Depreciation EffectiveIncomeTaxRateReconciliationNondeductibleExpenseDepreciation	1.227
CY2019	us-gaap	Income Tax Reconciliation Nondeductible Expense Depreciation IncomeTaxReconciliationNondeductibleExpenseDepreciation	-29400000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense Depreciation EffectiveIncomeTaxRateReconciliationNondeductibleExpenseDepreciation	-0.058
CY2018	us-gaap	Income Tax Reconciliation Nondeductible Expense Depreciation IncomeTaxReconciliationNondeductibleExpenseDepreciation	-29300000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense Depreciation EffectiveIncomeTaxRateReconciliationNondeductibleExpenseDepreciation	0.127
CY2020	us-gaap	Income Tax Reconciliation Nondeductible Expense Impairment Losses IncomeTaxReconciliationNondeductibleExpenseImpairmentLosses	0	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense Impairment Losses EffectiveIncomeTaxRateReconciliationNondeductibleExpenseImpairmentLosses	0
CY2019	us-gaap	Income Tax Reconciliation Nondeductible Expense Impairment Losses IncomeTaxReconciliationNondeductibleExpenseImpairmentLosses	43000000.0	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense Impairment Losses EffectiveIncomeTaxRateReconciliationNondeductibleExpenseImpairmentLosses	0.085
CY2018	us-gaap	Income Tax Reconciliation Nondeductible Expense Impairment Losses IncomeTaxReconciliationNondeductibleExpenseImpairmentLosses	0	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense Impairment Losses EffectiveIncomeTaxRateReconciliationNondeductibleExpenseImpairmentLosses	0
CY2020	us-gaap	Income Tax Reconciliation Nondeductible Expense IncomeTaxReconciliationNondeductibleExpense	11800000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense EffectiveIncomeTaxRateReconciliationNondeductibleExpense	-0.377
CY2019	us-gaap	Income Tax Reconciliation Nondeductible Expense IncomeTaxReconciliationNondeductibleExpense	11500000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense EffectiveIncomeTaxRateReconciliationNondeductibleExpense	0.023
CY2018	us-gaap	Income Tax Reconciliation Nondeductible Expense IncomeTaxReconciliationNondeductibleExpense	200000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense EffectiveIncomeTaxRateReconciliationNondeductibleExpense	-0.001
CY2020	us-gaap	Income Tax Reconciliation Deductions Other IncomeTaxReconciliationDeductionsOther	0	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Deductions Other EffectiveIncomeTaxRateReconciliationDeductionsOther	0
CY2019	us-gaap	Income Tax Reconciliation Deductions Other IncomeTaxReconciliationDeductionsOther	2500000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Deductions Other EffectiveIncomeTaxRateReconciliationDeductionsOther	0.005
CY2018	us-gaap	Income Tax Reconciliation Deductions Other IncomeTaxReconciliationDeductionsOther	0	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Deductions Other EffectiveIncomeTaxRateReconciliationDeductionsOther	0
CY2020	us-gaap	Income Tax Reconciliation Other Reconciling Items IncomeTaxReconciliationOtherReconcilingItems	0	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Other Reconciling Items Percent EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent	0
CY2019	us-gaap	Income Tax Reconciliation Other Reconciling Items IncomeTaxReconciliationOtherReconcilingItems	-9500000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Other Reconciling Items Percent EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent	-0.019
CY2018	us-gaap	Income Tax Reconciliation Other Reconciling Items IncomeTaxReconciliationOtherReconcilingItems	-127800000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Other Reconciling Items Percent EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent	0.554
CY2020	us-gaap	Income Tax Rate Reconciliation Deductions Employee Stock Ownership Plan Dividends IncomeTaxRateReconciliationDeductionsEmployeeStockOwnershipPlanDividends	1300000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Deductions Employee Stock Ownership Plan Dividends EffectiveIncomeTaxRateReconciliationDeductionsEmployeeStockOwnershipPlanDividends	-0.042
CY2019	us-gaap	Income Tax Rate Reconciliation Deductions Employee Stock Ownership Plan Dividends IncomeTaxRateReconciliationDeductionsEmployeeStockOwnershipPlanDividends	2000000.0	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Deductions Employee Stock Ownership Plan Dividends EffectiveIncomeTaxRateReconciliationDeductionsEmployeeStockOwnershipPlanDividends	0.004
CY2018	us-gaap	Income Tax Rate Reconciliation Deductions Employee Stock Ownership Plan Dividends IncomeTaxRateReconciliationDeductionsEmployeeStockOwnershipPlanDividends	2200000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Deductions Employee Stock Ownership Plan Dividends EffectiveIncomeTaxRateReconciliationDeductionsEmployeeStockOwnershipPlanDividends	-0.010
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Tax Cuts And Jobs Act Of2017 Amount EffectiveIncomeTaxRateReconciliationTaxCutsAndJobsActOf2017Amount	23300000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Tax Cuts And Jobs Act Of2017 Percent EffectiveIncomeTaxRateReconciliationTaxCutsAndJobsActOf2017Percent	-0.745
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Tax Cuts And Jobs Act Of2017 Amount EffectiveIncomeTaxRateReconciliationTaxCutsAndJobsActOf2017Amount	0	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Tax Cuts And Jobs Act Of2017 Percent EffectiveIncomeTaxRateReconciliationTaxCutsAndJobsActOf2017Percent	0
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Tax Cuts And Jobs Act Of2017 Amount EffectiveIncomeTaxRateReconciliationTaxCutsAndJobsActOf2017Amount	0	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Tax Cuts And Jobs Act Of2017 Percent EffectiveIncomeTaxRateReconciliationTaxCutsAndJobsActOf2017Percent	0
CY2020	nix	Effective Income Tax Rate Reconciliation Tax Accrual Adjustments Amount EffectiveIncomeTaxRateReconciliationTaxAccrualAdjustmentsAmount	8900000	USD
CY2020	nix	Effective Income Tax Rate Reconciliation Tax Accrual Adjustments Percent EffectiveIncomeTaxRateReconciliationTaxAccrualAdjustmentsPercent	-0.284
CY2019	nix	Effective Income Tax Rate Reconciliation Tax Accrual Adjustments Amount EffectiveIncomeTaxRateReconciliationTaxAccrualAdjustmentsAmount	0	USD
CY2019	nix	Effective Income Tax Rate Reconciliation Tax Accrual Adjustments Percent EffectiveIncomeTaxRateReconciliationTaxAccrualAdjustmentsPercent	0
CY2018	nix	Effective Income Tax Rate Reconciliation Tax Accrual Adjustments Amount EffectiveIncomeTaxRateReconciliationTaxAccrualAdjustmentsAmount	0	USD
CY2018	nix	Effective Income Tax Rate Reconciliation Tax Accrual Adjustments Percent EffectiveIncomeTaxRateReconciliationTaxAccrualAdjustmentsPercent	0
CY2020	us-gaap	Income Tax Reconciliation Tax Credits IncomeTaxReconciliationTaxCredits	2500000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0.080
CY2019	us-gaap	Income Tax Reconciliation Tax Credits IncomeTaxReconciliationTaxCredits	0	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0
CY2020	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	-600000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0.019
CY2019	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	-4200000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	-0.008
CY2018	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	2800000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	-0.012
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-17100000	USD
CY2020	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.546
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	123500000	USD
CY2019	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.244
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-180000000.0	USD
CY2018	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.781
CY2020	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.546	Rate
CY2019	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.244	Rate
CY2018	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.781	Rate
CY2020	nix	Increase Decreasein Effective Tax Rate IncreaseDecreaseinEffectiveTaxRate	0.302
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Accrued Liabilities DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities	41500000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Accrued Liabilities DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities	35300000	USD
CY2019Q4	nix	Accelerated Depreciation And Other Property Differences AcceleratedDepreciationAndOtherPropertyDifferences	2516900000	USD
CY2019	nix	Increase Decreasein Effective Tax Rate IncreaseDecreaseinEffectiveTaxRate	0.537
CY2020Q4	nix	Accelerated Depreciation And Other Property Differences AcceleratedDepreciationAndOtherPropertyDifferences	2339300000	USD
CY2020Q4	nix	Other Regulatory Assets OtherRegulatoryAssets	331800000	USD
CY2019Q4	nix	Other Regulatory Assets OtherRegulatoryAssets	381500000	USD
CY2020Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	2671100000	USD
CY2019Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	2898400000	USD
CY2020Q4	nix	Deferred Investment Tax Credits And Other Regulatory Liabilities DeferredInvestmentTaxCreditsAndOtherRegulatoryLiabilities	287800000	USD
CY2019Q4	nix	Deferred Investment Tax Credits And Other Regulatory Liabilities DeferredInvestmentTaxCreditsAndOtherRegulatoryLiabilities	336100000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Postretirement Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits	118100000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Postretirement Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits	152100000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	602100000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	765900000	USD
CY2020Q4	nix	Deferred Tax Assets Other Accrued Liabilities Environmental DeferredTaxAssetsOtherAccruedLiabilitiesEnvironmental	22600000	USD
CY2019Q4	nix	Deferred Tax Assets Other Accrued Liabilities Environmental DeferredTaxAssetsOtherAccruedLiabilitiesEnvironmental	25400000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	128400000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	98300000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	1200500000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	1413100000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	1470600000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	1485300000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Charitable Contribution Carryforwards DeferredTaxAssetsCharitableContributionCarryforwards	7800000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	6400000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	23200000	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1200000	USD
CY2017Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1400000	USD
CY2020	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	1500000	USD
CY2019	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	600000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	400000	USD
CY2020	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	0	USD
CY2019	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	22600000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	200000	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	21700000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	23200000	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1200000	USD
CY2020Q4	us-gaap	Operating Loss Carryforwards OperatingLossCarryforwards	21700000	USD
CY2019Q4	us-gaap	Operating Loss Carryforwards OperatingLossCarryforwards	22600000	USD
CY2018Q4	us-gaap	Operating Loss Carryforwards OperatingLossCarryforwards	0	USD
CY2020Q4	nix	Unrecognized Tax Benefits Netof Refundsand Net Operating Loss Carryforwards UnrecognizedTaxBenefitsNetofRefundsandNetOperatingLossCarryforwards	0	USD
CY2019Q4	nix	Unrecognized Tax Benefits Netof Refundsand Net Operating Loss Carryforwards UnrecognizedTaxBenefitsNetofRefundsandNetOperatingLossCarryforwards	600000	USD
CY2018Q4	nix	Unrecognized Tax Benefits Netof Refundsand Net Operating Loss Carryforwards UnrecognizedTaxBenefitsNetofRefundsandNetOperatingLossCarryforwards	1200000	USD
CY2020	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	1500000	USD
CY2020	us-gaap	Unrecognized Tax Benefits Income Tax Penalties Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesExpense	0	USD
CY2018	us-gaap	Unrecognized Tax Benefits Income Tax Penalties Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesExpense	0	USD
CY2019	us-gaap	Unrecognized Tax Benefits Income Tax Penalties Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesExpense	0	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAccrued	0	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAccrued	0	USD
CY2020Q4	nix	Net Asset Value Excluded From Fair Value By Input NetAssetValueExcludedFromFairValueByInput	918600000	USD
CY2019Q4	nix	Net Asset Value Excluded From Fair Value By Input NetAssetValueExcludedFromFairValueByInput	860500000	USD
CY2020Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	303500000	USD
CY2019Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	314300000	USD
CY2020	us-gaap	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Expected Long Term Return On Assets DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets	0.0570
CY2020Q4	us-gaap	Preferred Stock Par Or Stated Value Per Share PreferredStockParOrStatedValuePerShare	0.01
CY2015Q2	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant	10000000	shares
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Authorized ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized	10007832	shares
CY2020	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	13500000	USD
CY2019	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	16300000	USD
CY2018	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	15200000	USD
CY2020	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	3300000	USD
CY2019	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	4000000.0	USD
CY2018	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	3700000	USD
CY2020	nix	Excess Tax Expense Share Based Compensation ExcessTaxExpenseShareBasedCompensation	400000	USD
CY2019	us-gaap	Excess Tax Benefit From Share Based Compensation Operating Activities ExcessTaxBenefitFromShareBasedCompensationOperatingActivities	800000	USD
