L3 Inactive 10-Q29 Oct 132013 Q3 Quarterly reportFinancial data

Company Profile

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
Document and Entity Information	Sep. 27, 2013	Oct. 23, 2013
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	27-Sep-13
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q3
Trading Symbol	LLL
Entity Registrant Name	L 3 COMMUNICATIONS HOLDINGS INC
Entity Central Index Key	1056239
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		88,625,424

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Sep. 27, 2013	Dec. 31, 2012
In Millions, unless otherwise specified	Sep. 27, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$377	$349
Billed receivables, net of allowances of $26 in 2013 and $33 in 2012	1,084	968
Contracts in process	2,691	2,636
Inventories	420	363
Deferred income taxes	98	95
Other current assets	127	144
Total current assets	4,797	4,555
Property, plant and equipment, net	1,023	1,016
Goodwill	7,757	7,776
Identifiable intangible assets	286	314
Deferred debt issue costs	25	29
Other assets	187	151
Total assets	14,075	13,841
Current liabilities:
Accounts payable, trade	558	494
Accrued employment costs	585	551
Accrued expenses	414	462
Advance payments and billings in excess of costs incurred	557	668
Income taxes	6	21
Other current liabilities	383	395
Total current liabilities	2,503	2,591
Pension and postretirement benefits	1,343	1,360
Deferred income taxes	412	328
Other liabilities	357	390
Long-term debt	3,630	3,629
Total liabilities	8,245	8,298
Commitments and contingencies (see Note 17)
L-3 shareholders' equity:
L-3 Communications Holdings, Inc.'s common stock: $.01 par value; 300,000,000 shares authorized, 89,047,037 shares outstanding at September 27, 2013 and 90,433,743 shares outstanding at December 31, 2012 (L-3 Communications Corporation's common stock: $.01 par value, 100 shares authorized, issued and outstanding)	5,555	5,314
L-3 Communications Holdings, Inc.'s treasury stock (at cost), 62,194,678 shares at September 27, 2013 and 57,418,645 shares at December 31, 2012	-4,892	-4,488
Retained earnings	5,621	5,191
Accumulated other comprehensive loss	-529	-550
Total L-3 shareholders' equity	5,755	5,467
Noncontrolling interests	75	76
Total equity	5,830	5,543
Total liabilities and equity	$14,075	$13,841

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 27, 2013	Dec. 31, 2012
In Millions, except Share data, unless otherwise specified	Sep. 27, 2013	Dec. 31, 2012
Allowances for billed receivables	$26	$33
Treasury stock (at cost), shares	62,194,678	57,418,645
L-3 Communications Holdings, Inc. [Member]
Common stock, par value	$0.01	$0.01
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares outstanding	89,047,037	90,433,743
L-3 Communications Corporation's [Member]
Common stock, par value	$0.01	$0.01
Common stock, shares authorized	100	100
Common stock, shares issued	100	100
Common stock, shares outstanding	100	100

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations (USD $)	3 Months Ended		9 Months Ended
In Millions, except Per Share data, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Net sales:
Products	$1,696	$1,915	$5,319	$5,452
Services	1,300	1,368	4,054	4,134
Total net sales	2,996	3,283	9,373	9,586
Cost of sales:
Products	-1,486	-1,717	-4,729	-4,837
Services	-1,196	-1,235	-3,710	-3,762
Total cost of sales	-2,682	-2,952	-8,439	-8,599
Operating income	314	331	934	987
Interest expense	-44	-48	-131	-138
Interest and other income, net	3		11	6
Debt retirement charge		-8		-8
Income from continuing operations before income taxes	273	275	814	847
Provision for income taxes	-65	-80	-226	-274
Income from continuing operations	208	195	588	573
Income (Loss) from discontinued operations, net of income taxes		-1		32
Net income	208	194	588	605
Net income attributable to noncontrolling interests	-4	-2	-6	-7
Net income attributable to L-3	$204	$192	$582	$598
Basic earnings (loss) per share attributable to L-3 Holdings' common shareholders:
Continuing operations	$2.28	$2.01	$6.47	$5.85
Discontinued operations		($0.01)		$0.29
Basic earnings per share	$2.28	$2	$6.47	$6.14
Diluted earnings (loss) per share attributable to L-3 Holdings' common shareholders:
Continuing operations	$2.23	$1.98	$6.37	$5.78
Discontinued operations		($0.01)		$0.28
Diluted earnings per share	$2.23	$1.97	$6.37	$6.06
Cash dividends paid per common share	$0.55	$0.50	$1.65	$1.50
L-3 Holdings' weighted average common shares outstanding:
Basic	89.6	96.1	89.9	97.4
Diluted	91.3	97.4	91.3	98.7

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended				9 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2013		Sep. 28, 2012		Sep. 27, 2013		Sep. 28, 2012
Statement Of Income And Comprehensive Income [Abstract]
Net income	$208		$194		$588		$605
Other comprehensive income:
Foreign currency translation adjustments	34		46		-18		28
Unrealized gains (losses) on hedging instruments	3	[1]	2	[1]	-1	[1]	4	[1]
Pension and postretirement benefit plans:
Amortization of net loss and prior service cost previously recognized	13	[2]	9	[2]	40	[2]	31	[2]
Total other comprehensive income:	50		57		21		63
Comprehensive income	258		251		609		668
Comprehensive income attributable to noncontrolling interests	-4		-2		-6		-7
Comprehensive income attributable to L-3	$254		$249		$603		$661

[1]	Amounts are net of income taxes of $2 and $1 million for the quarterly periods ended September 27, 2013 and September 28, 2012, respectively, and income tax benefits of $1 million and income taxes of $2 million for the year-to-date periods ended September 27, 2013 and September 28, 2012, respectively.
[2]	Amounts are net of income taxes of $7 million and $8 million for the quarterly periods ended September 27, 2013 and September 28, 2012, respectively, and $23 million and $20 million for the year-to-date periods ended September 27, 2013 and September 28, 2012, respectively.

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Comprehensive Income (Parenthetical) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Statement Of Income And Comprehensive Income [Abstract]
Income tax expense (benefit) on unrealized gains (losses) on hedging instruments	$2	$1	($1)	$2
Income tax effect on amortization of net loss and prior service cost previously recognized	$7	$8	$23	$20

Condensed_Consolidated_Stateme3

Condensed Consolidated Statements of Equity (USD $)	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Noncontrolling Interests [Member]
In Millions, except Share data, unless otherwise specified	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Noncontrolling Interests [Member]
Beginning Balance at Dec. 31, 2011	$6,724	$1	$5,063	($3,616)	$5,641	($454)	$89
Beginning Balance, Shares at Dec. 31, 2011		99,000,000
Net income	605				598		7
Other comprehensive income	63					63
Distributions to noncontrolling interests	-7						-7
Cash dividends paid on common stock	-146				-146
Shares issued:
Employee savings plans	111		111
Employee savings plans, Shares		1,700,000
Exercise of stock options	12		12
Exercise of stock options, Shares		200,000
Employee stock purchase plan	21		21
Employee stock purchase plan, Shares		700,000
Stock-based compensation expense	46		46
Contributions received from the spin-off of Engility	335				335
Spin-off of Engility	-1,406				-1,393		-13
Treasury stock purchased	-504			-504
Treasury stock purchased, Shares		-7,200,000
Other	-12		-10		-2
Other, Shares		400,000
Ending Balance at Sep. 28, 2012	5,842	1	5,243	-4,120	5,033	-391	76
Ending Balance, Shares at Sep. 28, 2012		94,800,000
Beginning Balance at Dec. 31, 2012	5,543	1	5,313	-4,488	5,191	-550	76
Beginning Balance, Shares at Dec. 31, 2012		90,400,000
Net income	588				582		6
Other comprehensive income	21					21
Distributions to noncontrolling interests	-7						-7
Cash dividends paid on common stock	-149				-149
Shares issued:
Employee savings plans	97		97
Employee savings plans, Shares		1,300,000
Exercise of stock options	90		90
Exercise of stock options, Shares		1,300,000
Employee stock purchase plan	18		18
Employee stock purchase plan, Shares		500,000
Stock-based compensation expense	42		42
Treasury stock purchased	-404			-404
Treasury stock purchased, Shares		-4,800,000
Other	-9		-6		-3
Other, Shares		300,000
Ending Balance at Sep. 27, 2013	$5,830	$1	$5,554	($4,892)	$5,621	($529)	$75
Ending Balance, Shares at Sep. 27, 2013		89,000,000

Condensed_Consolidated_Stateme4

Condensed Consolidated Statements of Equity (Parenthetical) (USD $)	9 Months Ended
	Sep. 27, 2013	Sep. 28, 2012
Cash dividends paid on common stock, per share	$1.65	$1.50
Retained Earnings [Member]
Cash dividends paid on common stock, per share	$1.65	$1.50

Condensed_Consolidated_Stateme5

Condensed Consolidated Statements of Cash Flows (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012
Operating activities:
Net income	$588	$605
Income from discontinued operations, net of tax		-32
Income from continuing operations	588	573
Depreciation of property, plant and equipment	122	124
Amortization of intangibles and other assets	36	41
Deferred income tax provision	45	50
Stock-based employee compensation expense	42	44
Contributions to employee savings plans in L-3 Holdings' common stock	90	104
Amortization of pension and postretirement benefit plans net loss and prior service cost	63	51
Amortization of bond discounts and deferred debt issue costs (included in interest expense)	5	5
Other non-cash items	1	9
Changes in operating assets and liabilities, excluding amounts from acquisitions, divestitures and discontinued operations:
Billed receivables	-117	152
Contracts in process	-36	-351
Inventories	-55	-83
Other assets	-45	28
Accounts payable, trade	65	47
Accrued employment costs	27	35
Accrued expenses	-41	-137
Advance payments and billings in excess of costs incurred	-109	107
Income taxes	32	-6
Excess income tax benefits related to share-based payment arrangements	-3	-2
Other current liabilities	-8	-47
Pension and postretirement benefits	-23	-53
All other operating activities	-62	1
Net cash from operating activities from continuing operations	617	692
Investing activities:
Contribution received from the spin-off of Engility		335
Business acquisitions, net of cash acquired	-2	-349
Proceeds from the sale of a business	4
Capital expenditures	-147	-124
Dispositions of property, plant and equipment	10	6
Other investing activities	-6	-5
Net cash used in investing activities from continuing operations	-141	-137
Financing activities:
Redemption of Senior Notes		-250
Borrowings under revolving credit facility	1,382	199
Repayment of borrowings under revolving credit facility	-1,382	-199
Common stock repurchased	-404	-504
Dividends paid on L-3 Holdings' common stock	-151	-149
Proceeds from exercises of stock options	91	12
Proceeds from employee stock purchase plan	28	30
Debt issue costs		-6
Excess income tax benefits related to share-based payment arrangements	3	2
Other financing activities	-13	-18
Net cash used in financing activities from continuing operations	-446	-883
Effect of foreign currency exchange rate changes on cash and cash equivalents	-2	4
Cash from (used in) discontinued operations:
Operating activities		75
Financing activities		-1
Cash from discontinued operations		74
Net increase (decrease) in cash and cash equivalents	28	-250
Cash and cash equivalents, beginning of the period	349	764
Cash and cash equivalents, end of the period	$377	$514

Description_of_Business

Description of Business	9 Months Ended
Description of Business	Sep. 27, 2013
Accounting Policies [Abstract]
Description of Business	1. Description of Business
	L-3 Communications Holdings, Inc. derives all of its operating income and cash flows from its wholly-owned subsidiary, L-3 Communications Corporation (L-3 Communications). L-3 Communications Holdings, Inc. (L-3 Holdings and, together with its subsidiaries, referred to herein as L-3 or the Company) is a prime contractor in Intelligence, Surveillance and Reconnaissance (ISR) systems, Command, Control, Communications (C3) systems, platform and logistics solutions for aircrafts, maritime vessels and ground vehicles, and national security solutions. L-3 is also a leading provider of a broad range of electronic systems used on military and commercial platforms. The Company’s customers include the United States (U.S.) Department of Defense (DoD) and its prime contractors, U.S. Government intelligence agencies, the U.S. Department of Homeland Security (DHS), U.S. Department of State (DoS), allied international governments, and domestic and international commercial customers.
	The Company has the following four reportable segments: (1) C3ISR, (2) Electronic Systems, (3) Platform & Logistics Solutions (P&LS) and (4) National Security Solutions (NSS). Financial information with respect to each of the Company’s segments is included in Note 21. C3ISR provides products and services for the global ISR market, C3 systems, networked communication systems and secure communications products. The Company believes that these products and services are critical elements for a substantial number of major command, control and communication, intelligence gathering and space systems. These products and services are used to connect a variety of airborne, space, ground and sea-based communication systems and are used in the transmission, processing, recording, monitoring, and dissemination functions of these communication systems. Electronic Systems provides a broad range of products and services, including components, products, subsystems and systems and related services to military and commercial customers in several niche markets across several business areas. These business areas include microwave, power & control systems, marine systems international, sensor systems, simulation & training, aviation products, precision engagement, warrior systems, security & detection, space & propulsion, undersea warfare and marine services. P&LS provides modernization, upgrades and sustainment, maintenance and logistics support solutions for military and various government aircraft and other platforms. The Company sells these services primarily to the DoD, the Canadian Department of National Defence and other allied international governments. NSS provides a full range of cyber security, intelligence, enterprise information technology (IT) and security solutions services to the DoD, U.S. Government intelligence agencies, federal civilian agencies and allied international governments.

Basis_of_Presentation

Basis of Presentation	9 Months Ended
Basis of Presentation	Sep. 27, 2013
Accounting Policies [Abstract]
Basis of Presentation	2. Basis of Presentation
	These unaudited condensed consolidated financial statements for the quarterly and nine month (year-to-date) periods ended September 27, 2013 should be read in conjunction with the audited consolidated financial statements of L-3 Holdings and L-3 Communications included in their Annual Report on Form 10-K for the fiscal year ended December 31, 2012.
	The audited condensed consolidated balance sheet as of December 31, 2012 has been revised for the final purchase price allocation of the Link Simulation & Training U.K. Limited (Link U.K.) business acquisition. Link U.K is the commercial aircraft simulation business acquired from Thales Group effective August 6, 2012. During the third quarter of 2013, the Company completed the purchase price allocation, which was based on the final appraisals and valuations of the acquired assets and liabilities and estimated final closing date net working capital. The L-3 audited condensed consolidated balance sheet as of December 31, 2012 has been adjusted in accordance with the accounting standards for business combinations. See Note 4 for additional information regarding the final purchase price allocation for Link U.K. and resulting adjustments.

	Principles of Consolidation and Reporting
	The accompanying financial statements comprise the consolidated financial statements of L-3 Holdings and L-3 Communications. L-3 Holdings’ only asset is its investment in the common stock of L-3 Communications, its wholly-owned subsidiary, and its only obligations are: (1) the 3% Convertible Contingent Debt Securities (CODES) due 2035, which were issued by L-3 Holdings on July 29, 2005, (2) its guarantee of borrowings under the Amended and Restated Revolving Credit Facility of L-3 Communications and (3) its guarantee of other contractual obligations of L-3 Communications and its subsidiaries. L-3 Holdings’ obligations relating to the CODES have been jointly, severally, fully and unconditionally guaranteed by L-3 Communications and certain of its wholly-owned domestic subsidiaries. Accordingly, such debt has been reflected as debt of L-3 Communications in its consolidated financial statements in accordance with the accounting standards for pushdown accounting. All issuances of and conversions into L-3 Holdings’ equity securities, including grants of stock options, restricted stock, restricted stock units and performance units by L-3 Holdings to employees and directors of L-3 Communications and its subsidiaries, have been reflected in the consolidated financial statements of L-3 Communications. As a result, the consolidated financial positions, results of operations and cash flows of L-3 Holdings and L-3 Communications are substantially the same. See Note 24 for additional information regarding the unaudited financial information of L-3 Communications and its subsidiaries.
	The unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (U.S. GAAP) for interim financial information and in accordance with the instructions to Form 10-Q and Article 10 of Regulation S-X of the SEC. Accordingly, they do not include all of the disclosures required by U.S. GAAP for a complete set of annual audited financial statements. The December 31, 2012 condensed consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by U.S. GAAP. In the opinion of management, all adjustments (consisting of normal and recurring adjustments) considered necessary for a fair presentation of the results for the interim periods presented have been included. The results of operations for the interim periods are not necessarily indicative of results for the full year.
	It is the Company’s established practice to close its books for the quarters ending March, June and September on the Friday nearest to the end of the calendar quarter. The interim unaudited condensed consolidated financial statements included herein have been prepared and are labeled based on that convention. The Company closes its books for annual periods on December 31 regardless of what day it falls on.
	Accounting Estimates
	The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of sales and costs of sales during the reporting period. The most significant of these estimates and assumptions for L-3 relate to contract revenue, profit and loss recognition, fair values of assets acquired and liabilities assumed in business combinations, market values for inventories reported at lower of cost or market, pension and post-retirement benefit obligations, stock-based employee compensation expense, income taxes, including the valuation of deferred tax assets, litigation reserves and environmental obligations, accrued product warranty costs, and the recoverability, useful lives and valuation of recorded amounts of long-lived assets, identifiable intangible assets and goodwill. Changes in estimates are reflected in the periods during which they become known. Actual amounts will differ from these estimates and could differ materially.

	Sales and profits on contracts that are covered by accounting standards for construction-type and production-type contracts and federal government contractors are recognized using percentage-of-completion (POC) methods of accounting. Approximately 48% of the Company’s net sales in 2012 were accounted for under contract accounting standards, of which, approximately 39% were fixed-price type contracts and approximately 9% were cost-plus type contracts. For contracts accounted for under contract accounting standards, sales and profits are recognized based on: (1) a POC method of accounting (fixed-price contracts), (2) allowable costs incurred plus the estimated profit on those costs (cost-plus contracts), or (3) direct labor hours expended multiplied by the contractual fixed rate per hour plus incurred costs for material (time-and-material contracts). Sales and profits on fixed-price production contracts under which units are produced and delivered in a continuous or sequential process are recorded as units are delivered based on their contractual selling prices (the “units-of-delivery” method). Sales and profits on each fixed-price production contract under which units are not produced and delivered in a continuous or sequential process, or under which a relatively few number of units are produced, are recorded based on the ratio of actual cumulative costs incurred to total estimated costs at completion of the contract multiplied by the total estimated contract revenue, less cumulative sales recognized in prior periods (the “cost-to-cost” method). Under both POC methods of accounting, a single estimated total profit margin is used to recognize profit for each contract over its entire period of performance, which can exceed one year.
	Accounting for the sales and profit on these fixed-price type contracts requires the preparation of estimates of: (1) the total contract revenue, (2) the total costs at completion, which is equal to the sum of the actual incurred costs to date on the contract and the estimated costs to complete the contract’s statement of work, and (3) the measurement of progress towards completion. The estimated profit or loss at completion on a contract is equal to the difference between the total estimated contract revenue and the total estimated cost at completion. The profit recorded on a contract in any period using either the units-of-delivery method or cost-to-cost method is equal to the current estimated total profit margin multiplied by the cumulative sales recognized, less the amount of cumulative profit previously recorded for the contract.
	Sales and profits on cost-plus type contracts that are covered by contract accounting standards are recognized as allowable costs are incurred on the contract, at an amount equal to the allowable costs plus the estimated profit on those costs. The estimated profit on a cost-plus type contract is fixed or variable based on the contractual fee arrangement. Incentive and award fees are the primary variable fee contractual arrangement types for the Company. Incentive and award fees on cost-plus type contracts are included as an element of total estimated contract revenues and are recorded to sales when a basis exists for the reasonable prediction of performance in relation to established contractual targets and the Company is able to make reasonably dependable estimates for them.
	Sales and profits on time-and-material type contracts are recognized on the basis of direct labor hours expended multiplied by the contractual fixed rate per hour, plus the actual costs of materials and other direct non-labor costs.
	Revisions or adjustments to estimates for a contract’s revenue, estimated costs at completion and estimated profit or loss are often required as work progresses under a contract, as experience is gained, as facts and circumstances change and as new information is obtained, even though the scope of work required under the contract may not change. Revisions or adjustments may also be required if contract modifications occur. The impact of revisions in profit (loss) estimates for all types of contracts subject to POC accounting are recognized on a cumulative catch-up basis in the period in which the revisions are made. The revisions in contract estimates, if significant, can materially affect the Company’s results of operations and cash flows, as well as reduce the valuations of receivables and inventories, and in some cases result in liabilities to complete contracts in a loss position. Aggregate net changes in contract estimates increased consolidated operating income by $85 million, or 9.1%, for the year-to-date period ended September 27, 2013 and $75 million, or 7.6%, for the year-to-date period ended September 28, 2012.
	For a more complete discussion of these estimates and assumptions, see the Annual Report of L-3 Holdings and L-3 Communications on Form 10-K for the fiscal year ended December 31, 2012.

