1.0.0.3 false Unaudited Condensed Consolidated Balance Sheets (USD $) In Millions false 1 $ false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 false 2 $ false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 6 Current assets: 4 us-gaap_AssetsCurrentAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false No definition available. false 7 Cash and cash equivalents 5 us-gaap_CashAndCashEquivalentsAtCarryingValue us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 true true 1191000000 1191 false false 2 true true 867000000 867 false false No definition available. No authoritative reference available. false 8 Billed receivables, net of allowances, of $33 in 2009 and $26 in 2008 5 us-gaap_AccountsReceivableNetCurrent us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true 1270000000 1270 false false 2 false true 1226000000 1226 false false No definition available. No authoritative reference available. false 9 Contracts in process 5 lll_ContractsInProcess lll false debit instant monetary Inventoried contract costs, unbilled receivables, and unliquidated progress payments. false false false false false false false false false 1 false true 2398000000 2398 false false 2 false true 2267000000 2267 false false Inventoried contract costs, unbilled receivables, and unliquidated progress payments. No authoritative reference available. false 10 Inventories 5 lll_Inventories lll false debit instant monetary Carrying amount (lower of cost or market) as of the balance sheet date of inventories less all valuation and other... false false false false false false false false false 1 false true 258000000 258 false false 2 false true 259000000 259 false false 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. No authoritative reference available. false 11 Deferred income taxes 5 us-gaap_DeferredTaxAssetsNetCurrent us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true 169000000 169 false false 2 false true 211000000 211 false false No definition available. No authoritative reference available. false 12 Other current assets 5 us-gaap_OtherAssetsCurrent us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true 127000000 127 false false 2 false true 131000000 131 false false No definition available. No authoritative reference available. true 13 Total current assets 5 us-gaap_AssetsCurrent us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true 5413000000 5413 false false 2 false true 4961000000 4961 false false No definition available. No authoritative reference available. true 14 Property, plant and equipment, net 4 us-gaap_PropertyPlantAndEquipmentNet us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true 838000000 838 false false 2 false true 821000000 821 false false No definition available. No authoritative reference available. false 15 Goodwill 4 us-gaap_Goodwill us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true 8188000000 8188 false false 2 false true 8029000000 8029 false false No definition available. No authoritative reference available. false 16 Identifiable intangible assets 4 us-gaap_IntangibleAssetsNetExcludingGoodwill us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true 390000000 390 false false 2 false true 417000000 417 false false No definition available. No authoritative reference available. false 17 Deferred debt issue costs 4 us-gaap_DeferredFinanceCostsNoncurrentNet us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true 35000000 35 false false 2 false true 44000000 44 false false No definition available. No authoritative reference available. false 18 Other assets 4 us-gaap_OtherAssetsNoncurrent us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true 204000000 204 false false 2 false true 212000000 212 false false No definition available. No authoritative reference available. true 19 Total assets 4 us-gaap_Assets us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true 15068000000 15068 false false 2 false true 14484000000 14484 false false No definition available. No authoritative reference available. true 21 Current liabilities: 4 us-gaap_LiabilitiesCurrentAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false No definition available. false 22 Current portion of long-term debt 5 us-gaap_LongTermDebtCurrent us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 650000000 650 false false 2 false true 0 0 false false No definition available. No authoritative reference available. false 23 Accounts payable, trade 5 us-gaap_AccountsPayableCurrent us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 593000000 593 false false 2 false true 602000000 602 false false No definition available. No authoritative reference available. false 24 Accrued employment costs 5 us-gaap_EmployeeRelatedLiabilitiesCurrent us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 674000000 674 false false 2 false true 700000000 700 false false No definition available. No authoritative reference available. false 25 Accrued expenses 5 us-gaap_AccruedLiabilitiesCurrent us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 525000000 525 false false 2 false true 479000000 479 false false No definition available. No