CY2018	us-gaap	Excess Tax Benefit From Share Based Compensation Operating Activities ExcessTaxBenefitFromShareBasedCompensationOperatingActivities	1000000.0	USD
CY2020Q4	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized	19100000	USD
CY2020	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1 EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1	P1Y10M24D
CY2020	nix	Rtsr Modifier RTSRModifier	0.25	Rate
CY2020	nix	Rtsr Modifier RTSRModifier	0.25	Rate
CY2020	us-gaap	Defined Contribution Plan Employer Matching Contribution Percent DefinedContributionPlanEmployerMatchingContributionPercent	0.03
CY2020	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	37800000	USD
CY2019	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	37500000	USD
CY2018	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	37600000	USD
CY2020Q4	us-gaap	Senior Notes SeniorNotes	9003000000.0	USD
CY2019Q4	us-gaap	Senior Notes SeniorNotes	7581600000	USD
CY2020Q4	us-gaap	Medium Term Notes MediumTermNotes	132000000.0	USD
CY2019Q4	us-gaap	Medium Term Notes MediumTermNotes	157000000.0	USD
CY2020Q4	us-gaap	Capital Lease Obligations CapitalLeaseObligations	195000000.0	USD
CY2019Q4	us-gaap	Capital Lease Obligations CapitalLeaseObligations	201500000	USD
CY2020Q4	us-gaap	Debt Instrument Unamortized Discount Premium And Debt Issuance Costs Net DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet	-86900000	USD
CY2019Q4	us-gaap	Debt Instrument Unamortized Discount Premium And Debt Issuance Costs Net DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet	-70500000	USD
CY2020Q4	us-gaap	Debt Instrument Carrying Amount DebtInstrumentCarryingAmount	9243100000	USD
CY2019Q4	us-gaap	Debt Instrument Carrying Amount DebtInstrumentCarryingAmount	7869600000	USD
CY2020Q3	nix	Debt Instrument Tendered DebtInstrumentTendered	969300000	USD
CY2020Q3	nix	Working Capital Adjustment WorkingCapitalAdjustment	5300000	USD
CY2020	us-gaap	Debt Instrument Convertible Conversion Ratio1 DebtInstrumentConvertibleConversionRatio1	0.625	Rate
CY2020Q4	nix	Security Interest And Other Subset Of Asset SecurityInterestAndOtherSubsetOfAsset	150000000	USD
CY2020	nix	Asset Sale Covenant Percentage Of Consolidated Total Assets AssetSaleCovenantPercentageOfConsolidatedTotalAssets	0.10
CY2020Q4	nix	Cross Default Provision On Default Relating To Any Indebtedness CrossDefaultProvisionOnDefaultRelatingToAnyIndebtedness	50000000.0	USD
CY2020	nix	Percentage Of Additional Subset Of Assets Capped PercentageOfAdditionalSubsetOfAssetsCapped	0.10
CY2020Q4	us-gaap	Line Of Credit LineOfCredit	0	USD
CY2019Q4	us-gaap	Line Of Credit LineOfCredit	0	USD
CY2020Q4	us-gaap	Commercial Paper CommercialPaper	503000000.0	USD
CY2019Q4	us-gaap	Commercial Paper CommercialPaper	570000000.0	USD
CY2020Q4	us-gaap	Transfers Accounted For As Secured Borrowings Associated Liabilities Carrying Amount TransfersAccountedForAsSecuredBorrowingsAssociatedLiabilitiesCarryingAmount	0	USD
CY2019Q4	us-gaap	Transfers Accounted For As Secured Borrowings Associated Liabilities Carrying Amount TransfersAccountedForAsSecuredBorrowingsAssociatedLiabilitiesCarryingAmount	353200000	USD
CY2020Q4	us-gaap	Commercial Paper CommercialPaper	503000000.0	USD
CY2019Q4	us-gaap	Commercial Paper CommercialPaper	570000000.0	USD
CY2020Q4	us-gaap	Transfers Accounted For As Secured Borrowings Associated Liabilities Carrying Amount TransfersAccountedForAsSecuredBorrowingsAssociatedLiabilitiesCarryingAmount	0	USD
CY2019Q4	us-gaap	Transfers Accounted For As Secured Borrowings Associated Liabilities Carrying Amount TransfersAccountedForAsSecuredBorrowingsAssociatedLiabilitiesCarryingAmount	353200000	USD
CY2020Q4	us-gaap	Short Term Borrowings ShortTermBorrowings	503000000.0	USD
CY2019Q4	us-gaap	Short Term Borrowings ShortTermBorrowings	1773200000	USD
CY2019Q1	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	57000000.0	USD
CY2020	nix	Lessee Lease Renewal Term LesseeLeaseRenewalTerm	P25Y
CY2020Q4	us-gaap	Lessee Operating Lease Renewal Term LesseeOperatingLeaseRenewalTerm	P1Y
CY2020Q4	us-gaap	Lessee Finance Lease Term Of Contract1 LesseeFinanceLeaseTermOfContract1	P4Y
CY2020	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	23400000	USD
CY2019	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	15500000	USD
CY2020	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	11100000	USD
CY2019	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	11300000	USD
CY2020	nix	Finance Lease Cost Total FinanceLeaseCostTotal	34500000	USD
CY2019	nix	Finance Lease Cost Total FinanceLeaseCostTotal	26800000	USD
CY2020	us-gaap	Operating Lease Cost OperatingLeaseCost	20300000	USD
CY2019	us-gaap	Operating Lease Cost OperatingLeaseCost	17900000	USD
CY2020	us-gaap	Short Term Lease Cost ShortTermLeaseCost	0	USD
CY2019	us-gaap	Short Term Lease Cost ShortTermLeaseCost	1000000.0	USD
CY2020Q4	us-gaap	Finance Lease Liability Noncurrent FinanceLeaseLiabilityNoncurrent	171700000	USD
CY2020	us-gaap	Lease Cost LeaseCost	54800000	USD
CY2019	us-gaap	Lease Cost LeaseCost	45700000	USD
CY2020Q4	us-gaap	Finance Lease Right Of Use Asset FinanceLeaseRightOfUseAsset	176800000	USD
CY2019Q4	us-gaap	Finance Lease Right Of Use Asset FinanceLeaseRightOfUseAsset	179500000	USD
CY2020Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	39900000	USD
CY2019Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	64200000	USD
CY2020Q4	nix	Totalleasedassets Totalleasedassets	216700000	USD
CY2019Q4	nix	Totalleasedassets Totalleasedassets	243700000	USD
CY2020Q4	us-gaap	Finance Lease Liability Current FinanceLeaseLiabilityCurrent	23300000	USD
CY2019Q4	us-gaap	Finance Lease Liability Current FinanceLeaseLiabilityCurrent	13400000	USD
CY2020Q4	us-gaap	Operating Lease Liability Current OperatingLeaseLiabilityCurrent	10300000	USD
CY2019Q4	us-gaap	Operating Lease Liability Current OperatingLeaseLiabilityCurrent	13200000	USD
CY2020	us-gaap	Finance Lease Interest Payment On Liability FinanceLeaseInterestPaymentOnLiability	11100000	USD
CY2019Q4	nix	Total Lease Liability TotalLeaseLiability	266300000	USD
CY2019Q4	us-gaap	Finance Lease Liability Noncurrent FinanceLeaseLiabilityNoncurrent	188100000	USD
CY2020Q4	us-gaap	Operating Lease Liability Noncurrent OperatingLeaseLiabilityNoncurrent	29900000	USD
CY2019Q4	us-gaap	Operating Lease Liability Noncurrent OperatingLeaseLiabilityNoncurrent	51600000	USD
CY2020Q4	nix	Total Lease Liability TotalLeaseLiability	235200000	USD
CY2019	us-gaap	Finance Lease Interest Payment On Liability FinanceLeaseInterestPaymentOnLiability	11300000	USD
CY2020	us-gaap	Operating Lease Payments OperatingLeasePayments	20200000	USD
CY2019	us-gaap	Operating Lease Payments OperatingLeasePayments	17900000	USD
CY2020	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	18400000	USD
CY2019	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	10600000	USD
CY2020	us-gaap	Right Of Use Asset Obtained In Exchange For Finance Lease Liability RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability	59300000	USD
CY2019	us-gaap	Right Of Use Asset Obtained In Exchange For Finance Lease Liability RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability	26400000	USD
