<DefinitionAndReference>
  <Element Id="us-gaap_FiniteLivedIntangibleAssetsWeightedAverageUsefulLife">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DebtInstrumentFrequencyOfPeriodicPayment">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CashDividendsPaidToParentCompany">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_EntityFilerCategory">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsIncreaseDueToExpectedPerformance">
    <definition>The number of shares issuable under a share-based award plan pertaining to increases due to expected performance made during the period on other than stock option plans (for example, phantom stock plan, stock appreciation rights plan, performance target plan).</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_LiabilitiesCurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanAmountsThatWillBeAmortizedFromAccumulatedOtherComprehensiveIncomeLossInNextFiscalYear">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ShareBasedCompensationArrangementByShareBasedPaymentAwardsOptionsGrantsInPeriodWeightedAverageExercisePrice">
    <definition>Share Based Compensation Arrangement By Share Based Payment Awards Options Grants In Period Weighted Average Exercise Price.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredTaxLiabilities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_EarningsPerShareTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_StockholdersEquity">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredFederalIncomeTaxExpenseBenefit">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ComponentsOfNetPeriodicBenefitCostTextBlock">
    <definition>Components of net periodic benefit cost Text Block.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_AdditionalInformationRelatedToConvertibleContingentDebtSecuritiesTextBlock">
    <definition>Additional Information Related To Convertible Contingent Debt Securities Text Block.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredTaxLiabilitiesOther">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesOther">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DerivativeAssetNotDesignatedAsHedgingInstrumentFairValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_InterestExpense">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ScheduleOfGoodwillTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanHealthCareCostTrendRateAssumedForNextFiscalYear">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CommonStockSharesAuthorized">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CommonStockSharesOutstanding">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncreaseDecreaseInOtherOperatingLiabilities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_TotalPerformanceUnits">
    <definition>Total performance units earned.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_AmountOfDiscountOnNotesIssued">
    <definition>The amount of note discount on the newly issued note that will be amortized over the life of the note.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_Assets">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_PercentageOfIncurredCostsBilledMaximum">
    <definition>Percentage of incurred costs billed, maximum.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_OtherFinancingActivities">
    <definition>Other financing activities.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AmortizationOfIntangibleAssets">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PrescriptionDrugSubsidyReceiptsYearThree">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsInYearTwo">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_RepurchasedCodesThatHaveBeenClassifiedAsCurrentLiability">
    <definition>Repurchased Codes That Have Been Classified As Current Liability.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_GainOnSaleOfInterestInBusinessNetOfIncomeTaxes">
    <definition>Gain on Sale of Interest in Business, Net of Income Taxes.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DebtInstrumentFaceAmount">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_SegmentReportingInformationCapitalExpenditures">
    <definition>Segment Reporting Information Capital Expenditures.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_LongTermDebtNoncurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanServiceCost">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_MaximumConsolidatedSeniorLeverageRatioUnderRevolvingCreditFacilityCovenants">
    <definition>Maximum consolidated senior leverage ratio under revolving credit facility covenants.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_DocumentType">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_LiabilityForUncertainTaxPositionsNoncurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DebtInstrumentUnamortizedDiscount">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ChangeInOwnershipInterestInBusiness">
    <definition>Change in Ownership Interest in Business.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_AggregatePurchasePrice">
    <definition>Aggregate Purchase price.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncomeTaxesPaid">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PropertyPlantAndEquipmentNet">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_GuaranteeObligationsCurrentCarryingValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_LineOfCreditFacilityAmountOutstanding">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_TreasuryStockSharesAcquired">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointIncreaseOnAccumulatedPostretirementBenefitObligation">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_NetLossAndPriorServiceCostBalancesInAccumulatedOtherComprehensiveLossAccountTextBlock">
    <definition>Net loss and prior service cost balances in accumulated other comprehensive loss account Text Block.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_Other">
    <definition>Other.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_StockholdersEquityBeforeAccumulatedOtherComprehensiveLoss">
    <definition>Stockholders Equity Before Accumulated Other Comprehensive Loss.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitRealizedFromExerciseOfStockOptions">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_SalesRevenueNet">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_EntityCommonStockSharesOutstanding">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AccruedIncomeTaxesCurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanAmortizationOfNetGainsLosses">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanActuarialNetGainsLosses">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_AmountOfGoodwillRelatedToBusinessAcquisitionInYear">
    <definition>Amount of goodwill related to business acquisition in year.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_LongTermDebtsNoncurrent">
    <definition>Long term debts noncurrent.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_BasisOfPresentationPolicyTextBlock">
    <definition>Basis of Presentation Policy.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ApplicableSpreadOnLiborRateOption">
    <definition>Applicable spread on LIBOR rate option.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_OperatingIncomeReclassifiedFromGovernmentServicesReportableSegmentToElectronicSystemsReportableSegmentAsResultOfBusinessUnitReAlignment">
    <definition>Operating income reclassified from Government Services reportable segment to Electronic Systems reportable segment as a result of a business unit re-alignment.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_SalesRevenueGoodsNet">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PaymentsForProceedsFromOtherInvestingActivities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredTaxAssetsLiabilitiesNet">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_MinimumCashAmountUnderSettlementOfCodes">
    <definition>Minimum cash amount under settlement of CODES.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsInYearOne">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ContributionsFromParent">
    <definition>Contributions from Parent.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_NonoperatingGainsLosses">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ReconciliationOfChangeInUnrecognizedIncomeTaxBenefitsExcludingInterestAndPenaltiesTextBlock">
    <definition>Reconciliation of the change in unrecognized income tax benefits, excluding interest and penalties.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_OtherComprehensiveIncomeDefinedBenefitAndPostretirementPlansAdjustmentNetOfTaxPeriodIncreaseDecrease">
    <definition>Net changes to accumulated comprehensive income during the period related to defined benefit pension and other postretirement plans, after tax.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeReclassificationOfDefinedBenefitPlansNetGainLossRecognizedInNetPeriodicBenefitCostBeforeTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlanNetPriorServiceCostsCreditArisingDuringPeriodNetOfTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PropertyPlantAndEquipmentEstimatedUsefulLives">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_BalanceSheetsTextBlock">
    <definition>Condensed Combining Balance Sheet.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_GainIncludedInDilutedEarningPerShareDueToSaleOfProductLine">
    <definition>Gain included in diluted EPS due to sale of product line.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProductWarrantyAccrual">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_OtherCurrentLiabilities">
    <definition>Other current liabilities.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_GainOnSaleOfPmdProductLineBeforeIncomeTaxes">
    <definition>Gain on sale of a PMD product line, before income taxes.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_AmountOfGoodwillRelatedToEarnoutsFromCertainBusinessAcquisitionsBeforeYear">
    <definition>Amount of goodwill related to earnouts from certain business acquisitions before year.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ClassificationOfDeferredTaxAssetsAndLiabilitiesTextBlock">
    <definition>Classification of deferred tax assets and liabilities.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredTaxAssetsTaxCreditCarryforwards">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTen">
    <definition>Amount of long-term debt maturing in year ten following the date of the latest balance sheet presented in the financial statements, which may include maturities of long-term debt, sinking fund requirements, and other securities redeemable at fixed of determinable prices and dates.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsIncreaseDueToExpectedPerformanceWeightedAverageGrantDateFairValue">
    <definition>The weighted average fair value at grant for increases due to expected performance of nonvested share-based awards issued during the period on other than stock option plans (for example, phantom stock plan, stock appreciation rights plan, performance target plan).</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_DefinedBenefitPlansTargetAllocationPercentageOfAssetsInternationalEquitySecuritiesRangeMaximum">
    <definition>Defined Benefit Plans Target Allocation Percentage Of Assets International Equity Securities Range Maximum.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_TotalOutstandingLettersOfCredit">
    <definition>Total outstanding letters of credit.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ContractsInProcessOperatingActivities">
    <definition>Inventoried contract costs, Unbilled receivables, and unliquidated progress payments.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_DefinedBenefitPlanDomesticEquitySecurities">
    <definition>The percentage of the fair value of domestic equity to the fair value of total plan assets held as of the measurement date.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_UnliquidatedProgressPaymentsForUnbilledContractReceivables">
    <definition>unliquidated progress payments for Unbilled contract receivables.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedTerm">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanPlanAmendments">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredTaxLiabilitiesUndistributedForeignEarnings">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DerivativeAssetDesignatedAsHedgingInstrumentFairValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ConvertibleSubordinatedDebt">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_MultiemployerPlanPeriodContributions">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_RestructuringReserve">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherNoncurrentLiabilities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ShareBasedCompensationArrangementByShareBasedPaymentAwardsOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm">
    <definition>Share Based Compensation Arrangement By Share Based Payment Awards Options Vested And Expected To Vest Outstanding Weighted Average Remaining Contractual Term.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ScheduleOfDerivativeInstrumentsInStatementOfFinancialPositionFairValueTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_Goodwill">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherLiabilitiesNoncurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncomeTaxExaminationInterestExpense">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_UnamortizedDiscountOfLiabilityComponentBeingAmortized">
    <definition>Unamortized Discount Of Liability Component Being Amortized.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncomeLossFromContinuingOperations">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ExpectedForeignNetOperatingLossesToBeUtilized">
    <definition>Expected foreign net operating losses to be utilized.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncreaseDecreaseInAccountsPayableTrade">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_WeightedAverageAssumptionsUsedToDetermineNetPeriodicBenefitCostTextBlock">
    <definition>Weighted average assumptions used to determine net periodic benefit cost Text Block.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncomeTaxPolicyTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ConvertibleDebtPrincipalAmount">
    <definition>Principal amount of convertible debt as of the balance sheet date, which can be converted into cash under certain circumstances, at the option of the issuer, and if the settlement amount exceeds the principal amount, the excess will be settled in cash or stock or a combination thereof, at the Company's option.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredTaxAssetsGross">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_EquivalentNumberOfSharesForOneCommonSharesUnderFullValueAwardOption">
    <definition>Each share of common stock issued under a full value award (awards other than stock options or stock appreciation rights) will be counted as 2.6 shares for purposes of monitoring the share limit.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_NetCashProvidedByUsedInOperatingActivities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_MinimumLossContingencyDamagesSought">
    <definition>Describes the form and magnitude of the minimum award the plaintiff seeks in the legal matter.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_InterestPayableCurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointDecreaseOnAccumulatedPostretirementBenefitObligation">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_DocumentFiscalYearFocus">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_EntityCentralIndexKey">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanBenefitsPaid">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProductWarrantyAccrualWarrantiesIssued">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_NatureOfOperations">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_EarningsPerShareDiluted">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DebtInstrumentIssuanceDate">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_FutureAmortizationExpenseYearTwo">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleEstimatedRangeOfChange">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_OwnershipInterestSold">
    <definition>Ownership Interest Sold in METI.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_AmendmentFlag">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_TotalDamagesSought">
    <definition>Total Damages Sought.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_DefinedBenefitPlansTargetAllocationPercentageOfAssetsRealEstateRangeMaximum">
    <definition>Defined Benefit Plans Target Allocation Percentage Of Assets Real Estate Range Maximum.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CashAndCashEquivalentsPolicyTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_InventoryRawMaterialsAndSuppliesNetOfReserves">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_CircumstanceSixForConversionOfConvertibleContingentDebt">
    <definition>Circumstance six for conversion of convertible contingent debt.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAccrued">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_CarryingAmountsAndEstimatedFairValuesOfFinancialInstrumentsTextBlock">
    <definition>Carrying amounts and estimated fair values of financial instruments Text Block.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CostOfGoodsAndServicesSold">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_MinimumPayoutRange">
    <definition>Minimum payout range for performance units based on pre-determined performance goals established by the compensation committee.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_LiborRateUnderNewRevolvingCreditFacility">
    <definition>Libor Rate Under new revolving credit facility.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsInYearThree">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_SettlementAmountUponConversionOfCodesOptionTwoInCombinationOfCashAndCommonStockConditionOne">
    <definition>Settlement amount upon conversion of the CODES option two in  a combination of cash and common stock condition one.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_TreasuryStockValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_CircumstanceFourForConversionOfConvertibleContingentDebt">
    <definition>Circumstance four for conversion of convertible contingent debt.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_OtherLiabilitiesTextBlock">
    <definition>Other LiabilitiesText Block.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_PunitiveDamagesSought">
    <definition>Punitive Damages Sought.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncrementalCommonSharesAttributableToConversionOfDebtSecurities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanContributionsByPlanParticipants">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_Liabilities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredTaxLiabilitiesNoncurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncreaseDecreaseInAccountsReceivable">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ScheduleOfRestructuringAndRelatedCostsTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointDecreaseOnServiceAndInterestCostComponents">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ConvertibleSubordinatedDebtEstimatedFairValue">
    <definition>Including the current and noncurrent portions, the fair value of convertible subordinated debt, as of the balance sheet date, initially scheduled to be repaid after one year or beyond the normal operating cycle if longer. This form of debt can be exchanged for a specified amount of another security, typically the entity's common stock, at the option of the issuer or the holder, and places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_FutureAmortizationExpenseYearThree">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherLiabilitiesCurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ResidualGuaranteeAmount">
    <definition>Residual guarantee amount.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_EffectOfOnePercentagePointChangeInAssumedHealthCareCostTrendRatesTextBlock">
    <definition>Effect of One Percentage Point Change in Assumed Health Care Cost Trend Rates Text Block.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_AmountOfGoodwillRelatedToFinalPurchasePriceDeterminationsForCertainBusinessAcquisitionsCompletedBeforeYear">
    <definition>Amount of goodwill related to final purchase price determinations for certain business acquisitions completed before year.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_FeesForPerformanceAndCommercialLettersOfCredit">
    <definition>Fees For Performance and Commercial Letters of Credit.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_SeveranceCosts">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_SegmentReportingInformationGoodwill">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_GainLossRelatedToLitigationSettlement">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncreaseDecreaseInOperatingCapital">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OperatingIncomeLoss">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_CompanysStockOptionActivityAndChangesTextBlock">
    <definition>Companys Stock Option Activity And Changes Text Block.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_GainIncludedInDilutedEarnigPerShareDueToReversalOfCurrentLiability">
    <definition>Gain included in diluted EPS due to reversal of current liability.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ContractsInProcessPolicyTextBlock">
