Unaudited Condensed Consolidated Statements of Equity (Parenthetical) (USD $) In Millions, except Per Share data	6 Months Ended
Jul. 01, 2011	Jun. 25, 2010
Pension and postretirement benefit plans:
Income tax effect on amortization of net loss and prior service cost previously recognized	$ 10	$ 7
Income tax effect on unrealized gains (losses) on hedging instruments	(2)	2
Cash dividends paid on common stock, per share	$ 0.90	$ 0.80
Retained Earnings
Pension and postretirement benefit plans:
Cash dividends paid on common stock, per share	$ 0.90	$ 0.80
Accumulated Other Comprehensive (Loss) Income
Pension and postretirement benefit plans:
Income tax effect on amortization of net loss and prior service cost previously recognized	10	7
Income tax effect on unrealized gains (losses) on hedging instruments	$ (2)	$ 2

Tax effect on the amortization of pension and postretirement benefit plans net loss and prior service cost.

Name:	lll_TaxEffectOnAmortizationOfPensionAndPostretirementBenefitPlansNetLossAndPriorServiceCost
Namespace Prefix:	lll
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Aggregate dividends paid during the period for each share of common stock outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Article 3

+ Details

Name:	us-gaap_CommonStockDividendsPerShareCashPaid
Namespace Prefix:	us-gaap
Data Type:	us-types:perShareItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPeriodIncreaseDecreaseAbstract
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Tax effect on the change in accumulated gains and losses from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Includes an entity's share of an equity investee's increase (decrease) in deferred hedging gains or losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 38
-Subparagraph c(3)

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 130
-Paragraph 25

+ Details

Name:	us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration