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Such costs are capitalized if they meet both of the following criteria: a. It is probable that future revenue in an amount at least equal to the capitalized cost will result from inclusion of that cost in allowable costs for rate-making purposes. b. Based on available evidence, the future revenue will be provided to permit recovery of the previously incurred cost rather than to provide for expected levels of similar future costs. If the revenue will be provided through an automatic rate-adjustment clause, this criterion requires that the regulator's intent clearly be to permit recovery of the previously incurred cost. 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Treasury stock is issued but is not outstanding. This stock has no voting rights and receives no dividends. Note that treasury stock may be recorded at its total cost or separately as par (or stated) value and additional paid in capital. Note: number of treasury shares concept is in another section within stockholders' equity. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Technical Bulletin (FTB) -Number 85-6 -Paragraph 3 true 47 Total Common Stockholders' Equity 4 us-gaap_StockholdersEquity us-gaap true credit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 4894900000 4894.9 false false false 2 false true false false 4854100000 4854.1 false false false xbrli:monetaryItemType monetary Total of all Stockholders' Equity (deficit) items, net of receivables from officers, directors owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph A3 -Appendix A Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 4 -Section E Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 29, 30, 31 -Article 5 false 48 Long-term debt, excluding amounts due within one year 4 us-gaap_LongTermDebtAndCapitalLeaseObligations us-gaap true credit instant No definition available. false false false false false false false false false false false totallabel false 1 false true false false 5977300000 5977.3 false false false 2 false true false false 5969100000 5969.1 false false false xbrli:monetaryItemType monetary Sum of the carrying values as of the balance sheet date of all long-term debt, which is debt initially having maturities due after one year from the balance sheet date or beyond the operating cycle, if longer, but excluding the portions thereof scheduled to be repaid within one year or the normal operating cycle, if longer plus capital lease obligations due to be paid more than one year after the balance sheet date. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 6 -Section H true 49 Total Capitalization 4 us-gaap_CapitalizationLongtermDebtAndEquity us-gaap true credit instant No definition available. false false false false false false false false false false false totallabel false 1 false true false false 10872200000 10872.2 false false false 2 false true false false 10823200000 10823.2 false false false xbrli:monetaryItemType monetary This element represents the total consolidated (as applicable) capitalization of the entity which is comprised of its long-term debt and equity instruments. The table may be detailed by subsidiary (legal entity) and include information by type of debt or equity detailed by instrument. No authoritative reference available. true 50 Current Liabilities 2 us-gaap_LiabilitiesCurrentAbstract us-gaap true na duration No definition available. false false false false false true false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false xbrli:stringItemType string No definition available. false 51 Current portion of long-term debt 3 us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent us-gaap true credit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 718800000 718.8 false false false 2 false true false false 719700000 719.7 false false false xbrli:monetaryItemType monetary Obligation related to long-term debt (excluding convertible debt) and capital leases, the portion which is due in one year or less in the future. No authoritative reference available. false 52 Short-term borrowings 3 us-gaap_ShortTermBorrowings us-gaap true credit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 212800000 212.8 false false false 2 false true false false 103000000 103.0 false false false xbrli:monetaryItemType monetary Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19 -Subparagraph a -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 13 -Subparagraph 2, 3 -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Subparagraph a(1) -Article 7 false 53 Accounts payable 3 us-gaap_AccountsPayableCurrent us-gaap true credit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 278900000 278.9 false false false 2 false true false false 502300000 502.3 false false false xbrli:monetaryItemType monetary Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19 -Subparagraph a -Article 5 false 54 Dividends payable 3 us-gaap_DividendsPayableCurrent us-gaap true credit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 64100000 64.1 false false false 2 false true false false 200000 0.2 false false false xbrli:monetaryItemType monetary Carrying value as of the balance sheet date of dividends declared but unpaid on equity securities issued by the entity and outstanding. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 43 -Chapter 3 -Section A -Paragraph 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20 -Article 5 false 55 Customer deposits and credits 3 us-gaap_CustomerDepositsCurrent us-gaap true credit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 196500000 196.5 false false false 2 false true false false 301200000 301.2 false false false xbrli:monetaryItemType monetary The current portion, due within one year or the normal operating cycle, if longer, of money or property received from customers which is either to be returned upon satisfactory contract completion or applied to customer receivables in accordance with the terms of the contract or the understandings. No authoritative reference available. false 56 Taxes accrued 3 us-gaap_TaxesPayableCurrent us-gaap true credit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 227800000 227.8 false false false 2 false true false false 212900000 212.9 false false false xbrli:monetaryItemType monetary Carrying value as of the balance sheet date of obligations incurred and payable for statutory income, sales, use, payroll, excise, real, property and other taxes. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 20 -Article 5 false 57 Interest accrued 3 us-gaap_InterestPayableCurrent us-gaap true credit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 130600000 130.6 false false false 2 false true false false 125400000 125.4 false false false xbrli:monetaryItemType monetary Carrying value as of the balance sheet date of [accrued] interest payable on all forms of debt, including trade payables, that has been incurred and is unpaid. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 43 -Chapter 3 -Section A -Paragraph 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20 -Article 5 false 58 Overrecovered gas and fuel costs 3 ni_DeferredGasRevenue ni false credit instant Deferred Gas Revenue. false false false false false false false false false false false verboselabel false 1 false true false false 38100000 38.1 false false false 2 false true false false 220400000 220.4 false false false xbrli:monetaryItemType monetary Deferred Gas Revenue. No authoritative reference available. false 59 Price risk management liabilities 3 us-gaap_DerivativeInstrumentsAndHedgesLiabilities us-gaap true credit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 206900000 206.9 false false false 2 false true false false 190100000 190.1 false false false xbrli:monetaryItemType monetary Sum as of the balance sheet date of the (a) fair values of all liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments, and (b) the carrying amounts of the liabilities arising from financial instruments or contracts used to mitigate a specified risk (hedge), and which are expected to be extinguished or otherwise disposed of within a year or the normal operating cycle, if longer, net of the effects of master netting arrangements. No authoritative reference available. false 60 Exchange gas payable 3 ni_ExchangeGasPayable ni false credit instant Exchange gas payable false false false false false false false false false false false verboselabel false 1 false true false false 207100000 207.1 false false false 2 false true false false 222200000 222.2 false false false xbrli:monetaryItemType monetary Exchange gas payable No authoritative reference available. false 61 Deferred revenue 3 us-gaap_DeferredRevenueCurrent us-gaap true credit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 10100000 10.1 false false false 2 false true false false 27300000 27.3 false false false xbrli:monetaryItemType monetary The carrying amount of consideration received or receivable as of the balance sheet date on potential earnings that were not recognized as revenue in conformity with GAAP, and which are expected to be recognized as such within one year or the normal operating cycle, if longer, including sales, license fees, and royalties, but excluding interest income. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 43 -Chapter 3 -Section A -Paragraph 7, 8 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 13 -Section A false 62 Regulatory liabilities 3 us-gaap_RegulatoryLiabilityCurrent us-gaap true credit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 83600000 83.6 false false false 2 false true false false 43800000 43.8 false false false xbrli:monetaryItemType monetary The amount for the individual regulatory current liability as itemized in a table of regulatory current liabilities as of the end of the period Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 71 -Paragraph 11 false 63 Accrued liability for postretirement and postemployment benefits 3 ni_AccruedLiabilityForPostretirementAndPostemploymentBenefitsCurrent ni false credit instant Accrued liability for postretirement and postemployment benefits. false false false false false false false false false false false verboselabel false 1 false true false false 7600000 7.6 false false false 2 false true false false 23600000 23.6 false false false xbrli:monetaryItemType monetary Accrued liability for postretirement and postemployment benefits. No authoritative reference available. false 64 Liabilities of discontinued operations and liabilities held for sale 3 us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent us-gaap true credit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 0 0 false false false 2 false true false false 600000 0.6 false false false xbrli:monetaryItemType monetary Carrying value as of the balance sheet date of current obligations (due less than one year or one operating cycle, if longer) arising from the sale, disposal or planned sale in the near future (generally within one year) of a disposal group, including a component of the entity (discontinued operation). Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 144 -Paragraph 46 false 65 Temporary LIFO liquidation credit 3 us-gaap_InventoryLIFOReserve us-gaap true credit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 6400000 6.4 false false false 2 false true false false 0 0 false false false xbrli:monetaryItemType monetary Reflects the difference between (a) inventory at the lower of LIFO cost or market and (b) inventory at replacement cost or at the lower of some acceptable inventory accounting method (such as FIFO or average cost), or market. If material, reflects an excess of replacement or current cost over stated LIFO value parenthetically on the balance sheet or in a note to the financial statements. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 6 -Subparagraph c -Article 5 false 66 Legal and environmental reserves 3 ni_LegalAndEnvironmentalReserves ni false credit instant Legal and environmental reserves. false false false false false false false false false false false verboselabel false 1 false true false false 83900000 83.9 false false false 2 false true false false 146100000 146.1 false false false xbrli:monetaryItemType monetary Legal and environmental reserves. No authoritative reference available. false 67 Other accruals 3 us-gaap_OtherLiabilitiesCurrent us-gaap true credit instant No definition available. false false false false false false false false false false false totallabel false 1 false true false false 244200000 244.2 false false false 2 false true false false 310800000 310.8 false false false xbrli:monetaryItemType monetary Aggregate carrying amount, as of the balance sheet date, of current obligations not separately disclosed in the balance sheet due to materiality considerations. Current liabilities are expected to be paid within one year (or the normal operating cycle, if longer). Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 43 -Chapter 3 -Section A -Paragraph 8 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 6 -Paragraph 15 true 68 Total Current Liabilities 3 us-gaap_LiabilitiesCurrent us-gaap true credit instant No definition available. false false false false false false false false false false false totallabel false 1 false true false false 2717400000 2717.4 false false false 2 false true false false 3149600000 3149.6 false false false xbrli:monetaryItemType monetary Total obligations incurred as part of normal operations that are expected to be paid during the following twelve months or within one business cycle, if longer. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 21 -Article 5 true 69 Other Liabilities and Deferred Credits 2 us-gaap_LiabilitiesNoncurrentAbstract us-gaap true na duration No definition available. false false false false false true false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false xbrli:stringItemType string No definition available. false 70 Price risk management liabilities 3 us-gaap_DerivativeLiabilitiesNoncurrent us-gaap true credit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 177900000 177.9 false false false 2 false true false false 170200000 170.2 false false false xbrli:monetaryItemType monetary Fair values as of the balance sheet date of all liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments, and which are expected to be extinguished or otherwise disposed of after one year or beyond the normal operating cycle, if longer, net of the effects of master netting arrangements. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 4, 17 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 43 -Chapter 3 -Section A -Paragraph 7 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 107 -Paragraph 10 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FIN39-1 -Paragraph 10A, 10B false 71 Deferred income taxes 3 us-gaap_DeferredTaxLiabilitiesNoncurrent us-gaap true credit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 2074300000 2074.3 false false false 2 false true false false 2018200000 2018.2 false false false xbrli:monetaryItemType monetary Represents the noncurrent portion of deferred tax liabilities, which result from applying the applicable tax rate to net taxable temporary differences pertaining to each jurisdiction to which the entity is obligated to pay income tax. A noncurrent taxable temporary difference is a difference between the tax basis and the carrying amount of a noncurrent asset or liability in the financial statements prepared in accordance with generally accepted accounting principles. In a classified statement of financial position, an enterprise shall separate deferred tax liabilities and assets into a current amount and a noncurrent amount. Deferred tax liabilities and assets shall be classified as current or noncurrent based on the classification of the related asset or liability for financial reporting. A deferred tax liability or asset that is not related to an asset or liability for financial reporting, including deferred tax assets related to carryforwards, shall be classified according to the expected reversal date of the temporary difference. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 41, 42 false 72 Deferred investment tax credits 3 us-gaap_AccumulatedDeferredInvestmentTaxCredit us-gaap true credit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 36600000 36.6 false false false 2 false true false false 39600000 39.6 false false false xbrli:monetaryItemType monetary The noncurrent portion of the reserve for accumulated deferred investment tax credits as of the balance sheet date. This is the remaining investment credit, which will reduce the cost of services collected from ratepayers by a ratable portion over the investment's regulatory life. No authoritative reference available. false 73 Deferred credits 3 us-gaap_OtherDeferredCreditsNoncurrent us-gaap true credit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 75400000 75.4 false false false 2 false true false false 72400000 72.4 false false false xbrli:monetaryItemType monetary Carrying amount as of the balance sheet date of unearned revenue or income not otherwise specified in the taxonomy which is expected to be taken into income after one year or beyond the normal operating cycle, if longer. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 13 -Section A false 74 Deferred revenue 3 us-gaap_DeferredRevenueNoncurrent us-gaap true credit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 200000 0.2 false false false 2 false true false false 8500000 8.5 false false false xbrli:monetaryItemType monetary The noncurrent portion of deferred revenue amount as of balance sheet date. Deferred revenue is a liability related to a revenue producing activity for which revenue has not yet been recognized, and is not expected to be recognized in the next twelve months. Generally, an entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 43 -Chapter 3 -Section A -Paragraph 7, 8 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 13 -Section A Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 48 -Paragraph 6 false 75 Accrued liability for postretirement and postemployment benefits 3 us-gaap_PensionAndOtherPostretirementAndPostemploymentBenefitPlansLiabilitiesNoncurrent us-gaap true credit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 1190500000 1190.5 false false false 2 false true false false 1134200000 1134.2 false false false xbrli:monetaryItemType monetary This represents the noncurrent liability recognized in the balance sheet that is associated with the defined benefit pension plans and other postretirement and postemployment benefit plans. (The current liability will be separate, but it will normally be small, if there is even any at all.) Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph c Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 6 false 76 Liabilities of discontinued operations and liabilities held for sale 3 us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent us-gaap true credit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 0 0 false false false 2 false true false false 6200000 6.2 false false false xbrli:monetaryItemType monetary Carrying value of noncurrent obligations (due more than one year or one operating cycle, whichever is longer) relating to the sale, disposal or planned sale in the near future (generally within one year) of a disposal group, including a component of the entity (discontinued operation), as of the balance sheet date. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 144 -Paragraph 46, 47 false 77 Regulatory liabilities and other removal costs 3 us-gaap_RegulatoryLiabilityNoncurrent us-gaap true credit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 1591800000 1591.8 false false false 2 false true false false 1558800000 1558.8 false false false xbrli:monetaryItemType monetary The amount for the individual regulatory noncurrent liability as itemized in a table of regulatory noncurrent liabilities as of the end of the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 71 -Paragraph 11 false 78 Asset retirement obligations 3 us-gaap_AssetRetirementObligationsNoncurrent us-gaap true credit instant No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 136800000 136.8 false false false 2 false true false false 138200000 138.2 false false false xbrli:monetaryItemType monetary Noncurrent portion of the carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 143 -Paragraph 3, 10, 22 false 79 Other noncurrent liabilities 3 us-gaap_OtherLiabilitiesNoncurrent us-gaap true credit instant No definition available. false false false false false false false false false false false totallabel false 1 false true false false 175000000 175.0 false false false 2 false true false false 152600000 152.6 false false false xbrli:monetaryItemType monetary Aggregate carrying amount, as of the balance sheet date, of noncurrent obligations not separately disclosed in the balance sheet due to materiality considerations. Noncurrent liabilities are expected to be paid after one year (or the normal operating cycle, if longer). Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 24 -Article 5 true 80 Total Other Liabilities and Deferred Credits 3 us-gaap_LiabilitiesNoncurrent us-gaap true credit instant No definition available. false false false false false false false false false false false totallabel false 1 false true false false 5458500000 5458.5 false false false 2 false true false false 5298900000 5298.9 false false false xbrli:monetaryItemType monetary Total obligations incurred as part of normal operations that is expected to be repaid beyond the following twelve months or one business cycle. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22, 23, 24, 25, 26, 27 -Article 5 true 81 Total Capitalization and Liabilities 2 us-gaap_LiabilitiesAndStockholdersEquity us-gaap true credit instant No definition available. false false false false false false false false false false false totallabel false 1 true true false false 19048100000 19048.1 false false false 2 true true false false 19271700000 19271.7 false false false xbrli:monetaryItemType monetary Total of all Liabilities and Stockholders' Equity items. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 32 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 25 -Article 7 true 2 76 false HundredThousands UnKnown UnKnown false true