    <definition>Contracts in Process Policy.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_CombiningStatementsOfCashFlowsTextBlock">
    <definition>Condensed Combining Statements of Cash Flows.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_CompensatoryDamagesAwardedByTrialCourt">
    <definition>Compensatory damages awarded by trial court.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_RedemptionPriceOfNotes">
    <definition>Redemption price of notes.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProceedsFromPaymentsForOtherFinancingActivities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProductWarrantyDisclosureTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncomeLossFromContinuingOperationsPerBasicShare">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_DefinedBenefitPlansTargetAllocationPercentageOfAssetsRealEstateRangeMinimum">
    <definition>Defined Benefit Plans Target Allocation Percentage Of Assets Real Estate Range Minimum.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosureTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DebtInstrumentConvertibleConversionRatio">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlanNetPriorServiceCostsArisingDuringPeriodTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ConsolidationPolicyTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProceedsFromLinesOfCredit">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_EscrowDeposit">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_FairValueAssetsMeasuredOnRecurringBasisCashAndCashEquivalents">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_RepurchasesByHoldersOfCodes">
    <definition>Repurchases by the holders of the CODES.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisDerivativeFinancialInstrumentsLiabilities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ShareBasedCompensationArrangementsByShareBasedPaymentAwardsEquityInstrumentsOtherThanOptionsForfeitedInPeriodWeightedAverageGrantDateFairValue">
    <definition>Share Based Compensation Arrangements By Share Based Payment Awards Equity Instruments Other Than Options Forfeited In Period Weighted Average Grant Date Fair Value.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ReconciliationOfStatutoryFederalIncomeTaxRateToEffectiveIncomeTaxRateTextBlock">
    <definition>Reconciliation of the statutory federal income tax rate to the effective income tax rate.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PrescriptionDrugSubsidyReceiptsYearFour">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_SegmentReclassificationOfGoodwillAllocatedToReportableSegmentsOfCompany">
    <definition>Segment reclassification of goodwill allocated to the reportable segments of company.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_CompanysUnauditedQuarterlyResultsOfOperationsTextBlock">
    <definition>Companys Unaudited Quarterly Results Of Operations Text Block.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredForeignIncomeTaxExpenseBenefit">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BusinessAcquisitionCostOfAcquiredEntityCashPaid">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DerivativeFairValueOfDerivativeLiability">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ComponentsOfContractsInProcessTextBlock">
    <definition>Components of Contracts in Process.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_MaximumLossContingencyDamagesSought">
    <definition>Describes the form and magnitude of the maximum award the plaintiff seeks in the legal matter.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_NumberOfConsecutiveYearsAgreementWillContinue">
    <definition>Number of consecutive years agreement will continue.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_CurrentPortionOfLongTermDebt">
    <definition>Current Portion of Long term Debt.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_NumberOfSharesOfCommonStockForEachOfTradingDaysInConversionPeriod">
    <definition>Number of shares of common stock for each of the 20 trading days in the conversion period.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_EffectiveIncomeTaxRateReconciliationTaxContingencies">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_SeniorNotesEstimatedFairValue">
    <definition>Including the current and noncurrent portions, fair value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ExtinguishmentOfDebtGainLossPerShareNetOfTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_StockholdersEquityOther">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_RetainedEarningsAccumulatedDeficit">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ResearchAndDevelopmentExpenses">
    <definition>The aggregate costs for the company's commercial businesses, not included included in inventoried contract costs, incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_UnbilledContractReceivablesGross">
    <definition>Gross unbilled amounts due for services rendered or to be rendered, actions taken or to be taken, or a promise to refrain from taking certain actions in accordance with the terms of a legally binding agreement between the entity and, at a minimum, one other party. An example would be gross amounts associated with contracts or programs where the recognized revenue for performance thereunder exceeds the amounts billed under the terms thereof as of the date of the balance sheet.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ReconciliationOfBasicAndDilutedEarningsPerShareTextBlock">
    <definition>Reconciliation of basic and diluted earnings per share.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ApplicableSpreadOnBaseRateOption">
    <definition>Applicable spread on base rate option.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_FiniteLivedIntangibleAssetsGross">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_BaseRateUnderNewRevolvingCreditFacility">
    <definition>Base Rate under the new Revolving Credit Facility.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_SharesIssued">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredTaxAssetsNetCurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanUltimateHealthCareCostTrendRate">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ComponentsOfDeferredTaxAssetsAndLiabilitiesTextBlock">
    <definition>Components of deferred tax assets and liabilities.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_FiniteLivedIntangibleAssetsNet">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_MaximumConsolidatedInterestCoverageRatioUnderRevolvingCreditFacilityCovenants">
    <definition>Maximum consolidated interest coverage ratio under revolving credit facility covenants.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredTaxAssetsInventory">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DerivativeLiabilityNotDesignatedAsHedgingInstrumentFairValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_InterestPaid">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlanNetPriorServiceCostCreditArisingDuringPeriodBeforeTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BusinessAcquisitionProFormaNetIncomeLoss">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CommitmentsAndContingencies2009">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_AcquisitionsAndDispositionsTextBlock">
    <definition>Description of a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities. This element may be used as a single block of text to encapsulate the entire disclosure (including data and tables) regarding business combinations, including leverage buyout transactions (as applicable). Also, includes acquisition pro forma information and financial information related to acquisitions and dispositions.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PrescriptionDrugSubsidyReceiptsYearTwo">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_Land">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BusinessAcquisitionContingentConsiderationAtFairValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanAmortizationOfNetPriorServiceCostCredit">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_CommitmentFeesCalculatedOnDailyAmountsOfAvailableUnusedCommitments">
    <definition>Commitment fees calculated on the daily amounts of the available unused commitments.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OperatingLeasesFutureMinimumPaymentsDue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriods">
    <definition>Description of the estimated period of time over which a non-employee director is required to wait in exchange for the share-based payment award to vest.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PrescriptionDrugSubsidyReceiptsYearOne">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncreaseDecreaseInPensionAndPostretirementObligations">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_OtherCurrentAssets">
    <definition>Other current assets.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_DefinedBenefitPlansTargetAllocationPercentageOfAssetsOtherRangeMaximum">
    <definition>Defined Benefit  Plans Target Allocation Percentage Of Assets Other Range Maximum.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AssetImpairmentCharges">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredRevenueCurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_PercentageOfMutualFundInTotalInvestmentInFixedIncomeInvestmentGrade">
    <definition>Percentage Of Mutual Fund In Total Investment In Fixed Income Investment Grade.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IntangibleAssetsDisclosureTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CashAndCashEquivalentsAtCarryingValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecrease">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_FairValueByBalanceSheetGroupingTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsInYearFive">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PaymentsToAcquireEquityMethodInvestments">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_LossOnSaleOfInterestInBusinessNetOfIncomeTaxes">
    <definition>Loss On Sale Of Interest In Business Net Of Income Taxes.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_EntityCurrentReportingStatus">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AmortizationOfFinancingCosts">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_EstimatedAmortizationExpenseTextBlock">
    <definition>Estimated amortization expense.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_DefinedBenefitPlansTargetAllocationPercentageOfAssetsDomesticEquitySecuritiesRangeMaximum">
    <definition>Defined Benefit Plans Target Allocation Percentage Of Assets Domestic Equity Securities Range Maximum.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeBenefits">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_EntityWellKnownSeasonedIssuer">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DebtDisclosureTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_CircumstanceOneForConversionOfConvertibleContingentDebt">