CY2020	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	10900000	USD
CY2019	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	13400000	USD
CY2020Q4	us-gaap	Finance Lease Weighted Average Remaining Lease Term1 FinanceLeaseWeightedAverageRemainingLeaseTerm1	P11Y2M12D
CY2019Q4	us-gaap	Finance Lease Weighted Average Remaining Lease Term1 FinanceLeaseWeightedAverageRemainingLeaseTerm1	P14Y9M18D
CY2020Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P8Y
CY2019Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P9Y2M12D
CY2020Q4	us-gaap	Finance Lease Weighted Average Discount Rate Percent FinanceLeaseWeightedAverageDiscountRatePercent	0.051	Rate
CY2019Q4	us-gaap	Finance Lease Weighted Average Discount Rate Percent FinanceLeaseWeightedAverageDiscountRatePercent	0.059	Rate
CY2020Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.040	Rate
CY2019Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.043	Rate
CY2020Q4	nix	Total Future Minimum Lease Payments Due Next Twelve Months TotalFutureMinimumLeasePaymentsDueNextTwelveMonths	44400000	USD
CY2020Q4	nix	Total Future Minimum Lease Payments Duein Two Years TotalFutureMinimumLeasePaymentsDueinTwoYears	37400000	USD
CY2020Q4	nix	Total Future Minimum Lease Payments Duein Three Years TotalFutureMinimumLeasePaymentsDueinThreeYears	33500000	USD
CY2020Q4	nix	Total Future Minimum Lease Payments Duein Four Years TotalFutureMinimumLeasePaymentsDueinFourYears	25300000	USD
CY2019Q4	us-gaap	Derivative Assets DerivativeAssets	4400000	USD
CY2020Q4	nix	Total Future Minimum Lease Payments Duein Five Years TotalFutureMinimumLeasePaymentsDueinFiveYears	19800000	USD
CY2020Q4	nix	Total Future Minimum Lease Payments Due Thereafter TotalFutureMinimumLeasePaymentsDueThereafter	152300000	USD
CY2020Q4	nix	Total Future Minimum Lease Payments Due TotalFutureMinimumLeasePaymentsDue	312700000	USD
CY2020Q4	nix	Undiscounted Excess Amount UndiscountedExcessAmount	77500000	USD
CY2020Q4	nix	Total Lease Liability TotalLeaseLiability	235200000	USD
CY2020Q4	nix	Shortterm Lease Liability ShorttermLeaseLiability	33600000	USD
CY2020Q4	nix	Longterm Lease Liability LongtermLeaseLiability	201600000	USD
CY2020Q4	nix	Total Lease Liability TotalLeaseLiability	235200000	USD
CY2018	us-gaap	Operating Leases Rent Expense Net OperatingLeasesRentExpenseNet	49100000	USD
CY2020Q4	us-gaap	Derivative Assets DerivativeAssets	13200000	USD
CY2020Q4	us-gaap	Available For Sale Securities AvailableForSaleSecurities	170900000	USD
CY2020Q4	us-gaap	Assets Fair Value Disclosure AssetsFairValueDisclosure	184100000	USD
CY2020Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	222800000	USD
CY2020Q4	us-gaap	Financial Liabilities Fair Value Disclosure FinancialLiabilitiesFairValueDisclosure	222800000	USD
CY2019Q4	us-gaap	Financial Liabilities Fair Value Disclosure FinancialLiabilitiesFairValueDisclosure	146600000	USD
CY2020	nix	Transfersbetween Fair Value Hierarchies TransfersbetweenFairValueHierarchies	0	USD
CY2019	nix	Transfersbetween Fair Value Hierarchies TransfersbetweenFairValueHierarchies	0	USD
CY2019Q4	us-gaap	Available For Sale Securities AvailableForSaleSecurities	154200000	USD
CY2019Q4	us-gaap	Assets Fair Value Disclosure AssetsFairValueDisclosure	158600000	USD
CY2019Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	146600000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss DebtSecuritiesAvailableForSaleAllowanceForCreditLoss	-500000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	163900000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	8000000.0	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	500000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss DebtSecuritiesAvailableForSaleAllowanceForCreditLoss	-500000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	170900000	USD
CY2019Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	150100000	USD
CY2019Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	4300000	USD
CY2019Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	200000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss DebtSecuritiesAvailableForSaleAllowanceForCreditLoss	0	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	154200000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	0	USD
CY2020Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue	13200000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	17200000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue	12200000	USD
CY2020	us-gaap	Disposal Group Not Discontinued Operation Loss Gain On Write Down DisposalGroupNotDiscontinuedOperationLossGainOnWriteDown	412400000	USD
CY2020Q4	us-gaap	Debt Instrument Carrying Amount DebtInstrumentCarryingAmount	9243100000	USD
CY2020Q4	us-gaap	Long Term Debt Fair Value LongTermDebtFairValue	11034200000	USD
CY2019Q4	us-gaap	Debt Instrument Carrying Amount DebtInstrumentCarryingAmount	7869600000	USD
CY2019Q4	us-gaap	Long Term Debt Fair Value LongTermDebtFairValue	8764400000	USD
CY2020	nix	Number Of Agreements NumberOfAgreements	3
CY2020Q4	nix	Longterm Debt Future Minimum Payments Due Next Twelve Months LongtermDebtFutureMinimumPaymentsDueNextTwelveMonths	0	USD
CY2020Q4	nix	Longterm Debt Future Minimum Payments Due LongtermDebtFutureMinimumPaymentsDue	9135000000.0	USD
CY2020Q4	nix	Trade Receivables Available For Transfer TradeReceivablesAvailableForTransfer	607700000	USD
CY2019Q4	nix	Trade Receivables Available For Transfer TradeReceivablesAvailableForTransfer	569100000	USD
CY2020Q4	nix	Trade Receivables Not Transferred TradeReceivablesNotTransferred	607700000	USD
CY2019Q4	nix	Trade Receivables Not Transferred TradeReceivablesNotTransferred	215900000	USD
CY2020Q4	nix	Trade Receivables Transferred Net TradeReceivablesTransferredNet	0	USD
CY2019Q4	nix	Trade Receivables Transferred Net TradeReceivablesTransferredNet	353200000	USD
CY2020Q4	us-gaap	Transfers Accounted For As Secured Borrowings Associated Liabilities Carrying Amount TransfersAccountedForAsSecuredBorrowingsAssociatedLiabilitiesCarryingAmount	0	USD
CY2019Q4	us-gaap	Transfers Accounted For As Secured Borrowings Associated Liabilities Carrying Amount TransfersAccountedForAsSecuredBorrowingsAssociatedLiabilitiesCarryingAmount	353200000	USD
CY2020	nix	Cash From Financing Activities Related To Change In Short Term Borrowings Due To Securitization Transactions CashFromFinancingActivitiesRelatedToChangeInShortTermBorrowingsDueToSecuritizationTransactions	353200000	USD
CY2019	nix	Cash From Financing Activities Related To Change In Short Term Borrowings Due To Securitization Transactions CashFromFinancingActivitiesRelatedToChangeInShortTermBorrowingsDueToSecuritizationTransactions	46000000.0	USD
CY2019	nix	Securitization Transaction Fees SecuritizationTransactionFees	2600000	USD
CY2018	nix	Securitization Transaction Fees SecuritizationTransactionFees	2600000	USD
CY2020	nix	Securitization Transaction Fees SecuritizationTransactionFees	2600000	USD
CY2020Q4	nix	Longterm Debt Future Minimum Payments Duein Two Years LongtermDebtFutureMinimumPaymentsDueinTwoYears	30000000.0	USD
CY2020Q4	nix	Interest Paymentson Longterm Debt Future Minimum Payments Due Next Twelve Months InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueNextTwelveMonths	336300000	USD