New_Accounting_Standards

New Accounting Standards	9 Months Ended
New Accounting Standards	Sep. 27, 2013
Accounting Changes And Error Corrections [Abstract]
New Accounting Standards	3. New Accounting Standards
New Accounting Standards	Effective January 1, 2013, the Company adopted a new accounting standard issued by the Financial Accounting Standards Board (FASB), which adds new disclosure requirements for items reclassified out of accumulated other comprehensive income (loss) (AOCI). This standard requires entities to disclose additional information about reclassification adjustments, including: (1) changes in AOCI balances by component and (2) significant items reclassified out of AOCI. The adoption of this standard resulted in additional disclosures of items reclassified out of AOCI and did not impact the Company’s financial position, results of operations or cash flows. See Note 11 for these additional disclosures.

Dispositions_and_Acquisitions

Dispositions and Acquisitions	9 Months Ended
Dispositions and Acquisitions	Sep. 27, 2013
Business Combinations [Abstract]
Dispositions and Acquisitions	4. Dispositions and Acquisitions
	2012 Spin-off of Engility
	The Company completed the spin-off of its subsidiary, Engility Holdings, Inc. (Engility), to its shareholders on July 17, 2012. L-3 incurred transaction expenses in connection with the spin-off of $19 million ($14 million after income taxes) for the year-to-date period ended September 28, 2012, which have been included in discontinued operations. In addition, L-3 allocated interest expense for debt not directly attributable or related to L-3’s other operations of $14 million to discontinued operations for the year-to-date period ended September 28, 2012. Interest expense was allocated in accordance with the accounting standards for discontinued operations and was based on the ratio of Engility net assets to the sum of: (1) total L-3 consolidated net assets and (2) L-3 consolidated total debt.
	Statement of operations data classified as discontinued operations related to Engility is provided in the table below.




		Third Quarter Ended			Year-to-Date Ended
		September 28, 2012			September 28, 2012
		(in millions)
	Product and service revenues	$	68		$	911

	Operating income from discontinued operations before income taxes		2			68
	Interest expense allocated to discontinued operations		(1	)		(14	)

	Income from discontinued operations before income taxes	$	1		$	54
	Income tax expense		(2	)		(22	)

	(Loss) income from discontinued operations, net of income taxes	$	(1	)	$	32
	Net income from discontinued operations attributable to noncontrolling interests		—			(4	)

	Net (loss) income from discontinued operations attributable to L-3	$	(1	)	$	28



	2012 Business Acquisitions
	All of the business acquisitions discussed below are included in the Company’s results of operations from their respective dates of acquisition.
	During the year ended December 31, 2012, in separate transactions, the Company acquired: (1) the Kollmorgen Electro-Optical (L-3 KEO) business, (2) the assets and liabilities of MAVCO, Inc. (MAVCO), and (3) Link U.K., for an aggregate purchase price of $349 million. All business acquisitions were financed with cash on hand. Based on the final purchase price allocations, the aggregate goodwill recognized for these acquired businesses was $282 million, of which $184 million is expected to be deductible for income tax purposes. The goodwill recognized for these three acquired businesses was assigned to the Electronic Systems segment.
	The purchase prices and purchase price allocations for L-3 KEO and MAVCO were finalized as of June 28, 2013 and December 31, 2012, respectively, with no significant changes from the preliminary amounts. The Link U.K. purchase price allocation was finalized as of September 27, 2013 based on the results of the final appraisals and valuations of the assets and liabilities acquired and estimated final closing date net working capital. The final purchase price allocation resulted in certain adjustments to the preliminary valuations, the most significant of which included an increase to goodwill of $32 million, an increase to other liabilities of $17 million, and a decrease of $16 million to contracts in process. As discussed in Note 2, the audited condensed consolidated balance sheet as of December 31, 2012 has been revised for these adjustments in accordance with accounting standards for business combinations.
	The final purchase price for the Link U.K. acquisition is subject to adjustment based on final closing date net working capital, which is currently in negotiation and is expected to be completed by December 31, 2013. Differences between the estimated and final closing date net working capital will impact goodwill.
	Unaudited Pro Forma Statement of Operations Data
	The following unaudited pro forma Statement of Operations data presents the combined results of the Company and its business acquisitions completed during the year ended December 31, 2012, in each case assuming that the business acquisitions completed during the year ended December 31, 2012 had occurred on January 1, 2012.


		Third Quarter Ended			Year-to-Date Ended
		September 28,			September 28,
		2012			2012
		(in millions, except per share data)
	Pro forma net sales	$	3,295		$	9,688
	Pro forma income from continuing operations		195			574
	Pro forma net income attributable to L-3		192			599
	Pro forma diluted earnings per share from continuing operations		1.98			5.79
	Pro forma diluted earnings per share		1.97			6.07
	The unaudited pro forma results disclosed in the table above are based on various assumptions and are not necessarily indicative of the results of operations that would have occurred had the Company completed these acquisitions on January 1, 2012.

Contracts_in_Process

Contracts in Process	9 Months Ended
Contracts in Process	Sep. 27, 2013
Text Block [Abstract]
Contracts in Process	5. Contracts in Process
	The components of contracts in process are presented in the table below.


		September 27,			December 31,
		2013			2012
		(in millions)
	Unbilled contract receivables, gross	$	2,714		$	2,879
	Unliquidated progress payments		(1,051	)		(1,265	)

	Unbilled contract receivables, net		1,663			1,614

	Inventoried contract costs, gross		1,093			1,090
	Unliquidated progress payments		(65	)		(68	)

	Inventoried contract costs, net		1,028			1,022

	Total contracts in process	$	2,691		$	2,636

	Inventoried Contract Costs. In accordance with contract accounting standards, the Company’s U.S. Government contractor businesses account for the portion of their general and administrative (G&A), independent research and development (IRAD) and bids and proposal (B&P) costs that are allowable and reimbursable indirect contract costs under U.S. Government procurement regulations on their U.S. Government contracts (revenue arrangements) as inventoried contract costs. G&A, IRAD and B&P costs are allocated to contracts for which the U.S. Government is the end customer and are charged to costs of sales when sales on the related contracts are recognized. The Company’s U.S. Government contractor businesses record the unallowable portion of their G&A, IRAD and B&P costs to expense as incurred, and do not include them in inventoried contract costs.
	The table below presents a summary of G&A, IRAD and B&P costs included in inventoried contract costs and the changes to them, including amounts charged to cost of sales by the Company’s U.S. Government contractor businesses for the periods presented.


		Third Quarter Ended						Year-to-Date Ended
		September 27,			September 28,			September 27,			September 28,
		2013			2012			2013			2012
		(in millions)
	Amounts included in inventoried contract costs at beginning of the period	$	115		$	105		$	110		$	91
	IRAD and B&P costs		66			83			219			254
	Other G&A costs		218			213			655			647

	Total contract costs incurred		284			296			874			901

	Amounts charged to cost of sales		(273	)		(289	)		(858	)		(880	)

	Amounts included in inventoried contract costs at end of the period	$	126		$	112		$	126		$	112


	The table below presents a summary of selling, general and administrative expenses and research and development expenses for the Company’s commercial businesses, which are expensed as incurred and not included in inventoried contract costs.


	.	Third Quarter Ended						Year-to-Date Ended
		September 27,			September 28,			September 27,			September 28,
		2013			2012			2013			2012
		(in millions)
	Selling, general and administrative expenses	$	68		$	58		$	212		$	196
	Research and development expenses		17			18			62			63

	Total	$	85		$	76		$	274		$	259

Inventories

Inventories	9 Months Ended
Inventories	Sep. 27, 2013
Inventory Disclosure [Abstract]
Inventories	6. Inventories
	Inventories at Lower of Cost or Market. The table below presents the components of inventories at the lower of cost (first-in, first-out or average cost) or realizable value.


		September 27,		December 31,
		2013		2012
		(in millions)
	Raw materials, components and sub-assemblies	$	174	$	168
	Work in process		155		124
	Finished goods		91		71

	Total	$	420	$	363

Goodwill_and_Identifiable_Inta

Goodwill and Identifiable Intangible Assets	9 Months Ended
Goodwill and Identifiable Intangible Assets	Sep. 27, 2013
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Identifiable Intangible Assets	7. Goodwill and Identifiable Intangible Assets
	Goodwill. In accordance with the accounting standards for business combinations, the Company records the assets acquired and liabilities assumed based on their estimated fair values at the date of acquisition (commonly referred to as the purchase price allocation). The table below presents the changes in goodwill by segment for the year-to-date period ended September 27, 2013.


			C3ISR		Electronic			P&LS			NSS		Consolidated
			C3ISR		Systems			P&LS			NSS		Total
			(in millions)
	Balance at December 31, 2012		$	797	$	4,836		$	1,175		$	968	$	7,776
	Business dispositions			—		(2	)		—			—		(2	)
	Foreign currency translation adjustments(1)			—		(7	)		(10	)		—		(17	)

	Balance at September 27, 2013		$	797	$	4,827		$	1,165		$	968	$	7,757


	(1)	The decreases in goodwill presented in the Electronic Systems and P&LS segments were primarily due to the strengthening of the U.S. dollar against the Canadian dollar and Australian dollar, partially offset by the weakening of the U.S. dollar against the Euro during the year-to-date period ended September 27, 2013.
	The Company’s accumulated goodwill impairment losses, which were recorded in the Electronic Systems segment, were $58 million at September 27, 2013 and December 31, 2012.

	Identifiable Intangible Assets. Information on the Company’s identifiable intangible assets that are subject to amortization is presented in the table below.


			September 27, 2013										December 31, 2012
			Weighted		Gross			Accumulated			Net		Gross			Accumulated		Net
			Average		Carrying			Amortization			Carrying		Carrying			Amortization		Carrying
			Amortization		Amount						Amount		Amount					Amount
			Period
			(in years)								(in millions)
	Customer contractual relationships			19	$	461		$	246		$	215	$	460		$	225	$	235
	Technology			11		164			105			59		164			98		66
	Other			17		27			15			12		27			14		13

	Total			17	$	652		$	366		$	286	$	651		$	337	$	314

	Amortization expense recorded by the Company for its identifiable intangible assets is presented in the table below.


			Third Quarter Ended					Year-to-Date Ended
			September 27,		September 28,			September 27,			September 28,
			2013		2012			2013			2012
			(in millions)
	Amortization Expense		$	10	$	13		$	29		$	34

	Based on gross carrying amounts at September 27, 2013, the Company’s estimate of amortization expense for identifiable intangible assets for the years ending December 31, 2013 through 2017 are presented in the table below.


			Year Ending December 31,
			2013		2014			2015			2016		2017
			(in millions)
	Estimated amortization expense		$	38	$	42		$	39		$	32	$	31

Other_Current_Liabilities_and_

Other Current Liabilities and Other Liabilities	9 Months Ended
Other Current Liabilities and Other Liabilities	Sep. 27, 2013
Text Block [Abstract]
Other Current Liabilities and Other Liabilities	8. Other Current Liabilities and Other Liabilities
	The table below presents the components of other current liabilities.


			September 27,			December 31,
			2013			2012
			(in millions)
	Other Current Liabilities:
	Accruals for pending and threatened litigation (see Note 17)		$	5		$	7
	Accrued product warranty costs			76			78
	Estimated costs in excess of estimated contract value to complete contracts in process in a loss position			67			72
	Accrued interest			46			53
	Deferred revenues			38			37
	Estimated contingent purchase price payable for acquired businesses			—			4
	Other			151			144

	Total other current liabilities		$	383		$	395


	The table below presents the components of other liabilities.


			September 27,			December 31,
			2013			2012
			(in millions)
	Other Liabilities:
	Non-current income taxes payable (see Note 10)		$	145		$	137
	Accrued workers’ compensation			53			57
	Deferred compensation			45			43
	Accrued product warranty costs			24			22
	Notes payable and capital lease obligations			17			24
	Estimated contingent purchase price payable for acquired businesses			—			5
	Other			73			102

	Total other liabilities		$	357		$	390

	The table below presents the changes in the Company’s accrued product warranty costs.


			Year-to-Date Ended
			September 27,			September 28,
			2013			2012
			(in millions)
	Accrued product warranty costs:(1)
	Balance at January 1		$	100		$	94
	Acquisitions during the period			—			2
	Accruals for product warranties issued during the period			56			56
	Settlements made during the period			(56	)		(58	)

	Balance at end of period		$	100		$	94


	(1)	Warranty obligations incurred in connection with long-term production contracts that are accounted for under the POC cost-to-cost method are included within the contract estimates at completion and are excluded from the above amounts. The balances above include both the current and non-current amounts.

Debt

Debt	9 Months Ended
Debt	Sep. 27, 2013
Debt Disclosure [Abstract]
Debt	9. Debt
	The components of debt and a reconciliation to the carrying amount of long-term debt is presented in the table below.


			September 27,			December 31,
			2013			2012
			(in millions)
	L-3 Communications:
	Borrowings under Amended and Restated Revolving Credit Facility(1)		$	—		$	—
	3.95% Senior Notes due 2016			500			500
	5.20% Senior Notes due 2019			1,000			1,000
	4.75% Senior Notes due 2020			800			800
	4.95% Senior Notes due 2021			650			650

	Subtotal			2,950			2,950

	L-3 Holdings:
	3% Convertible Contingent Debt Securities due 2035(2)			689			689

	Principal amount of long-term debt			3,639			3,639
	Unamortized discounts			(9	)		(10	)

	Carrying amount of long-term debt		$	3,630		$	3,629


	(1)	During the year-to-date period ended September 27, 2013, L-3 Communications’ aggregate borrowings and repayments under the Amended and Restated Revolving Credit Facility was $1,382 million. At September 27, 2013, L-3 Communications had the availability of substantially all of its $1 billion Amended and Restated Revolving Credit Facility, which expires on February 3, 2017.

	(2)	Under select conditions, including if L-3 Holdings’ common stock price is more than 120% (currently $108.29) of the then current conversion price (currently $90.24) for a specified period, the conversion feature of the CODES will require L-3 Holdings, upon conversion, to pay the holders of the CODES the principal amount in cash, 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. At the current conversion price of $90.24, the aggregate consideration to be delivered upon conversion would be determined based on 7.6 million shares of L-3 Holdings’ common stock. See Note 10 to the audited consolidated financial statements for the year ended December 31, 2012, included in the Company’s Annual Report on Form 10-K, for additional information regarding the CODES, including conditions for conversion. L-3 Holdings’ closing stock price on October 23, 2013 was $95.98 share. Interest expense recognized was $5 million for both quarterly periods ended September 27, 2013 and September 28, 2012 and $15 million for both year-to-date periods ended September 27, 2013 and September 28, 2012. A portion of this interest expense was allocated to discontinued operations for the quarterly and year-to-date periods ended September 28, 2012 as a result of the spin-off of Engility. The carrying amount of the equity component (conversion feature) of the CODES was $64 million at September 27, 2013 and December 31, 2012.

Income_Taxes

Income Taxes	9 Months Ended
Income Taxes	Sep. 27, 2013
Income Tax Disclosure [Abstract]
Income Taxes	10. Income Taxes
	The Company and its subsidiaries file income tax returns in the U.S. Federal jurisdiction and various state and foreign jurisdictions. As of September 27, 2013, the statutes of limitations for the Company’s U.S. Federal income tax returns for the years ended December 31, 2010 through 2012 were open. The U.S Internal Revenue Service (IRS) plans to commence an audit of the Company’s 2011 and 2010 U.S. Federal tax returns, the outcome of which cannot be predicted at this time.
	The effective tax rate for the year-to-date period ended September 27, 2013 decreased to 27.8% from 32.3% for the year-to-date period ended September 28, 2012. The decrease was primarily due to a tax benefit in the year-to-date period ended September 27, 2013 of $28 million related to the U.S. Federal research and experimentation tax credit (R&E Credit), of which $17 million relates to 2012 and $11 million relates to the year-to-date period ended September 27, 2013. The R&E Credit was retroactively reinstated from January 1, 2012 to December 31, 2013 as part of the American Taxpayer Relief Act of 2012, which was signed into law on January 2, 2013. Accounting standards for income taxes require that the impact for tax law changes be recognized in the period that the law is enacted.
	In the third quarter of 2013, the Company reversed previously accrued amounts relating to its provision for income taxes of $10 million for the expiration of the statutes of limitations for several tax returns, including the Company’s 2009 U.S. Federal income tax return as well as certain state and foreign tax returns. As of September 27, 2013, the Company anticipates that unrecognized tax benefits will decrease by approximately $6 million over the next 12 months due to the potential resolution of unrecognized tax benefits involving several jurisdictions and tax periods. The actual amount of the decrease over the next 12 months could vary significantly depending on the ultimate timing and nature of any settlement.
	Non-current income taxes payable include accrued potential interest of $10 million ($6 million after income taxes) at September 27, 2013 and $11 million ($6 million after income taxes) at December 31, 2012, and potential penalties of $7 million at September 27, 2013 and $7 million at December 31, 2012.

Amounts_Reclassified_Out_of_Ac

Amounts Reclassified Out of Accumulated Other Comprehensive (Loss) Income	9 Months Ended
	Sep. 27, 2013
Text Block [Abstract]
Amounts Reclassified Out of Accumulated Other Comprehensive (Loss) Income	11. Amounts Reclassified Out of Accumulated Other Comprehensive (Loss) Income
	Amounts reclassified out of AOCI for the year-to-date period ended September 27, 2013 are presented in the table below.


			Foreign			Unrealized			Unrecognized			Total
			currency			gains			losses and			accumulated
			translation			(losses) on			prior service			other
						hedging			cost, net			comprehensive
						instruments						(loss) income
			(in millions)
	Balance at December 31, 2012		$	167		$	3		$	(720	)	$	(550	)
	Other comprehensive loss before reclassifications, net of tax			(18	)		(2	)		—			(20	)
	Amounts reclassified from other comprehensive income, net of tax			—			1			40			41

	Net current period other comprehensive (loss) income			(18	)		(1	)		40			21

	Balance at September 27, 2013		$	149		$	2		$	(680	)	$	(529	)


	Further details regarding the amounts reclassified from AOCI for the quarterly and year-to-date periods ended September 27, 2013 are presented in the table below.


			Amount Reclassified from Accumulated						Affected Line Item in the
			Other Comprehensive (Loss) Income						Unaudited Condensed Consolidated
			Third Quarter Ended			Year-to-Date			Statement of Operations
			Third Quarter Ended			Ended
	Details About Accumulated Other		September 27,			September 27,
	Comprehensive (Loss) Income Components		2013			2013
			(in millions)
	Gain on hedging instruments		$	—		$	1		Cost of sales-products

				—			1		Income from continuing operations
				—			1		before income taxes
				—			—		Provision for income taxes

			$	—		$	1		Income from continuing operations

	Amortization of defined benefit pension items:
	Net loss		$	20		$	63		(a)

				20			63		Income from continuing operations
				20			63		before income taxes
				(7	)		(23	)	Provision for income taxes

			$	13		$	40		Income from continuing operations

	Total reclassification for the period		$	13		$	41		Income from continuing operations


	(a)	Amounts related to pension and postretirement benefit plans were reclassified from AOCI and recorded as a component of net periodic benefit cost (see Note 18 for additional information).

Equity

Equity	9 Months Ended
Equity	Sep. 27, 2013
Text Block [Abstract]
Equity	12. Equity
	The $1.5 billion share repurchase program authorized on April 26, 2011 by L-3 Holdings’ Board of Directors expired on April 30, 2013. On February 5, 2013, L-3 Holdings’ Board of Directors approved a new share repurchase program that authorizes L-3 Holdings to repurchase up to an additional $1.5 billion of its common stock through June 30, 2015. Repurchases of L-3 Holdings’ common stock under the February 5, 2013 share repurchase program are made at management’s discretion in accordance with applicable U.S. Federal securities laws in the open market or otherwise. The timing and actual number of shares to be repurchased in the future will depend on a variety of factors, including the Company’s financial position, earnings, legal requirements, other investment opportunities (including acquisitions), market conditions and other factors. L-3 Holdings repurchased 4.8 million shares of its common stock at an average price of $84.59 per share for an aggregate amount of $404 million from January 1, 2013 through September 27, 2013. Approximately 2.1 million of the share repurchases, for an aggregate amount of $168 million, were repurchased pursuant to the April 26, 2011 share repurchase program. The remaining share repurchases were made pursuant to the share repurchase program authorized on February 5, 2013. All share repurchases of L-3 Holdings’ common stock have been recorded as treasury shares.

	At September 27, 2013, the remaining dollar value of authorization under the February 5, 2013 share repurchase program was $1,264 million. From September 28, 2013 through October 23, 2013, L-3 Holdings repurchased 527,135 shares of its common stock at an average price of $93.88 per share for an aggregate amount of $49 million under the February 5, 2013 share repurchase program.
	On June 19, 2013, L-3 Holdings’ Board of Directors declared a cash dividend of $0.55 per share, which resulted in the Company paying total cash dividends of $50 million on September 16, 2013. Also, on October 22, 2013, L-3 Holdings’ Board of Directors declared a quarterly cash dividend of $0.55 per share, payable on December 16, 2013, to shareholders of record at the close of business on November 18, 2013.

L3_Holdings_Earnings_Per_Commo

L-3 Holdings' Earnings Per Common Share	9 Months Ended
L-3 Holdings' Earnings Per Common Share	Sep. 27, 2013
Earnings Per Share [Abstract]
L-3 Holdings' Earnings Per Common Share	13. L-3 Holdings’ Earnings Per Common Share
	A reconciliation of basic and diluted earnings per share (EPS) is presented in the table below.


			Third Quarter Ended						Year-to-Date Ended
			September 27,			September 28,			September 27,			September 28,
			2013			2012			2013			2012
			(in millions, except per share data)
	Reconciliation of net income:
	Net income		$	208		$	194		$	588		$	605
	Net income from continuing operations attributable to noncontrolling interests			(4	)		(2	)		(6	)		(3	)
	Net income from discontinued operations attributable to noncontrolling interests			—			—			—			(4	)

	Net income attributable to L-3 Holdings’ common shareholders		$	204		$	192		$	582		$	598

	Earnings (loss) attributable to L-3 Holdings’ common shareholders:
	Continuing operations		$	204		$	193		$	582		$	570
	Discontinued operations, net of income tax			—			(1	)		—			28

	Net income attributable to L-3 Holdings’ common shareholders		$	204		$	192		$	582		$	598

	Earnings (loss) per share attributable to L-3 Holdings’ common shareholders:
	Basic:
	Weighted average common shares outstanding			89.6			96.1			89.9			97.4

	Basic earnings (loss) per share:
	Continuing operations		$	2.28		$	2.01		$	6.47		$	5.85
	Discontinued operations, net of income tax			—			(0.01	)		—			0.29

	Basic earnings per share		$	2.28		$	2		$	6.47		$	6.14

	Diluted:
	Common and potential common shares:
	Weighted average common shares outstanding			89.6			96.1			89.9			97.4
	Assumed exercise of stock options			4.7			2.1			3.9			1.7
	Unvested restricted stock awards			1.8			2			1.8			2.1
	Employee stock purchase plan contributions			0.2			0.3			0.2			0.3
	Performance unit awards			0.1			—			0.1			—
	Assumed purchase of common shares for treasury			(5.2	)		(3.1	)		(4.7	)		(2.8	)
	Assumed conversion of the CODES(1)			0.1			—			0.1			—

	Common and potential common shares			91.3			97.4			91.3			98.7

	Diluted earnings (loss) per share:
	Continuing operations		$	2.23		$	1.98		$	6.37		$	5.78
	Discontinued operations, net of income tax			—			(0.01	)		—			0.28

	Diluted earnings per share		$	2.23		$	1.97		$	6.37		$	6.06


	(1)	L-3 Holdings’ CODES had no impact on diluted EPS for the quarterly or year-to-date periods ended September 28, 2012 as the average market price of L-3 Holdings common stock during these periods was less than the price at which the CODES would have been convertible into L-3 Holdings common stock. As of September 27, 2013, the conversion price was $90.24.

	The computation of diluted EPS excluded stock options of 3.2 million for the quarterly period ended September 28, 2012, and 1.2 million and 3.5 million for the year-to-date periods ended September 27, 2013 and September 28, 2012, respectively, as they were anti-dilutive.

Fair_Value_Measurements

Fair Value Measurements	9 Months Ended
Fair Value Measurements	Sep. 27, 2013
Fair Value Disclosures [Abstract]
Fair Value Measurements	14. Fair Value Measurements
	The following table presents the fair value hierarchy level for each of the Company’s assets and liabilities that are measured and recorded at fair value on a recurring basis.


			September 27, 2013						December 31, 2012
	Description		Level 1(1)		Level 2(2)		Level 3(3)		Level 1(1)		Level 2(2)		Level 3(3)
			(in millions)
	Assets
	Cash equivalents		$	199	$	—	$	—	$	284	$	—	$	—
	Derivatives (foreign currency forward contracts)			—		8		—		—		8		—

	Total Assets		$	199	$	8	$	—	$	284	$	8	$	—

	Liabilities
	Derivatives (foreign currency forward contracts)		$	—	$	2	$	—	$	—	$	3	$	—

	(1)	Level 1 is based on quoted market prices available in active markets for identical assets or liabilities as of the reporting date. Cash equivalents are primarily held in registered money market funds, which are valued using quoted market prices.

	(2)	Level 2 is based on pricing inputs other than quoted prices in active markets, which are either directly or indirectly observable. The fair value is determined using a valuation model based on observable market inputs, including quoted foreign currency forward exchange rates and consideration of non-performance risk.

	(3)	Level 3 is based on pricing inputs that are not observable and not corroborated by market data. The Company has no Level 3 assets or liabilities.

Financial_Instruments

Financial Instruments	9 Months Ended
Financial Instruments	Sep. 27, 2013
Investments All Other Investments [Abstract]
Financial Instruments	15. Financial Instruments
	At September 27, 2013 and December 31, 2012, the Company’s financial instruments consisted primarily of cash and cash equivalents, billed receivables, trade accounts payable, Senior Notes, CODES and foreign currency forward contracts. The carrying amounts of cash and cash equivalents, billed receivables and trade accounts payable are representative of their respective fair values because of their short-term maturities or the expected settlement dates of these instruments. The carrying amounts and estimated fair values of the Company’s financial instruments are presented in the table below.


			September 27, 2013				December 31, 2012
			Carrying		Estimated		Carrying		Estimated
			Amount		Fair Value		Amount		Fair Value
			(in millions)
	Senior Notes(1)		$	2,941	$	3,131	$	2,940	$	3,301
	CODES(1)			689		752		689		697
	Foreign currency forward contracts(2)			6		6		5		5

	(1)	The Company measures the fair value of its Senior Notes and CODES using Level 2 inputs based primarily on current market yields for its existing debt traded in the secondary market.

	(2)	See Note 16 for additional disclosures regarding the notional amounts and fair values of foreign currency forward contracts.

Derivative_Financial_Instrumen

Derivative Financial Instruments	9 Months Ended
Derivative Financial Instruments	Sep. 27, 2013
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	16. Derivative Financial Instruments
	The Company’s derivative financial instruments include foreign currency forward contracts, which are entered into for risk management purposes, and an embedded derivative representing the contingent interest payment provision related to the CODES.
	Foreign Currency Forward Contracts. The Company’s U.S. and foreign businesses enter into contracts with customers, subcontractors or vendors that are denominated in currencies other than their functional currencies. To protect the functional currency equivalent cash flows associated with certain of these contracts, the Company enters into foreign currency forward contracts. The Company’s activities involving foreign currency forward contracts are designed to hedge the changes in the functional currency equivalent cash flows due to movements in foreign exchange rates compared to the functional currency. The foreign currencies hedged are primarily the Canadian dollar, the U.S. dollar, the Euro, and the British pound. The Company manages exposure to counterparty non-performance credit risk by entering into foreign currency forward contracts with major financial institutions that are expected to fully perform under the terms of such contracts. Foreign currency forward contracts are recorded in the Company’s condensed consolidated balance sheets at fair value and are generally designated and accounted for as cash flow hedges in accordance with the accounting standards for derivative instruments and hedging activities. Gains and losses on designated foreign currency forward contracts that are highly effective in offsetting the corresponding change in the cash flows of the hedged transactions are recorded net of income taxes in AOCI and then recognized in income when the underlying hedged transaction affects income. Gains and losses on foreign currency forward contracts that do not meet hedge accounting criteria are recognized in income immediately. Notional amounts are used to measure the volume of foreign currency forward contracts and do not represent exposure to foreign currency losses. The table below presents the notional amounts of the Company’s outstanding foreign currency forward contracts by currency at September 27, 2013.


	Currency		Notional Amounts
			(in millions)
	Canadian dollar		$	182
	U.S. dollar			119
	Euro			59
	British pound			21

	Total		$	381

	At September 27, 2013, the Company’s foreign currency forward contracts had maturities through 2018.
	Embedded Derivative. The embedded derivative related to the issuance of the CODES is recorded at fair value, which was zero at September 27, 2013 and December 31, 2012.

	The table below presents the location of the Company’s derivative instruments recorded at fair value on the condensed consolidated balance sheets.


			September 27, 2013								December 31, 2012
			Other		Other		Other		Other		Other		Other		Other		Other
			Current		Assets		Current		Liabilities		Current		Assets		Current		Liabilities
			Assets				Liabilities				Assets				Liabilities
			(in millions)
	Derivatives designated as hedging instruments:
	Foreign currency forward contracts(1)		$	6	$	2	$	1	$	1	$	4	$	4	$	2	$	1
	Derivatives not designated as hedging instruments:
	Foreign currency forward contracts(1)			—		—		—		—		—		—		—		—
	Embedded derivative related to the CODES			—		—		—		—		—		—		—		—

	Total derivative instruments		$	6	$	2	$	1	$	1	$	4	$	4	$	2	$	1


	(1)	See Note 14 for a description of the fair value hierarchy related to the Company’s foreign currency forward contracts.
	The effect of gains or losses from foreign currency forward contracts was not material to the unaudited condensed consolidated statements of operations for the quarterly or year-to-date periods ended September 27, 2013 and September 28, 2012. At September 27, 2013, the estimated amount of existing losses that are expected to be reclassified into income within the next 12 months is $3 million.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 27, 2013
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	17. Commitments and Contingencies
	Guarantees
	In connection with the spin-off of Engility, L-3 entered into a Distribution Agreement and several other agreements that govern certain aspects of L-3’s relationship with Engility, including employee matters, tax matters, transition services, and the future supplier/customer relationship between L-3 and Engility. These agreements generally provide cross-indemnities that, except as otherwise provided, are principally designed to place the financial responsibility for the obligations and liabilities of each entity with that respective entity. Engility has joint and several liability with L-3 to the U.S. Internal Revenue Service (IRS) for the consolidated U.S. Federal income taxes of L-3’s consolidated group for taxable periods in which Engility was a part of that group. However, the Tax Matters Agreement specifies the portion of this tax liability for which L-3 and Engility will each bear responsibility, and L-3 and Engility have agreed to indemnify each other against any amounts for which the other is not responsible. The Tax Matters Agreement also allocates responsibility between L-3 and Engility for other taxes, including special rules for allocating tax liabilities in the event that the spin-off is determined not to be tax-free. Though valid as between the parties, the Tax Matters Agreement is not binding on the IRS.
	Procurement Regulations
	A substantial majority of the Company’s revenues are generated from providing products and services under legally binding agreements or contracts with U.S. Government and foreign government customers. U.S. Government contracts are subject to extensive legal and regulatory requirements, and from time to time, agencies of the U.S. Government investigate whether such contracts were and are being conducted in accordance with these requirements. The Company is currently cooperating with the U.S. Government on several investigations from which civil, criminal or administrative proceedings have or could result and give rise to fines, penalties, compensatory and treble damages, restitution and/or forfeitures. The Company does not currently anticipate that any of these investigations will have a material adverse effect, individually or in the aggregate, on its consolidated financial position, results of operations or cash flows. However, under U.S. Government regulations, an indictment of the Company by a federal grand jury, or an administrative finding against the Company as to its present responsibility to be a U.S. Government contractor or subcontractor, could result in the Company being suspended for a period of time from eligibility for awards of new government contracts or task orders or in a loss of export privileges. A conviction, or an administrative finding against the Company that satisfies the requisite level of seriousness, could result in debarment from contracting with the federal government for a specified term. In addition, all of the Company’s U.S. Government contracts: (1) are subject to audit and various pricing and cost controls, (2) include standard provisions for termination for the convenience of the U.S. Government or for default, and (3) are subject to cancellation if funds for contracts become unavailable. Foreign government contracts generally include comparable provisions relating to terminations for convenience and default, as well as other procurement clauses relevant to the foreign government.
	Litigation Matters
	The Company is also subject to litigation, proceedings, claims or assessments and various contingent liabilities incidental to its businesses, including those specified below. Furthermore, in connection with certain business acquisitions, the Company has assumed some or all claims against, and liabilities of, such acquired businesses, including both asserted and unasserted claims and liabilities.
	In accordance with the accounting standard for contingencies, the Company records a liability when management believes that it is both probable that a liability has been incurred and the Company can reasonably estimate the amount of the loss. Generally, the loss is recorded at the amount the Company expects to resolve the liability. The estimated amounts of liabilities recorded for pending and threatened litigation are disclosed in Note 8. Amounts recoverable from insurance contracts or third parties are recorded as assets when deemed probable. At September 27, 2013, the Company did not record any amounts for recoveries from insurance contracts or third parties in connection with the amount of liabilities recorded for pending and threatened litigation. Legal defense costs are expensed as incurred. The Company believes it has recorded adequate provisions for its litigation matters. The Company reviews these provisions quarterly and adjusts these provisions to reflect the impact of negotiations, settlements, rulings, advice of legal counsel and other information and events pertaining to a particular matter. While it is reasonably possible that an unfavorable outcome may occur in one or more of the following matters, unless otherwise stated below, the Company believes that it is not probable that a loss has been incurred in any of these matters. With respect to the litigation matters below for which it is reasonably possible that an unfavorable outcome may occur, an estimate of loss or range of loss is disclosed when such amount or amounts can be reasonably estimated. Although the Company believes that it has valid defenses with respect to legal matters and investigations pending against it, the results of litigation can be difficult to predict, particularly those involving jury trials. Accordingly, our current judgment as to the likelihood of our loss (or our current estimate as to the potential range of loss, if applicable) with respect to any particular litigation matter may turn out to be wrong. Therefore, it is possible that the financial position, results of operations or cash flows of the Company could be materially adversely affected in any particular period by the unfavorable resolution of one or more of these or other contingencies.

	Kalitta Air. On January 31, 1997, a predecessor of Kalitta Air filed a lawsuit in the U.S. District Court for the Northern District of California (the trial court) asserting, among other things, negligence and negligent misrepresentation against Central Texas Airborne Systems, Inc. (CTAS), a predecessor to L-3 Integrated Systems (L-3 IS), in connection with work performed by a predecessor to CTAS to convert two Boeing 747 aircraft from passenger configuration to cargo freighters. CTAS’ insurance carrier has accepted defense of this matter and has retained counsel, subject to a reservation of rights by the insurer to dispute its obligations under the applicable insurance policies in the event a judgment is ultimately rendered against CTAS. The work at issue in the lawsuit was performed using Supplemental Type Certificates (STCs) issued in 1988 by the Federal Aviation Administration (FAA). In 1996, following completion of the work, the FAA issued an airworthiness directive with respect to the STCs that effectively grounded the aircraft. Following two jury trials (in which Kalitta Air did not prevail) and related appeals to the U.S. Court of Appeals for the Ninth Circuit (the Court of Appeals), a third jury trial for this matter began on October 31, 2011, during which Kalitta Air sought damages of approximately $235 million plus an unspecified amount of pre-judgment interest that, in other contexts, has been claimed by Kalitta Air to exceed $240 million. Following the completion of the third trial on November 30, 2011, the jury rendered a verdict in favor of CTAS, finding no negligence on the part of CTAS. The trial court entered a judgment upon the verdict on March 20, 2012. Kalitta Air filed an appeal of the judgment with the Court of Appeals on July 23, 2012. The appeal has been fully briefed, and oral argument has been scheduled for November 8, 2013.
	Bashkirian Airways. On July 1, 2004, lawsuits were filed on behalf of the estates of 31 Russian children in the state courts of Washington, Arizona, California, Florida, New York and New Jersey against Honeywell, Honeywell TCAS, Thales USA, Thales France, the Company and Aviation Communications & Surveillance Systems (ACSS), which is a joint venture of L-3 and Thales. The suits relate to the crash over southern Germany of a Bashkirian Airways Tupelov TU 154M aircraft and a DHL Boeing 757 cargo aircraft. On-board the Tupelov aircraft were 9 crew members and 60 passengers, including 45 children. The Boeing aircraft carried a crew of two. Both aircraft were equipped with Honeywell/ACSS Model 2000, Change 7 Traffic Collision and Avoidance Systems (TCAS). Sensing the other aircraft, the on-board DHL TCAS instructed the DHL pilot to descend, and the Tupelov on-board TCAS instructed the Tupelov pilot to climb. However, the Swiss air traffic controller ordered the Tupelov pilot to descend. The Tupelov pilot disregarded the on-board TCAS and put the Tupelov aircraft into a descent striking the DHL aircraft in midair at approximately 35,000 feet. All crew and passengers of both planes were lost. Investigations by the National Transportation Safety Board after the crash revealed that both TCAS units were performing as designed. The suits allege negligence and strict product liability based upon the design of the units and the training provided to resolve conflicting commands and seek approximately $315 million in damages, including $150 million in punitive damages. The Company’s insurers have accepted defense of this matter and have retained counsel. The matters were consolidated in the U.S. District Court for the District of New Jersey, which then dismissed the actions on the basis of forum non conveniens. Plaintiffs representing 30 of the estates re-filed their complaint against ACSS on April 23, 2007 with the Barcelona Court’s Registry in Spain. On March 9, 2010, the court ruled in favor of the plaintiffs and entered judgment against ACSS in the amount of approximately $6.7 million, all of which represented compensatory damages. Both ACSS and the plaintiffs appealed the judgment. In May 2012, the appellate court ruled in favor of the plaintiffs and entered judgment against ACSS in the amount of $48 million. ACSS filed an appeal of the judgment with the Supreme Court of Spain on September 28, 2012. On July 1, 2013, the Supreme Court agreed to consider the appeal, and the parties are awaiting the Supreme Court’s decision. The Company believes that the ruling and the damages awarded are inconsistent with the law and evidence presented, and accordingly, that it is not probable that the Company has incurred a loss with respect to this matter. As of the date of this filing, 18 out of the 30 plaintiffs have released their claims against ACSS in consideration for payments made by the Company’s insurance carriers.

Pension_and_Other_Postretireme

Pension and Other Postretirement Benefits	9 Months Ended
Pension and Other Postretirement Benefits	Sep. 27, 2013
Compensation And Retirement Disclosure [Abstract]
Pension and Other Postretirement Benefits	18. Pension and Other Postretirement Benefits
	The following table summarizes the components of net periodic benefit cost for the Company’s pension and other postretirement benefit plans.


