2.2.0.25falsefalse003000 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited)truefalseIn Thousandsfalse1falsefalseUSDfalsefalse1/1/2011 - 3/31/2011 USD ($) USD ($) / shares $c00005http://www.sec.gov/CIK0000741508duration2011-01-01T00:00:002011-03-31T00:00:00u000Standardhttp://www.xbrl.org/2003/iso4217USDiso42170u001Standardhttp://www.xbrl.org/2003/instancesharesxbrli0u002Dividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0USDUSD$2falsefalseUSDfalsefalse1/1/2010 - 3/31/2010 USD ($) USD ($) / shares $c00010http://www.sec.gov/CIK0000741508duration2010-01-01T00:00:002010-03-31T00:00:00u000Standardhttp://www.xbrl.org/2003/iso4217USDiso42170u002Dividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0u001Standardhttp://www.xbrl.org/2003/instancesharesxbrli0USDUSD$3true0us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstractus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringThe net cash from (used in) all of the entity's operating activities, including those of discontinued operations, of the reporting entity. Operating activities include all transactions and events that are not defined as investing or financing activities. Operating activities generally involve producing and delivering goods and providing services. Cash flows from operating activities are generally the cash effects of transactions and other events that enter into the determination of net income.falsefalseCASH FLOWS FROM OPERATING ACTIVITIES:4false0us-gaap_ProfitLossus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse23300002330falsetruefalsefalsefalse2truefalsefalse-1721000-1721falsetruefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph A1, A4, A5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 5 -Subparagraph b Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 29 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 38 -Subparagraph a Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 38 -Subparagraph c(1) falsefalseNet Income (Loss)5true0nve_AdjustmentsToReconcileNetIncomeToNetCashFromOperatingActivitiesnvefalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseAdjustments to reconcile net income to net cash from operating activities:6false0us-gaap_DepreciationAndAmortizationus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse8310200083102falsefalsefalsefalsefalse2truefalsefalse8094800080948falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe current period expense charged against earnings on long-lived, physical assets not used in production, and which are not intended for resale, to allocate or recognize the cost of such assets over their useful lives; or to record the reduction in book value of an intangible asset over the benefit period of such asset; or to reflect consumption during the period of an asset that is not used in production.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 12 -Paragraph 5 falsefalseDepreciation and amortization7false0us-gaap_DeferredIncomeTaxesAndTaxCreditsus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse-414000-414falsefalsefalsefalsefalse2truefalsefalse12840001284falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net amount of deferred income taxes and income tax credits less the tax benefit from exercise of stock options.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 falsefalseDeferred taxes and deferred investment tax credit8false0nve_AllowanceForEquityFundsnvefalsecreditdurationTotal increase in earnings in the period representing the cost of equity (rate of return) used to finance construction of...falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse-7642000-7642falsefalsefalsefalsefalse2truefalsefalse-5953000-5953falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryTotal increase in earnings in the period representing the cost of equity (rate of return) used to finance construction of regulated assets, which is expected to be recovered through rate adjustments.No authoritative reference available.falsefalseAFUDC-equity9false0nve_DeferredEnergyChangenvefalsecreditdurationThe net change during the reporting period in carrying amount of capitalized fuel costs of a regulated entity that are...falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse31180003118falsefalsefalsefalsefalse2truefalsefalse2682400026824falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net change during the reporting period in carrying amount of capitalized fuel costs of a regulated entity that are expected to be recoverable through rate adjustments within one year or the normal operating cycle, if longer. and may include amortization of previously approved deferred energy under/over collection.No authoritative reference available.falsefalseDeferred energy10false0us-gaap_AmortizationOfRegulatoryAssetus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse3883900038839falsefalsefalsefalsefalse2truefalsefalse2034900020349falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe expense charged against earnings during the period to allocate the capitalized costs of regulatory assets over the periods expected to benefit from such costs.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 falsefalseAmortization of other regulatory assets11false0nve_DeferredRateIncreasenvefalsedebitdurationRepresents revenue recorded for which billings have been deferred into the future by order of rate regulator. 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This is an adjustment to net income because no cash flows for this transaction but is recorded within net income.No authoritative reference available.falsefalseDeferred Rate Increase12false0us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesOtherus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse19150001915falsefalsefalsefalsefalse2truefalsefalse28580002858falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryTransactions that do not result in cash inflows or outflows in the period in which they occur, but affect net income and thus are removed when calculating net cash flow from operating activities using the indirect cash flow method. This element is used when there is not a more specific and appropriate element.