L3 10-Q/A 10 Oct 14 2014 Q1 Quarterly report (amended) Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 28, 2014	Apr. 23, 2014
Document And Entity Information [Abstract]	'	'
Document Type	'10-Q/A	'
Amendment Flag	'true	'
Amendment Description	'We are filing this Amendment No. 1 (this “Amendment” or “Form 10-Q/A”) to our Quarterly Report on Form 10-Q for the quarter ended March 28, 2014 following the completion of the internal review of our Aerospace Systems segment (discussed further in our document).	'
Document Period End Date	28-Mar-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q1	'
Trading Symbol	'LLL	'
Entity Registrant Name	'L 3 COMMUNICATIONS HOLDINGS INC	'
Entity Central Index Key	'0001056239	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	86,232,242

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Mar. 28, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$227	$500
Billed receivables, net of allowances of $24 in 2014 and $26 in 2013	1,068	991
Contracts in process	2,648	2,431
Inventories	375	359
Deferred income taxes	144	147
Other current assets	160	166
Total current assets	4,622	4,594
Property, plant and equipment, net	1,033	1,042
Goodwill	7,821	7,796
Identifiable intangible assets	283	285
Deferred debt issue costs	23	24
Other assets	245	247
Total assets	14,027	13,988
Current liabilities:	'	'
Accounts payable, trade	590	541
Accrued employment costs	543	545
Accrued expenses	404	458
Advance payments and billings in excess of costs incurred	529	576
Income taxes	29	31
Other current liabilities	382	383
Total current liabilities	2,477	2,534
Pension and postretirement benefits	729	727
Deferred income taxes	661	635
Other liabilities	394	406
Long-term debt	3,631	3,630
Total liabilities	7,892	7,932
Commitments and contingencies (see Note 18)	'	'
L-3 shareholders' equity:	'	'
L-3 Communications Holdings, Inc.'s common stock: $.01 par value; 300,000,000 shares authorized, 86,423,244 shares outstanding at March 28, 2014 and 85,828,485 shares outstanding at December 31, 2013 (L-3 Communications Corporation's common stock: $.01 par value, 100 shares authorized, issued and outstanding)	5,767	5,653
L-3 Communications Holdings, Inc.'s treasury stock (at cost), 67,335,382 shares at March 28, 2014 and 66,118,406 shares at December 31, 2013	-5,421	-5,288
Retained earnings	5,842	5,726
Accumulated other comprehensive loss	-128	-110
Total L-3 shareholders' equity	6,060	5,981
Noncontrolling interests	75	75
Total equity	6,135	6,056
Total liabilities and equity	$14,027	$13,988

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 28, 2014	Dec. 31, 2013
In Millions, except Share data, unless otherwise specified
Class of Stock [Line Items]	'	'
Net allowances for billed receivables	$24	$26
Treasury stock (at cost), shares	67,335,382	66,118,406
L-3 Communications Holdings, Inc. [Member]	'	'
Class of Stock [Line Items]	'	'
Common stock, par value	$0.01	$0.01
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares outstanding	86,423,244	85,828,485
L-3 Communications Corporation [Member]	'	'
Class of Stock [Line Items]	'	'
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

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 28, 2014	Mar. 29, 2013
Net sales:	'	'
Products	$1,649	$1,821
Services	1,308	1,376
Total net sales	2,957	3,197
Cost of sales:	'	'
Products	-1,466	-1,622
Services	-1,205	-1,265
Total cost of sales	-2,671	-2,887
Operating income	286	310
Interest expense	-43	-43
Interest and other income, net	5	3
Income before income taxes	248	270
Provision for income taxes	-76	-78
Net income	172	192
Net income attributable to noncontrolling interests	-2	-1
Net income attributable to L-3	$170	$191
Earnings per share attributable to L-3 Holdings' common shareholders:	'	'
Basic	$1.97	$2.12
Diluted	$1.90	$2.09
Cash dividends paid per common share	$0.60	$0.55
L-3 Holdings' weighted average common shares outstanding:	'	'
Basic	86.1	90.3
Diluted	89.4	91.5

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 28, 2014		Mar. 29, 2013
Statement of Comprehensive Income [Abstract]	'		'
Net income	$172		$192
Other comprehensive income:	'		'
Foreign currency translation adjustments	-16		-34
Unrealized losses on hedging instruments	-5	[1]	-3	[1]
Pension and postretirement benefit plans:	'		'
Amortization of net loss and prior service cost previously recognized	3	[2]	13	[2]
Total other comprehensive loss	-18		-24
Comprehensive income	154		168
Comprehensive income attributable to noncontrolling interests	-2		-1
Comprehensive income attributable to L-3	$152		$167
[1]	Amounts are net of income tax benefits of $2 million for both of the quarterly periods ended March 28, 2014 and March 29, 2013.
[2]	Amounts are net of income taxes of $1 million and $9 million for the quarterly periods ended March 28, 2014 and March 29, 2013, respectively.

Consolidated_Statements_of_Com1

Consolidated Statements of Comprehensive Income (Parenthetical) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 28, 2014	Mar. 29, 2013
Statement of Comprehensive Income [Abstract]	'	'
Income tax benefits on unrealized losses on hedging instruments	$2	$2
Income tax effect on amortization of net loss and prior service cost previously recognized	$1	$9

Consolidated_Statements_of_Equ

Consolidated Statements of Equity (USD $)	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Noncontrolling Interests [Member]
In Millions, except Share data, unless otherwise specified
Beginning Balance at Dec. 31, 2012	$5,527	$1	$5,313	($4,488)	$5,175	($550)	$76
Beginning Balance, Shares at Dec. 31, 2012	'	90,400,000	'	'	'	'	'
Class of Stock [Line Items]	'	'	'	'	'	'	'
Net income	192	'	'	'	191	'	1
Other comprehensive income	-24	'	'	'	'	-24	'
Distributions to noncontrolling interests	-2	'	'	'	'	'	-2
Cash dividends paid on common stock	-50	'	'	'	-50	'	'
Shares issued:	'	'	'	'	'	'	'
Employee savings plans	37	'	37	'	'	'	'
Employee savings plans, Shares	'	500,000	'	'	'	'	'
Exercise of stock options	16	'	16	'	'	'	'
Exercise of stock options, Shares	'	300,000	'	'	'	'	'
Employee stock purchase plan	'	'	'	'	'	'	'
Employee stock purchase plan, Shares	'	300,000	'	'	'	'	'
Stock-based compensation expense	14	'	14	'	'	'	'
Treasury stock purchased	-122	'	'	-122	'	'	'
Treasury stock purchased, Shares	'	-1,600,000	'	'	'	'	'
Other	-14	'	-14	'	'	'	'
Other, Shares	'	300,000	'	'	'	'	'
Ending Balance at Mar. 29, 2013	5,574	1	5,366	-4,610	5,316	-574	75
Ending Balance, Shares at Mar. 29, 2013	'	90,200,000	'	'	'	'	'
Beginning Balance at Dec. 31, 2013	6,056	1	5,652	-5,288	5,726	-110	75
Beginning Balance, Shares at Dec. 31, 2013	'	85,800,000	'	'	'	'	'
Class of Stock [Line Items]	'	'	'	'	'	'	'
Net income	172	'	'	'	170	'	2
Other comprehensive income	-18	'	'	'	'	-18	'
Distributions to noncontrolling interests	-2	'	'	'	'	'	-2
Cash dividends paid on common stock	-52	'	'	'	-52	'	'
Shares issued:	'	'	'	'	'	'	'
Employee savings plans	44	'	44	'	'	'	'
Employee savings plans, Shares	'	400,000	'	'	'	'	'
Exercise of stock options	81	'	81	'	'	'	'
Exercise of stock options, Shares	'	900,000	'	'	'	'	'
Employee stock purchase plan	'	'	'	'	'	'	'
Employee stock purchase plan, Shares	'	200,000	'	'	'	'	'
Stock-based compensation expense	15	'	15	'	'	'	'
Treasury stock purchased	-133	'	'	-133	'	'	'
Treasury stock purchased, Shares	'	-1,200,000	'	'	'	'	'
Other	-28	'	-26	'	-2	'	'
Other, Shares	'	300,000	'	'	'	'	'
Ending Balance at Mar. 28, 2014	$6,135	$1	$5,766	($5,421)	$5,842	($128)	$75
Ending Balance, Shares at Mar. 28, 2014	'	86,400,000	'	'	'	'	'

Consolidated_Statements_of_Equ1

Consolidated Statements of Equity (Parenthetical) (USD $)	3 Months Ended
	Mar. 28, 2014	Mar. 29, 2013
Class of Stock [Line Items]	'	'
Cash dividends paid on common stock, per share	$0.60	$0.55
Retained Earnings [Member]	'	'
Class of Stock [Line Items]	'	'
Cash dividends paid on common stock, per share	$0.60	$0.55

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 28, 2014	Mar. 29, 2013
Operating activities:	'	'
Net income	$172	$192
Depreciation of property, plant and equipment	42	42
Amortization of intangibles and other assets	12	12
Deferred income tax provision	23	18
Stock-based employee compensation expense	15	14
Contributions to employee savings plans in L-3 Holdings' common stock	44	32
Amortization of pension and postretirement benefit plans net loss and prior service cost	4	22
Amortization of bond discounts and deferred debt issue costs (included in interest expense)	2	2
Other non-cash items	1	3
Changes in operating assets and liabilities, excluding amounts from acquisitions and divestitures:	'	'
Billed receivables	-73	-146
Contracts in process	-214	-125
Inventories	-16	8
Other assets	-10	47
Accounts payable, trade	49	94
Accrued employment costs	-10	17
Accrued expenses	-51	-41
Advance payments and billings in excess of costs incurred	-46	-37
Income taxes	28	51
Excess income tax benefits related to share-based payment arrangements	-14	-2
Other current liabilities	-6	4
Pension and postretirement benefits	-2	4
All other operating activities	-12	-65
Net cash (used in) from operating activities	-62	146
Investing activities:	'	'
Business acquisitions, net of cash acquired	-57	'
Capital expenditures	-30	-49
Dispositions of property, plant and equipment	1	1
Other investing activities	'	-6
Net cash used in investing activities	-86	-54
Financing activities:	'	'
Borrowings under revolving credit facility	524	477
Repayment of borrowings under revolving credit facility	-524	-477
Common stock repurchased	-133	-122
Dividends paid on L-3 Holdings' common stock	-55	-52
Proceeds from exercises of stock options	69	18
Proceeds from employee stock purchase plan	9	9
Excess income tax benefits related to share-based payment arrangements	14	2
Other financing activities	-28	-13
Net cash used in financing activities	-124	-158
Effect of foreign currency exchange rate changes on cash and cash equivalents	-1	-7
Net decrease in cash and cash equivalents	-273	-73
Cash and cash equivalents, beginning of the period	500	349
Cash and cash equivalents, end of the period	$227	$276