		Pension Plans												Postretirement Benefit Plans
		Third Quarter Ended						Year-to-Date Ended						Third Quarter Ended						Year-to-Date Ended
		September 27,			September 28,			September 27,			September 28,			September 27,			September 28,			September 27,			September 28,
		2013			2012			2013			2012			2013			2012			2013			2012
		(in millions)
	Components of net periodic benefit cost:
	Service cost	$	30		$	26		$	95		$	85		$	1		$	—		$	3		$	3
	Interest cost		33			34			99			100			2			2			5			7
	Expected return on plan assets		(41	)		(37	)		(124	)		(108	)		—			—			(2	)		(2	)
	Amortization of prior service costs (credits)		1			1			1			1			(1	)		(1	)		(2	)		(2	)
	Amortization of net loss		20			17			63			51			—			—			1			1
	Curtailment loss		2			4			2			5			—			—			—			—

	Net periodic benefit cost	$	45		$	45		$	136		$	134		$	2		$	1		$	5		$	7

	Contributions. The Company contributed cash of $93 million to its pension plans and $5 million to its other postretirement benefit plans during the year-to-date period ended September 27, 2013. The Company expects to contribute an additional $13 million to $52 million to its pension plans and $6 million to its other postretirement benefit plans during the fourth quarter ended December 31, 2013.

Employee_StockBased_Compensati

Employee Stock-Based Compensation	9 Months Ended
Employee Stock-Based Compensation	Sep. 27, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Employee Stock-Based Compensation	19. Employee Stock-Based Compensation
	During the year-to-date period ended September 27, 2013, the Company granted stock-based compensation under the Amended and Restated 2008 Long Term Performance Plan (2008 LTPP) in the form of stock options, restricted stock units and performance units further discussed below.
	Stock Options. The Company granted 741,692 stock options with an exercise price equal to the closing price of L-3 Holdings’ common stock on the date of grant. The options expire after 10 years from the date of grant and vest ratably over a three-year period on the annual anniversary of the date of grant. The options granted to our Chairman, President and Chief Executive Officer are also subject to performance-based vesting conditions. The weighted average grant date fair value for the options awarded on February 20, 2013, was $12.09 per option and was estimated using the Black-Scholes option-pricing model. The weighted average assumptions used in the valuation model for this grant are presented in the table below.


	Expected holding period (in years)	5.6
	Expected volatility	26.4	%
	Expected dividend yield	3.6	%
	Risk-free interest rate	1	%
	Restricted Stock Units. The Company granted 604,982 restricted stock units with a weighted average grant date fair value of $77.12 per share. Restricted stock units automatically convert into shares of L-3 Holdings’ common stock upon vesting, and are subject to forfeiture until certain restrictions have lapsed, including a three year cliff vesting period for employees and a one year cliff vesting period for non-employee directors, in each case starting on the date of grant.
	Performance Units. The Company granted 61,690 performance units with a weighted average grant date fair value per unit of $77.00. The final payout for these units is based on the achievement of pre-determined EPS goals established by the compensation committee of the Company’s Board of Directors for the three-year period ending December 31, 2015. The payout can range from zero to 200% of the original number of units awarded, which are converted into shares of L-3 Holdings’ common stock based on the then existing closing price at the end of the performance period.

Supplemental_Cash_Flow_Informa

Supplemental Cash Flow Information	9 Months Ended
Supplemental Cash Flow Information	Sep. 27, 2013
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	20. Supplemental Cash Flow Information


		Year-to-Date Ended
		September 27,		September 28,
		2013		2012
		(in millions)
	Interest paid on outstanding debt	$	133	$	152
	Income tax payments		168		248
	Income tax refunds		20		18

Segment_Information

Segment Information	9 Months Ended
Segment Information	Sep. 27, 2013
Segment Reporting [Abstract]
Segment Information	21. Segment Information
	The Company has four reportable segments, as described in Note 1. The Company evaluates the performance of its operating segments and reportable segments based on their sales and operating income. All corporate expenses are allocated to the Company’s operating segments using an allocation methodology prescribed by U.S. Government regulations for government contractors. Accordingly, all costs and expenses are included in the Company’s measure of segment profitability. Certain corporate expenses of $10 million for the year-to-date period ended September 28, 2012, that had previously been allocated to the Engility businesses, were retained by the Company and have been allocated to L-3’s four reportable segments.

	The tables below present net sales, operating income, depreciation and amortization and total assets by reportable segment.


		Third Quarter Ended						Year-to-Date Ended
		September 27,			September 28,			September 27,			September 28,
		2013			2012			2013			2012
		(in millions)
	Net Sales:
	C3ISR	$	754		$	889		$	2,533		$	2,642
	Electronic Systems		1,368			1,432			4,156			4,191
	P&LS		654			715			2,022			2,033
	NSS		323			353			987			1,042
	Elimination of intercompany sales		(103	)		(106	)		(325	)		(322	)

	Consolidated total	$	2,996		$	3,283		$	9,373		$	9,586

	Operating Income:
	C3ISR	$	63		$	93		$	224		$	272
	Electronic Systems		173			158			468			480
	P&LS		52			65			176			179
	NSS		26			15			66			56

	Consolidated total	$	314		$	331		$	934		$	987

	Depreciation and amortization:
	C3ISR	$	12		$	11		$	33		$	34
	Electronic Systems		34			34			105			105
	P&LS		4			4			12			15
	NSS		2			5			8			11

	Consolidated total	$	52		$	54		$	158		$	165



		September 27,			December 31,
		2013			2012
		(in millions)
	Total Assets:
	C3ISR	$	2,051		$	2,030
	Electronic Systems		8,277			8,077
	P&LS		2,091			1,997
	NSS		1,264			1,228
	Corporate		392			509

	Consolidated total	$	14,075		$	13,841

Accounting_Standards_Issued_an

Accounting Standards Issued and Not Yet Implemented	9 Months Ended
Accounting Standards Issued and Not Yet Implemented	Sep. 27, 2013
Accounting Changes And Error Corrections [Abstract]
Accounting Standards Issued and Not Yet Implemented	22. Accounting Standards Issued and Not Yet Implemented
Accounting Standards Issued and Not Yet Implemented	In July 2013, the FASB issued amendments to an accounting standard which requires an unrecognized tax benefit or portion of an unrecognized tax benefit to be presented as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward except when certain conditions exist. The amendments are effective for the Company for fiscal years beginning after December 15, 2013, including that year’s interim periods. The adoption of this standard will not impact the Company’s financial position, results of operations or cash flows.

Employee_Severance_and_Termina

Employee Severance and Termination Costs	9 Months Ended
Employee Severance and Termination Costs	Sep. 27, 2013
Restructuring And Related Activities [Abstract]
Employee Severance and Termination Costs	23. Employee Severance and Termination Costs
	Consistent with the Company’s strategy to continuously improve its cost structure and right-size its businesses, especially in view of sequestration and other DoD budget reductions, L-3 is completing employment reduction actions across several of its businesses to reduce both direct and indirect costs, including overhead and general and administrative costs. As a result of these initiatives and due to the impact of sequestration at certain affected business units, the Company recorded $19 million in employee severance and other termination costs with respect to approximately 1,400 employees during the year-to-date period ended September 27, 2013. During the year ended December 31, 2012, the Company recorded a total of $23 million in employee severance and other termination costs with respect to approximately 1,600 employees. Employee severance and other termination costs are reported within cost of sales on the unaudited condensed consolidated statement of operations. The remaining balance to be paid in connection with these initiatives was $8 million at September 27, 2013 and $9 million at December 31, 2012. Employee severance and other termination costs incurred by reportable segment for the year-to-date periods ended September 27, 2013 and September 28, 2012 are presented in the table below.


		Year-to-Date Ended
		September 27,		September 28,
		2013		2012
		(in millions)
	Reportable Segment
	C3ISR	$	5	$	4
	Electronic Systems		13		14
	P&LS		—		1
	NSS		1		—

	Consolidated	$	19	$	19

Condensed_Combining_Financial_

Condensed Combining Financial Information of L-3 Communications and Its Subsidiaries	9 Months Ended
	Sep. 27, 2013
Text Block [Abstract]
Condensed Combining Financial Information of L-3 Communications and Its Subsidiaries	24. Condensed Combining Financial Information of L-3 Communications and Its Subsidiaries
	L-3 Communications is a wholly-owned subsidiary of L-3 Holdings. The debt of L-3 Communications, including the Senior Notes and borrowings under amounts drawn against the Amended and Restated Revolving Credit Facility is guaranteed, on a joint and several, full and unconditional basis, by certain of its domestic subsidiaries (the “Guarantor Subsidiaries”) and, in the case of the Amended and Restated Revolving Credit Facility, by L-3 Holdings. The debt of L-3 Holdings, including the CODES, is guaranteed on a joint and several, full and unconditional basis, by L-3 Communications and the Guarantor Subsidiaries. See Note 10 to the audited consolidated financial statements for the year ended December 31, 2012, included in the Company’s Annual Report on Form 10-K. The foreign subsidiaries and certain domestic subsidiaries of L-3 Communications (the “Non-Guarantor Subsidiaries”) do not guarantee the debt of L-3 Communications or L-3 Holdings. None of the debt of L-3 Communications has been issued by its subsidiaries. There are no restrictions on the payment of dividends from the Guarantor Subsidiaries to L-3 Communications or from L-3 Communications to L-3 Holdings.
	Prior to the spin-off of Engility on July 17, 2012, Engility Holdings, Inc., Engility Corporation, International Resources Group Ltd. and LinCom Wireless, Inc. were guarantor subsidiaries. As a result of the spin-off, these entities no longer guarantee the debt of L-3 Communications or L-3 Holdings. Therefore, the results of operations and cash flows of the Engility businesses have been reclassified from guarantor subsidiaries to L-3 Communications as discontinued operations in the following condensed combining financial information.

	Under the terms of the indentures governing the Senior Notes, the guarantees of the Senior Notes will automatically and unconditionally be released and discharged: (1) upon the release of all guarantees of all other outstanding indebtedness of L-3 Communications Corporation, or (2) upon the determination that such guarantor is no longer a “domestic subsidiary”. Under the terms of the indenture governing the CODES, the guarantees of the CODES will be automatically and unconditionally released and discharged: (1) upon the release of guarantees of all other outstanding indebtedness of L-3 Holdings and its subsidiaries (other than a foreign subsidiary) or (2) upon the designation of such guarantor as an “excluded subsidiary.” In addition, the guarantees of the Senior Notes and the CODES will unconditionally be released and discharged in the event of a sale or other disposition of all of the assets of any guarantor, by way of merger, consolidation or otherwise, or a sale or other disposition of all of the capital stock of such guarantor.

	The following unaudited condensed combining financial information presents the results of operations, financial position and cash flows of: (1) L-3 Holdings, excluding L-3 Communications and its consolidated subsidiaries (the “Parent”), (2) L-3 Communications, excluding its consolidated subsidiaries, (3) the Guarantor Subsidiaries, (4) the Non-Guarantor Subsidiaries, and (5) the eliminations to arrive at the information for L-3 on a consolidated basis.




			L-3			L-3			Guarantor			Non-			Eliminations				Consolidated
			Holdings			Communications			Subsidiaries			Guarantor							L-3
			(Parent)									Subsidiaries
			(in millions)
	Condensed Combining Balance Sheets:
	At September 27, 2013:
	Current assets:
	Cash and cash equivalents		$	—		$	154		$	1		$	244		$	(22	)		$	377
	Billed receivables, net			—			381			480			223			—				1,084
	Contracts in process			—			1,053			1,260			378			—				2,691
	Other current assets			—			291			149			205			—				645

	Total current assets			—			1,879			1,890			1,050			(22	)			4,797
	Goodwill			—			2,290			4,285			1,182			—				7,757
	Other assets			—			797			517			207			—				1,521
	Investment in and amounts due from consolidated subsidiaries			6,444			7,075			3,584			—			(17,103	)			—

	Total assets		$	6,444		$	12,041		$	10,276		$	2,439		$	(17,125	)		$	14,075

	Current liabilities		$	—		$	852		$	1,038		$	635		$	(22	)		$	2,503
	Amounts due to consolidated subsidiaries			—			—			—			310			(310	)			—
	Other long-term liabilities			—			1,804			193			115			—				2,112
	Long-term debt			689			3,630			—			—			(689	)			3,630

	Total liabilities			689			6,286			1,231			1,060			(1,021	)			8,245

	L-3 shareholders’ equity			5,755			5,755			9,045			1,379			(16,179	)			5,755
	Noncontrolling interests			—			—			—			—			75				75

	Total equity			5,755			5,755			9,045			1,379			(16,104	)			5,830

	Total liabilities and equity		$	6,444		$	12,041		$	10,276		$	2,439		$	(17,125	)		$	14,075

	At December 31, 2012:
	Current assets:
	Cash and cash equivalents		$	—		$	246		$	—		$	242		$	(139	)		$	349
	Billed receivables, net			—			290			441			237			—				968
	Contracts in process			—			945			1,351			340			—				2,636
	Other current assets			—			248			163			191			—				602

	Total current assets			—			1,729			1,955			1,010			(139	)			4,555
	Goodwill			—			1,993			4,586			1,197			—				7,776
	Other assets			—			734			565			211			—				1,510
	Investment in and amounts due from consolidated subsidiaries			6,156			7,208			3,326			43			(16,733	)			—

	Total assets		$	6,156		$	11,664		$	10,432		$	2,461		$	(16,872	)		$	13,841

	Current liabilities		$	—		$	823		$	1,255		$	652		$	(139	)		$	2,591
	Other long-term liabilities			—			1,745			210			123			—				2,078
	Long-term debt			689			3,629			—			—			(689	)			3,629

	Total liabilities			689			6,197			1,465			775			(828	)			8,298

L-3 shareholders’ equity			5,467			5,467			8,967			1,686			(16,120	)			5,467
Noncontrolling interests			—			—			—			—			76				76

Total equity			5,467			5,467			8,967			1,686			(16,044	)			5,543

Total liabilities and equity		$	6,156		$	11,664		$	10,432		$	2,461		$	(16,872	)		$	13,841




		L-3			L-3			Guarantor			Non-			Eliminations				Consolidated
		Holdings			Communications			Subsidiaries			Guarantor							L-3
		(Parent)									Subsidiaries
		(in millions)
Condensed Combining Statements of Operations:
For the quarter ended September 27, 2013:
Total net sales		$	—		$	913		$	1,636		$	546		$	(99	)		$	2,996
Total cost of sales			(14	)		(855	)		(1,443	)		(483	)		113				(2,682	)

Operating (loss) income			(14	)		58			193			63			14				314
Interest expense			(5	)		(43	)		—			(1	)		5				(44	)
Interest and other income, net			—			2			1			—			—				3

(Loss) income before income taxes			(19	)		17			194			62			19				273
Benefit (provision) for income taxes			5			(3	)		(47	)		(15	)		(5	)			(65	)
Equity in net income of consolidated subsidiaries			218			190			—			—			(408	)			—

Net income			204			204			147			47			(394	)			208
Net income attributable to noncontrolling interests			—			—			—			—			(4	)			(4	)

Net income attributable to L-3		$	204		$	204		$	147		$	47		$	(398	)		$	204

Comprehensive income attributable to L-3		$	254		$	254		$	148		$	79		$	(481	)		$	254

For the quarter ended September 28, 2012:
Total net sales		$	—		$	892		$	1,929		$	550		$	(88	)		$	3,283
Total cost of sales			(15	)		(808	)		(1,743	)		(489	)		103				(2,952	)

Operating (loss) income			(15	)		84			186			61			15				331
Interest expense			(5	)		(48	)		—			—			5				(48	)
Interest and other income, net			—			3			(4	)		1			—				—
Debt retirement charge			—			(8	)		—			—			—				(8	)

(Loss) income from continuing operations before income taxes			(20	)		31			182			62			20				275
Benefit (provision) for income taxes			6			(9	)		(53	)		(18	)		(6	)			(80	)
Equity in net income of consolidated subsidiaries from continuing operations			206			171			—			—			(377	)			—

Income from continuing operations			192			193			129			44			(363	)			195
Loss from discontinued operations, net of income tax			—			(1	)		—			—			—				(1	)

Net income			192			192			129			44			(363	)			194
Net income attributable to noncontrolling interests			—			—			—			—			(2	)			(2	)

Net income attributable to L-3		$	192		$	192		$	129		$	44		$	(365	)		$	192

Comprehensive income attributable to L-3		$	249		$	249		$	129		$	92		$	(470	)		$	249



		L-3			L-3			Guarantor			Non-			Eliminations				Consolidated
		Holdings			Communications			Subsidiaries			Guarantor							L-3
		(Parent)									Subsidiaries
		(in millions)
Condensed Combining Statements of Operations:
For the year-to-date ended September 27, 2013:
Total net sales		$	—		$	2,841		$	5,089		$	1,711		$	(268	)		$	9,373
Total cost of sales			(42	)		(2,630	)		(4,550	)		(1,527	)		310				(8,439	)

Operating (loss) income			(42	)		211			539			184			42				934
Interest expense			(15	)		(130	)		—			(1	)		15				(131	)
Interest and other income, net			—			6			1			4			—				11

(Loss) income from continuing operations before income taxes			(57	)		87			540			187			57				814
Benefit (provision) for income taxes			16			(24	)		(150	)		(52	)		(16	)			(226	)
Equity in net income of consolidated subsidiaries			623			519			—			—			(1,142	)			—

Net income			582			582			390			135			(1,101	)			588
Net income attributable to noncontrolling interests			—			—			—			—			(6	)			(6	)

Net income attributable to L-3		$	582		$	582		$	390		$	135		$	(1,107	)		$	582

Comprehensive income attributable to L-3		$	603		$	603		$	391		$	112		$	(1,106	)		$	603

For the year-to-date ended September 28, 2012:
Total net sales		$	—		$	2,715		$	5,476		$	1,648		$	(253	)		$	9,586
Total cost of sales			(44	)		(2,475	)		(4,936	)		(1,441	)		297				(8,599	)

Operating (loss) income			(44	)		240			540			207			44				987
Interest expense			(15	)		(138	)		—			—			15				(138	)
Interest and other income, net			—			8			(4	)		2			—				6
Debt retirement charge			—			(8	)		—			—			—				(8	)

(Loss) income from continuing operations before income taxes			(59	)		102			536			209			59				847
Benefit (provision) for income taxes			19			(32	)		(173	)		(69	)		(19	)			(274	)
Equity in net income of consolidated subsidiaries from continuing operations			638			496			—			—			(1,134	)			—

Income from continuing operations			598			566			363			140			(1,094	)			573
Income from discontinued operations, net of income tax			—			32			—			—			—				32

Net income			598			598			363			140			(1,094	)			605
Net income attributable to noncontrolling interests			—			—			—			—			(7	)			(7	)

Net income attributable to L-3		$	598		$	598		$	363		$	140		$	(1,101	)		$	598

Comprehensive income attributable to L-3		$	661		$	661		$	366		$	168		$	(1,195	)		$	661



		L-3			L-3			Guarantor			Non-			Eliminations				Consolidated
		Holdings			Communications			Subsidiaries			Guarantor							L-3
		(Parent)									Subsidiaries
		(in millions)
Condensed Combining Statements of Cash Flows:
For the year-to-date ended September 27, 2013:
Operating activities:
Net cash from operating activities		$	555		$	86		$	523		$	101		$	(648	)		$	617

Investing activities:
Business acquisitions, net of cash acquired			—			(2	)		—			—			—				(2	)
Investments in L-3 Communications			(104	)		—			—			—			104				—
Other investing activities			—			(70	)		(53	)		(16	)		—				(139	)

Net cash used in investing activities			(104	)		(72	)		(53	)		(16	)		104				(141	)

Financing activities:
Common stock repurchased			(404	)		—			—			—			—				(404	)
Dividends paid on L-3 Holdings common stock			(151	)		—			—			—			—				(151	)
Dividends paid to L-3 Holdings			—			(555	)		—			—			555				—
Investments from L-3 Holdings			—			104			—			—			(104	)			—
Other financing activities			104			345			(469	)		(81	)		210				109

Net cash used in financing activities			(451	)		(106	)		(469	)		(81	)		661				(446	)

Effect of foreign currency exchange rate changes on cash			—			—			—			(2	)		—				(2	)

Net (decrease) increase in cash			—			(92	)		1			2			117				28
Cash and cash equivalents, beginning of the period			—			246			—			242			(139	)			349

Cash and cash equivalents, end of the period		$	—		$	154		$	1		$	244		$	(22	)		$	377

For the year-to-date ended September 28, 2012:
Operating activities:
Net cash from operating activities from continuing operations		$	653		$	83		$	527		$	182		$	(753	)		$	692

Investing activities:
Business acquisitions, net of cash acquired			—			(349	)		—			—			—				(349	)
Investments in L-3 Communications			(27	)		—			—			—			27				—
Other investing activities			—			262			(41	)		(9	)		—				212

Net cash used in investing activities from continuing operations			(27	)		(87	)		(41	)		(9	)		27				(137	)

Financing activities:
Redemption of senior subordinated notes			—			(250	)		—			—			—				(250	)
Common stock repurchased			(504	)		—			—			—			—				(504	)
Dividends paid on L-3 Holdings common stock			(149	)		—			—			—			—				(149	)
Dividends paid to L-3 Holdings			—			(653	)		—			—			653				—
Investments from L-3 Holdings			—			27			—			—			(27	)			—
Other financing activities			27			523			(485	)		(182	)		137				20

Net cash used in financing activities from continuing operations			(626	)		(353	)		(485	)		(182	)		763				(883	)

Effect of foreign currency exchange rate changes on cash			—			—			—			4			—				4
Net increase in cash and cash equivalents of discontinued operations			—			74			—			—			—				74

Net (decrease) increase in cash			—			(283	)		1			(5	)		37				(250	)
Cash and cash equivalents, beginning of the period			—			644			—			222			(102	)			764

Cash and cash equivalents, end of the period		$	—		$	361		$	1		$	217		$	(65	)		$	514

New_Accounting_Standards_Polic

New Accounting Standards (Policies)	9 Months Ended
New Accounting Standards (Policies)	Sep. 27, 2013
Accounting Changes And Error Corrections [Abstract]
Comprehensive Income	Effective January 1, 2013, the Company adopted a new accounting standard issued by the Financial Accounting Standards Board (FASB), which adds new disclosure requirements for items reclassified out of accumulated other comprehensive income (loss) (AOCI). This standard requires entities to disclose additional information about reclassification adjustments, including: (1) changes in AOCI balances by component and (2) significant items reclassified out of AOCI. The adoption of this standard resulted in additional disclosures of items reclassified out of AOCI and did not impact the Company’s financial position, results of operations or cash flows. See Note 11 for these additional disclosures.

Dispositions_and_Acquisitions_

Dispositions and Acquisitions (Tables)	9 Months Ended
Dispositions and Acquisitions (Tables)	Sep. 27, 2013
Business Combinations [Abstract]
Statement of Operations Data Classified as Discontinued Operations	Statement of operations data classified as discontinued operations related to Engility is provided in the table below.




		Third Quarter Ended			Year-to-Date Ended
		September 28, 2012			September 28, 2012
		(in millions)
	Product and service revenues	$	68		$	911

	Operating income from discontinued operations before income taxes		2			68
	Interest expense allocated to discontinued operations		(1	)		(14	)

	Income from discontinued operations before income taxes	$	1		$	54
	Income tax expense		(2	)		(22	)

	(Loss) income from discontinued operations, net of income taxes	$	(1	)	$	32
	Net income from discontinued operations attributable to noncontrolling interests		—			(4	)

	Net (loss) income from discontinued operations attributable to L-3	$	(1	)	$	28

Unaudited Pro Forma Statements of Operations Data	The following unaudited pro forma Statement of Operations data presents the combined results of the Company and its business acquisitions completed during the year ended December 31, 2012, in each case assuming that the business acquisitions completed during the year ended December 31, 2012 had occurred on January 1, 2012.


		Third Quarter Ended			Year-to-Date Ended
		September 28,			September 28,
		2012			2012
		(in millions, except per share data)
	Pro forma net sales	$	3,295		$	9,688
	Pro forma income from continuing operations		195			574
	Pro forma net income attributable to L-3		192			599
	Pro forma diluted earnings per share from continuing operations		1.98			5.79
	Pro forma diluted earnings per share		1.97			6.07

Contracts_in_Process_Tables

Contracts in Process (Tables)	9 Months Ended
Contracts in Process (Tables)	Sep. 27, 2013
Text Block [Abstract]
Components of Contracts in Process	The components of contracts in process are presented in the table below.


		September 27,			December 31,
		2013			2012
		(in millions)
	Unbilled contract receivables, gross	$	2,714		$	2,879
	Unliquidated progress payments		(1,051	)		(1,265	)

	Unbilled contract receivables, net		1,663			1,614

	Inventoried contract costs, gross		1,093			1,090
	Unliquidated progress payments		(65	)		(68	)

	Inventoried contract costs, net		1,028			1,022

	Total contracts in process	$	2,691		$	2,636

General and Administrative, Independent Research and Development and Bid and Proposal Costs	The table below presents a summary of G&A, IRAD and B&P costs included in inventoried contract costs and the changes to them, including amounts charged to cost of sales by the Company’s U.S. Government contractor businesses for the periods presented.


		Third Quarter Ended						Year-to-Date Ended
		September 27,			September 28,			September 27,			September 28,
		2013			2012			2013			2012
		(in millions)
	Amounts included in inventoried contract costs at beginning of the period	$	115		$	105		$	110		$	91
	IRAD and B&P costs		66			83			219			254
	Other G&A costs		218			213			655			647

	Total contract costs incurred		284			296			874			901

	Amounts charged to cost of sales		(273	)		(289	)		(858	)		(880	)

	Amounts included in inventoried contract costs at end of the period	$	126		$	112		$	126		$	112

Selling, General and Administrative Expenses and Research and Development Expenses	The table below presents a summary of selling, general and administrative expenses and research and development expenses for the Company’s commercial businesses, which are expensed as incurred and not included in inventoried contract costs.


		Third Quarter Ended						Year-to-Date Ended
		September 27,			September 28,			September 27,			September 28,
		2013			2012			2013			2012
		(in millions)
	Selling, general and administrative expenses	$	68		$	58		$	212		$	196
	Research and development expenses		17			18			62			63

	Total	$	85		$	76		$	274		$	259

Inventories_Tables

Inventories (Tables)	9 Months Ended
Inventories (Tables)	Sep. 27, 2013
Inventory Disclosure [Abstract]
Inventories at Lower of Cost or Market	Inventories at Lower of Cost or Market. The table below presents the components of inventories at the lower of cost (first-in, first-out or average cost) or realizable value.


		September 27,		December 31,
		2013		2012
		(in millions)
	Raw materials, components and sub-assemblies	$	174	$	168
	Work in process		155		124
	Finished goods		91		71

	Total	$	420	$	363

Goodwill_and_Identifiable_Inta1

Goodwill and Identifiable Intangible Assets (Tables)	9 Months Ended
Goodwill and Identifiable Intangible Assets (Tables)	Sep. 27, 2013
Goodwill And Intangible Assets Disclosure [Abstract]
Changes in Goodwill by Segment	The table below presents the changes in goodwill by segment for the year-to-date period ended September 27, 2013.


			C3ISR				Electronic				P&LS				NSS				Consolidated
			C3ISR				Systems				P&LS				NSS				Total
			(in millions)
	Balance at December 31, 2012		$	797			$	4,836			$	1,175			$	968			$	7,776
	Business dispositions			—				(2	)			—				—				(2	)
	Foreign currency translation adjustments(1)			—				(7	)			(10	)			—				(17	)

	Balance at September 27, 2013		$	797			$	4,827			$	1,165			$	968			$	7,757


	(1)	The decreases in goodwill presented in the Electronic Systems and P&LS segments were primarily due to the strengthening of the U.S. dollar against the Canadian dollar and Australian dollar, partially offset by the weakening of the U.S. dollar against the Euro during the year-to-date period ended September 27, 2013.
Identifiable Intangible Assets	Identifiable Intangible Assets. Information on the Company’s identifiable intangible assets that are subject to amortization is presented in the table below.


			September 27, 2013														December 31, 2012
			Weighted		Gross				Accumulated				Net				Gross				Accumulated		Net
			Average		Carrying				Amortization				Carrying				Carrying				Amortization		Carrying
			Amortization		Amount								Amount				Amount						Amount
			Period
			(in years)		(in millions)
	Customer contractual relationships		19		$	461			$	246			$	215			$	460			$	225	$	235
	Technology		11			164				105				59				164				98		66
	Other		17			27				15				12				27				14		13

	Total		17		$	652			$	366			$	286			$	651			$	337	$	314

Amortization Expense	Amortization expense recorded by the Company for its identifiable intangible assets is presented in the table below.


			Third Quarter Ended								Year-to-Date Ended
			September 27,				September 28,				September 27,				September 28,
			2013				2012				2013				2012
			(in millions)
	Amortization Expense		$	10			$	13			$	29			$	34

Estimated Amortization Expense	Based on gross carrying amounts at September 27, 2013, the Company’s estimate of amortization expense for identifiable intangible assets for the years ending December 31, 2013 through 2017 are presented in the table below.


			Year Ending December 31,
			2013				2014				2015				2016				2017
			(in millions)
	Estimated amortization expense		$	38			$	42			$	39			$	32			$	31

Other_Current_Liabilities_and_1

Other Current Liabilities and Other Liabilities (Tables)	9 Months Ended
Other Current Liabilities and Other Liabilities (Tables)	Sep. 27, 2013
Text Block [Abstract]
Other Current Liabilities	The table below presents the components of other current liabilities.


			September 27,			December 31,
			2013			2012
			(in millions)
	Other Current Liabilities:
	Accruals for pending and threatened litigation (see Note 17)		$	5		$	7
	Accrued product warranty costs			76			78
	Estimated costs in excess of estimated contract value to complete contracts in process in a loss position			67			72
	Accrued interest			46			53
	Deferred revenues			38			37
	Estimated contingent purchase price payable for acquired businesses			—			4
	Other			151			144

	Total other current liabilities		$	383		$	395


Other Liabilities	The table below presents the components of other liabilities.


			September 27,			December 31,
			2013			2012
			(in millions)
	Other Liabilities:
	Non-current income taxes payable (see Note 10)		$	145		$	137
	Accrued workers’ compensation			53			57
	Deferred compensation			45			43
	Accrued product warranty costs			24			22
	Notes payable and capital lease obligations			17			24
	Estimated contingent purchase price payable for acquired businesses			—			5
	Other			73			102

	Total other liabilities		$	357		$	390

Changes in Company's Accrued Product Warranty Costs	The table below presents the changes in the Company’s accrued product warranty costs.


			Year-to-Date Ended
			September 27,			September 28,
			2013			2012
			(in millions)
	Accrued product warranty costs:(1)
	Balance at January 1		$	100		$	94
	Acquisitions during the period			—			2
	Accruals for product warranties issued during the period			56			56
	Settlements made during the period			(56	)		(58	)

	Balance at end of period		$	100		$	94


	(1)	Warranty obligations incurred in connection with long-term production contracts that are accounted for under the POC cost-to-cost method are included within the contract estimates at completion and are excluded from the above amounts. The balances above include both the current and non-current amounts.

Debt_Tables

Debt (Tables)	9 Months Ended
Debt (Tables)	Sep. 27, 2013
Debt Disclosure [Abstract]
Components of Debt and Reconciliation to Carrying Amount of Long-Term Debt	The components of debt and a reconciliation to the carrying amount of long-term debt is presented in the table below.


			September 27,			December 31,
			2013			2012
			(in millions)
	L-3 Communications:
	Borrowings under Amended and Restated Revolving Credit Facility(1)		$	—		$	—
	3.95% Senior Notes due 2016			500			500
	5.20% Senior Notes due 2019			1,000			1,000
	4.75% Senior Notes due 2020			800			800
	4.95% Senior Notes due 2021			650			650

	Subtotal			2,950			2,950

	L-3 Holdings:
	3% Convertible Contingent Debt Securities due 2035(2)			689			689

	Principal amount of long-term debt			3,639			3,639
	Unamortized discounts			(9	)		(10	)

	Carrying amount of long-term debt		$	3,630		$	3,629


	(1)	During the year-to-date period ended September 27, 2013, L-3 Communications’ aggregate borrowings and repayments under the Amended and Restated Revolving Credit Facility was $1,382 million. At September 27, 2013, L-3 Communications had the availability of substantially all of its $1 billion Amended and Restated Revolving Credit Facility, which expires on February 3, 2017.

	(2)	Under select conditions, including if L-3 Holdings’ common stock price is more than 120% (currently $108.29) of the then current conversion price (currently $90.24) for a specified period, the conversion feature of the CODES will require L-3 Holdings, upon conversion, to pay the holders of the CODES the principal amount in cash, 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. At the current conversion price of $90.24, the aggregate consideration to be delivered upon conversion would be determined based on 7.6 million shares of L-3 Holdings’ common stock. See Note 10 to the audited consolidated financial statements for the year ended December 31, 2012, included in the Company’s Annual Report on Form 10-K, for additional information regarding the CODES, including conditions for conversion. L-3 Holdings’ closing stock price on October 23, 2013 was $95.98 share. Interest expense recognized was $5 million for both quarterly periods ended September 27, 2013 and September 28, 2012 and $15 million for both year-to-date periods ended September 27, 2013 and September 28, 2012. A portion of this interest expense was allocated to discontinued operations for the quarterly and year-to-date periods ended September 28, 2012 as a result of the spin-off of Engility. The carrying amount of the equity component (conversion feature) of the CODES was $64 million at September 27, 2013 and December 31, 2012.

Amounts_Reclassified_Out_of_Ac1

Amounts Reclassified Out of Accumulated Other Comprehensive (Loss) Income (Tables)	9 Months Ended
	Sep. 27, 2013
Text Block [Abstract]
Summary of Amounts Reclassified Out of Accumulated Other Comprehensive (Loss) Income	Amounts reclassified out of AOCI for the year-to-date period ended September 27, 2013 are presented in the table below.


			Foreign			Unrealized			Unrecognized			Total
			currency			gains			losses and			accumulated
			translation			(losses) on			prior service			other
						hedging			cost, net			comprehensive
						instruments						(loss) income
			(in millions)
	Balance at December 31, 2012		$	167		$	3		$	(720	)	$	(550	)
	Other comprehensive loss before reclassifications, net of tax			(18	)		(2	)		—			(20	)
	Amounts reclassified from other comprehensive income, net of tax			—			1			40			41

	Net current period other comprehensive (loss) income			(18	)		(1	)		40			21

	Balance at September 27, 2013		$	149		$	2		$	(680	)	$	(529	)


	Further details regarding the amounts reclassified from AOCI for the quarterly and year-to-date periods ended September 27, 2013 are presented in the table below.


			Amount Reclassified from Accumulated						Affected Line Item in the
			Other Comprehensive (Loss) Income						Unaudited Condensed Consolidated
			Third Quarter Ended			Year-to-Date			Statement of Operations
			Third Quarter Ended			Ended
	Details About Accumulated Other		September 27,			September 27,
	Comprehensive (Loss) Income Components		2013			2013
			(in millions)
	Gain on hedging instruments		$	—		$	1		Cost of sales-products

				—			1		Income from continuing operations
				—			1		before income taxes
				—			—		Provision for income taxes

			$	—		$	1		Income from continuing operations

	Amortization of defined benefit pension items:
	Net loss		$	20		$	63		(a)

				20			63		Income from continuing operations
				20			63		before income taxes
				(7	)		(23	)	Provision for income taxes

			$	13		$	40		Income from continuing operations

	Total reclassification for the period		$	13		$	41		Income from continuing operations


	(a)	Amounts related to pension and postretirement benefit plans were reclassified from AOCI and recorded as a component of net periodic benefit cost (see Note 18 for additional information).

L3_Holdings_Earnings_Per_Commo1

L-3 Holdings' Earnings Per Common Share (Tables)	9 Months Ended
L-3 Holdings' Earnings Per Common Share (Tables)	Sep. 27, 2013
Earnings Per Share [Abstract]
Reconciliation of Basic and Diluted Earnings Per Share	A reconciliation of basic and diluted earnings per share (EPS) is presented in the table below.


			Third Quarter Ended						Year-to-Date Ended
			September 27,			September 28,			September 27,			September 28,
			2013			2012			2013			2012
			(in millions, except per share data)
	Reconciliation of net income:
	Net income		$	208		$	194		$	588		$	605
	Net income from continuing operations attributable to noncontrolling interests			(4	)		(2	)		(6	)		(3	)
	Net income from discontinued operations attributable to noncontrolling interests			—			—			—			(4	)

	Net income attributable to L-3 Holdings’ common shareholders		$	204		$	192		$	582		$	598

	Earnings (loss) attributable to L-3 Holdings’ common shareholders:
	Continuing operations		$	204		$	193		$	582		$	570
	Discontinued operations, net of income tax			—			(1	)		—			28

	Net income attributable to L-3 Holdings’ common shareholders		$	204		$	192		$	582		$	598

	Earnings (loss) per share attributable to L-3 Holdings’ common shareholders:
	Basic:
	Weighted average common shares outstanding			89.6			96.1			89.9			97.4

	Basic earnings (loss) per share:
	Continuing operations		$	2.28		$	2.01		$	6.47		$	5.85
	Discontinued operations, net of income tax			—			(0.01	)		—			0.29

	Basic earnings per share		$	2.28		$	2		$	6.47		$	6.14

	Diluted:
	Common and potential common shares:
	Weighted average common shares outstanding			89.6			96.1			89.9			97.4
	Assumed exercise of stock options			4.7			2.1			3.9			1.7
	Unvested restricted stock awards			1.8			2			1.8			2.1
	Employee stock purchase plan contributions			0.2			0.3			0.2			0.3
	Performance unit awards			0.1			—			0.1			—
	Assumed purchase of common shares for treasury			(5.2	)		(3.1	)		(4.7	)		(2.8	)
	Assumed conversion of the CODES(1)			0.1			—			0.1			—

	Common and potential common shares			91.3			97.4			91.3			98.7

	Diluted earnings (loss) per share:
	Continuing operations		$	2.23		$	1.98		$	6.37		$	5.78
	Discontinued operations, net of income tax			—			(0.01	)		—			0.28

	Diluted earnings per share		$	2.23		$	1.97		$	6.37		$	6.06


	(1)	L-3 Holdings’ CODES had no impact on diluted EPS for the quarterly or year-to-date periods ended September 28, 2012 as the average market price of L-3 Holdings common stock during these periods was less than the price at which the CODES would have been convertible into L-3 Holdings common stock. As of September 27, 2013, the conversion price was $90.24.

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	9 Months Ended
Fair Value Measurements (Tables)	Sep. 27, 2013
Fair Value Disclosures [Abstract]
Company's Assets and Liabilities at Fair Value on Recurring Basis	The following table presents the fair value hierarchy level for each of the Company’s assets and liabilities that are measured and recorded at fair value on a recurring basis.


			September 27, 2013						December 31, 2012
	Description		Level 1(1)		Level 2(2)		Level 3(3)		Level 1(1)		Level 2(2)		Level 3(3)
			(in millions)
	Assets
	Cash equivalents		$	199	$	—	$	—	$	284	$	—	$	—
	Derivatives (foreign currency forward contracts)			—		8		—		—		8		—

	Total Assets		$	199	$	8	$	—	$	284	$	8	$	—

	Liabilities
	Derivatives (foreign currency forward contracts)		$	—	$	2	$	—	$	—	$	3	$	—

	(1)	Level 1 is based on quoted market prices available in active markets for identical assets or liabilities as of the reporting date. Cash equivalents are primarily held in registered money market funds, which are valued using quoted market prices.

	(2)	Level 2 is based on pricing inputs other than quoted prices in active markets, which are either directly or indirectly observable. The fair value is determined using a valuation model based on observable market inputs, including quoted foreign currency forward exchange rates and consideration of non-performance risk.

	(3)	Level 3 is based on pricing inputs that are not observable and not corroborated by market data. The Company has no Level 3 assets or liabilities.

Financial_Instruments_Tables

Financial Instruments (Tables)	9 Months Ended
Financial Instruments (Tables)	Sep. 27, 2013
Investments All Other Investments [Abstract]
Carrying Amounts and Estimated Fair Values of Company's Long-Term Debt and Foreign Currency Forward Contracts	The carrying amounts and estimated fair values of the Company’s financial instruments are presented in the table below.


			September 27, 2013				December 31, 2012
			Carrying		Estimated		Carrying		Estimated
			Amount		Fair Value		Amount		Fair Value
			(in millions)
	Senior Notes(1)		$	2,941	$	3,131	$	2,940	$	3,301
	CODES(1)			689		752		689		697
	Foreign currency forward contracts(2)			6		6		5		5

	(1)	The Company measures the fair value of its Senior Notes and CODES using Level 2 inputs based primarily on current market yields for its existing debt traded in the secondary market.

	(2)	See Note 16 for additional disclosures regarding the notional amounts and fair values of foreign currency forward contracts.

Derivative_Financial_Instrumen1

Derivative Financial Instruments (Tables)	9 Months Ended
Derivative Financial Instruments (Tables)	Sep. 27, 2013
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Notional Amounts of Company's Outstanding Foreign Currency Forward Contracts by Currency	The table below presents the notional amounts of the Company’s outstanding foreign currency forward contracts by currency at September 27, 2013.


	Currency		Notional Amounts
			(in millions)
	Canadian dollar		$	182
	U.S. dollar			119
	Euro			59
	British pound			21

	Total		$	381

Location of Company's Derivative Instruments Recorded at Fair Value on Condensed Consolidated Balance Sheets	The table below presents the location of the Company’s derivative instruments recorded at fair value on the condensed consolidated balance sheets.


			September 27, 2013								December 31, 2012
			Other		Other		Other		Other		Other		Other		Other		Other
			Current		Assets		Current		Liabilities		Current		Assets		Current		Liabilities
			Assets				Liabilities				Assets				Liabilities
			(in millions)
	Derivatives designated as hedging instruments:
	Foreign currency forward contracts(1)		$	6	$	2	$	1	$	1	$	4	$	4	$	2	$	1
	Derivatives not designated as hedging instruments:
	Foreign currency forward contracts(1)			—		—		—		—		—		—		—		—
	Embedded derivative related to the CODES			—		—		—		—		—		—		—		—

	Total derivative instruments		$	6	$	2	$	1	$	1	$	4	$	4	$	2	$	1


	(1)	See Note 14 for a description of the fair value hierarchy related to the Company’s foreign currency forward contracts.

Pension_and_Other_Postretireme1

Pension and Other Postretirement Benefits (Tables)	9 Months Ended
Pension and Other Postretirement Benefits (Tables)	Sep. 27, 2013
Compensation And Retirement Disclosure [Abstract]
Components of Net Periodic Benefit Cost	The following table summarizes the components of net periodic benefit cost for the Company’s pension and other postretirement benefit plans.


		Pension Plans												Postretirement Benefit Plans
		Third Quarter Ended						Year-to-Date Ended						Third Quarter Ended						Year-to-Date Ended
		September 27,			September 28,			September 27,			September 28,			September 27,			September 28,			September 27,			September 28,
		2013			2012			2013			2012			2013			2012			2013			2012
		(in millions)
	Components of net periodic benefit cost:
	Service cost	$	30		$	26		$	95		$	85		$	1		$	—		$	3		$	3
	Interest cost		33			34			99			100			2			2			5			7
	Expected return on plan assets		(41	)		(37	)		(124	)		(108	)		—			—			(2	)		(2	)
	Amortization of prior service costs (credits)		1			1			1			1			(1	)		(1	)		(2	)		(2	)
	Amortization of net loss		20			17			63			51			—			—			1			1
	Curtailment loss		2			4			2			5			—			—			—			—

	Net periodic benefit cost	$	45		$	45		$	136		$	134		$	2		$	1		$	5		$	7

Employee_StockBased_Compensati1

Employee Stock-Based Compensation (Tables)	9 Months Ended
Employee Stock-Based Compensation (Tables)	Sep. 27, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Weighted Average Assumptions in Valuation Model	The weighted average assumptions used in the valuation model for this grant are presented in the table below.


	Expected holding period (in years)	5.6
	Expected volatility	26.4	%
	Expected dividend yield	3.6	%
	Risk-free interest rate	1	%

Supplemental_Cash_Flow_Informa1

Supplemental Cash Flow Information (Tables)	9 Months Ended
Supplemental Cash Flow Information (Tables)	Sep. 27, 2013
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information
		Year-to-Date Ended
		September 27,		September 28,
		2013		2012
		(in millions)
	Interest paid on outstanding debt	$	133	$	152
	Income tax payments		168		248
	Income tax refunds		20		18

Segment_Information_Tables

Segment Information (Tables)	9 Months Ended
Segment Information (Tables)	Sep. 27, 2013
Segment Reporting [Abstract]
Summary of Segment Information	The tables below present net sales, operating income, depreciation and amortization and total assets by reportable segment.


		Third Quarter Ended						Year-to-Date Ended
		September 27,			September 28,			September 27,			September 28,
		2013			2012			2013			2012
		(in millions)
	Net Sales:
	C3ISR	$	754		$	889		$	2,533		$	2,642
	Electronic Systems		1,368			1,432			4,156			4,191
	P&LS		654			715			2,022			2,033
	NSS		323			353			987			1,042
	Elimination of intercompany sales		(103	)		(106	)		(325	)		(322	)

	Consolidated total	$	2,996		$	3,283		$	9,373		$	9,586

	Operating Income:
	C3ISR	$	63		$	93		$	224		$	272
	Electronic Systems		173			158			468			480
	P&LS		52			65			176			179
	NSS		26			15			66			56

	Consolidated total	$	314		$	331		$	934		$	987

	Depreciation and amortization:
	C3ISR	$	12		$	11		$	33		$	34
	Electronic Systems		34			34			105			105
	P&LS		4			4			12			15
	NSS		2			5			8			11

	Consolidated total	$	52		$	54		$	158		$	165



		September 27,			December 31,
		2013			2012
		(in millions)
	Total Assets:
	C3ISR	$	2,051		$	2,030
	Electronic Systems		8,277			8,077
	P&LS		2,091			1,997
	NSS		1,264			1,228
	Corporate		392			509

	Consolidated total	$	14,075		$	13,841

Employee_Severance_and_Termina1

Employee Severance and Termination Costs (Tables)	9 Months Ended
Employee Severance and Termination Costs (Tables)	Sep. 27, 2013
Restructuring And Related Activities [Abstract]
Employee Severance and Other Termination Costs Incurred by Reportable Segment	Employee severance and other termination costs incurred by reportable segment for the year-to-date periods ended September 27, 2013 and September 28, 2012 are presented in the table below.


		Year-to-Date Ended
		September 27,		September 28,
		2013		2012
		(in millions)
	Reportable Segment
	C3ISR	$	5	$	4
	Electronic Systems		13		14
	P&LS		—		1
	NSS		1		—

	Consolidated	$	19	$	19

Condensed_Combining_Financial_1

Condensed Combining Financial Information of L-3 Communications and Its Subsidiaries (Tables)	9 Months Ended
	Sep. 27, 2013
Text Block [Abstract]
Condensed Combining Balance Sheets


			L-3				L-3				Guarantor				Non-				Eliminations				Consolidated
			Holdings				Communications				Subsidiaries				Guarantor								L-3
			(Parent)												Subsidiaries
			(in millions)
	Condensed Combining Balance Sheets:
	At September 27, 2013:
	Current assets:
	Cash and cash equivalents		$	—			$	154			$	1			$	244			$	(22	)		$	377
	Billed receivables, net			—				381				480				223				—				1,084
	Contracts in process			—				1,053				1,260				378				—				2,691
	Other current assets			—				291				149				205				—				645

	Total current assets			—				1,879				1,890				1,050				(22	)			4,797
	Goodwill			—				2,290				4,285				1,182				—				7,757
	Other assets			—				797				517				207				—				1,521
	Investment in and amounts due from consolidated subsidiaries			6,444				7,075				3,584				—				(17,103	)			—

	Total assets		$	6,444			$	12,041			$	10,276			$	2,439			$	(17,125	)		$	14,075

	Current liabilities		$	—			$	852			$	1,038			$	635			$	(22	)		$	2,503
	Amounts due to consolidated subsidiaries			—				—				—				310				(310	)			—
	Other long-term liabilities			—				1,804				193				115				—				2,112
	Long-term debt			689				3,630				—				—				(689	)			3,630

	Total liabilities			689				6,286				1,231				1,060				(1,021	)			8,245

	L-3 shareholders’ equity			5,755				5,755				9,045				1,379				(16,179	)			5,755
	Noncontrolling interests			—				—				—				—				75				75

	Total equity			5,755				5,755				9,045				1,379				(16,104	)			5,830

	Total liabilities and equity		$	6,444			$	12,041			$	10,276			$	2,439			$	(17,125	)		$	14,075

	At December 31, 2012:
	Current assets:
	Cash and cash equivalents		$	—			$	246			$	—			$	242			$	(139	)		$	349
	Billed receivables, net			—				290				441				237				—				968
	Contracts in process			—				945				1,351				340				—				2,636
	Other current assets			—				248				163				191				—				602

	Total current assets			—				1,729				1,955				1,010				(139	)			4,555
	Goodwill			—				1,993				4,586				1,197				—				7,776
	Other assets			—				734				565				211				—				1,510
	Investment in and amounts due from consolidated subsidiaries			6,156				7,208				3,326				43				(16,733	)			—

	Total assets		$	6,156			$	11,664			$	10,432			$	2,461			$	(16,872	)		$	13,841

	Current liabilities		$	—			$	823			$	1,255			$	652			$	(139	)		$	2,591
	Other long-term liabilities			—				1,745				210				123				—				2,078
	Long-term debt			689				3,629				—				—				(689	)			3,629

	Total liabilities			689				6,197				1,465				775				(828	)			8,298

	L-3 shareholders’ equity			5,467				5,467				8,967				1,686				(16,120	)			5,467
	Noncontrolling interests			—				—				—				—				76				76

	Total equity			5,467				5,467				8,967				1,686				(16,044	)			5,543

	Total liabilities and equity		$	6,156			$	11,664			$	10,432			$	2,461			$	(16,872	)		$	13,841

Condensed Combining Statements of Operations
			L-3				L-3				Guarantor				Non-				Eliminations				Consolidated
			Holdings				Communications				Subsidiaries				Guarantor								L-3
			(Parent)												Subsidiaries
			(in millions)
	Condensed Combining Statements of Operations:
	For the quarter ended September 27, 2013:
	Total net sales		$	—			$	913			$	1,636			$	546			$	(99	)		$	2,996
	Total cost of sales			(14	)			(855	)			(1,443	)			(483	)			113				(2,682	)

	Operating (loss) income			(14	)			58				193				63				14				314
	Interest expense			(5	)			(43	)			—				(1	)			5				(44	)
	Interest and other income, net			—				2				1				—				—				3

	(Loss) income before income taxes			(19	)			17				194				62				19				273
	Benefit (provision) for income taxes			5				(3	)			(47	)			(15	)			(5	)			(65	)
	Equity in net income of consolidated subsidiaries			218				190				—				—				(408	)			—

	Net income			204				204				147				47				(394	)			208
	Net income attributable to noncontrolling interests			—				—				—				—				(4	)			(4	)

	Net income attributable to L-3		$	204			$	204			$	147			$	47			$	(398	)		$	204

	Comprehensive income attributable to L-3		$	254			$	254			$	148			$	79			$	(481	)		$	254

	For the quarter ended September 28, 2012:
	Total net sales		$	—			$	892			$	1,929			$	550			$	(88	)		$	3,283
	Total cost of sales			(15	)			(808	)			(1,743	)			(489	)			103				(2,952	)

	Operating (loss) income			(15	)			84				186				61				15				331
	Interest expense			(5	)			(48	)			—				—				5				(48	)
	Interest and other income, net			—				3				(4	)			1				—				—
	Debt retirement charge			—				(8	)			—				—				—				(8	)

	(Loss) income from continuing operations before income taxes			(20	)			31				182				62				20				275
	Benefit (provision) for income taxes			6				(9	)			(53	)			(18	)			(6	)			(80	)
	Equity in net income of consolidated subsidiaries from continuing operations			206				171				—				—				(377	)			—

	Income from continuing operations			192				193				129				44				(363	)			195
	Loss from discontinued operations, net of income tax			—				(1	)			—				—				—				(1	)

	Net income			192				192				129				44				(363	)			194
	Net income attributable to noncontrolling interests			—				—				—				—				(2	)			(2	)

	Net income attributable to L-3		$	192			$	192			$	129			$	44			$	(365	)		$	192

	Comprehensive income attributable to L-3		$	249			$	249			$	129			$	92			$	(470	)		$	249



			L-3				L-3				Guarantor				Non-				Eliminations				Consolidated
			Holdings				Communications				Subsidiaries				Guarantor								L-3
			(Parent)												Subsidiaries
			(in millions)
	Condensed Combining Statements of Operations:
	For the year-to-date ended September 27, 2013:
	Total net sales		$	—			$	2,841			$	5,089			$	1,711			$	(268	)		$	9,373
	Total cost of sales			(42	)			(2,630	)			(4,550	)			(1,527	)			310				(8,439	)

	Operating (loss) income			(42	)			211				539				184				42				934
	Interest expense			(15	)			(130	)			—				(1	)			15				(131	)
	Interest and other income, net			—				6				1				4				—				11

	(Loss) income from continuing operations before income taxes			(57	)			87				540				187				57				814
Benefit (provision) for income taxes			16				(24	)			(150	)			(52	)			(16	)			(226	)
Equity in net income of consolidated subsidiaries			623				519				—				—				(1,142	)			—

Net income			582				582				390				135				(1,101	)			588
Net income attributable to noncontrolling interests			—				—				—				—				(6	)			(6	)

Net income attributable to L-3		$	582			$	582			$	390			$	135			$	(1,107	)		$	582

Comprehensive income attributable to L-3		$	603			$	603			$	391			$	112			$	(1,106	)		$	603

For the year-to-date ended September 28, 2012:
Total net sales		$	—			$	2,715			$	5,476			$	1,648			$	(253	)		$	9,586
Total cost of sales			(44	)			(2,475	)			(4,936	)			(1,441	)			297				(8,599	)

Operating (loss) income			(44	)			240				540				207				44				987
Interest expense			(15	)			(138	)			—				—				15				(138	)
Interest and other income, net			—				8				(4	)			2				—				6
Debt retirement charge			—				(8	)			—				—				—				(8	)

(Loss) income from continuing operations before income taxes			(59	)			102				536				209				59				847
Benefit (provision) for income taxes			19				(32	)			(173	)			(69	)			(19	)			(274	)
Equity in net income of consolidated subsidiaries from continuing operations			638				496				—				—				(1,134	)			—

Income from continuing operations			598				566				363				140				(1,094	)			573
Income from discontinued operations, net of income tax			—				32				—				—				—				32

Net income			598				598				363				140				(1,094	)			605
Net income attributable to noncontrolling interests			—				—				—				—				(7	)			(7	)

Net income attributable to L-3		$	598			$	598			$	363			$	140			$	(1,101	)		$	598

Comprehensive income attributable to L-3		$	661			$	661			$	366			$	168			$	(1,195	)		$	661

Condensed Combining Statements of Cash Flows	L-3				L-3				Guarantor				Non-				Eliminations				Consolidated
	Holdings				Communications				Subsidiaries				Guarantor								L-3
	(Parent)												Subsidiaries
			(in millions)
	Condensed Combining Statements of Cash Flows:
	For the year-to-date ended September 27, 2013:
	Operating activities:
	Net cash from operating activities		$	555			$	86			$	523			$	101			$	(648	)		$	617

	Investing activities:
	Business acquisitions, net of cash acquired			—				(2	)			—				—				—				(2	)
	Investments in L-3 Communications			(104	)			—				—				—				104				—
	Other investing activities			—				(70	)			(53	)			(16	)			—				(139	)

	Net cash used in investing activities			(104	)			(72	)			(53	)			(16	)			104				(141	)

	Financing activities:
	Common stock repurchased			(404	)			—				—				—				—				(404	)
	Dividends paid on L-3 Holdings common stock			(151	)			—				—				—				—				(151	)
	Dividends paid to L-3 Holdings			—				(555	)			—				—				555				—
	Investments from L-3 Holdings			—				104				—				—				(104	)			—
	Other financing activities			104				345				(469	)			(81	)			210				109

	Net cash used in financing activities			(451	)			(106	)			(469	)			(81	)			661				(446	)

	Effect of foreign currency exchange rate changes on cash			—				—				—				(2	)			—				(2	)

	Net (decrease) increase in cash			—				(92	)			1				2				117				28
	Cash and cash equivalents, beginning of the period			—				246				—				242				(139	)			349

	Cash and cash equivalents, end of the period		$	—			$	154			$	1			$	244			$	(22	)		$	377

	For the year-to-date ended September 28, 2012:
	Operating activities:
	Net cash from operating activities from continuing operations		$	653			$	83			$	527			$	182			$	(753	)		$	692

	Investing activities:
	Business acquisitions, net of cash acquired			—				(349	)			—				—				—				(349	)
	Investments in L-3 Communications			(27	)			—				—				—				27				—
	Other investing activities			—				262				(41	)			(9	)			—				212

	Net cash used in investing activities from continuing operations			(27	)			(87	)			(41	)			(9	)			27				(137	)

	Financing activities:
	Redemption of senior subordinated notes			—				(250	)			—				—				—				(250	)
	Common stock repurchased			(504	)			—				—				—				—				(504	)
	Dividends paid on L-3 Holdings common stock			(149	)			—				—				—				—				(149	)
	Dividends paid to L-3 Holdings			—				(653	)			—				—				653				—
	Investments from L-3 Holdings			—				27				—				—				(27	)			—
	Other financing activities			27				523				(485	)			(182	)			137				20

	Net cash used in financing activities from continuing operations			(626	)			(353	)			(485	)			(182	)			763				(883	)

	Effect of foreign currency exchange rate changes on cash			—				—				—				4				—				4
	Net increase in cash and cash equivalents of discontinued operations			—				74				—				—				—				74

	Net (decrease) increase in cash			—				(283	)			1				(5	)			37				(250	)
	Cash and cash equivalents, beginning of the period			—				644				—				222				(102	)			764

	Cash and cash equivalents, end of the period		$	—			$	361			$	1			$	217			$	(65	)		$	514

Description_of_Business_Additi

Description of Business - Additional Information (Detail)	9 Months Ended
	Sep. 27, 2013
	Segment
Disclosure Description Of Business Additional Information [Abstract]
Number of segments	4

Basis_of_Presentation_Addition

Basis of Presentation - Additional Information (Detail) (USD $)	9 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Dec. 31, 2012
Basis Of Presentation And Significant Accounting Policies [Line Items]
Percentage of sales accounted for under contract accounting standards			48.00%
Percentage of fixed-price type contracts			39.00%
Percentage of cost-plus type contracts			9.00%
Period of performance for contracts accounted for under the percentage-of-completion method of accounting, minimum	1 year
Increase in consolidated operating income due to changes in contract estimates	$85	$75
Percentage of increase in consolidated operating income due to changes in contract estimates	9.10%	7.60%
CODES Due 2035 [Member]
Basis Of Presentation And Significant Accounting Policies [Line Items]
Interest rate on debt instruments	3.00%
Debt instruments, maturity year	2035

Dispositions_and_Acquisitions_1

Dispositions and Acquisitions - Additional Information (Detail) (USD $)	12 Months Ended				3 Months Ended	9 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2012	Sep. 27, 2013	Dec. 31, 2012	Sep. 27, 2013	Sep. 28, 2012	Sep. 28, 2012
	Business		Kollmorgen Electro-Optical [Member]	Link U.K. [Member]	Engility [Member]	Engility [Member]
				Adjustments to Preliminary Valuations Adjustments [Member]
Acquisitions And Discontinued Operations [Line Items]
Transaction expenses in connection with the spin-off, before income taxes						$19
Transaction expenses in connection with the spin-off, after income taxes						14
Interest expense for debt					1	14
Aggregate purchase price of acquisitions			349
Amount of goodwill recognized	7,776	7,757	282	32
Goodwill deductible for income tax purposes			184
Number of businesses acquired	3
Other liabilities				17
Contracts in process				($16)

Dispositions_and_Acquisitions_2

Dispositions and Acquisitions - Statement of Operations Data Classified as Discontinued Operations (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
(Loss) income from discontinued operations, net of income taxes		($1)		$32
Net (loss) income from discontinued operations attributable to L-3		-1		28
Engility [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Product and service revenues		68		911
Operating income from discontinued operations before income taxes		2		68
Interest expense allocated to discontinued operations		-1		-14
Income from discontinued operations before income taxes		1		54
Income tax expense		-2		-22
(Loss) income from discontinued operations, net of income taxes		-1		32
Net income from discontinued operations attributable to noncontrolling interests				-4
Net (loss) income from discontinued operations attributable to L-3		($1)		$28