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 falsefalseOther, net13true0nve_ChangesInCertainAssetsAndLiabilitiesnvefalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseChanges in certain assets and liabilities:14false0us-gaap_IncreaseDecreaseInAccountsReceivableus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse3818500038185falsefalsefalsefalsefalse2truefalsefalse6292100062921falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net change during the reporting period in amount due within one year (or one business cycle) from customers for the credit sale of goods and services.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 falsefalseAccounts receivable15false0us-gaap_IncreaseDecreaseInInventoriesus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse-8639000-8639falsefalsefalsefalsefalse2truefalsefalse25990002599falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net change during the reporting period in the aggregate value of all inventory held by the reporting entity, associated with underlying transactions that are classified as operating activities.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 falsefalseMaterials, supplies and fuel16false0us-gaap_IncreaseDecreaseInOtherOperatingAssetsus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse-5653000-5653falsefalsefalsefalsefalse2truefalsefalse-16113000-16113falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net change during the reporting period in other operating assets not otherwise defined in the taxonomy.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 falsefalseOther current assets17false0us-gaap_IncreaseDecreaseInAccountsPayableus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse-23364000-23364falsefalsefalsefalsefalse2truefalsefalse-16406000-16406falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net change during the reporting period in the aggregate amount of obligations due within one year (or one business cycle). This may include trade payables, amounts due to related parties, royalties payable, and other obligations.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 falsefalseAccounts payable18false0us-gaap_IncreaseDecreaseInPensionAndPostretirementObligationsus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsetruenegated1truefalsefalse35210003521falsefalsefalsefalsefalse2truefalsefalse-4767000-4767falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net change during the reporting period in the amount due to fund pension and non-pension benefits to employees, retired and disabled former employees.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 falsefalseAccrued retirement benefits19false0us-gaap_IncreaseDecreaseInOtherAccruedLiabilitiesus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse-34708000-34708falsefalsefalsefalsefalse2truefalsefalse-19100000-19100falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net change during the reporting period in other expenses incurred but not yet paid. This element should be used when there is no other more specific or appropriate element.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 falsefalseOther current liabilities20false0nve_RiskManagementAssetsAndLiabilitiesnvefalsenadurationNet Increase (Decrease) in Derivative Instruments (Assets and Liabilities)falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse13540001354falsefalsefalsefalsefalse2truefalsefalse26330002633falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryNet Increase (Decrease) in Derivative Instruments (Assets and Liabilities)No authoritative reference available.falsefalseRisk management assets and liabilities21false0us-gaap_IncreaseDecreaseInDeferredChargesus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse-511000-511falsefalsefalsefalsefalse2truefalsefalse-921000-921falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net change during the reporting period in the value of expenditures made during the current reporting period for benefits that will be received over a period of years. Deferred charges differ from prepaid expenses in that they usually extend over a long period of time and may or may not be regularly recurring costs of operation.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 falsefalseOther deferred assets22false0us-gaap_IncreaseDecreaseInOtherRegulatoryAssetsus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse-18608000-18608falsefalsefalsefalsefalse2truefalsefalse-9462000-9462falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net change during the reporting period in the value of other assets that are created when regulatory agencies permits public utilities to defer costs to the balance sheet.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 falsefalseOther regulatory assets23false0us-gaap_IncreaseDecreaseInOtherDeferredLiabilityus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse-2636000-2636falsefalsefalsefalsefalse2truefalsefalse-4058000-4058falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net change during the reporting period in other obligations not otherwise defined in the taxonomy where the payments will be made in future periods.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 falsefalseOther deferred liabilities24false0us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperationsus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalsetotallabel1truefalsefalse8552300085523falsefalsefalsefalsefalse2truefalsefalse119914000119914falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net cash from (used in) the entity's continuing operations. This element specifically EXCLUDES the cash flows derived by the entity from its discontinued operations, if any. This element is only to be used when the entity reports its cash flows attributable to discontinued operations separately from the cash flow provided by or used in operating activities.