CY2020Q4	nix	Longterm Debt Future Minimum Payments Duein Three Years LongtermDebtFutureMinimumPaymentsDueinThreeYears	0	USD
CY2020Q4	nix	Longterm Debt Future Minimum Payments Duein Four Years LongtermDebtFutureMinimumPaymentsDueinFourYears	0	USD
CY2020Q4	nix	Longterm Debt Future Minimum Payments Duein Five Years LongtermDebtFutureMinimumPaymentsDueinFiveYears	1260000000.0	USD
CY2020Q4	nix	Longterm Debt Future Minimum Payments Due Thereafter LongtermDebtFutureMinimumPaymentsDueThereafter	7845000000.0	USD
CY2020Q4	nix	Interest Paymentson Longterm Debt Future Minimum Payments Due InterestPaymentsonLongtermDebtFutureMinimumPaymentsDue	6046300000	USD
CY2020Q4	nix	Interest Paymentson Longterm Debt Future Minimum Payments Duein Two Years InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueinTwoYears	335700000	USD
CY2020Q4	nix	Interest Paymentson Longterm Debt Future Minimum Payments Duein Three Years InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueinThreeYears	334100000	USD
CY2020Q4	nix	Interest Paymentson Longterm Debt Future Minimum Payments Duein Four Years InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueinFourYears	334100000	USD
CY2020Q4	nix	Interest Paymentson Longterm Debt Future Minimum Payments Duein Five Years InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueinFiveYears	334100000	USD
CY2020Q4	nix	Interest Paymentson Longterm Debt Future Minimum Payments Due Thereafter InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueThereafter	4372000000.0	USD
CY2020Q4	us-gaap	Finance Lease Liability Payments Due FinanceLeaseLiabilityPaymentsDue	264700000	USD
CY2020Q4	us-gaap	Finance Lease Liability Payments Due Next Twelve Months FinanceLeaseLiabilityPaymentsDueNextTwelveMonths	32700000	USD
CY2020Q4	us-gaap	Finance Lease Liability Payments Due Year Two FinanceLeaseLiabilityPaymentsDueYearTwo	32200000	USD
CY2020Q4	us-gaap	Finance Lease Liability Payments Due Year Three FinanceLeaseLiabilityPaymentsDueYearThree	28800000	USD
CY2020Q4	us-gaap	Finance Lease Liability Payments Due Year Four FinanceLeaseLiabilityPaymentsDueYearFour	20800000	USD
CY2020Q4	us-gaap	Finance Lease Liability Payments Due Year Five FinanceLeaseLiabilityPaymentsDueYearFive	16100000	USD
CY2020Q4	us-gaap	Finance Lease Liability Payments Due After Year Five FinanceLeaseLiabilityPaymentsDueAfterYearFive	134100000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	48000000.0	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	11700000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	5200000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	4700000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	4500000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	3700000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	18200000	USD
CY2020Q4	nix	Energy Commodity Contracts Future Minimum Payments Due EnergyCommodityContractsFutureMinimumPaymentsDue	42100000	USD
CY2020Q4	nix	Energy Commodity Contracts Future Minimum Payments Due Next Twelve Months EnergyCommodityContractsFutureMinimumPaymentsDueNextTwelveMonths	42100000	USD
CY2020Q4	nix	Energy Commodity Contracts Future Minimum Payments Duein Two Years EnergyCommodityContractsFutureMinimumPaymentsDueinTwoYears	0	USD
CY2020Q4	nix	Energy Commodity Contracts Future Minimum Payments Duein Three Years EnergyCommodityContractsFutureMinimumPaymentsDueinThreeYears	0	USD
CY2020Q4	nix	Energy Commodity Contracts Future Minimum Payments Duein Four Years EnergyCommodityContractsFutureMinimumPaymentsDueinFourYears	0	USD
CY2020Q4	nix	Energy Commodity Contracts Future Minimum Payments Duein Five Years EnergyCommodityContractsFutureMinimumPaymentsDueinFiveYears	0	USD
CY2020Q4	nix	Energy Commodity Contracts Future Minimum Payments Due Thereafter EnergyCommodityContractsFutureMinimumPaymentsDueThereafter	0	USD
CY2020Q4	nix	Service Obligations Pipeline Service Obligations Future Minimum Payments Due ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDue	1495600000	USD
CY2020Q4	nix	Service Obligations Other Service Obligations Future Minimum Payments Duein Three Years ServiceObligationsOtherServiceObligationsFutureMinimumPaymentsDueinThreeYears	0	USD
CY2020Q4	nix	Service Obligations Pipeline Service Obligations Future Minimum Payments Due Next Twelve Months ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueNextTwelveMonths	468700000	USD
CY2020Q4	nix	Service Obligations Pipeline Service Obligations Future Minimum Payments Duein Two Years ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueinTwoYears	422500000	USD
CY2020Q4	nix	Service Obligations Pipeline Service Obligations Future Minimum Payments Due Thereafter ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueThereafter	141700000	USD
CY2020Q4	nix	Service Obligations Pipeline Service Obligations Future Minimum Payments Duein Three Years ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueinThreeYears	256000000.0	USD
CY2020Q4	nix	Service Obligations Pipeline Service Obligations Future Minimum Payments Duein Four Years ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueinFourYears	150500000	USD
CY2020Q4	nix	Service Obligations Pipeline Service Obligations Future Minimum Payments Duein Five Years ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueinFiveYears	56200000	USD
CY2020Q4	nix	Service Obligations It Service Obligations Future Minimum Payments Due ServiceObligationsITServiceObligationsFutureMinimumPaymentsDue	240300000	USD
CY2020Q4	nix	Service Obligations It Service Obligations Future Minimum Payments Due Next Twelve Months ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueNextTwelveMonths	74900000	USD
CY2020Q4	nix	Service Obligations It Service Obligations Future Minimum Payments Duein Two Years ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueinTwoYears	74000000.0	USD
CY2020Q4	nix	Service Obligations It Service Obligations Future Minimum Payments Duein Three Years ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueinThreeYears	38100000	USD
CY2020Q4	nix	Service Obligations It Service Obligations Future Minimum Payments Duein Four Years ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueinFourYears	30500000	USD
CY2020Q4	nix	Service Obligations It Service Obligations Future Minimum Payments Duein Five Years ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueinFiveYears	22800000	USD
CY2020Q4	nix	Service Obligations It Service Obligations Future Minimum Payments Due Thereafter ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueThereafter	0	USD
CY2020Q4	nix	Service Obligations Other Service Obligations Future Minimum Payments Due ServiceObligationsOtherServiceObligationsFutureMinimumPaymentsDue	12600000	USD
CY2020Q4	nix	Service Obligations Other Service Obligations Future Minimum Payments Due Next Twelve Months ServiceObligationsOtherServiceObligationsFutureMinimumPaymentsDueNextTwelveMonths	12600000	USD
CY2020Q4	nix	Service Obligations Other Service Obligations Future Minimum Payments Duein Two Years ServiceObligationsOtherServiceObligationsFutureMinimumPaymentsDueinTwoYears	0	USD
CY2020Q4	nix	Other Liabilities Future Minimum Payments Due Next Twelve Months OtherLiabilitiesFutureMinimumPaymentsDueNextTwelveMonths	26000000.0	USD