Dispositions_and_Acquisitions_3

Dispositions and Acquisitions - Unaudited Pro Forma Statements of Operations Data (Detail) (USD $)	3 Months Ended	9 Months Ended
In Millions, except Per Share data, unless otherwise specified	Sep. 28, 2012	Sep. 28, 2012
Business Combinations [Abstract]
Pro forma net sales	$3,295	$9,688
Pro forma income from continuing operations	195	574
Pro forma net income attributable to L-3	$192	$599
Pro forma diluted earnings per share from continuing operations	$1.98	$5.79
Pro forma diluted earnings per share	$1.97	$6.07

Contracts_in_Process_Component

Contracts in Process - Components of Contracts in Process (Detail) (USD $)	Sep. 27, 2013	Dec. 31, 2012
In Millions, unless otherwise specified	Sep. 27, 2013	Dec. 31, 2012
Components of contracts in process
Unbilled contract receivables, gross	$2,714	$2,879
Unliquidated progress payments	-1,051	-1,265
Unbilled contract receivables, net	1,663	1,614
Inventoried contract costs, gross	1,093	1,090
Unliquidated progress payments	-65	-68
Inventoried contract costs, net	1,028	1,022
Total contracts in process	$2,691	$2,636

Contracts_in_Process_General_a

Contracts in Process - General and Administrative, Independent Research and Development and Bid and Proposal Costs (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Inventory Disclosure [Abstract]
Amounts included in inventoried contract costs at beginning of the period	$115	$105	$110	$91
IRAD and B&P costs	66	83	219	254
Other G&A costs	218	213	655	647
Total contract costs incurred	284	296	874	901
Amounts charged to cost of sales	-273	-289	-858	-880
Amounts included in inventoried contract costs at end of the period	$126	$112	$126	$112

Contracts_in_Process_Selling_G

Contracts in Process - Selling, General and Administrative Expenses and Research and Development Expenses (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Inventory Disclosure [Abstract]
Selling, general and administrative expenses	$68	$58	$212	$196
Research and development expenses	17	18	62	63
Total	$85	$76	$274	$259

Inventories_Inventories_at_Low

Inventories - Inventories at Lower of Cost or Market (Detail) (USD $)	Sep. 27, 2013	Dec. 31, 2012
In Millions, unless otherwise specified	Sep. 27, 2013	Dec. 31, 2012
Inventory Disclosure [Abstract]
Raw materials, components and sub-assemblies	$174	$168
Work in process	155	124
Finished goods	91	71
Total	$420	$363

Goodwill_and_Identifiable_Inta2

Goodwill and Identifiable Intangible Assets - Changes in Goodwill by Segment (Detail) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2013
Goodwill [Line Items]
Balance, Beginning	$7,776
Business dispositions	-2
Foreign currency translation adjustments	-17
Balance, Ending	7,757
C3ISR [Member]
Goodwill [Line Items]
Balance, Beginning	797
Business dispositions
Foreign currency translation adjustments
Balance, Ending	797
Electronic Systems [Member]
Goodwill [Line Items]
Balance, Beginning	4,836
Business dispositions	-2
Foreign currency translation adjustments	-7
Balance, Ending	4,827
P&LS [Member]
Goodwill [Line Items]
Balance, Beginning	1,175
Business dispositions
Foreign currency translation adjustments	-10
Balance, Ending	1,165
NSS [Member]
Goodwill [Line Items]
Balance, Beginning	968
Business dispositions
Foreign currency translation adjustments
Balance, Ending	$968

Goodwill_and_Identifiable_Inta3

Goodwill and Identifiable Intangible Assets - Additional Information (Detail) (Operating Segments [Member], Electronic Systems [Member], USD $)	Sep. 27, 2013	Dec. 31, 2012
In Millions, unless otherwise specified	Sep. 27, 2013	Dec. 31, 2012
Operating Segments [Member] \| Electronic Systems [Member]
Goodwill [Line Items]
Accumulated goodwill impairment losses	$58	$58

Goodwill_and_Identifiable_Inta4

Goodwill and Identifiable Intangible Assets - Identifiable Intangible Assets (Detail) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2013	Dec. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (in years)	17 years
Gross Carrying Amount	$652	$651
Accumulated Amortization	366	337
Net Carrying Amount	286	314
Customer Contractual Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (in years)	19 years
Gross Carrying Amount	461	460
Accumulated Amortization	246	225
Net Carrying Amount	215	235
Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (in years)	11 years
Gross Carrying Amount	164	164
Accumulated Amortization	105	98
Net Carrying Amount	59	66
Other [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (in years)	17 years
Gross Carrying Amount	27	27
Accumulated Amortization	15	14
Net Carrying Amount	$12	$13

Goodwill_and_Identifiable_Inta5

Goodwill and Identifiable Intangible Assets - Amortization Expense (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Goodwill And Intangible Assets Disclosure [Abstract]
Amortization Expense	$10	$13	$29	$34

Goodwill_and_Identifiable_Inta6

Goodwill and Identifiable Intangible Assets - Estimated Amortization Expense (Detail) (USD $)	Sep. 27, 2013
In Millions, unless otherwise specified	Sep. 27, 2013
Goodwill And Intangible Assets Disclosure [Abstract]
Estimated amortization expense, 2013	$38
Estimated amortization expense, 2014	42
Estimated amortization expense, 2015	39
Estimated amortization expense, 2016	32
Estimated amortization expense, 2017	$31

Other_Current_Liabilities_and_2

Other Current Liabilities and Other Liabilities - Other Current Liabilities (Detail) (USD $)	Sep. 27, 2013	Dec. 31, 2012
In Millions, unless otherwise specified	Sep. 27, 2013	Dec. 31, 2012
Other Current Liabilities:
Accruals for pending and threatened litigation (see Note 17)	$5	$7
Accrued product warranty costs	76	78
Estimated costs in excess of estimated contract value to complete contracts in process in a loss position	67	72
Accrued interest	46	53
Deferred revenues	38	37
Estimated contingent purchase price payable for acquired businesses		4
Other	151	144
Total other current liabilities	$383	$395

Other_Current_Liabilities_and_3

Other Current Liabilities and Other Liabilities - Other Liabilities (Detail) (USD $)	Sep. 27, 2013	Dec. 31, 2012
In Millions, unless otherwise specified	Sep. 27, 2013	Dec. 31, 2012
Other Liabilities:
Non-current income taxes payable (see Note 10)	$145	$137
Accrued workers' compensation	53	57
Deferred compensation	45	43
Accrued product warranty costs	24	22
Notes payable and capital lease obligations	17	24
Estimated contingent purchase price payable for acquired businesses		5
Other	73	102
Total other liabilities	$357	$390

Other_Current_Liabilities_and_4

Other Current Liabilities and Other Liabilities - Changes in Company's Accrued Product Warranty Costs (Detail) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012
Accrued product warranty costs:
Balance at January 1	$100	$94
Acquisitions during the period		2
Accruals for product warranties issued during the period	56	56
Settlements made during the period	-56	-58
Balance at end of period	$100	$94

Debt_Components_of_Debt_and_Re

Debt - Components of Debt and Reconciliation to Carrying Amount of Long-Term Debt (Detail) (USD $)	Sep. 27, 2013	Dec. 31, 2012
In Millions, unless otherwise specified	Sep. 27, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Aggregate borrowings and requirements for restated revolving credit facility	$1,382
L-3 Communications Corporation's [Member]
Debt Instrument [Line Items]
Borrowings under Amended and Restated Revolving Credit Facility
3.95% Senior Notes due 2016	500	500
5.20% Senior Notes due 2019	1,000	1,000
4.75% Senior Notes due 2020	800	800
4.95% Senior Notes due 2021	650	650
Subtotal	2,950	2,950
L-3 Communications Holdings, Inc. [Member]
Debt Instrument [Line Items]
3% Convertible Contingent Debt Securities due 2035	689	689
Principal amount of long-term debt	3,639	3,639
Unamortized discounts	-9	-10
Carrying amount of long-term debt	$3,630	$3,629

Debt_Components_of_Debt_and_Re1

Debt - Components of Debt and Reconciliation to Carrying Amount of Long-Term Debt (Parenthetical) (Detail) (USD $)

9 Months Ended

3 Months Ended

9 Months Ended

Share data in Millions, except Per Share data, unless otherwise specified

Sep. 27, 2013

Dec. 31, 2012

Sep. 27, 2013

Dec. 31, 2012

Sep. 27, 2013

Dec. 31, 2012

Sep. 27, 2013

Dec. 31, 2012

Sep. 27, 2013

Dec. 31, 2012

Sep. 27, 2013

Sep. 28, 2012

Sep. 27, 2013

Sep. 28, 2012

Oct. 23, 2013

Sep. 27, 2013

Dec. 31, 2012

CODES Due 2035 [Member]

L-3 Communications Corporation's [Member]

L-3 Communications Holdings, Inc. [Member]

3.95% Senior Notes due 2016 [Member]

5.20% Senior Notes due 2019 [Member]

4.75% Senior Notes due 2020 [Member]

4.95% Senior Notes due 2021 [Member]

Subsequent Event [Member]

CODES Due 2035 [Member]

Debt Instrument [Line Items]

Interest rate on Senior Notes

3.00%

3.95%

5.20%

4.75%

4.95%

3.00%

Borrowings under Amended and Restated Revolving Credit Facility

$1,000,000,000

Revolving Credit Facility expiry date

3-Feb-17

Excess of current common stock price over common stock conversion price

120.00%

Common stock, shares

7.6

Current convertible common stock price

$108.29

Conversion price of L-3 Holdings' CODES

$90.24

Closing stock price

$95.98

Interest expense recognized

5,000,000

15,000,000

Carrying amount of the equity component (conversion feature)

$64,000,000

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	9 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Dec. 31, 2012
Schedule Of Income Taxes [Line Items]
Effective tax rate	27.80%	32.30%
Tax benefit	$11		$17
Provision for income tax due to the expiration of the statue of limitations	10
Anticipated decrease in unrecognized tax benefits over the next 12 months	6
Accrued potential interest included within non-current income taxes payable	10		11
Accrued potential interest included within non-current income taxes payable, after income taxes	6		6
Potential penalties	7		7
U.S. Federal Research and Experimentation Tax Credit [Member]
Schedule Of Income Taxes [Line Items]
Tax benefit	$28

Amounts_Reclassified_Out_of_Ac2

Amounts Reclassified Out of Accumulated Other Comprehensive (Loss) Income - Summary of Amounts Reclassified Out of Accumulated Other Comprehensive (Loss) Income (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at December 31, 2012			($550)
Other comprehensive loss before reclassifications, net of tax			-20
Amounts reclassified from other comprehensive income, net of tax			41
Net current period other comprehensive (loss) income			21
Balance at September 27, 2013	-529		-529
Cost of sales-products	1,486	1,717	4,729	4,837
Income from continuing operations before income taxes	273	275	814	847
Provision for income taxes	-65	-80	-226	-274
Income from continuing operations	208	195	588	573
Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income from continuing operations	13		41
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at December 31, 2012			167
Other comprehensive loss before reclassifications, net of tax			-18
Amounts reclassified from other comprehensive income, net of tax
Net current period other comprehensive (loss) income			-18
Balance at September 27, 2013	149		149
Unrealized Gains (Losses) on Hedging Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at December 31, 2012			3
Other comprehensive loss before reclassifications, net of tax			-2
Amounts reclassified from other comprehensive income, net of tax			1
Net current period other comprehensive (loss) income			-1
Balance at September 27, 2013	2		2
Unrealized Gains (Losses) on Hedging Instruments [Member] \| Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cost of sales-products			1
Income from continuing operations before income taxes			1
Provision for income taxes
Income from continuing operations			1
Unrecognized Losses and Prior Service Cost, Net [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at December 31, 2012			-720
Other comprehensive loss before reclassifications, net of tax
Amounts reclassified from other comprehensive income, net of tax			40
Net current period other comprehensive (loss) income			40
Balance at September 27, 2013	-680		-680
Accumulated Defined Benefit Plans Adjustment [Member] \| Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net loss	20		63
Income from continuing operations before income taxes	20		63
Provision for income taxes	-7		-23
Income from continuing operations	$13		$40

Equity_Additional_Information_

Equity - Additional Information (Detail) (USD $)

1 Months Ended

9 Months Ended

1 Months Ended

9 Months Ended

1 Months Ended

9 Months Ended

1 Months Ended

Sep. 16, 2013

Jun. 19, 2013

Apr. 30, 2013

Sep. 27, 2013

Sep. 28, 2012

Feb. 05, 2013

Oct. 22, 2013

Sep. 27, 2013

Oct. 23, 2013

Sep. 27, 2013

Sep. 28, 2012

Oct. 23, 2013

Subsequent Event [Member]

February 5, 2013 Share Repurchase Programs [Member]

Common Stock [Member]

Subsequent Event [Member]

February 5, 2013 Share Repurchase Programs [Member]

Subsequent Event [Member]

Equity [Line Items]

Share repurchase program expired

$1,500,000,000

Additional amount of shares authorized to be repurchased

1,500,000,000

Average price per share of repurchased shares

$84.59

$93.88

Number of common shares repurchased

4,800,000

7,200,000

527,135

Aggregate amount of repurchased shares

404,000,000

504,000,000

168,000,000

49,000,000

Shares repurchased

2,100,000

Remaining value under share repurchase program

1,264,000,000

Cash dividend, declared per share

$0.55

Cash dividend paid

$50,000,000

$149,000,000

$146,000,000

Dividend payable date

16-Dec-13

Dividend record date

18-Nov-13

L3_Holdings_Earnings_Per_Commo2

L-3 Holdings' Earnings Per Common Share - Reconciliation of Basic and Diluted Earnings Per Share (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, except Per Share data, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Reconciliation of net income:
Net income	$208	$194	$588	$605
Net income from continuing operations attributable to noncontrolling interests	-4	-2	-6	-3
Net income from discontinued operations attributable to noncontrolling interests				-4
Net income attributable to L-3	204	192	582	598
Earnings (loss) attributable to L-3 Holdings' common shareholders:
Continuing operations	204	193	582	570
Discontinued operations, net of income tax		-1		28
Net income attributable to L-3	$204	$192	$582	$598
Basic:
Weighted average common shares outstanding	89.6	96.1	89.9	97.4
Basic earnings (loss) per share:
Continuing operations	$2.28	$2.01	$6.47	$5.85
Discontinued operations, net of income tax		($0.01)		$0.29
Basic earnings per share	$2.28	$2	$6.47	$6.14
Common and potential common shares:
Weighted average common shares outstanding	89.6	96.1	89.9	97.4
Assumed purchase of common shares for treasury	-5.2	-3.1	-4.7	-2.8
Assumed conversion of the CODES	0.1		0.1
Common and potential common shares	91.3	97.4	91.3	98.7
Diluted earnings (loss) per share:
Continuing operations	$2.23	$1.98	$6.37	$5.78
Discontinued operations, net of income tax		($0.01)		$0.28
Diluted earnings per share	$2.23	$1.97	$6.37	$6.06
Assumed Exercise of Stock Options [Member]
Common and potential common shares:
Common and potential common shares	4.7	2.1	3.9	1.7
Unvested Restricted Stock Awards [Member]
Common and potential common shares:
Common and potential common shares	1.8	2	1.8	2.1
Employee Stock Purchase Plan Contributions [Member]
Common and potential common shares:
Common and potential common shares	0.2	0.3	0.2	0.3
Performance Unit Awards [Member]
Common and potential common shares:
Common and potential common shares	0.1		0.1

L3_Holdings_Earnings_Per_Commo3

L-3 Holdings' Earnings Per Common Share - Reconciliation of Basic and Diluted Earnings Per Share (Parenthetical) (Detail) (USD $)	Sep. 27, 2013
Earnings Per Share [Abstract]
Conversion price of L-3 Holdings' CODES	$90.24

L3_Holdings_Earnings_Per_Commo4

L-3 Holdings' Earnings Per Common Share - Additional Information (Detail)	3 Months Ended	9 Months Ended
In Millions, unless otherwise specified	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Earnings Per Share [Abstract]
Shares excluded from computation of diluted earnings per share	3.2	1.2	3.5

Fair_Value_Measurements_Compan

Fair Value Measurements - Company's Assets and Liabilities at Fair Value on Recurring Basis (Detail) (USD $)	Sep. 27, 2013	Dec. 31, 2012
In Millions, unless otherwise specified	Sep. 27, 2013	Dec. 31, 2012
Level 1 [Member]
Assets
Cash equivalents	$199	$284
Derivatives (foreign currency forward contracts)
Total Assets	199	284
Liabilities
Derivatives (foreign currency forward contracts)
Level 2 [Member]
Assets
Cash equivalents
Derivatives (foreign currency forward contracts)	8	8
Total Assets	8	8
Liabilities
Derivatives (foreign currency forward contracts)	2	3
Level 3 [Member]
Assets
Cash equivalents
Derivatives (foreign currency forward contracts)
Total Assets
Liabilities
Derivatives (foreign currency forward contracts)

Financial_Instruments_Carrying

Financial Instruments - Carrying Amounts and Estimated Fair Values of Company's Long-Term Debt and Foreign Currency Forward Contracts (Detail) (USD $)	Sep. 27, 2013	Dec. 31, 2012
In Millions, unless otherwise specified	Sep. 27, 2013	Dec. 31, 2012
Fair Value Of Other Financial Instrument [Line Items]
Senior Notes, Carrying Amount	$2,941	$2,940
CODES, Carrying Amount	689	689
Senior Notes, Estimated Fair Value	3,131	3,301
CODES, Estimated Fair Value	752	697
Carrying Amount [Member]
Fair Value Of Other Financial Instrument [Line Items]
Foreign currency forward contracts	6	5
Estimated Fair Value [Member]
Fair Value Of Other Financial Instrument [Line Items]
Foreign currency forward contracts	$6	$5

Derivative_Financial_Instrumen2

Derivative Financial Instruments - Notional Amounts of Company's Outstanding Foreign Currency Forward Contracts by Currency (Detail) (USD $)	Sep. 27, 2013
In Millions, unless otherwise specified	Sep. 27, 2013
Derivative [Line Items]
Notional amounts of foreign currency forward contracts	$381
Canadian Dollar [Member]
Derivative [Line Items]
Notional amounts of foreign currency forward contracts	182
U.S. Dollar [Member]
Derivative [Line Items]
Notional amounts of foreign currency forward contracts	119
Euro [Member]
Derivative [Line Items]
Notional amounts of foreign currency forward contracts	59
British Pound [Member]
Derivative [Line Items]
Notional amounts of foreign currency forward contracts	$21

Derivative_Financial_Instrumen3

Derivative Financial Instruments - Additional Information (Detail) (USD $)	Sep. 27, 2013	Dec. 31, 2012
In Millions, unless otherwise specified	Sep. 27, 2013	Dec. 31, 2012
Derivative [Line Items]
Estimated amount of existing losses expected to be reclassified into income within the next 12 months	($3)
CODES Due 2035 [Member]
Derivative [Line Items]
Fair value of embedded derivative related to the issuance of the CODES	$0	$0

Derivative_Financial_Instrumen4

Derivative Financial Instruments - Location of Company's Derivative Instruments Recorded at Fair Value on Condensed Consolidated Balance Sheets (Detail) (USD $)	Sep. 27, 2013	Dec. 31, 2012
In Millions, unless otherwise specified	Sep. 27, 2013	Dec. 31, 2012
Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, assets	$6	$4
Other Current Assets [Member] \| Foreign Currency Forward Contracts [Member] \| Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, assets	6	4
Other Current Assets [Member] \| Foreign Currency Forward Contracts [Member] \| Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, assets
Other Current Assets [Member] \| CODES Due 2035 [Member] \| Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, assets
Other Assets [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, assets	2	4
Other Assets [Member] \| Foreign Currency Forward Contracts [Member] \| Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, assets	2	4
Other Assets [Member] \| Foreign Currency Forward Contracts [Member] \| Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, assets
Other Assets [Member] \| CODES Due 2035 [Member] \| Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, assets
Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, liabilities	1	2
Other Current Liabilities [Member] \| Foreign Currency Forward Contracts [Member] \| Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, liabilities	1	2
Other Current Liabilities [Member] \| Foreign Currency Forward Contracts [Member] \| Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, liabilities
Other Current Liabilities [Member] \| CODES Due 2035 [Member] \| Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, liabilities
Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, liabilities	1	1
Other Liabilities [Member] \| Foreign Currency Forward Contracts [Member] \| Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, liabilities	1	1
Other Liabilities [Member] \| Foreign Currency Forward Contracts [Member] \| Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, liabilities
Other Liabilities [Member] \| CODES Due 2035 [Member] \| Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total derivative instruments, liabilities