    <definition>Circumstance one for conversion of convertible contingent debt.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_GainLossOnSaleOfProductLine">
    <definition>The gains and losses included in earning resulting from the sale of a product line. This element refers to the gain (loss).</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PaymentsOfDividendsCommonStock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProvisionForLossOnContracts">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_OperatingLeasesFutureMinimumPaymentsDueNetOfSubleaseRentals">
    <definition>Operating leases future minimum payments due net of sublease rentals.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredFinanceCostsNoncurrentNet">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_SharePurchasesFundedThroughPayrollInValue">
    <definition>Share purchases funded through payroll deductions up to a maximum value.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BusinessAcquisitionProFormaRevenue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_AggregatePurchasePricePayableForAcquiredBusinesses">
    <definition>The additional purchase price of the acquired entity generally resulting from purchase price obligations resulting from contractual or contingent obligations recorded pursuant to the purchase agreement and subsequent to the completion of the acquisition.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ContractsInProcessTextBlock">
    <definition>Includes inventoried contract costs, unbilled receivables, and unliquidated progress payment amounts capitalized and descriptions for long-term contracts. Separately, includes Selling, General, and Administrative costs and Research and Development costs related to commercial businesses incurred and expensed during the period.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_LineOfCreditFacilityInterestRateDescription">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_AdditionalRentToBePaidForSimulatorSystemsAfterExpirationDate">
    <definition>Additional rent to be paid for simulator systems after expiration date.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_LongTermDebtCurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PropertyPlantAndEquipmentPolicyTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProductWarrantyAccrualPayments">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_SellingGeneralAndAdministrativeExpensesAndResearchAndDevelopmentExpenses">
    <definition>Selling, General and Administrative Expenses and Research and Development Expenses for the company's commercial businesses.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateProjectedBenefitObligation">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_SharePurchasesFundedThroughPayrollInPercentage">
    <definition>Share purchases funded through payroll deductions up to a maximum percentage.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_UnbilledContractsReceivable">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PensionAndOtherPostretirementBenefitExpense">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CommitmentsAndContingenciesDisclosureTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProductWarrantyAccrualClassifiedCurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredTaxAssetsLiabilitiesNetCurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_InventoriesTextBlock">
    <definition>This element represents the complete disclosure related to inventory. This may include, but is not limited to, the basis of stating inventory, the method of determining inventory cost, the major classes of inventory, and the nature of the cost elements included in inventory. If inventory is stated above cost, accrued net losses on firm purchase commitments for inventory and losses resulting from valuing inventory at the lower-of-cost-or-market may also be included. For LIFO inventory, may disclose the amount and basis for determining the excess of replacement or current cost over stated LIFO value and the effects of a LIFO quantities liquidation that impacts net income (excluding inventoried contract costs already included in CIP).</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_AmountsIncludedInAcquiredInventoriedContractCosts">
    <definition>Amounts included in acquired inventoried contract costs.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_LongTermDebt">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ShareBasedCompensationArrangementByShareBasedPaymentAwardsOptionsExercisableIntrinsicValue">
    <definition>Share Based Compensation Arrangement By Share Based Payment Awards Options Exercisable Intrinsic Value.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensation">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_FairValueMeasurementInputsDisclosureTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredTaxAssetsValuationAllowance">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_AssetsReclassifiedFromGovernmentServicesReportableSegmentToElectronicSystemsReportableSegmentAsResultOfBusinessUnitReAlignment">
    <definition>Assets reclassified from the Government Services reportable segment to the Electronic Systems reportable segment as a result of a business unit re-alignment.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PaymentsForRepurchaseOfCommonStock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_RepurchaseOfAdditionalOutstandingShares">
    <definition>Repurchase of additional outstanding shares.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_SettlementAmountUponConversionOfCodesOptionOneInCash">
    <definition>Settlement amount upon conversion of CODES option One in cash.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_SegmentReportingInformationDepreciationDepletionAndAmortizationExpense">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ForeignCurrencyTransactionsAndTranslationsPolicyTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ShareBasedCompensationArrangementsByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriodWeightedAverageGrantDateFairValue">
    <definition>The weighted average fair value as of grant dates pertaining to the number of shares under a share-based award plan, other than a stock option plan, that were settled during the reporting period due to a failure to satisfy vesting conditions pertaining to all award plans.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ContributionsToEmployeeSavingsPlansInCompanysCommonStock">
    <definition>Contributions To Employee Savings Plans In Companys Common Stock.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_PreJudgmentInterestForDamagesMaximum">
    <definition>The pre-judgment interest maximum sought.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_OutstandingSeniorSubordinatedNoteTermsTextBlock">
    <definition>Outstanding Senior Subordinated Note Terms Text Block.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_Inventories">
    <definition>Carrying amount (lower of cost or market) as of the balance sheet date of inventories less all valuation and other allowances. Excludes noncurrent inventory balances (expected to remain on hand past one year or one operating cycle, if longer). Excludes inventoried contract costs already included in CIP.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPeriodIncreaseDecrease">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DerivativeFairValueOfDerivativeAsset">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ChangeInInventories">
    <definition>The net change during the reporting period in the aggregate value of inventory held by the reporting entity, associated with underlying transactions that are classified as operating activities. Excludes inventoried contract costs already included in CIP.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_IncomeBeforeIncomeTaxesTextBlock">
    <definition>Income before income taxes Text Block.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_GoodwillAcquiredDuringPeriod">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_FiniteLivedIntangibleAssetsUsefulLifeMinimum">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProfitLoss">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_InventoryPolicyTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_NetCashProvidedByUsedInInvestingActivities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_DefinedBenefitPlansTargetAllocationPercentageOfAssetsFixedIncomeSecuritiesRangeMaximum">
    <definition>Defined Benefit Plans Target Allocation Percentage Of Assets Fixed Income Securities Range Maximum.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CommonStockSharesIssued">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_LongTermDebtNoncurrentSubtotal">
    <definition>Long Term Debt Noncurrent Subtotal.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_FairMarketValueOfSimulatorSystemsMaximum">
    <definition>Fair market value of simulator systems, Minimum.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_QuarterlyFinancialInformationTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_MinorityInterestDecreaseFromRedemptions">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PrescriptionDrugSubsidyReceiptsYearFive">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ShareBasedCompensationArrangementByShareBasedPaymentAwardsOptionsOutstandingWeightedAverageRemainingContractualTermEndingBalance">
    <definition>Share Based Compensation Arrangement By Share Based Payment Awards Options Outstanding Weighted Average Remaining Contractual Term Ending Balance.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncomeTaxExpenseBenefit">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_LiabilitiesAndStockholdersEquity">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_GainsLossesOnExtinguishmentOfDebt">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_InventoriesAtLowerOfCostOrMarketTextBlock">
    <definition>Inventories At Lower Of Cost Or Market.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProceedsFromDivestitureOfBusinessesAndInterestsInAffiliates">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_UnliquidatedProgressPaymentsForInventoriedContractCosts">
    <definition>unliquidated progress payments for Inventoried contract costs.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_NumberOfBusinessesAcquired">
    <definition>Number of businesses acquired.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_CashFlowSupplementalDisclosuresTablesTextBlock">
    <definition>Supplemental Cash Flow Information.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_SegmentReportingInformationAssets">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_FairValueAssetsMeasuredOnRecurringBasisTotalAssets">