CY2020Q4	nix	Service Obligations Other Service Obligations Future Minimum Payments Duein Four Years ServiceObligationsOtherServiceObligationsFutureMinimumPaymentsDueinFourYears	0	USD
CY2020Q4	nix	Other Liabilities Future Minimum Payments Duein Two Years OtherLiabilitiesFutureMinimumPaymentsDueinTwoYears	800000	USD
CY2020Q4	nix	Other Liabilities Future Minimum Payments Duein Five Years OtherLiabilitiesFutureMinimumPaymentsDueinFiveYears	0	USD
CY2020Q4	nix	Other Liabilities Future Minimum Payments Duein Three Years OtherLiabilitiesFutureMinimumPaymentsDueinThreeYears	90100000	USD
CY2020Q4	nix	Other Liabilities Future Minimum Payments Duein Four Years OtherLiabilitiesFutureMinimumPaymentsDueinFourYears	0	USD
CY2020Q4	nix	Service Obligations Other Service Obligations Future Minimum Payments Duein Five Years ServiceObligationsOtherServiceObligationsFutureMinimumPaymentsDueinFiveYears	0	USD
CY2020Q4	nix	Service Obligations Other Service Obligations Future Minimum Payments Due Thereafter ServiceObligationsOtherServiceObligationsFutureMinimumPaymentsDueThereafter	0	USD
CY2020Q4	nix	Other Liabilities Future Minimum Payments Due OtherLiabilitiesFutureMinimumPaymentsDue	116900000	USD
CY2020Q4	nix	Other Liabilities Future Minimum Payments Due Thereafter OtherLiabilitiesFutureMinimumPaymentsDueThereafter	0	USD
CY2020Q4	nix	Total Future Contractual Obligations Due TotalFutureContractualObligationsDue	17401500000	USD
CY2020Q4	nix	Total Future Contractual Obligations Due Next Twelve Months TotalFutureContractualObligationsDueNextTwelveMonths	1005000000.0	USD
CY2020Q4	nix	Total Future Contractual Obligations Duein Two Years TotalFutureContractualObligationsDueinTwoYears	900400000	USD
CY2020Q4	nix	Total Future Contractual Obligations Duein Three Years TotalFutureContractualObligationsDueinThreeYears	751800000	USD
CY2020Q4	nix	Total Future Contractual Obligations Duein Four Years TotalFutureContractualObligationsDueinFourYears	540400000	USD
CY2020Q4	nix	Total Future Contractual Obligations Duein Five Years TotalFutureContractualObligationsDueinFiveYears	1692900000	USD
CY2020Q4	nix	Total Future Contractual Obligations Due Thereafter TotalFutureContractualObligationsDueThereafter	12511000000.0	USD
	nix	Expenses Relatedto Third Party Claims ExpensesRelatedtoThirdPartyClaims	1041000000	USD
CY2020Q4	us-gaap	Debt Instrument Unamortized Discount Premium And Debt Issuance Costs Net DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet	-86900000	USD
CY2020Q4	nix	Finance Leases Future Minimum Payments Interest Includedin Payments FinanceLeasesFutureMinimumPaymentsInterestIncludedinPayments	69700000	USD
CY2020Q4	nix	Operating Leases Future Minimum Payaments Interest Includedin Payments OperatingLeasesFutureMinimumPayamentsInterestIncludedinPayments	7800000	USD
CY2020Q4	nix	Wind Power Purchase Agreement Capacity WindPowerPurchaseAgreementCapacity	500	MW
CY2020Q4	nix	Major Rail Operators MajorRailOperators	3
CY2019Q4	us-gaap	Accrual For Environmental Loss Contingencies AccrualForEnvironmentalLossContingencies	104400000	USD
CY2020Q4	us-gaap	Guaranty Liabilities GuarantyLiabilities	40700000	USD
CY2019Q3	nix	Proposed Class Action Settlement ProposedClassActionSettlement	143000000	USD
	nix	Expenses Relatedto Third Party Claims ExpensesRelatedtoThirdPartyClaims	1036000000	USD
CY2020Q4	nix	Liability Insurancefor Damages LiabilityInsuranceforDamages	800000000	USD
	nix	Proceeds From Insurance Settlement ProceedsFromInsuranceSettlement	800000000	USD
CY2020Q4	us-gaap	Accrual For Environmental Loss Contingencies AccrualForEnvironmentalLossContingencies	92600000	USD
CY2020Q4	nix	Coalfired Generating Capacity CoalfiredGeneratingCapacity	2080	MW
CY2020	nix	Coalfired Generating Capacity Percentof Total Capacity CoalfiredGeneratingCapacityPercentofTotalCapacity	0.72	Rate
CY2020	nix	Coalfired Generating Capacity Percentof Total Coal Fired Capacity CoalfiredGeneratingCapacityPercentofTotalCoalFiredCapacity	1	Rate
CY2020Q4	nix	Liability Associated With Schahfer Generating Station Retirement LiabilityAssociatedWithSchahferGeneratingStationRetirement	4600000	USD
CY2020Q4	nix	Wind Power Purchase Agreement Purchase Percentage WindPowerPurchaseAgreementPurchasePercentage	1	Rate
CY2020	nix	Expenses Relatedto Third Party Claims ExpensesRelatedtoThirdPartyClaims	-5000000	USD
	nix	Costs Resultingfromthe Greater Lawrence Incident CostsResultingfromtheGreaterLawrenceIncident	1478000000	USD
	nix	Expenses Relatedto Third Party Claims ExpensesRelatedtoThirdPartyClaims	1036000000	USD
	nix	Expenses Other Than Third Party Claims ExpensesOtherThanThirdPartyClaims	420000000	USD
CY2020	nix	Expenses Other Than Third Party Claims ExpensesOtherThanThirdPartyClaims	22000000	USD
	nix	Expenses Other Than Third Party Claims ExpensesOtherThanThirdPartyClaims	442000000	USD
	nix	Costs Resultingfromthe Greater Lawrence Incident CostsResultingfromtheGreaterLawrenceIncident	1461000000	USD
CY2020	nix	Costs Resultingfromthe Greater Lawrence Incident CostsResultingfromtheGreaterLawrenceIncident	17000000	USD
	us-gaap	Insurance Recoveries InsuranceRecoveries	800000000	USD
CY2020	us-gaap	Insurance Recoveries InsuranceRecoveries	0	USD
	us-gaap	Insurance Recoveries InsuranceRecoveries	800000000	USD
	nix	Greater Lawrence Incident Impacton Operationand Maintenance Expense GreaterLawrenceIncidentImpactonOperationandMaintenanceExpense	661000000	USD
CY2020	nix	Greater Lawrence Incident Impacton Operationand Maintenance Expense GreaterLawrenceIncidentImpactonOperationandMaintenanceExpense	17000000	USD
	nix	Greater Lawrence Incident Impacton Operationand Maintenance Expense GreaterLawrenceIncidentImpactonOperationandMaintenanceExpense	678000000	USD
CY2020Q4	nix	Liability Insurancefor Damages LiabilityInsuranceforDamages	800000000	USD
	nix	Proceeds From Insurance Settlement ProceedsFromInsuranceSettlement	800000000	USD
	nix	Costs Resultingfromthe Greater Lawrence Incident CostsResultingfromtheGreaterLawrenceIncident	1023000000	USD
CY2020Q4	us-gaap	Restructuring And Related Cost Expected Cost1 RestructuringAndRelatedCostExpectedCost1	38000000	USD
CY2019Q4	us-gaap	Restructuring Reserve RestructuringReserve	0	USD
CY2020	us-gaap	Restructuring Reserve Period Increase Decrease RestructuringReservePeriodIncreaseDecrease	33500000	USD
CY2020	us-gaap	Payments For Restructuring PaymentsForRestructuring	21200000	USD
CY2020	us-gaap	Restructuring Reserve Accrual Adjustment1 RestructuringReserveAccrualAdjustment1	-1200000	USD
CY2020Q4	us-gaap	Restructuring Reserve RestructuringReserve	11100000	USD
CY2017Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-43400000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	48400000	USD
CY2018	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	-32700000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	15700000	USD
CY2018Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-37200000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	-55900000	USD
CY2019	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	500000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-55400000	USD
CY2019Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-92600000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	-64600000	USD
