Compensatory damages awarded by trial court.

No definition available.

Name:	lll_CompensatoryDamagesAwardedByTrialCourt
Namespace Prefix:	lll_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

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Namespace Prefix:	lll_
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Period Type:	duration

- Definition

Litigation settlement amount held in escrow account

+ References

No definition available.

+ Details

Name:	lll_LitigationSettlementAmountHeldInEscrowAccount
Namespace Prefix:	lll_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount recovered from insurance. These recoveries reduce costs and losses that are reported as a separate line item under operating expenses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.3)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of judgment or settlement awarded to (against) the entity in respect of litigation.

+ References

No definition available.

+ Details

Name:	us-gaap_LitigationSettlementAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of litigation expense, including but not limited to legal, forensic, accounting, and investigative fees.

+ References

No definition available.

+ Details

Name:	us-gaap_LitigationSettlementExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The number of claims settled and dismissed during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of claims settled.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The value (monetary amount) of the award the plaintiff seeks in the legal matter.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 9

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14557-108349

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Number of plaintiffs that have filed claims pertaining to a loss contingency.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
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Commitments and Contingencies - Additional Information (Detail) In Millions, unless otherwise specified	0 Months Ended					3 Months Ended				0 Months Ended
	Mar. 27, 2015 USD ($)	Feb. 10, 2015 USD ($) Plaintiff	Dec. 31, 2014 USD ($)	Sep. 28, 2012 Plaintiff	Apr. 23, 2007 Plaintiff	Mar. 27, 2015 USD ($)	Dec. 31, 2014 USD ($)	May 31, 2012 USD ($)	Mar. 09, 2010 USD ($)	Jul. 23, 2014 Property Damages [Member] EUR (€)	Jul. 23, 2014 Business Interruption [Member] EUR (€)
Contingencies And Commitments [Line Items]
Liability in anticipation of a settlement							$ 18us-gaap_LitigationSettlementExpense
Recoveries from insurance contracts	11us-gaap_InsuranceRecoveries		11us-gaap_InsuranceRecoveries
Number of plaintiffs re-filed their complaint against ACSS					30
Compensatory damages								48.0	6.7
Number of plaintiffs released their claims against ACSS				18
Number of plaintiffs settled their claims against ACSS		12
Aggregate expenses incurred by plaintiff		11us-gaap_LitigationSettlementAmount
Award amount paid by insurer into escrow account						11
Claims for estimated damages										€ 11	€ 35