    <definition>Fair Value, Assets Measured on Recurring Basis, Total assets.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_TotalRecognizedInNetPeriodicBenefitCostAndOtherComprehensiveIncomeBeforeTax">
    <definition>Total Recognized In Net Periodic Benefit Cost And Other Comprehensive Income Before Tax.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_AblilityToIncurAdditionalIndebtednessUnderFixedChargeCoverageRatioTest">
    <definition>Ablility to incur additional indebtedness under the fixed charge coverage ratio test.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProductWarrantyAccrualCurrencyTranslationIncreaseDecrease">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_AllowableRangeForEachMajorCategoryOfPlansAssetsAndWeightedAverageAssetAllocationsByAssetCategoryTextBlock">
    <definition>Allowable range for each major category of the plans assets and weighted-average asset allocations by asset category Text Block.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriod">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CostOfServices">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_PercentageOfUnbilledContractReceivablesBilledAndCollectedWithinOneYear">
    <definition>Percentage of unbilled contract receivables billed and collected within one year.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_NotionalAmountOfForeignCurrencyDerivatives">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_NetCashProvidedByUsedInFinancingActivities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_SellingGeneralAndAdministrativeExpenses">
    <definition>The aggregate total costs of selling the company's commerical businesses products and services, as well as all other general and administrative expenses not included in inventoried contract costs. Direct selling expenses (for example, credit and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_SeniorSubordinatedNotesEstimatedFairValue">
    <definition>Including the current and noncurrent portions, fair value as of the balance sheet date of subordinated debt (with initial maturities beyond one year or beyond the operating cycle if longer). Subordinated debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_NumberOfCommonSharesRepurchased">
    <definition>Number of common shares  repurchased.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_DefinedBenefitPlansTargetAllocationPercentageOfAssetsDomesticEquitySecuritiesRangeMinimum">
    <definition>Defined Benefit Plans Target Allocation Percentage Of Assets Domestic Equity Securities Range Minimum.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_NetCarryingAmountOfLiabilityComponent">
    <definition>Net carrying amount of liability component.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_DefinedBenefitPlansTargetAllocationPercentageOfAssetsInternationalEquitySecuritiesRangeMinimum">
    <definition>Defined Benefit Plans Target Allocation Percentage Of Assets International Equity Securities Range Minimum.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_PercentageAmountForGettingRightToReceiveContingentInterestPayments">
    <definition>Percentage amount for getting right to receive contingent interest payments.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherAssetsCurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AmortizationOfDebtDiscountPremium">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOnVestingDateTotalFairMarketValue">
    <definition>The fair market value as of the vesting date pertaining to the total number of performance units earned under a share-based award plan, other than a stock option plan, that were achieved during the performance period.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProceedsFromIssuanceOfSubordinatedLongTermDebt">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DiscontinuedOperationTaxEffectOfIncomeLossFromDisposalOfDiscontinuedOperation">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProceedsFromIncomeTaxRefunds">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanInterestCost">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_FiniteLivedIntangibleAssetsUsefulLifeMaximum">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardExpirationDating">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_MinimumAggregatePrincipalAmountOfSeniorSubordinatedNotesAcceleratedToTriggerCrossDefaultProvisions">
    <definition>Minimum aggregate principal amount of senior subordinated notes accelerated to trigger cross default provisions.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_EquityInNetIncomeOfConsolidatedSubsidiaries">
    <definition>Equity in net income of consolidated subsidiaries.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CommitmentsAndContingenciesPolicyTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_RemainingValueUnderShareRepurchaseProgram">
    <definition>Remaining Value Under Share Repurchase Program.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_OtherLongTermLiabilities">
    <definition>Other long-term liabilities.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_WorkersCompensationLiabilityCurrentAndNoncurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredTaxAssetsOther">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_GainOnSaleOfProductLineNetOfIncomeTaxes">
    <definition>Gain on Sale of Product Line, Net of Income Taxes.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_SalesReclassifiedFromGovernmentServicesReportableSegmentToElectronicSystemsReportableSegmentAsResultOfBusinessUnitReAlignment">
    <definition>Sales reclassified from Government Services reportable segment to Electronic Systems reportable segment as a result of a business unit re-alignment.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_PreJudgmentInterestForDamagesMinimum">
    <definition>The pre-judgment interest minimum sought.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_DividendsToParent">
    <definition>Dividends To Parent.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_OtherCurrentLiabilitiesAndOtherLiabilitiesTextBlock">
    <definition>Other current liabilites includes accruals for pending and threatened litigation, accrued product warranty costs, accrued interest, estimated costs in excess of estimated contract value to complete contracts in process in a loss position, deferred revenues, aggregate purchase price payable for acquired businesses and other. Other liabilities includes non-current income taxes payable, deferred compensation, accrued workers compensation, unfavorable lease obligations, non-current portion of net deferred gains from terminated interest rate swap agreements, notes payable and capital lease obligations, accrued product warranty costs, and other non-current liabilities.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_DefinedBenefitPlanInternationalEquitySecurities">
    <definition>The percentage of the fair value of international equity to the fair value of total plan assets held as of the measurement date.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_StatementsOfOperationsTextBlock">
    <definition>Condensed Combining Statements of Operations.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AccruedLiabilitiesCurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ApproximateNumberOfEmployees">
    <definition>Approximate number of employees.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_MaximumPayoutRange">
    <definition>Maximum payout range for performance units based on pre-determined performance goals established by the compensation committee.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_EmployeeRelatedLiabilitiesCurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_MaximumAmountOfSupplementalRentPayment">
    <definition>Maximum amount of supplemental rent payment.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_WeightedAverageAssumptionsUsedToDetermineBenefitObligationsTextBlock">
    <definition>Weighted average assumptions used to determine benefit obligations Text Block.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardTermsOfAward">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_EmployeeServiceShareBasedCompensationUnrecognizedCompensationCostsOnNonvestedAwardsAfterTax">
    <definition>As of the latest balance-sheet date presented, the total compensation cost related to outstanding, nonvested share-based compensation awards not yet recognized (will be charged against earnings as services are performed or other vesting criteria are met), after income taxes.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_IndependentResearchAndDevelopmentAndBidAndProposalCostsIncludedInInventoriedContractCosts">
    <definition>Independent research and development and bid and proposal costs included in inventoried contract costs.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncomeTaxDisclosureTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_SellingGeneralAndAdministrativeExpensesAndResearchAndDevelopmentExpensesTextBlock">
    <definition>Selling, General and Administrative Expenses and Research and Development Expenses.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ForeignCurrencyCashFlowHedgeGainLossToBeReclassifiedDuringNext12Months">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_FairValueDisclosuresTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CompensationRelatedCostsPolicyTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_PensionPlansWithAboInExcessOfFairValueOfPlanAssetsTextBlock">
    <definition>Pension plans with an ABO in excess of fair value of plan assets Text Block.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredTaxAssetsOperatingLossCarryforwards">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_MaximumRedemptionOrMaturityPeriodAfterMaturityDateOfExistingNotes">
    <definition>Maximum redemption or maturity period after maturity date of existing notes.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssets">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_NonCashImpairmentChargeIncludedInDilutedEarningPerShare">
    <definition>Non cash impairment charge included in diluted EPS.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_GeneralAndAdministrativeIndependentResearchAndDevelopmentAndBidAndProposalCostsIncludedInInventoriedContractCostsAtBeginningOfPeriod">
    <definition>General &amp; Administrative, Independent Research &amp; Development and Bid &amp; Proposal Costs Included in Inventoried Contract costs at beginning of period.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_MaximumDaysToCureDefaultsTriggeringCrossDefaultProvisions">