CY2020	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	500000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-64100000	USD
CY2020Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-156700000	USD
CY2020	us-gaap	Interest Income Expense Nonoperating Net InterestIncomeExpenseNonoperatingNet	5500000	USD
CY2019	us-gaap	Interest Income Expense Nonoperating Net InterestIncomeExpenseNonoperatingNet	7700000	USD
CY2018	us-gaap	Interest Income Expense Nonoperating Net InterestIncomeExpenseNonoperatingNet	6600000	USD
CY2020	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Interest PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedInterest	9900000	USD
CY2020	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	32100000	USD
CY2019	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	-5200000	USD
CY2019	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Interest PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedInterest	8000000.0	USD
CY2018	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Interest PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedInterest	14200000	USD
CY2020	nix	Charitable Contributions CharitableContributions	-1500000	USD
CY2019	nix	Charitable Contributions CharitableContributions	-5100000	USD
CY2018	nix	Charitable Contributions CharitableContributions	-45300000	USD
CY2020	nix	Pensionand Other Postretirement Non Service Cost PensionandOtherPostretirementNonServiceCost	9300000	USD
CY2019	nix	Pensionand Other Postretirement Non Service Cost PensionandOtherPostretirementNonServiceCost	-16500000	USD
CY2018	nix	Pensionand Other Postretirement Non Service Cost PensionandOtherPostretirementNonServiceCost	18000000.0	USD
CY2020	nix	Sale Of Emission Reduction Credits SaleOfEmissionReductionCredits	4600000	USD
CY2019	nix	Sale Of Emission Reduction Credits SaleOfEmissionReductionCredits	0	USD
CY2018	nix	Sale Of Emission Reduction Credits SaleOfEmissionReductionCredits	0	USD
CY2019	us-gaap	Gain Loss On Sale Of Derivatives GainLossOnSaleOfDerivatives	0	USD
CY2018	us-gaap	Gain Loss On Sale Of Derivatives GainLossOnSaleOfDerivatives	46200000	USD
CY2020	nix	Miscellaneous Non Operating Income Expense MiscellaneousNonOperatingIncomeExpense	4300000	USD
CY2019	nix	Miscellaneous Non Operating Income Expense MiscellaneousNonOperatingIncomeExpense	700000	USD
CY2018	nix	Miscellaneous Non Operating Income Expense MiscellaneousNonOperatingIncomeExpense	3800000	USD
CY2018	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	43500000	USD
CY2018	nix	Charitable Contributions Greater Lawrence Incident CharitableContributionsGreaterLawrenceIncident	20700000	USD
CY2018Q4	nix	Charitable Contributions CharitableContributions	20000000.0	USD
CY2020	us-gaap	Interest Expense Long Term Debt InterestExpenseLongTermDebt	354200000	USD
CY2019	us-gaap	Interest Expense Long Term Debt InterestExpenseLongTermDebt	327700000	USD
CY2018	us-gaap	Interest Expense Long Term Debt InterestExpenseLongTermDebt	342200000	USD
CY2020	us-gaap	Interest Expense Short Term Borrowings InterestExpenseShortTermBorrowings	14700000	USD
CY2019	us-gaap	Interest Expense Short Term Borrowings InterestExpenseShortTermBorrowings	50800000	USD
CY2018	us-gaap	Interest Expense Short Term Borrowings InterestExpenseShortTermBorrowings	31800000	USD
CY2018	us-gaap	Interest Expense InterestExpense	353300000	USD
CY2020	nix	Discount On Prepayment Transaction DiscountOnPrepaymentTransaction	9100000	USD
CY2019	nix	Discount On Prepayment Transaction DiscountOnPrepaymentTransaction	8300000	USD
CY2018	nix	Discount On Prepayment Transaction DiscountOnPrepaymentTransaction	7700000	USD
CY2020	nix	Securitization Transaction Fees SecuritizationTransactionFees	2600000	USD
CY2019	nix	Securitization Transaction Fees SecuritizationTransactionFees	2600000	USD
CY2018	nix	Securitization Transaction Fees SecuritizationTransactionFees	2600000	USD
CY2020	nix	Allowance For Borrowed Funds Used And Interest Capitalized During Construction AllowanceForBorrowedFundsUsedAndInterestCapitalizedDuringConstruction	7000000.0	USD
CY2019	nix	Allowance For Borrowed Funds Used And Interest Capitalized During Construction AllowanceForBorrowedFundsUsedAndInterestCapitalizedDuringConstruction	7500000	USD
CY2018	nix	Allowance For Borrowed Funds Used And Interest Capitalized During Construction AllowanceForBorrowedFundsUsedAndInterestCapitalizedDuringConstruction	9100000	USD
CY2020	nix	Debtbasedpostinservicecarryingcharges Debtbasedpostinservicecarryingcharges	14600000	USD
CY2019	nix	Debtbasedpostinservicecarryingcharges Debtbasedpostinservicecarryingcharges	18700000	USD
CY2018	nix	Debtbasedpostinservicecarryingcharges Debtbasedpostinservicecarryingcharges	35000000.0	USD
CY2020	us-gaap	Interest Expense Other InterestExpenseOther	11700000	USD
CY2019	us-gaap	Interest Expense Other InterestExpenseOther	15700000	USD
CY2018	us-gaap	Interest Expense Other InterestExpenseOther	13100000	USD
CY2020	us-gaap	Interest Expense InterestExpense	370700000	USD
CY2019	us-gaap	Interest Expense InterestExpense	378900000	USD
CY2020	us-gaap	Number Of Reportable Segments NumberOfReportableSegments	2
CY2020	us-gaap	Regulated Operating Revenue RegulatedOperatingRevenue	4681700000	USD
CY2019	us-gaap	Regulated Operating Revenue RegulatedOperatingRevenue	5208900000	USD
CY2018	us-gaap	Regulated Operating Revenue RegulatedOperatingRevenue	5114500000	USD
CY2020	us-gaap	Operating Income Loss OperatingIncomeLoss	550800000	USD
CY2019	us-gaap	Operating Income Loss OperatingIncomeLoss	890700000	USD
CY2018	us-gaap	Operating Income Loss OperatingIncomeLoss	124700000	USD
CY2020	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	725900000	USD
CY2019	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	717400000	USD
CY2018	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	599600000	USD
CY2020Q4	us-gaap	Assets Assets	22040500000	USD
CY2019Q4	us-gaap	Assets Assets	22659800000	USD
CY2018Q4	us-gaap	Assets Assets	21804000000.0	USD
CY2020	nix	Payments To Acquire Property Plant And Equipment Including Captial Expenditures From Current Liabilities And Equity Method Investments PaymentsToAcquirePropertyPlantAndEquipmentIncludingCaptialExpendituresFromCurrentLiabilitiesAndEquityMethodInvestments	1720800000	USD
CY2019	nix	Payments To Acquire Property Plant And Equipment Including Captial Expenditures From Current Liabilities And Equity Method Investments PaymentsToAcquirePropertyPlantAndEquipmentIncludingCaptialExpendituresFromCurrentLiabilitiesAndEquityMethodInvestments	1867800000	USD
CY2018	nix	Payments To Acquire Property Plant And Equipment Including Captial Expenditures From Current Liabilities And Equity Method Investments PaymentsToAcquirePropertyPlantAndEquipmentIncludingCaptialExpendituresFromCurrentLiabilitiesAndEquityMethodInvestments	1814600000	USD
CY2020	us-gaap	Disposal Group Not Discontinued Operation Loss Gain On Write Down DisposalGroupNotDiscontinuedOperationLossGainOnWriteDown	412400000	USD
CY2020Q1	us-gaap	Gross Profit GrossProfit	1605500000	USD
CY2020Q2	us-gaap	Gross Profit GrossProfit	962700000	USD
CY2020Q3	us-gaap	Gross Profit GrossProfit	902500000	USD