Commitments_and_Contingencies_

Commitments and Contingencies - Additional Information (Detail) (USD $)	Sep. 27, 2013	31-May-12	Mar. 09, 2010	Jul. 01, 2004
In Millions, unless otherwise specified	Sep. 27, 2013	31-May-12	Mar. 09, 2010	Jul. 01, 2004
Commitments And Contingencies Disclosure [Abstract]
Kalitta Air damages, minimum	$235
Pre-judgment interest in Kalitta Air damages, minimum	240
Total damages sought				315
Punitive damages sought				150
Compensatory damages		$48	$6.70

Pension_and_Other_Postretireme2

Pension and Other Postretirement Benefits - Components of Net Periodic Benefit Cost (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Pension Plans [Member]
Components of net periodic benefit cost:
Service cost	$30	$26	$95	$85
Interest cost	33	34	99	100
Expected return on plan assets	-41	-37	-124	-108
Amortization of prior service costs (credits)	1	1	1	1
Amortization of net loss	20	17	63	51
Curtailment loss	2	4	2	5
Net periodic benefit cost	45	45	136	134
Other Postretirement Benefit Plans [Member]
Components of net periodic benefit cost:
Service cost	1		3	3
Interest cost	2	2	5	7
Expected return on plan assets			-2	-2
Amortization of prior service costs (credits)	-1	-1	-2	-2
Amortization of net loss			1	1
Curtailment loss
Net periodic benefit cost	$2	$1	$5	$7

Pension_and_Other_Postretireme3

Pension and Other Postretirement Benefits - Additional Information (Detail) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2013
Pension Plans [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Contribution to pension plans	$93
Pension Plans [Member] \| Minimum [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Expected contributions to plans	13
Pension Plans [Member] \| Maximum [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Expected contributions to plans	52
Other Postretirement Benefit Plans [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Contribution to other postretirement benefit plans	5
Expected contributions to plans	$6

Employee_StockBased_Compensati2

Employee Stock-Based Compensation - Additional Information (Detail) (USD $)	9 Months Ended
	Sep. 27, 2013
Employee Restricted Equity Awards And Performance Stock Awards Vesting Activity [Line Items]
Stock options granted	741,692
Expiration period of stock options granted from date of grant	10 years
Vesting period	3 years
Weighted average grant date fair value of stock options	$12.09
Restricted Stock Units [Member]
Employee Restricted Equity Awards And Performance Stock Awards Vesting Activity [Line Items]
Vesting period	3 years
Units granted	604,982
Weighted average grant date fair value	$77.12
Vesting period of units granted for non-employee directors	1 year
Performance Units [Member]
Employee Restricted Equity Awards And Performance Stock Awards Vesting Activity [Line Items]
Units granted	61,690
Weighted average grant date fair value	$77
Length of service after grant date	3 years
Minimum payout range	0.00%
Maximum payout range	200.00%

Employee_StockBased_Compensati3

Employee Stock-Based Compensation - Weighted Average Assumptions in Valuation Model (Detail)	1 Months Ended
	Feb. 20, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Expected holding period (in years)	5 years 7 months 6 days
Expected volatility	26.40%
Expected dividend yield	3.60%
Risk-free interest rate	1.00%

Supplemental_Cash_Flow_Informa2

Supplemental Cash Flow Information - Supplemental Cash Flow Information (Detail) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012
Additional Cash Flow Elements And Supplemental Cash Flow Information [Abstract]
Interest paid on outstanding debt	$133	$152
Income tax payments	168	248
Income tax refunds	$20	$18

Segment_Information_Additional

Segment Information - Additional Information (Detail) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012
	Segment	Sep. 28, 2012
Segment Reporting [Abstract]
Number of segments	4
Corporate expenses		$10

Segment_Information_Summary_of

Segment Information - Summary of Segment Information (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012	Dec. 31, 2012
Net Sales:
Net sales	$2,996	$3,283	$9,373	$9,586
Operating income	314	331	934	987
Depreciation and amortization	52	54	158	165
Total Assets:
Total assets	14,075		14,075		13,841
Operating Segments [Member] \| C3ISR [Member]
Net Sales:
Net sales	754	889	2,533	2,642
Operating income	63	93	224	272
Depreciation and amortization	12	11	33	34
Total Assets:
Total assets	2,051		2,051		2,030
Operating Segments [Member] \| Electronic Systems [Member]
Net Sales:
Net sales	1,368	1,432	4,156	4,191
Operating income	173	158	468	480
Depreciation and amortization	34	34	105	105
Total Assets:
Total assets	8,277		8,277		8,077
Operating Segments [Member] \| P&LS [Member]
Net Sales:
Net sales	654	715	2,022	2,033
Operating income	52	65	176	179
Depreciation and amortization	4	4	12	15
Total Assets:
Total assets	2,091		2,091		1,997
Operating Segments [Member] \| NSS [Member]
Net Sales:
Net sales	323	353	987	1,042
Operating income	26	15	66	56
Depreciation and amortization	2	5	8	11
Total Assets:
Total assets	1,264		1,264		1,228
Corporate [Member]
Total Assets:
Total assets	392		392		509
Elimination of intercompany sales [Member]
Net Sales:
Net sales	($103)	($106)	($325)	($322)

Employee_Severance_and_Termina2

Employee Severance and Termination Costs - Additional Information (Detail) (USD $)	9 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Dec. 31, 2012
	Employees	Sep. 28, 2012	Employees
Restructuring And Related Activities [Abstract]
Employee severance and other related termination costs	$19	$19	$23
Number of employees terminated	1,400		1,600
Remaining balance of employee termination costs	$8		$9

Employee_Severance_and_Termina3

Employee Severance and Termination Costs - Employee Severance and Other Termination Costs Incurred by Reportable Segment (Detail) (USD $)	9 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Dec. 31, 2012
Reportable Segment:
Employee severance and other related termination costs	$19	$19	$23
C3ISR [Member]
Reportable Segment:
Employee severance and other related termination costs	5	4
Electronic Systems [Member]
Reportable Segment:
Employee severance and other related termination costs	13	14
P&LS [Member]
Reportable Segment:
Employee severance and other related termination costs		1
NSS [Member]
Reportable Segment:
Employee severance and other related termination costs	$1

Condensed_Combining_Financial_2

Condensed Combining Financial Information of L-3 Communications and Its Subsidiaries - Condensed Combining Balance Sheets (Detail) (USD $)	Sep. 27, 2013	Dec. 31, 2012	Sep. 28, 2012	Dec. 31, 2011
In Millions, unless otherwise specified	Sep. 27, 2013	Dec. 31, 2012	Sep. 28, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$377	$349	$514	$764
Billed receivables, net	1,084	968
Contracts in process	2,691	2,636
Other current assets	645	602
Total current assets	4,797	4,555
Goodwill	7,757	7,776
Other assets	1,521	1,510
Investment in and amounts due from consolidated subsidiaries
Total assets	14,075	13,841
Current liabilities	2,503	2,591
Amounts due to consolidated subsidiaries
Other long-term liabilities	2,112	2,078
Long-term debt	3,630	3,629
Total liabilities	8,245	8,298
L-3 shareholders' equity	5,755	5,467
Noncontrolling interests	75	76
Total equity	5,830	5,543	5,842	6,724
Total liabilities and equity	14,075	13,841
L-3 Communications Holdings, Inc. [Member]
Current assets:
Cash and cash equivalents
Billed receivables, net
Contracts in process
Other current assets
Total current assets
Goodwill
Other assets
Investment in and amounts due from consolidated subsidiaries	6,444	6,156
Total assets	6,444	6,156
Current liabilities
Amounts due to consolidated subsidiaries
Other long-term liabilities
Long-term debt	689	689
Total liabilities	689	689
L-3 shareholders' equity	5,755	5,467
Noncontrolling interests
Total equity	5,755	5,467
Total liabilities and equity	6,444	6,156
L-3 Communications Corporation's [Member]
Current assets:
Cash and cash equivalents	154	246	361	644
Billed receivables, net	381	290
Contracts in process	1,053	945
Other current assets	291	248
Total current assets	1,879	1,729
Goodwill	2,290	1,993
Other assets	797	734
Investment in and amounts due from consolidated subsidiaries	7,075	7,208
Total assets	12,041	11,664
Current liabilities	852	823
Amounts due to consolidated subsidiaries
Other long-term liabilities	1,804	1,745
Long-term debt	3,630	3,629
Total liabilities	6,286	6,197
L-3 shareholders' equity	5,755	5,467
Noncontrolling interests
Total equity	5,755	5,467
Total liabilities and equity	12,041	11,664
Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	1		1
Billed receivables, net	480	441
Contracts in process	1,260	1,351
Other current assets	149	163
Total current assets	1,890	1,955
Goodwill	4,285	4,586
Other assets	517	565
Investment in and amounts due from consolidated subsidiaries	3,584	3,326
Total assets	10,276	10,432
Current liabilities	1,038	1,255
Amounts due to consolidated subsidiaries
Other long-term liabilities	193	210
Long-term debt
Total liabilities	1,231	1,465
L-3 shareholders' equity	9,045	8,967
Noncontrolling interests
Total equity	9,045	8,967
Total liabilities and equity	10,276	10,432
Non-Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	244	242	217	222
Billed receivables, net	223	237
Contracts in process	378	340
Other current assets	205	191
Total current assets	1,050	1,010
Goodwill	1,182	1,197
Other assets	207	211
Investment in and amounts due from consolidated subsidiaries		43
Total assets	2,439	2,461
Current liabilities	635	652
Amounts due to consolidated subsidiaries	310
Other long-term liabilities	115	123
Long-term debt
Total liabilities	1,060	775
L-3 shareholders' equity	1,379	1,686
Noncontrolling interests
Total equity	1,379	1,686
Total liabilities and equity	2,439	2,461
Eliminations [Member]
Current assets:
Cash and cash equivalents	-22	-139	-65	-102
Billed receivables, net
Contracts in process
Other current assets
Total current assets	-22	-139
Goodwill
Other assets
Investment in and amounts due from consolidated subsidiaries	-17,103	-16,733
Total assets	-17,125	-16,872
Current liabilities	-22	-139
Amounts due to consolidated subsidiaries	-310
Other long-term liabilities
Long-term debt	-689	-689
Total liabilities	-1,021	-828
L-3 shareholders' equity	-16,179	-16,120
Noncontrolling interests	75	76
Total equity	-16,104	-16,044
Total liabilities and equity	($17,125)	($16,872)

Condensed_Combining_Financial_3

Condensed Combining Financial Information of L-3 Communications and Its Subsidiaries - Condensed Combining Statements of Operations (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Condensed Financial Statements, Captions [Line Items]
Total net sales	$2,996	$3,283	$9,373	$9,586
Total cost of sales	-2,682	-2,952	-8,439	-8,599
Operating (loss) income	314	331	934	987
Interest expense	-44	-48	-131	-138
Interest and other income, net	3		11	6
Debt retirement charge		-8		-8
(Loss) income from continuing operations before income taxes	273	275	814	847
Benefit (provision) for income taxes	-65	-80	-226	-274
Equity in net income of consolidated subsidiaries
Income from continuing operations	208	195	588	573
Income (loss) from discontinued operations, net of income tax		-1		32
Net income	208	194	588	605
Net income attributable to noncontrolling interests	-4	-2	-6	-7
Net income attributable to L-3	204	192	582	598
Comprehensive income attributable to L-3	254	249	603	661
L-3 Communications Holdings, Inc. [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales
Total cost of sales	-14	-15	-42	-44
Operating (loss) income	-14	-15	-42	-44
Interest expense	-5	-5	-15	-15
Interest and other income, net
(Loss) income from continuing operations before income taxes	-19	-20	-57	-59
Benefit (provision) for income taxes	5	6	16	19
Equity in net income of consolidated subsidiaries	218	206	623	638
Income from continuing operations		192		598
Net income	204	192	582	598
Net income attributable to noncontrolling interests
Net income attributable to L-3	204	192	582	598
Comprehensive income attributable to L-3	254	249	603	661
L-3 Communications Corporation's [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	913	892	2,841	2,715
Total cost of sales	-855	-808	-2,630	-2,475
Operating (loss) income	58	84	211	240
Interest expense	-43	-48	-130	-138
Interest and other income, net	2	3	6	8
Debt retirement charge		-8		-8
(Loss) income from continuing operations before income taxes	17	31	87	102
Benefit (provision) for income taxes	-3	-9	-24	-32
Equity in net income of consolidated subsidiaries	190	171	519	496
Income from continuing operations		193		566
Income (loss) from discontinued operations, net of income tax		-1		32
Net income	204	192	582	598
Net income attributable to noncontrolling interests
Net income attributable to L-3	204	192	582	598
Comprehensive income attributable to L-3	254	249	603	661
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	1,636	1,929	5,089	5,476
Total cost of sales	-1,443	-1,743	-4,550	-4,936
Operating (loss) income	193	186	539	540
Interest expense
Interest and other income, net	1	-4	1	-4
(Loss) income from continuing operations before income taxes	194	182	540	536
Benefit (provision) for income taxes	-47	-53	-150	-173
Equity in net income of consolidated subsidiaries
Income from continuing operations		129		363
Net income	147	129	390	363
Net income attributable to noncontrolling interests
Net income attributable to L-3	147	129	390	363
Comprehensive income attributable to L-3	148	129	391	366
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	546	550	1,711	1,648
Total cost of sales	-483	-489	-1,527	-1,441
Operating (loss) income	63	61	184	207
Interest expense	-1		-1
Interest and other income, net		1	4	2
(Loss) income from continuing operations before income taxes	62	62	187	209
Benefit (provision) for income taxes	-15	-18	-52	-69
Equity in net income of consolidated subsidiaries
Income from continuing operations		44		140
Net income	47	44	135	140
Net income attributable to noncontrolling interests
Net income attributable to L-3	47	44	135	140
Comprehensive income attributable to L-3	79	92	112	168
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Total net sales	-99	-88	-268	-253
Total cost of sales	113	103	310	297
Operating (loss) income	14	15	42	44
Interest expense	5	5	15	15
Interest and other income, net
(Loss) income from continuing operations before income taxes	19	20	57	59
Benefit (provision) for income taxes	-5	-6	-16	-19
Equity in net income of consolidated subsidiaries	-408	-377	-1,142	-1,134
Income from continuing operations		-363		-1,094
Net income	-394	-363	-1,101	-1,094
Net income attributable to noncontrolling interests	-4	-2	-6	-7
Net income attributable to L-3	-398	-365	-1,107	-1,101
Comprehensive income attributable to L-3	($481)	($470)	($1,106)	($1,195)

Condensed_Combining_Financial_4

Condensed Combining Financial Information of L-3 Communications and Its Subsidiaries - Condensed Combining Statements of Cash Flows (Detail) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012
Operating activities:
Net cash from operating activities	$617
Net cash from operating activities from continuing operations	617	692
Investing activities:
Business acquisitions, net of cash acquired	-2	-349
Investments in L-3 Communications
Other investing activities	-139	212
Net cash used in investing activities from continuing operations	-141	-137
Net cash used in investing activities	-141
Financing activities:
Redemption of senior subordinated notes		-250
Common stock repurchased	-404	-504
Dividends paid on L-3 Holdings common stock	-151	-149
Dividends paid to L-3 Holdings
Investments from L-3 Holdings
Other financing activities	109	20
Net cash used in financing activities from continuing operations	-446	-883
Net cash used in financing activities	-446
Effect of foreign currency exchange rate changes on cash	-2	4
Net increase in cash and cash equivalents of discontinued operations		74
Net increase (decrease) in cash and cash equivalents	28	-250
Cash and cash equivalents, beginning of the period	349	764
Cash and cash equivalents, end of the period	377	514
L-3 Communications Holdings, Inc. [Member]
Operating activities:
Net cash from operating activities	555
Net cash from operating activities from continuing operations		653
Investing activities:
Business acquisitions, net of cash acquired
Investments in L-3 Communications	-104	-27
Other investing activities
Net cash used in investing activities from continuing operations		-27
Net cash used in investing activities	-104
Financing activities:
Common stock repurchased	-404	-504
Dividends paid on L-3 Holdings common stock	-151	-149
Dividends paid to L-3 Holdings
Investments from L-3 Holdings
Other financing activities	104	27
Net cash used in financing activities from continuing operations		-626
Net cash used in financing activities	-451
Effect of foreign currency exchange rate changes on cash
Net increase (decrease) in cash and cash equivalents
Cash and cash equivalents, beginning of the period
Cash and cash equivalents, end of the period
L-3 Communications Corporation's [Member]
Operating activities:
Net cash from operating activities	86
Net cash from operating activities from continuing operations		83
Investing activities:
Business acquisitions, net of cash acquired	-2	-349
Investments in L-3 Communications
Other investing activities	-70	262
Net cash used in investing activities from continuing operations		-87
Net cash used in investing activities	-72
Financing activities:
Redemption of senior subordinated notes		-250
Common stock repurchased
Dividends paid on L-3 Holdings common stock
Dividends paid to L-3 Holdings	-555	-653
Investments from L-3 Holdings	104	27
Other financing activities	345	523
Net cash used in financing activities from continuing operations		-353
Net cash used in financing activities	-106
Effect of foreign currency exchange rate changes on cash
Net increase in cash and cash equivalents of discontinued operations		74
Net increase (decrease) in cash and cash equivalents	-92	-283
Cash and cash equivalents, beginning of the period	246	644
Cash and cash equivalents, end of the period	154	361
Guarantor Subsidiaries [Member]
Operating activities:
Net cash from operating activities	523
Net cash from operating activities from continuing operations		527
Investing activities:
Business acquisitions, net of cash acquired
Investments in L-3 Communications
Other investing activities	-53	-41
Net cash used in investing activities from continuing operations		-41
Net cash used in investing activities	-53
Financing activities:
Common stock repurchased
Dividends paid on L-3 Holdings common stock
Dividends paid to L-3 Holdings
Investments from L-3 Holdings
Other financing activities	-469	-485
Net cash used in financing activities from continuing operations		-485
Net cash used in financing activities	-469
Effect of foreign currency exchange rate changes on cash
Net increase (decrease) in cash and cash equivalents	1	1
Cash and cash equivalents, beginning of the period
Cash and cash equivalents, end of the period	1	1
Non-Guarantor Subsidiaries [Member]
Operating activities:
Net cash from operating activities	101
Net cash from operating activities from continuing operations		182
Investing activities:
Business acquisitions, net of cash acquired
Investments in L-3 Communications
Other investing activities	-16	-9
Net cash used in investing activities from continuing operations		-9
Net cash used in investing activities	-16
Financing activities:
Common stock repurchased
Dividends paid on L-3 Holdings common stock
Dividends paid to L-3 Holdings
Investments from L-3 Holdings
Other financing activities	-81	-182
Net cash used in financing activities from continuing operations		-182
Net cash used in financing activities	-81
Effect of foreign currency exchange rate changes on cash	-2	4
Net increase (decrease) in cash and cash equivalents	2	-5
Cash and cash equivalents, beginning of the period	242	222
Cash and cash equivalents, end of the period	244	217
Eliminations [Member]
Operating activities:
Net cash from operating activities	-648
Net cash from operating activities from continuing operations		-753
Investing activities:
Business acquisitions, net of cash acquired
Investments in L-3 Communications	104	27
Other investing activities
Net cash used in investing activities from continuing operations		27
Net cash used in investing activities	104
Financing activities:
Common stock repurchased
Dividends paid on L-3 Holdings common stock
Dividends paid to L-3 Holdings	555	653
Investments from L-3 Holdings	-104	-27
Other financing activities	210	137
Net cash used in financing activities from continuing operations		763
Net cash used in financing activities	661
Effect of foreign currency exchange rate changes on cash
Net increase (decrease) in cash and cash equivalents	117	37
Cash and cash equivalents, beginning of the period	-139	-102
Cash and cash equivalents, end of the period	($22)	($65)