Description_of_Business

Description of Business	3 Months Ended
	Mar. 28, 2014
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 aerospace systems and national security solutions. L-3 is also a leading provider of a broad range of communication and electronic systems and products 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.
	In the first quarter of 2014, the Company reorganized its business segments to better align its organizational structure with customer priorities and increase operational efficiencies. After the realignment, L-3’s structure consists of the following four segments: Aerospace Systems, Electronic Systems, Communication Systems and National Security Solutions, as further described below.
	Aerospace Systems: combines the operations of the former Platform & Logistics Solutions (P&LS) segment with Intelligence, Surveillance and Reconnaissance (ISR) Systems. ISR Systems was part of the former Command, Control, Communications, Intelligence, Surveillance and Reconnaissance (C3ISR) segment. Aerospace Systems delivers integrated solutions for the global ISR market and provides modernization, upgrade, sustainment, and maintenance and logistics support for a wide variety of aircraft and ground systems.
	Electronic Systems: includes all of its previous businesses historically included in this segment except the Microwave Products businesses, which are now part of Communication Systems. Electronic Systems provides a broad range of components, products, subsystems, systems and related services for military and commercial customers.
	Communication Systems: combines the operations of the Microwave Products businesses, which were previously part of the Electronic Systems reportable segment, with the operations of the Networked and Secure Communications Products businesses, previously part of the former C3ISR segment. Communication Systems delivers products and services for the global communications market, specializing in strategic and tactical airborne, space, ground and sea-based communication systems.
	National Security Solutions (NSS): remains unchanged. NSS will continue to provide cybersecurity solutions, high-performance computing, enterprise information technology (IT) services, analytics and intelligence analysis.
	Financial information with respect to the Company’s segments is included in Note 22 to the unaudited condensed consolidated financial statements. Financial information for the first quarter of 2013 in these unaudited condensed consolidated financial statements has been revised for the segment realignment discussed above.

Basis_of_Presentation

Basis of Presentation	3 Months Ended
	Mar. 28, 2014
Accounting Policies [Abstract]	'
Basis of Presentation	'
	2.  Basis of Presentation
	These unaudited condensed consolidated financial statements for the quarterly period ended March 28, 2014 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/A for the fiscal year ended December 31, 2013, filed on October 10, 2014.
	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/A 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, 2013 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 47% of the Company’s net sales in 2013 were accounted for under contract accounting standards, of which approximately 38% 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 $32 million, or 11%, for the quarterly period ended March 28, 2014 and $17 million, or 5%, for the quarterly period ended March 29, 2013.
	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/A for the fiscal year ended December 31, 2013, filed on October 10, 2014.