    <definition>Maximum days to cure defaults triggering cross default provisions.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherSundryLiabilitiesCurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredTaxAssetsNet">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PrescriptionDrugSubsidyReceiptsFiveFiscalYearsThereafter">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ShareBasedCompensationArrangementByShareBasedPaymentAwardsOptionsForfeituresInPeriodWeightedAverageExercisePrice">
    <definition>Share Based Compensation Arrangement By ShareBased Payment Awards Options Forfeitures In Period Weighted Average Exercise Price.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_AllocatedShareBasedCompensationExpenseAfterIncomeTax">
    <definition>Represents the expense recognized during the period arising from share-based compensation arrangements (for example, shares of stock, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees, after income taxes.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_PercentageOfBankDebtGuaranteedToFinanceActivities">
    <definition>Percentage of bank debt guaranteed to finance the activities.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_DocumentFiscalPeriodFocus">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_MinorityInterestIncreaseFromStockIssuance">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_SegmentReportingDisclosureTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_FutureAmortizationExpenseYearFive">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_CompanysNonvestedRestrictedStockUnitAwardsAndChangesTextBlock">
    <definition>Companys Nonvested Restricted Stock Unit Awards And Changes Text Block.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_EffectiveIncomeTaxRateReconciliationManufacturingBenefits">
    <definition>The sum of the differences between the effective income tax rate and domestic federal statutory income tax rate attributable to all manufacturing benefits.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_EffectiveIncomeTaxRateContinuingOperations">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_PercentageOfIncurredCostsBilledMinimum">
    <definition>Percentage of incurred costs billed, minimum.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OperatingLossCarryforwards">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_GoodwillTranslationAndPurchaseAccountingAdjustments">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_RepaymentsOfNotesPayable">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_RevenueRecognitionPolicyTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_AmortizationExpenseTextBlock">
    <definition>Amortization expense.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_StockholdersEquityOtherShares">
    <definition>Stockholders equity other.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_AmountsExpectedToBeAmortizedFromAccumulatedOtherComprehensiveLossIncomeAndRecognizedAsComponentsOfNetPeriodicBenefitCostsTextBlock">
    <definition>Amounts expected to be amortized from accumulated other comprehensive (loss) income and recognized as components of net periodic benefit costs Text Block.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_EarningsPerShareBasic">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DividendsCommonStockCash">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_NumberOfTradingDaysEndingOnSecondTradingDayPrecedingFirstDayOfApplicableSixMonthInterestPeriod">
    <definition>Number of trading days ending on the second trading day preceding the first day of the applicable six-month interest period.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PropertyPlantAndEquipmentGross">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncreaseDecreaseInEmployeeRelatedLiabilities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_SalesRevenueServicesNet">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_MaximumConsolidatedLeverageRatioUnderRevolvingCreditFacilityCovenants">
    <definition>Maximum consolidated leverage ratio under revolving credit facility covenants.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_PeriodRepresentingRedemptionPriceOfPrincipalStartingOnFirstAllowableDateOfRedemption">
    <definition>Period representing redemption price of principal starting on the first allowable date of redemption.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_EntityRegistrantName">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_RedemptionPriceDeclineOfPrincipal">
    <definition>Redemption Price Decline Of Principal.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_StockIssuedDuringPeriodSharesEmployeeStockOwnershipPlan">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_WeightedAverageAssumptionsInValuationModelTextBlock">
    <definition>Weighted average assumptions in valuation model.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_UnrecognizedTaxBenefits">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_RepaymentsOfLinesOfCredit">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeReclassificationOfDefinedBenefitPlansNetGainLossRecognizedInNetPeriodicBenefitCostNetOfTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_SignificantAccountingPoliciesTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredIncomeTaxExpenseBenefit">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DebtInstrumentInterestRateEffectivePercentage">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProductWarrantyAccrualNoncurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_TaxCreditCarryforwardAmount">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_MinorityInterest">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_TaxEffectOnAmortizationOfPensionAndPostretirementBenefitPlansNetLossAndPriorServiceCost">
    <definition>Tax effect on the amortization of pension and postretirement benefit plans net loss and prior service cost.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_MinimumAggregateAmountOfSeniorNotesAcceleratedToTriggerCrossDefaultProvisions">
    <definition>Minimum aggregate amount of senior notes accelerated to trigger cross default provisions.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_FinancialInformationOfParentCompanyAndItsSubsidiariesTextBlock">
    <definition>Disclosure of the equity of L-3 Communications and description of the terms of certain debt and the structure of the guarantees of that specific debt. Includes certain condensed combining financial information at different legal entity levels, including aggregating the financial information by Guarantor Subsidiaries and Non-Guarantor Subsidiaries.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DebtInstrumentPrincipalOutstanding">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_TermForOperatingLeaseAgreements">
    <definition>Term for operating lease agreements.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_MinimumFixedChargeCoverageRatioUnderSeniorSubordinatedNotesIndenturesCovenants">
    <definition>Minimum fixed charge coverage ratio under senior subordinated notes indentures covenants.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_CurrentFiscalYearEndDate">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ExtinguishmentOfDebtGainLossNetOfTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateAccumulatedBenefitObligation">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_OtherInvestingActivities">
    <definition>Other investing activities.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanFundedStatusOfPlan">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_FairValueOfCompanysPensionPlansAndPostretirementBenefitPlansAssetsTextBlock">
    <definition>Fair value of the Company's pension plans' and postretirement benefit plans' assets Text Block.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_CashRedemptionPrice">
    <definition>Cash redemption price.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_EmployeeServiceShareBasedCompensationUnrecognizedCompensationCostsOnNonvestedAwards">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_FutureAmortizationExpenseYearOne">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ContractCostsIncurred">
    <definition>Contract costs incurred.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_InventoriedContractCostsGross">
    <definition>Inventoried contract costs, gross.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_GainOnSaleOfInterestInBuisnessBeforeIncomeTaxes">
    <definition>Gain on Sale of Interest in Buisness, Before Income Taxes.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_CurtailmentsSettlementsAndSpecialTerminationBenefits">
    <definition>Curtailments, settlements and special termination benefits.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_CertainTaxBenefitsAcquired">
    <definition>Certain tax benefits acquired.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_DocumentPeriodEndDate">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_FairValueAssetsMeasuredOnRecurringBasisDerivativeFinancialInstrumentsAssets">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DebtInstrumentCallDateEarliest">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_PrincipalAmountOfConvertibleDebtSold">
    <definition>Principal amount of convertible debt sold.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DebtInstrumentInterestRateStatedPercentage">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_VariableInterestEntityPolicyTextBlock">
    <definition>Revised standard for the accounting for variable interest entities.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DerivativeLiabilityDesignatedAsHedgingInstrumentFairValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ScheduleOfNewAccountingPronouncementsAndChangesInAccountingPrinciplesTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_GeneralAndAdministrativeIndependentResearchAndDevelopmentAndBidAndProposalCostsIncludedInInventoriedContractCostsTextBlock">
    <definition>General and administrative independent research and development and bid and proposal costs included in inventoried contract costs.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_DeferredTaxLiabilitiesIncomeRecognitionOnContractsInProcess">
    <definition>The amount as of the balance sheet date of the estimated future tax effects arising from contracts in process that is included in accounting income in conformity with generally accepted accounting principles but excluded from tax-basis income, which will increase future taxable income when such income is recognized for tax purposes.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DerivativesPolicyTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_DebtRetirementCharge">
    <definition>The aggregate costs related to the retirement of debt, including call premium and the write-off of deferred debt issuance costs.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanEstimatedFutureEmployerContributionsInNextFiscalYear">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ScheduleOfRevenueFromExternalCustomersAttributedToDomesticCountryAndForeignCountriesByGeographicAreaTextBlock">