authoritative reference available. false 26 Advance payments and billings in excess of costs incurred 5 lll_AdvancePaymentsAndBillingsInExcessOfCostsIncurred lll false credit instant monetary The current portion, due within one year or one operating cycle, if longer, of aggregate prepayments received from customers... false false false false false false false false false 1 false true 499000000 499 false false 2 false true 530000000 530 false false 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. No authoritative reference available. false 27 Income taxes 5 us-gaap_AccruedIncomeTaxesCurrent us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 30000000 30 false false 2 false true 45000000 45 false false No definition available. No authoritative reference available. false 28 Other current liabilities 5 us-gaap_OtherLiabilitiesCurrent us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 336000000 336 false false 2 false true 351000000 351 false false No definition available. No authoritative reference available. true 29 Total current liabilities 5 us-gaap_LiabilitiesCurrent us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 3307000000 3307 false false 2 false true 2707000000 2707 false false No definition available. No authoritative reference available. true 30 Pension and postretirement benefits 4 us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 844000000 844 false false 2 false true 802000000 802 false false No definition available. No authoritative reference available. false 31 Deferred income taxes 4 us-gaap_DeferredTaxLiabilitiesNoncurrent us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 179000000 179 false false 2 false true 127000000 127 false false No definition available. No authoritative reference available. false 32 Other liabilities 4 us-gaap_OtherLiabilitiesNoncurrent us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 424000000 424 false false 2 false true 414000000 414 false false No definition available. No authoritative reference available. false 33 Long-term debt 4 us-gaap_LongTermDebtNoncurrent us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 3860000000 3860 false false 2 false true 4493000000 4493 false false No definition available. No authoritative reference available. true 34 Total liabilities 4 us-gaap_Liabilities us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 8614000000 8614 false false 2 false true 8543000000 8543 false false No definition available. No authoritative reference available. true 37 L-3 shareholders' equity: 5 lll_ShareholdersEquity lll false na duration string Shareholders equity. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false Shareholders equity. false 38 L-3 Communications Holdings, Inc.'s common stock: $.01 par value; 300,000,000 shares authorized, 116,136,178 shares outstanding at September 25, 2009 and 118,633,746 shares outstanding at December 31, 2008 (L-3 Communications Corporation's common stock: $.01 par value, 100 shares authorized, issued and outstanding) 6 us-gaap_CommonStockValue us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 4345000000 4345 false false 2 false true 4136000000 4136 false false No definition available. No authoritative reference available. false 39 L-3 Communications Holdings, Inc.'s treasury stock at cost, 19,633,649 shares at September 25, 2009 and 13,995,450 shares at December 31, 2008 6 us-gaap_TreasuryStockValue us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true -1715000000 -1715 false false 2 false true -1319000000 -1319 false false No definition available. No authoritative reference available. false 40 Retained earnings 6 us-gaap_RetainedEarningsAccumulatedDeficit us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 3922000000 3922 false false 2 false true 3373000000 3373 false false No definition available. No authoritative reference available. false 41 Accumulated other comprehensive loss 6 us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true -190000000 -190 false false 2 false true -332000000 -332 false false No definition available. No authoritative reference available. true 42 Total L-3 shareholders' equity 6 us-gaap_StockholdersEquity us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 6362000000 6362 false false 2 false true 5858000000 5858 false false No definition available. No authoritative reference available. false 43 Noncontrolling interests 6 us-gaap_MinorityInterest us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 92000000 92 false false 2 false true 83000000 83 false false No definition available. No authoritative reference available. true 44 Total equity 6 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 6454000000 6454 false false 2 false true 5941000000 5941 false false No definition available. No authoritative reference available. true 45 Total liabilities and equity 4 us-gaap_LiabilitiesAndStockholdersEquity us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 true true 15068000000 15068 false false 2 true true 14484000000 14484 false false No definition available. No authoritative reference available. true false 2 37 false Millions UnKnown UnKnown false true