Revisions_to_Previously_Issued

Revisions to Previously Issued Financial Statements	3 Months Ended
	Mar. 28, 2014
Accounting Changes and Error Corrections [Abstract]	'
Revisions to Previously Issued Financial Statements	'
	3.  Revisions to Previously Issued Financial Statements
	The Company is revising its previously issued financial statements to update for: (1) accounting adjustments due to the internal review at its Aerospace Systems segment, (2) accounting error related to a sales-type lease transaction for flight simulator systems within its Electronic Systems segment, and (3) previously identified immaterial errors already recognized in its financial statements but not recorded in the appropriate periods. The accounting errors related to the sales-type lease transaction and immaterial out of period amounts are not related to the internal review at its Aerospace Systems segment.
	Internal Review of Aerospace Systems Segment: The Company conducted an internal review related to instances of misconduct and accounting errors at its Aerospace Systems segment. This review was conducted with the assistance of outside legal and accounting advisors, and has been completed. As a result of the internal review, the Company identified and recorded aggregate pre-tax charges as follows: (1) $60 million for 2013, (2) $25 million for 2012, (3) $5 million for 2011, and (4) $4 million for periods prior to 2011. Furthermore, this Form 10-Q/A also includes aggregate pre-tax charges related to the internal review of the Aerospace Systems segment. The pre-tax charges related to the internal review of the Aerospace Systems segment for the three months ended March 28, 2014 is approximately $20 million.
	The adjustments related to the internal review only affected the Logistics Solutions and Platform Systems sectors of the Aerospace Systems segment. The cumulative aggregate adjustments attributable to the Logistics Solutions sector are approximately $91 million, and at the Platform Systems sector are approximately $23 million through March 28, 2014. The Logistics Solutions sector adjustments relate to: (1) losses of $58 million through March 28, 2014 with respect to the U.S. Army C-12 fixed-price maintenance and logistics support contract due to cost overruns inappropriately deferred, sales invoices inappropriately prepared, and the failure to timely and accurately perform contract estimates at completion and valuation assessments of inventories and receivables at the Army Sustainment Division, and (2) accounting errors of $33 million through March 28, 2014 in connection with the valuation of inventories and receivables, as well as the correction for certain accruals on other logistics support contracts. The Platform Systems sector adjustments are primarily due to: (1) losses of $11 million on two aircraft modification contracts and two contracts for rotary wing sub-assemblies and parts, and (2) write-offs of deferred costs of $12 million to design and test aerostructures for a new commercial aircraft.
	Sales-Type Lease Transaction: The Company routinely performs on-site accounting and internal control review procedures on a rotational basis As part of a previously planned review of its Simulation & Training business in its Electronic Systems segment and unrelated to the internal review at its Aerospace Systems segment, the Company evaluated the accounting treatment related to a sales-type lease transaction with the U.S. Army for rotary wing flight simulator systems. The period of performance under this contract began in 2004 and ends in 2023. Based on the results of this evaluation, the Company has adjusted its previously issued financial statements to: (1) increase interest income accretion on the net investment related to this sales-type lease transaction by an estimated aggregate amount of approximately $5 million for 2013, $3 million for each of 2012 and 2011 and $12 million for periods prior to 2011, and (2) decrease sales by approximately $5 million for the quarter ended March 28, 2014 and $7 million for 2013 and related decrease in cost of sales by approximately $5 million for the quarter ended March 28, 2014 and $7 million for 2013 and $5 million for periods prior to 2011.
	Out of Period Amounts: The Company identified various out of period amounts included in its previously issued financial statements that were deemed to be immaterial individually and in the aggregate. In prior periods, in accordance with Accounting Standards Codification (“ASC”) 650-10-S99 and S55 (formerly Staff Accounting Bulletins (“SAB”) No. 99 and No. 108), Accounting Changes and Error Corrections, the Company concluded that these errors were individually, and in the aggregate, not material, quantitatively or qualitatively, to the financial statements in the period recorded or to the relevant prior periods. Accordingly, the Company recorded these errors in its financial statements in the period that the error was identified. The Company, on a voluntary basis, is revising its previously issued financial statements to correct for these errors already recognized in its financial statements but not recorded in the appropriate periods to reflect them in the appropriate period. These out of period amounts were not discovered as part of the internal review of the Aerospace Systems segment discussed above, but rather represent previously identified errors “resulting from mathematical mistakes, mistakes in application of generally accepted accounting principles, or oversight or misuse of facts that existed at the time the financial statements were prepared,” as defined in ASC 250-10-20 Accounting Changes and Error Corrections. The Company, therefore, is not treating these amounts as changes in estimates. These errors consist of: (1) increases in development and material costs related to Broadband Communication Systems that were recorded in the first quarter of 2013 but should have been recorded in the fourth quarter of 2012, (2) a sub-contractor subscription deposit that was recorded as sales and income in the fourth quarter of 2012 but should have been amortized to sales and income during 2013, (3) costs accrued in the fourth quarter of 2012 for goods or services received in the first quarter of 2013, (4) several unrecorded liabilities that were recorded in the first quarter of 2013 but should have been recorded in the fourth quarter of 2012, (5) a correction of accrued vacation that was recorded in the fourth quarter of 2013 but should have been recorded in the fourth quarter of 2012 and the first, second and third quarters of 2013, and (6) a warranty reserve reduction recorded in the third quarter of 2012 that should have been recorded in the fourth quarter of 2011.
	With respect to each of these immaterial out of period amounts included in the Company’s previously issued financial statements, the table below presents the: (1) nature of the adjustments, (2) applicable segment and (3) amount of increase (or decrease) to sales and operating income for the quarters ended December 31, September 27, June 28, and March 29, 2013.
					December 31,								September 27,								June 28,								March 29,
					2013								2013								2013								2013
	Nature of Adjustment		Applicable		Sales				Operating				Sales				Operating				Sales				Operating				Sales				Operating
			Segment						Income								Income								Income								Income
					($ in millions)
	Higher development and material costs for networked communications systems		Communication Systems		$	—			$	—			$	—			$	—			$	—			$	—			$	10			$	10
	Sub-contractor subscription deposit		Aerospace Systems			5				—				7				1				7				1				7				1
	Costs accruals for goods/services received		Aerospace Systems			—				—				—				—				—				—				5				1
	Unrecorded liabilities		Aerospace Systems			—				—				—				—				—				—				(2	)			—
	Accrued vacation		Aerospace Systems			—				6				—				(2	)			—				(2	)			—				(2	)
	Overstated revenue		Aerospace Systems			4				—				(4	)			—				—				—				—				—
	Warranty reserve		Electronic Systems			—				—				—				—				—				—				—				—
	Total				$	9			$	6			$	3			$	(1	)		$	7			$	(1	)		$	20			$	10
	The table below presents the impact of the matters discussed above on sales and pre-tax income for the years ended December 31, 2013, 2012 and 2011, and for the years ended prior to December 31, 2011.
			2013								2012								2011								Prior to 2011
			Sales				Pre-tax				Sales				Pre-tax				Sales				Pre-tax				Sales				Pre-tax
							Income								Income								Income								Income
			(in millions)
	Army C-12 Contract		$	(25	)		$	(35	)		$	(3	)		$	(16	)		$	(1	)		$	(3	)		$	—			$	—
	Other Logistics Support Contracts			(2	)			(11	)			(2	)			(11	)			—				(2	)			(1	)			(4	)
	Logistics Solutions		$	(27	)		$	(46	)		$	(5	)		$	(27	)		$	(1	)		$	(5	)		$	(1	)		$	(4	)
	Platform Systems			(12	)			(14	)			3				2				—				—				—				—
	Total Internal Review of Aerospace		$	(39	)		$	(60	)		$	(2	)		$	(25	)		$	(1	)		$	(5	)		$	(1	)		$	(4	)
	Systems Segment
	Sales-Type Lease Transaction			(7	)			5				—				3				—				3				—				17
	Out of Period Amounts			39				14				(36	)			(18	)			(3	)			4				—				—
	Total Revisions		$	(7	)		$	(41	)		$	(38	)		$	(40	)		$	(4	)		$	2			$	(1	)		$	13
	The table below presents the impact of the matters discussed above on sales and pre-tax income for the quarters ended March 28, 2014, December 31, September 27, June 28, and March 29, 2013.
			March 28, 2014								December 31, 2013								September 27, 2013								28-Jun-13								March 29, 2013
			Sales				Pre-tax				Sales				Pre-tax				Sales				Pre-tax				Sales				Pre-tax				Sales			Pre-tax
							Income								Income								Income								Income							Income
			(in millions)
	Army C-12 Contract		$	(2	)		$	(4	)		$	(24	)		$	(20	)		$	3			$	(2	)		$	(3	)		$	(7	)		$	(1	)	$	(6	)
	Other Logistics Support Contracts			—				(5	)			(1	)			(2	)			(1	)			(5	)			—				(2	)			—			(2	)
	Logistics Solutions			(2	)			(9	)			(25	)			(22	)			2				(7	)			(3	)			(9	)			(1	)		(8	)
	Platform Systems			(6	)			(11	)			(2	)			(2	)			1				—				(6	)			(6	)			(5	)		(6	)
	Total Internal Review of Aerospace Systems Segment			(8	)			(20	)			(27	)			(24	)			3				(7	)			(9	)			(15	)			(6	)		(14	)
	Sales-Type Lease Transaction			(5	)			—				(3	)			1				(1	)			2				(1	)			1				(2	)		1
	Out of Period Amounts			—				—				9				6				3				(1	)			7				(1	)			20			10
	Total Revisions		$	(13	)		$	(20	)		$	(21	)		$	(17	)		$	5			$	(6	)		$	(3	)		$	(15	)		$	12		$	(3	)
	In accordance with ASC 650-10-S99 and S55, the Company performed an analysis to determine if the impact of the amounts disclosed above were material to its previously issued financial statements. Based on that analysis, the Company believes that its previously issued financial statements are not materially misstated on either a quantitative or qualitative basis. However, as a result of completing the review, the Company believes that correcting these errors in the quarterly report on Form 10-Q for the second quarter of 2014 would, in the aggregate, cause a material misstatement to forecasted pre-tax income and net income for the fiscal year ending December 31, 2014. Accordingly, the Company is correcting these errors by revising its previously issued financial statements to record all the adjustments in the tables above in the appropriate period.
	The tables below present the Company’s: (1) As Previously Reported, (2) Adjustments, and (3) As Currently Reported Condensed Consolidated Balance Sheets as of March 28, 2014, Statements of Operations for the quarterly periods ended March 28, 2014 and March 29, 2013 and the Operating Activities for the Statement of Cash Flows for the period ended March 29, 2013. The Adjustments correct for: (1) the results of the Aerospace Systems internal review, (2) the accounting related to a sales-type lease transaction within the Company’s Electronic Systems segment and (3) immaterial out of period amounts previously recorded in the Company’s financial statements but not recorded in the appropriate period to reflect them in the appropriate period.
							Adjustments for:
			As				Aerospace				Sales-Type				Out of Period				As
			Previously				Systems				Lease				Amounts				Revised
			Reported				Segment				Transaction
							Internal
							Review
			(in millions)
	Unaudited Condensed Consolidated Balance Sheet as of March 28, 2014:
	ASSETS
	Current Assets:
	Cash and cash equivalents		$	227			$	—			$	—			$	—			$	227
	Billed receivables, net of allowances of $24 in 2014			1,093				(25	)			—				—				1,068
	Contracts in process			2,763				(82	)			(33	)			—				2,648
	Inventories			375				—				—				—				375
Deferred income taxes			118				26				—				—				144
Other current assets			126				8				30				(4	)			160
Total current assets			4,702				(73	)			(3	)			(4	)			4,622
Property, plant and equipment, net			1,028				5				—				—				1,033
Goodwill			7,821				—				—				—				7,821
Identifiable intangible assets			283				—				—				—				283
Deferred debt issue costs			23				—				—				—				23
Other assets			208				—				37				—				245
Total assets		$	14,065			$	(68	)		$	34			$	(4	)		$	14,027
LIABILITIES AND EQUITY
Current Liabilities:
Accounts payable, trade		$	590			$	—			$	—			$	—			$	590
Accrued employment costs			538				5				—				—				543
Accrued expenses			403				1				—				—				404
Advance payments and billings in excess of costs incurred			523				1				5				—				529
Income taxes			22				(10	)			—				17				29
Other current liabilities			380				2				—				—				382
Total current liabilities			2,456				(1	)			5				17				2,477
Pension and postretirement benefits			729				—				—				—				729
Deferred income taxes			679				3				—				(21	)			661
Other liabilities			382				—				12				—				394
Long-term debt			3,631				—				—				—				3,631
Total liabilities			7,877				2				17				(4	)			7,892
Equity:
L-3 shareholders’ equity:
L-3 Communications Holdings, Inc.’s common stock			5,767				—				—				—				5,767
L-3 Communications Holdings, Inc.’s treasury stock at cost			(5,421	)			—				—				—				(5,421	)
Retained earnings			5,895				(73	)			18				2				5,842
Accumulated other comprehensive loss			(128	)			—				—				—				(128	)
Total L-3 shareholders’ equity			6,113				(73	)			18				2				6,060
Noncontrolling interests			75				—				—				—				75
Total equity			6,188				(73	)			18				2				6,135
Total liabilities and equity		$	14,065			$	(71	)		$	35			$	(2	)		$	14,027
		As				Adjustments for:												As
		Previously																Revised
		Reported				Aerospace				Sales-Type				Out of Period
						Systems				Lease				Amounts
						Segment				Transaction
						Internal
						Review
		(in millions, except per share data)
Unaudited Condensed Consolidated Statement of Operations, for the quarter ended March 28, 2014:
Net sales:
Products		$	1,661			$	(7	)		$	(5	)		$	—			$	1,649
Services			1,310				(2	)			—				—				1,308
Total net sales			2,971				(9	)			(5	)			—				2,957
Cost of sales:
Products			(1,467	)			(4	)			5				—				(1,466	)
Services			(1,197	)			(7	)			—				(1	)			(1,205	)
Total cost of sales			(2,664	)			(11	)			5				(1	)			(2,671	)
Operating income			307				(20	)			—				(1	)			286
Interest expense			(43	)			—				—				—				(43	)
Interest and other income, net			3				—				2				—				5
Income before income taxes			267				(20	)			2				(1	)			248
Provision for income taxes			(85	)			9				—				—				(76	)
Net income		$	182			$	(11	)		$	2			$	(1	)		$	172
Net income attributable to noncontrolling interests			(2	)			—				—				—				(2	)
Net income attributable to L-3		$	180			$	(11	)		$	2			$	(1	)		$	170
Earnings per share attributable to L-3 Holdings’ common shareholders:
Basic		$	2.09			$	(0.13	)		$	0.02			$	(0.01	)		$	1.97
Diluted		$	2.01			$	(0.12	)		$	0.02			$	(0.01	)		$	1.9
Cash dividends paid per common share		$	0.6			$	—			$	—			$	—			$	0.6
L-3 Holdings’ weighted average common shares outstanding:
Basic			86.1				—				—				—				86.1
Diluted			89.4				—				—				—				89.4
		As				Adjustments for:												As
		Previously																Revised
		Reported				Aerospace				Sales-Type				Out of Period
						Systems				Lease				Amounts
						Segment				Transaction
						Internal
						Review
		(in millions, except per share data)
Unaudited Condensed Consolidated Statement of Operations, for the quarter ended March 29, 2013:
Net sales:
Products		$	1,813			$	(4	)		$	(2	)		$	14			$	1,821
Services			1,372				(1	)			—				5				1,376
Total net sales			3,185				(5	)			(2	)			19	(1)			3,197
Cost of sales:
Products			(1,620	)			(1	)			2				(3	)			(1,622	)
Services			(1,252	)			(7	)			—				(6	)			(1,265	)
Total cost of sales			(2,872	)			(8	)			2				(9	)			(2,887	)
Operating income			313				(13	)			—				10				310
Interest expense			(43	)			—				—				—				(43	)
Interest and other income, net			3				—				1				(1	)			3
Income before income taxes			273				(13	)			1				9				270
Provision for income taxes			(79	)			4				—				(3	)			(78	)
Net income		$	194			$	(9	)		$	1			$	6			$	192
Net income attributable to noncontrolling interests			(1	)			—				—				—				(1	)
Net income attributable to L-3		$	193			$	(9	)		$	1			$	6			$	191
Earnings per share attributable to L-3 Holdings’ common shareholders:
Basic		$	2.14			$	(0.10	)		$	0.01			$	0.07			$	2.12
Diluted		$	2.11			$	(0.10	)		$	0.01			$	0.07			$	2.09
Cash dividends paid per common share		$	0.55			$	—			$	—			$	—			$	0.55
L-3 Holdings’ weighted average common shares outstanding:
Basic			90.3				—				—				—				90.3
Diluted			91.5				—				—				—				91.5
(1)	Includes rounding of $1 million.
		As				Net				As
		Previously				Adjustments				Revised
		Reported
		(in millions)
Unaudited Condensed Consolidated Statement of Cash Flows for the quarter ended March 28, 2014:
Operating activities:
Net income		$	182			$	(10	)		$	172
Depreciation of property, plant and equipment			42				—				42
Amortization of intangibles and other assets			12				—				12
Deferred income tax provision			22				1				23
Stock-based employee compensation expense			15				—				15
Contributions to employee savings plans in L-3 Holdings’ common stock			44				—				44
Amortization of pension and postretirement benefit plans net loss and prior service cost			4				—				4
Amortization of bond discounts and deferred debt issue costs (included in interest expense)			2				—				2
Other non-cash items			1				—				1
Changes in operating assets and liabilities, excluding amounts from acquisitions and divestitures:
Billed receivables			(74	)			1				(73	)
Contracts in process			(236	)			22				(214	)
Inventories			(16	)			—				(16	)
Other assets			(4	)			(6	)			(10	)
Accounts payable, trade			49				—				49
Accrued employment costs			(12	)			2				(10	)
Accrued expenses			(49	)			(2	)			(51	)
Advance payments and billings in excess of costs incurred			(46	)			—				(46	)
Income taxes			38				(10	)			28
Excess income tax benefits related to share-based payment arrangements			(14	)			—				(14	)
Other current liabilities			(8	)			2				(6	)
Pension and postretirement benefits			(2	)			—				(2	)
All other operating activities			(12	)			—				(12	)
Net cash (used in) from operating activities		$	(62	)		$	—			$	(62	)
		As				Net				As
		Previously				Adjustments				Revised
		Reported
		(in millions)
Unaudited Condensed Consolidated Statement of Cash Flows for the quarter ended March 29, 2013:
Operating activities:
Net income		$	194			$	(2	)		$	192
Depreciation of property, plant and equipment			42				—				42
Amortization of intangibles and other assets			12				—				12
Deferred income tax provision			19				(1	)			18
Stock-based employee compensation expense			14				—				14
Contributions to employee savings plans in L-3 Holdings’ common stock			32				—				32
Amortization of pension and postretirement benefit plans net loss and prior service cost			22				—				22
Amortization of bond discounts and deferred debt issue costs (included in interest expense)			2				—				2
Other non-cash items			3				—				3
Changes in operating assets and liabilities, excluding amounts from acquisitions and divestitures:
Billed receivables			(146	)			—				(146	)
Contracts in process			(145	)			20				(125	)
Inventories			8				—				8
Other assets			49				(2	)			47
Accounts payable, trade			105				(11	)			94
Accrued employment costs			13				4				17
Accrued expenses			(41	)			—				(41	)
Advance payments and billings in excess of costs incurred			(37	)			—				(37	)
Income taxes			51				—				51
Excess income tax benefits related to share-based payment arrangements			(2	)			—				(2	)
Other current liabilities			4				—				4
Pension and postretirement benefits			4				—				4
All other operating activities			(57	)			(8	)			(65	)
Net cash (used in) from operating activities		$	146			$	—			$	146