    <definition>Schedule Of Revenue From External Customers Attributed To Domestic Country And Foreign Countries by Geographic Area Text Block.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BuildingsAndImprovementsGross">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccruedAfterTax">
    <definition>This element represents the amount of interest expense accrued, after tax, as of the date of the statement of financial position for an underpayment of income taxes computed by applying the applicable statutory rate of interest to the difference between a tax position recognized for financial reporting purposes and the amount previously taken or expected to be taken in a tax return of the entity.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_DeferredTaxAssetsPensionAndPostretirementBenefits">
    <definition>The tax effect as of the balance sheet date of the amount of estimated future tax deductions arising from pension and postretirement benefits, which can only be deducted for tax purposes when actual costs are incurred, and which can only be realized if sufficient tax-basis income is generated in future periods to enable the deduction to be taken.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_UltimateRedemptionPricePercentageOfPrincipal">
    <definition>Ultimate redemption price percentage of principal.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OperatingLeasesOfLesseeDisclosureTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DebtInstrumentConvertibleCarryingAmountOfTheEquityComponent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_EquityNoteDisclosureTextBlock">
    <definition>Disclosures include the authorization and status of L-3 Holdings share repurchase program, the remaining dollar value of the repurchase program and the shares repurchased subsequent to year end through the date of the 10-K filing.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_AmountsChargedToCostOfSales">
    <definition>Amounts charged to cost of sales.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_RevolvingCreditFacilityPermitsToWhollyOwnedSubsidiary">
    <definition>Revolving credit facility permits to wholly owned subsidiary.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_MaximumAmountOfPurchasePriceAdjustmentPostAcquisition">
    <definition>Maximum amount of purchase price adjustment post-acquisition.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredTaxAssetsLiabilitiesNetNoncurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BusinessAcquisitionCostOfAcquiredEntityPurchasePrice">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_OtherChangesInPlanAssetsAndBenefitObligationsRecognizedInOtherComprehensiveIncomeTextBlock">
    <definition>Other changes in plan assets and benefit obligations recognized in other comprehensive income Text Block.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_InventoryForLongTermContractsOrPrograms">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_AdvancePaymentsAndBillingsInExcessOfCostsIncurred">
    <definition>The current portion, due within one year or one operating cycle, if longer, of aggregate prepayments received from customers for goods or services to be provided in the future, as well as the current portion of money or property received from customers that are to be returned upon satisfactory contract completion or as partial prepayment for goods or services to be provided in the future and also includes liabilities due to billings on long term contracts that exceed the income recorded under the percentage of completion contract accounting method, or that exceed the accumulated costs under the completed contract accounting method.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CurrentFederalTaxExpenseBenefit">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_TreasuryStockShares">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_MachineryEquipmentFurnitureAndFixturesGross">
    <definition>Carrying amount as of the balance sheet date of long-lived, depreciable asset used in production process to produce goods and services, or commonly used in offices and stores (examples include desks, chairs, and store fixtures).</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_TreasuryStockValueAcquiredCostMethod">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProceedsFromStockOptionsExercised">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_NetIncomeLossAttributableToNoncontrollingInterest">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpense">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CostOfGoodsSold">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_EffectiveIncomeTaxRateReconciliationTaxCredits">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_FutureAmortizationExpenseYearFour">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecrease">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_RedemptionPricePercentageOfPrincipal">
    <definition>Redemption Price Percentage of Principal.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ShareBasedCompensationArrangementByShareBasedPaymentAwardsOptionsExercisesInPeriodWeightedAverageExercisePrice">
    <definition>Share Based Compensation Arrangement By Share Based Payment Awards Options Exercises In Period Weighted Average Exercise Price.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PropertyPlantAndEquipmentTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_GeneralAndAdministrativeIndependentResearchAndDevelopmentAndBidAndProposalCostsIncludedInInventoriedContractCostsAtEndOfPeriodCostsIncludedInInventoriedContractCostsAtEndOfPeriod">
    <definition>General &amp; Administrative, Independent Research &amp; Development and Bid &amp; Proposal Costs Included in Inventoried Contract costs at end of period.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CurrentIncomeTaxExpenseBenefit">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_AgeOfRetirementEligibleEmployees">
    <definition>Age of retirement eligible employees with at least five years of service.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherAssetsNoncurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_SeniorNotes">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_IncomeLossFromContinuingOperationsBeforeIncomeTaxes">
    <definition>Income from continuing operations before income taxes.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AssetsCurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_NetSalesToPrincipalCustomersTextBlock">
    <definition>Net Sales To Principal Customers Text Block.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesPlanAssets">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProceedsFromContributionsFromParent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CommonStockDividendsPerShareCashPaid">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CommonStockValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsInFiveFiscalYearsThereafter">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanOtherPlanAssets">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_PercentageOfAverageTradingPriceOfOneThousandDollarsInPrincipalAmountOfCodesForContingentInterestPayable">
    <definition>Percentage of average trading price of one thousand dollars in principal amount of CODES for contingent interest payable.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_DefinedBenefitPlanFixedIncomeSecurities">
    <definition>The percentage of the fair value of fixed income securities to the fair value of total plan assets held as of the measurement date.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_RemainingCodesThatHaveBeenReclassifiedAsLongTermDebt">
    <definition>Remaining CODES that have been reclassified as long-term debt.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PaymentsToAcquireAdditionalInterestInSubsidiaries">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_RepurchasePriceOfNotesAboveInterest">
    <definition>Repurchase price of notes above interest.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ComponentsOfDebtAndReconciliationToCarryingAmountTextBlock">
    <definition>Components Of Debt And Reconciliation To Carrying Amount Text Block.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_InventoryWorkInProcessNetOfReserves">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DebtInstrumentConvertibleConversionPrice">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ResearchAndDevelopmentPolicyTextBlock">
    <definition>Research and Development Policy.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OperatingLeasesFutureMinimumPaymentsDueFutureMinimumSubleaseRentals">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BusinessAcquisitionPurchasePriceAllocationCurrentAssetsCashAndCashEquivalents">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_CurrentConvertibleCommonStockPrice">
    <definition>Current convertible common stock price, which is 120% of the current conversion price. Used for calculating the conversion of its convertible debt as contained in the provisions of the Convertible Contingent Debt Securities, which is used under certain conditions to settle the principal in cash based on a 120% of the conversion price, and if the settlement amount exceeds the principal amount, the excess will be settled in cash or stock or a combination thereof, at the Company's option.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AllocatedShareBasedCompensationExpense">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_NetWorkingCapitalAdjustment">
    <definition>Net working capital adjustment.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_StatementsOfEquityTextBlock">
    <definition>Condensed Combining Statements of Equity.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProductWarrantyAccrualPreexistingIncreaseDecrease">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ScheduleOfDerivativeInstrumentsTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AcquiredFiniteLivedIntangibleAssetWeightedAverageUsefulLife">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_CompanysPerformanceUnitAwardsBasedOnExpectedPerformanceTextBlock">
    <definition>Companys performance unit awards based on expected performance Text Block.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ComponentsOfCurrentAndDeferredPortionsOfProvisionForIncomeTaxesTextBlock">
    <definition>Components of the current and deferred portions of the provision for income taxes.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_GoodwillByReportableSegmentTextBlock">
    <definition>Goodwill by reportable segment.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CashFlowSupplementalDisclosuresTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_CircumstanceTwoForConversionOfConvertibleContingentDebt">
