Additional amount of shares authorized to be repurchased.

Name:	lll_AdditionalAmountOfSharesAuthorizedToBeRepurchased
Namespace Prefix:	lll
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Equity Textuals.

+ Details

Name:	lll_EquityTextualsAbstract
Namespace Prefix:	lll
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of common shares repurchased.

+ Details

Name:	lll_NumberOfCommonSharesRepurchased
Namespace Prefix:	lll
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Remaining value under share repurchase program.

+ Details

Name:	lll_RemainingValueUnderShareRepurchaseProgram
Namespace Prefix:	lll
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Repurchase of additional outstanding shares.

+ Details

Name:	lll_RepurchaseOfAdditionalOutstandingShares
Namespace Prefix:	lll
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Aggregate dividends declared 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_CommonStockDividendsPerShareDeclared
Namespace Prefix:	us-gaap
Data Type:	us-types:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Total cost of shares repurchased divided by the total number of shares repurchased.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 43
-Chapter 1
-Section B
-Paragraph 7
-Subparagraph b

+ Details

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

- Definition

Cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Principles Board Opinion (APB)
-Number 12
-Paragraph 10

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Article 3

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 43
-Chapter 1
-Section B
-Paragraph 7
-Subparagraph b

+ Details

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

Equity (Details) (USD $)	1 Months Ended	6 Months Ended
Equity (Details) (USD $)	Aug. 03, 2011	Jul. 12, 2011	Jul. 01, 2011	Jun. 25, 2010	Apr. 26, 2011	Jul. 14, 2010
Equity (Textuals)
Repurchase of additional outstanding shares			$ 1,000,000,000
Remaining value under share repurchase program						164,000,000
Additional amount of shares authorized to be repurchased					1,500,000,000
Number of common shares repurchased	587,992
Average price per share of repurchased shares	$ 83.09
Treasury stock purchased	$ 49,000,000		$ (429,000,000)	$ (254,000,000)
Cash dividend, declared per share		$ 0.45