Recently_Issued_Accounting_Sta

Recently Issued Accounting Standards	3 Months Ended
	Mar. 28, 2014
Accounting Changes and Error Corrections [Abstract]	'
Recently Issued Accounting Standards	'
	4.  Recently Issued Accounting Standards
	Effective January 1, 2014, the Company adopted Financial Accounting Standards Board (FASB) issued amendments to an accounting standard that require 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 adoption of this standard did not impact the Company’s financial position, results of operations or cash flows.
	In April 2014, the FASB issued an accounting standards update that provides new guidance on the accounting and reporting of discontinued operations. Under the new guidance, only disposals representing a strategic shift in operations should be presented as discontinued operations. Those strategic shifts should have a major effect on the organization’s operations and financial results. Additionally, the new guidance requires additional disclosures about discontinued operations. The update is effective for the Company for interim and annual periods beginning January 1, 2015. The adoption of this standard is not expected to impact the Company’s financial position, results of operations or cash flows and will only affect the treatment of future discontinued operations.

Acquisitions

Acquisitions	3 Months Ended
	Mar. 28, 2014
Business Combinations [Abstract]	'
Acquisitions	'
	5.  Acquisitions
	The business acquisitions discussed below are included in the Company’s results of operations from their respective dates of acquisition.
	2014 Business Acquisition
	On March 4, 2014, the Company acquired Data Tactics Corporation, renamed L-3 Data Tactics, for a purchase price of $57 million, which was financed with cash on hand. The purchase price is subject to adjustment based on closing date actual net assets. L-3 Data Tactics is a specialized provider of large-scale data analytics, cybersecurity and cloud computing solution services, primarily to the DoD. Based on the preliminary purchase price, the aggregate goodwill recognized for this business was $40 million, most of which is expected to be deductible for income tax purposes. The goodwill was assigned to the NSS reportable segment. The final purchase price allocation, which is expected to be completed by the third quarter of 2014, will be based on final purchase price, final appraisals and other analysis of fair values of acquired assets and liabilities. The Company does not expect that differences between the preliminary and final purchase price allocations will have a material impact on its results of operations or financial position.
	2013 Business Acquisition
	On December 19, 2013, the Company acquired Mustang Technology Group, L.P. (Mustang) business for a purchase price of $54 million, which was financed with cash on hand. The purchase price is subject to adjustment based on closing date net working capital. Mustang develops and manufactures radar-based sensors and systems used in precision-guided weapons, electronic warfare, unmanned systems and other military applications. Based on the preliminary purchase price allocations, the aggregate goodwill recognized for this business was $44 million, most of which is expected to be deductible for income tax purposes. The goodwill was assigned to the Electronic Systems reportable segment. The final purchase price allocation is expected to be completed in the second quarter of 2014 and will be based on final purchase price, final appraisals and other analysis of fair values of acquired assets and liabilities. The Company does not expect that differences between the preliminary and final purchase price allocations will have a material impact on its results of operations or financial position.
	Unaudited Pro Forma Statements of Operations Data
	The following unaudited pro forma Statements of Operations data presents the combined results of the Company and its business acquisitions completed during the quarter ended March 28, 2014 and the year ended December 31, 2013, in each case assuming that the business acquisitions completed during these periods had occurred on January 1, 2013.
		First Quarter Ended
		March 28,		March 29,
		2014		2013
		(in millions, except per share data)
	Pro forma net sales	$	2,964	$	3,215
	Pro forma net income attributable to L-3	$	169	$	191
	Pro forma diluted earnings per share	$	1.89	$	2.09
	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, 2013.

Contracts_in_Process

Contracts in Process	3 Months Ended
	Mar. 28, 2014
Text Block [Abstract]	'
Contracts in Process	'
	6.  Contracts in Process
	The components of contracts in process are presented in the table below.
		March 28,			December 31,
		2014			2013
		(in millions)
	Unbilled contract receivables, gross	$	2,626		$	2,502
	Unliquidated progress payments		(990	)		(1,035	)
	Unbilled contract receivables, net		1,636			1,467
	Inventoried contract costs, gross		1,088			1,044
	Unliquidated progress payments		(76	)		(80	)
	Inventoried contract costs, net		1,012			964
	Total contracts in process	$	2,648		$	2,431
	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.
		First Quarter Ended
		March 28,			March 29,
		2014			2013
		(in millions)
	Amounts included in inventoried contract costs at beginning of the period	$	138		$	110
	IRAD and B&P costs		72			73
	Other G&A costs		204			205
	Total contract costs incurred		276			278
	Amounts charged to cost of sales		(273	)		(275	)
	Amounts included in inventoried contract costs at end of the period	$	141		$	113
	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.
		First Quarter Ended
		March 28,			March 29,
		2014			2013
		(in millions)
	Selling, general and administrative expenses	$	71		$	72
	Research and development expenses		17			20
	Total	$	88		$	92