    <definition>Circumstance two for conversion of convertible contingent debt.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OperatingLeasesRentExpenseSubleaseRentals">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_InterestExpenseDebt">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_Revenues">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ShareBasedCompensationArrangementByShareBasedPaymentAwardsOptionsOutstandingWeightedAverageRemainingContractualTermBeginningBalance">
    <definition>Share Based Compensation Arrangement By Share Based Payment Awards Options Outstanding Weighted Average Remaining Contractual Term Beginning Balance.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_StockIssuedDuringPeriodValueEmployeeStockOwnershipPlan">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointIncreaseOnServiceAndInterestCostComponents">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_MaximumNumberOfSharesOfParentCommonStockMayBeIssuedPursuantToIncentiveStockOptionAwards">
    <definition>Maximum number of shares of parent common stock that may be issued pursuant to incentive stock option awards.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_LetterOfCreditFeesForFinancialLettersOfCredit">
    <definition>Letter of credit fees for financial letters of credit.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsInYearFour">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_GoodwillWrittenOffRelatedToSaleOfBusinessUnit">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanBenefitObligation">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CommonStockParOrStatedValuePerShare">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_PurchasePriceOfPropertyOnOrBeforeExpirationDate">
    <definition>Purchase price of property on or before expiration date.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_InventoryFinishedGoodsNetOfReserves">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeAmortizationOfDefinedBenefitPlanNetPriorServiceCostCreditRecognizedInNetPeriodicBenefitCostBeforeTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_AdvancePaymentsBillingsInExcessCostsIncurred">
    <definition>The current portion, due within one year or one operating cycle, if longer, of aggregate prepayments received from customers for goods or services to be provided in the future, as well as the current portion of money or property received from customers that are to be returned upon satisfactory contract completion or as partial prepayment for goods or services to be provided in the future and also includes liabilities due to billings on long term contracts that exceed the income recorded under the percentage of completion contract accounting method, or that exceed the accumulated costs under the completed contract accounting method.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_Depreciation">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_DefinedBenefitPlansTargetAllocationPercentageOfAssetsFixedIncomeSecuritiesRangeMinimum">
    <definition>Defined Benefit Plans Target Allocation Percentage Of Assets Fixed Income Securities Range Minimum.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_CircumstanceThreeForConversionOfConvertibleContingentDebt">
    <definition>Circumstance three for conversion of convertible contingent debt.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_CircumstanceSevenForConversionOfConvertibleContingentDebt">
    <definition>Circumstance seven for conversion of convertible contingent debt.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_EstimatedFutureBenefitPaymentsTextBlock">
    <definition>Estimated Future Benefit Payments Text Block.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_AssumedPurchaseOfCommonSharesForTreasury">
    <definition>Assumed purchase of common shares for treasury.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_PurchasePriceForOwnership">
    <definition>Purchase price for ownership in METI.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_OtherCurrentLiabilitiesTextBlock">
    <definition>Other current liabilities.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ComprehensiveIncomeNoteTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_GainOnSaleOfProductLineBeforeIncomeTaxes">
    <definition>Gain on Sale of Product Line, Before Income Taxes.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ChangesInAccumulatedOtherComprehensiveLossIncomeBalancesNetOfRelatedTaxEffectsTextBlock">
    <definition>Changes in the accumulated other comprehensive (loss) income balances, net of related tax effects.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_MinimumAggregateAmountOfIndebtnessSwapContractsOrUaranteesToTriggerCrossDefaultProvisions">
    <definition>Minimum aggregate amount of indebtness, swap contracts or uarantees to trigger cross default provisions.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DueToRelatedPartiesNoncurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ChangesInBenefitObligationsPlanAssetsAndFundedStatusAndAggregateBalanceSheetImpactTextBlock">
    <definition>Changes in benefit obligations plan assets and funded status and aggregate balance sheet impact.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AccountsReceivableNetCurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CurrentStateAndLocalTaxExpenseBenefit">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_MaximumNumberOfSharesOfParentCommonStockMayBeIssuedPursuantToAllAwardsGrantedToIndividual">
    <definition>Maximum number of shares of parent common stock that may be issued pursuant to all awards granted during a calendar year to an individual.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_NetIncomeAllocableToParticipatingSecurities">
    <definition>Net income allocable to participating securities.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanContributionsByEmployer">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_CircumstanceFiveForConversionOfConvertibleContingentDebt">
    <definition>Circumstance five for conversion of convertible contingent debt.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_LeaseholdImprovementsGross">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_DefinedBenefitPlansTargetAllocationPercentageOfAssetsOtherRangeMinimum">
    <definition>Defined Benefit Plans Target Allocation Percentage Of Assets Other Range Minimum.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProceedsFromStockPlans">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_MaximumPercentageOfTotalOutstandingSharesOfCommonStockIssuedInRespectToPerformanceBasedAwards">
    <definition>Maximum percentage of total outstanding shares of common stock that may be issued to any participant over the life of the 2008 Long Term Performance Plan in respect to performance based awards.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_EntityPublicFloat">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ShareBasedCompensationArrangementByShareBasedPaymentAwardAveragePricePerShare">
    <definition>Share Based Compensation Arrangement By Share Based Payment Award Average Price Per Share.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_RepaymentsOfSubordinatedDebt">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_NetIncomeLoss">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_CompanyMatchingContributionsInParentCommonStockAndCash">
    <definition>Company Matching Contributions In Parent Common Stock And Cash.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_EntityVoluntaryFilers">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BusinessAcquisitionProFormaInformationTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_FairMarketValueOfSimulatorSystemsMinimum">
    <definition>Fair market value of simulator systems, Minimum.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_LitigationReserveCurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CurrentForeignTaxExpenseBenefit">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BusinessAcquisitionContingentConsiderationPotentialCashPayment">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DebtPolicyTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillAmount">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_TreasuryStockAcquiredAverageCostPerShare">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PaymentsOfDebtIssuanceCosts">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ContractsInProcess">
    <definition>Net unbilled contract receivables and net inventoried contract costs.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProductWarrantyAccrualAdditionsFromBusinessAcquisition">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ShareBasedCompensationArrangementByShareBasedPaymentAwardsOptionsExercisableWeightedAverageRemainingContractualTerm">
    <definition>Share Based Compensation Arrangement By ShareBased Payment Awards Options Exercisable Weighted Average Remaining Contractual Term.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IntangibleAssetsNetExcludingGoodwill">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_NumberOfEmployeeTerminated">
    <definition>Number of employee terminated.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProceedsFromNotesPayable">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_ExpectedStateNetOperatingLossesToBeUtilized">
    <definition>Expected state net operating losses to be utilized based on generating sufficient taxable income.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_SettlementAmountUponConversionOfCodesOptionTwoInCombinationOfCashAndCommonStockConditionTwo">
    <definition>Settlement amount upon conversion of the CODES option two in  a combination of cash and common stock condition two.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_LongTermNotesPayable">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_SubordinatedDebt">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AccountsPayableCurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_NumberOfReportableSegments">
    <definition>Number of reportable segments.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_PercentageOfPooledBondFundsInTotalInvestmentInFixedIncomeInvestmentGrade">
    <definition>Percentage Of Pooled Bond Funds In Total Investment In Fixed Income Investment Grade.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="lll_OtherAssetNoncurrent">
    <definition>Other Asset.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_EmployeeServiceShareBasedCompensationUnrecognizedCompensationCostsOnNonvestedAwardsWeightedAveragePeriodOfRecognition">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncreaseDecreaseInAccruedLiabilities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanRealEstate">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
</DefinitionAndReference>