CY2020Q4	us-gaap	Gross Profit GrossProfit	1211000000.0	USD
CY2020Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	148200000	USD
CY2020Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	91700000	USD
CY2020Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	92800000	USD
CY2020Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	218100000	USD
CY2020Q1	us-gaap	Profit Loss ProfitLoss	75600000	USD
CY2020Q2	us-gaap	Profit Loss ProfitLoss	-4700000	USD
CY2020Q3	us-gaap	Profit Loss ProfitLoss	-172900000	USD
CY2020Q4	us-gaap	Profit Loss ProfitLoss	87800000	USD
CY2020Q1	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	0	USD
CY2020Q2	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	0	USD
CY2020Q3	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	0	USD
CY2020Q4	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	3400000	USD
CY2020Q1	us-gaap	Net Income Loss NetIncomeLoss	75600000	USD
CY2020Q2	us-gaap	Net Income Loss NetIncomeLoss	-4700000	USD
CY2020Q3	us-gaap	Net Income Loss NetIncomeLoss	-172900000	USD
CY2020Q4	us-gaap	Net Income Loss NetIncomeLoss	84400000	USD
CY2020Q1	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	13800000	USD
CY2020Q2	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	13800000	USD
CY2020Q3	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	13800000	USD
CY2020Q4	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	13700000	USD
CY2020Q1	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	61800000	USD
CY2020Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-18500000	USD
CY2020Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-186700000	USD
CY2020Q4	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	70700000	USD
CY2020Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.16
CY2020Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.05
CY2020Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.49
CY2020Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.18
CY2020Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.16
CY2020Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.05
CY2020Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.49
CY2020Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.18
CY2019Q1	us-gaap	Gross Profit GrossProfit	1869800000	USD
CY2019Q2	us-gaap	Gross Profit GrossProfit	1010400000	USD
CY2019Q3	us-gaap	Gross Profit GrossProfit	931500000	USD
CY2019Q4	us-gaap	Gross Profit GrossProfit	1397200000	USD
CY2019Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	374200000	USD
CY2019Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	463500000	USD
CY2019Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	91000000.0	USD
CY2019Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	-38000000.0	USD
CY2019Q1	us-gaap	Net Income Loss NetIncomeLoss	218900000	USD
CY2019Q2	us-gaap	Net Income Loss NetIncomeLoss	296900000	USD
CY2019Q3	us-gaap	Net Income Loss NetIncomeLoss	6600000	USD
CY2019Q4	us-gaap	Net Income Loss NetIncomeLoss	-139300000	USD
CY2019Q1	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	13800000	USD
CY2019Q2	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	13800000	USD
CY2019Q3	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	13800000	USD
CY2019Q4	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	13700000	USD
CY2019Q1	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	205100000	USD
CY2019Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	283100000	USD
CY2019Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-7200000	USD
CY2019Q4	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-153000000.0	USD
CY2019Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.55
CY2019Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.76
CY2019Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.02
CY2019Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.41
CY2019Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.55
CY2019Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.75
CY2019Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.02
CY2019Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.41
CY2019Q1	nix	Proceeds From Insurance Settlement ProceedsFromInsuranceSettlement	108000000.0	USD
CY2019Q2	nix	Proceeds From Insurance Settlement ProceedsFromInsuranceSettlement	297000000.0	USD
CY2020Q3	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	243400000	USD
CY2020	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	170400000	USD
CY2019	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	223600000	USD
CY2018	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	152000000.0	USD
CY2020	us-gaap	Right Of Use Asset Obtained In Exchange For Finance Lease Liability RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability	59300000	USD
CY2019	us-gaap	Noncash Or Part Noncash Acquisition Fixed Assets Acquired1 NoncashOrPartNoncashAcquisitionFixedAssetsAcquired1	26400000	USD
CY2018	us-gaap	Noncash Or Part Noncash Acquisition Fixed Assets Acquired1 NoncashOrPartNoncashAcquisitionFixedAssetsAcquired1	54600000	USD
CY2020	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	10900000	USD
CY2019	nix	Noncashor Part Noncash Acquisition Fixed Assets Acquired Operating Lease NoncashorPartNoncashAcquisitionFixedAssetsAcquiredOperatingLease	13400000	USD
CY2018	nix	Noncashor Part Noncash Acquisition Fixed Assets Acquired Operating Lease NoncashorPartNoncashAcquisitionFixedAssetsAcquiredOperatingLease	0	USD
CY2020	nix	Reclassificationof Other Propertyto Regulatory Assets ReclassificationofOtherPropertytoRegulatoryAssets	0	USD
CY2019	nix	Reclassificationof Other Propertyto Regulatory Assets ReclassificationofOtherPropertytoRegulatoryAssets	0	USD
CY2018	nix	Reclassificationof Other Propertyto Regulatory Assets ReclassificationofOtherPropertytoRegulatoryAssets	245300000	USD
CY2020	us-gaap	Increase Decrease In Asset Retirement Obligations IncreaseDecreaseInAssetRetirementObligations	91500000	USD
CY2019	us-gaap	Increase Decrease In Asset Retirement Obligations IncreaseDecreaseInAssetRetirementObligations	54600000	USD
CY2018	us-gaap	Increase Decrease In Asset Retirement Obligations IncreaseDecreaseInAssetRetirementObligations	78100000	USD
CY2020Q4	nix	Obligation To The Developer ObligationToTheDeveloper	69700000	USD
CY2019Q4	nix	Obligation To The Developer ObligationToTheDeveloper	0	USD
CY2018Q4	nix	Obligation To The Developer ObligationToTheDeveloper	0	USD
CY2020	us-gaap	Interest Paid Net InterestPaidNet	349000000.0	USD
CY2019	us-gaap	Interest Paid Net InterestPaidNet	349700000	USD
CY2018	us-gaap	Interest Paid Net InterestPaidNet	354200000	USD
CY2020	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	-1000000.0	USD
CY2019	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	10800000	USD
CY2018	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	3300000	USD

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$NI
NISOURCE INC. Stock $ni

2020 Q4 Form 10-K Financial Statement

#000111171121000010 Filed on February 17, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$NI NISOURCE INC. Stock $ni

2020 Q4 Form 10-K Financial Statement

#000111171121000010 Filed on February 17, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$NI
NISOURCE INC. Stock $ni