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 26 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 26 -Footnote 10 truefalseNet Cash from Operating Activities25true0us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstractus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseCASH FLOWS USED BY INVESTING ACTIVITIES:26false0us-gaap_PaymentsToAcquirePropertyPlantAndEquipmentus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsetruenegated1truefalsefalse-144097000-144097falsefalsefalsefalsefalse2truefalsefalse-200046000-200046falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe cash outflow associated with the acquisition of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale; includes cash outflows to pay for construction of self-constructed assets.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 15 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 17 -Subparagraph c falsefalseAdditions to Utility Plant (excluding AFUDC-equity)27false0us-gaap_ProceedsFromSaleOfOtherPropertyPlantAndEquipmentus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse131789000131789falsefalsefalsefalsefalse2truefalsefalse32540003254falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe cash inflow from sale of other property, plant and equipment, used to produce goods or deliver services, and not otherwise defined in the taxonomy.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 15 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 16 -Subparagraph c falsefalseProceeds from sale of asset28false0us-gaap_ProceedsFromAdvancesForConstructionus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse-672000-672falsefalsefalsefalsefalse2truefalsefalse-794000-794falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe cash inflow from borrowing by the entity from developers, builders, government agencies and municipalities for construction that are repaid in cash, generally on a straight-line basis over periods ranging from five to forty years.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 15, 16 falsefalseCustomer advances for construction29false0us-gaap_ProceedsFromContributionInAidOfConstructionus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse2017800020178falsefalsefalsefalsefalse2truefalsefalse1570700015707falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryDevelopers, builders, governmental agencies and municipalities will provide the entity with cash, or in some cases property, to extend its services to their properties. Nonrefundable contributions are recorded as contributions in aid of construction (CIAC) and are amortized as a reduction of the depreciation expense associated with the contributed asset.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 15, 16 falsefalseContributions in aid of construction30false0us-gaap_PaymentsForProceedsFromOtherInvestingActivitiesus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsetruenegated1truefalsefalse286000286falsefalsefalsefalsefalse2truefalsefalse-1093000-1093falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net cash outflow (inflow) from other investing activities. This element is used when there is not a more specific and appropriate element in the taxonomy.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 15 falsefalseInvestments and other property - net31false0us-gaap_NetCashProvidedByUsedInInvestingActivitiesus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalsetotallabel1truefalsefalse74840007484falsefalsefalsefalsefalse2truefalsefalse-182972000-182972falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net cash inflow (outflow) from investing activity.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 26 truefalseNet Cash from (used by) Investing Activities32true0us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstractus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseCASH FLOWS FROM FINANCING ACTIVITIES:33false0us-gaap_ProceedsFromIssuanceOfLongTermDebtus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse00falsefalsefalsefalsefalse2truefalsefalse144999000144999falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 18 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 19 -Subparagraph b falsefalseProceeds from issuance of long-term debt34false0us-gaap_RepaymentsOfLongTermDebtus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsetruenegated1truefalsefalse-18481000-18481falsefalsefalsefalsefalse2truefalsefalse-44011000-44011falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 18 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 20 -Subparagraph b falsefalseRetirement of long-term debt35false0us-gaap_ProceedsFromIssuanceOfCommonStockus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse53530005353falsefalsefalsefalsefalse2truefalsefalse11240001124falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe cash inflow from the additional capital contribution to the entity.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 18 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 19 -Subparagraph a falsefalseSale of Common Stock36false0us-gaap_PaymentsOfDividendsus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsetruenegated1truefalsefalse-28276000-28276falsefalsefalsefalsefalse2truefalsefalse-25832000-25832falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe cash outflow from the entity's earnings to the shareholders.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 18 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 20 -Subparagraph a falsefalseDividends paid37false0us-gaap_NetCashProvidedByUsedInFinancingActivitiesus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalsetotallabel1truefalsefalse-41404000-41404falsefalsefalsefalsefalse2truefalsefalse7628000076280falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net cash inflow (outflow) from financing activity for the period.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 26 truefalseNet Cash from (used by) Financing Activities38false0us-gaap_CashAndCashEquivalentsPeriodIncreaseDecreaseus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalsetotallabel1truefalsefalse5160300051603falsefalsefalsefalsefalse2truefalsefalse1322200013222falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net change between the beginning and ending balance of cash and cash equivalents.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 26 truefalseNet Increase in Cash and Cash Equivalents39false0us-gaap_CashAndCashEquivalentsAtCarryingValueus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsetruefalsefalseperiodstartlabel1truefalsefalse8618900086189falsefalsefalsefalsefalse2truefalsefalse6270600062706falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryIncludes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the Entity may deposit additional funds at any time and also effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Compensating balance arrangements that do not legally restrict the withdrawal or usage of cash amounts may be reported as Cash and Cash Equivalents, while legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or company statements of intention with regard to particular deposits should not be reported as cash and cash equivalents.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 7, 26 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 8, 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 7 -Footnote 1 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 1 -Article 5 falsefalseBeginning Balance in Cash and Cash Equivalents40false0us-gaap_CashAndCashEquivalentsAtCarryingValueus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsetruefalseperiodendlabel1truefalsefalse137792000137792falsefalsefalsefalsefalse2truefalsefalse7592800075928falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryIncludes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the Entity may deposit additional funds at any time and also effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Compensating balance arrangements that do not legally restrict the withdrawal or usage of cash amounts may be reported as Cash and Cash Equivalents, while legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or company statements of intention with regard to particular deposits should not be reported as cash and cash equivalents.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 7, 26 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 8, 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 7 -Footnote 1 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 1 -Article 5 falsefalseEnding Balance in Cash and Cash Equivalents42true0nve_CashPaidDuringPeriodFornvefalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseCash paid (received) during period for:43false0us-gaap_InterestPaidNetus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse9232300092323falsefalsefalsefalsefalse2truefalsefalse9955900099559falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe amount of cash paid during the current period for interest owed on money borrowed, net of interest capitalized.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 29 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 27 -Subparagraph e falsefalseInterest44false0us-gaap_IncomeTaxesPaidNetus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse10001falsefalsefalsefalsefalse2truefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income, net of any cash received during the current period as refunds for the overpayment of taxes.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 29 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 27 -Subparagraph f falsefalseIncome taxes45true0us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstractus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringDesignated to encapsulate the entire footnote disclosure that gives information on the supplemental cash flow activities for noncash (or part noncash) transactions for the period. Noncash is defined as information about all investing and financing activities of an enterprise during a period that affect recognized assets or liabilities but that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.falsefalseSignificant non-cash transactions:46false0us-gaap_NoncashOrPartNoncashAcquisitionFixedAssetsAcquiredus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1truefalsefalse7703300077033falsefalsefalsefalsefalse2truefalsefalse9735700097357falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe amount of fixed assets that an Entity acquires in a noncash (or part noncash) acquisition. Noncash is defined as information about all investing and financing activities of an enterprise during a period that affect recognized assets or liabilities but that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 32 falsefalseAccrued construction expenses as of March 31,47false0us-gaap_CapitalLeaseObligationsIncurredus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse00falsetruefalsefalsefalse2truefalsefalse1533600015336falsetruefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe increase during the period in capital lease obligations due to entering into new capital leases.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 32 falsefalseCapital lease obligations incurred244CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) (USD $)ThousandsUnKnownUnKnownUnKnownfalsetrue