Inventories

Inventories	3 Months Ended
	Mar. 28, 2014
Inventory Disclosure [Abstract]	'
Inventories	'
	7.  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.
		March 28,		December 31,
		2014		2013
		(in millions)
	Raw materials, components and sub-assemblies	$	166	$	160
	Work in process		128		125
	Finished goods		81		74
	Total	$	375	$	359

Goodwill_and_Identifiable_Inta

Goodwill and Identifiable Intangible Assets	3 Months Ended
	Mar. 28, 2014
Goodwill and Intangible Assets Disclosure [Abstract]	'
Goodwill and Identifiable Intangible Assets	'
	8.  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 quarter ended March 28, 2014.
			Aerospace			Electronic			Communication		NSS		Consolidated
			Systems			Systems			Systems				Total
			(in millions)
	Balance at December 31, 2013		$	1,751		$	4,085		$	992	$	968	$	7,796
	Business acquisition(1)			—			—			—		40		40
	Foreign currency translation adjustments(2)			(9	)		(6	)		—		—		(15	)
	Balance at March 28, 2014		$	1,742		$	4,079		$	992	$	1,008	$	7,821
	(1)	The increase in goodwill for the NSS segment is due to the L-3 Data Tactics business acquisition.
	(2)	The decrease in goodwill presented in the Aerospace Systems and Electronic Systems segments was primarily due to the strengthening of the U.S. dollar against the Canadian dollar during the quarter ended March 28, 2014.
	The Company’s accumulated goodwill impairment losses were $58 million at March 28, 2014 and December 31, 2013, of which $43 million and $15 million were recorded in the Electronic Systems and Communication Systems segments, respectively.
	Identifiable Intangible Assets. The table below presents information for the Company’s identifiable intangible assets that are subject to amortization.
			March 28, 2014										December 31, 2013
			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		$	474		$	261	$	213	$	466		$	253	$	213
	Technology			11			168			110		58		168			108		60
	Other			17			27			15		12		27			15		12
	Total			17		$	669		$	386	$	283	$	661		$	376	$	285
	The table below presents amortization expense recorded by the Company for its identifiable intangible assets.
			First Quarter Ended
			March 28,			March 29,
			2014			2013
			(in millions)
	Amortization Expense		$	10		$	9
	Based on gross carrying amounts at March 28, 2014, the Company’s estimate of amortization expense for identifiable intangible assets for the years ending December 31, 2014 through 2018 is presented in the table below.
			Year Ending December 31,
			2014			2015			2016		2017		2018
			(in millions)
	Estimated amortization expense		$	43		$	41		$	34	$	32	$	26

Other_Current_Liabilities_and_

Other Current Liabilities and Other Liabilities	3 Months Ended
	Mar. 28, 2014
Text Block [Abstract]	'
Other Current Liabilities and Other Liabilities	'
	9.  Other Current Liabilities and Other Liabilities
	The table below presents the components of other current liabilities.
			March 28,			December 31,
			2014			2013
			(in millions)
	Other Current Liabilities:
	Accruals for pending and threatened litigation (see Note 18)		$	7		$	6
	Accrued product warranty costs			76			75
	Estimated costs in excess of estimated contract value to complete contracts in process in a loss position			75			78
	Accrued interest			46			52
	Deferred revenues			40			35
	Other			138			137
	Total other current liabilities		$	382		$	383
	The table below presents the components of other liabilities.
			March 28,			December 31,
			2014			2013
			(in millions)
	Other Liabilities:
	Non-current income taxes payable (see Note 11)		$	177		$	177
	Deferred compensation			47			45
	Accrued workers’ compensation			42			46
	Accrued product warranty costs			21			24
	Notes payable and capital lease obligations			12			15
	Other			95			99
	Total other liabilities		$	394		$	406
	The table below presents the changes in the Company’s accrued product warranty costs.
			First Quarter Ended
			March 28,			March 29,
			2014			2013
			(in millions)
	Accrued product warranty costs:(1)
	Balance at January 1		$	99		$	99
	Accruals for product warranties issued during the period			17			19
	Settlements made during the period			(19	)		(20	)
	Foreign currency translation adjustments			—			(1	)
	Balance at end of period		$	97		$	97
	(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	3 Months Ended
	Mar. 28, 2014
Debt Disclosure [Abstract]	'
Debt	'
	10.  Debt
	The components of debt and a reconciliation to the carrying amount of long-term debt is presented in the table below.
			March 28,			December 31,
			2014			2013
			(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 (CODES)(2)			689			689
	Principal amount of long-term debt			3,639			3,639
	Unamortized discounts			(8	)		(9	)
	Carrying amount of long-term debt		$	3,631		$	3,630
	(1)	During the quarter ended March 28, 2014, L-3 Communications’ aggregate borrowings and repayments under the Amended and Restated Revolving Credit Facility were $524 million. At March 28, 2014, L-3 Communications had the availability of all of its $1 billion Amended and Restated Revolving Credit Facility, which expires on February 3, 2017.
	(2)	The CODES have been classified as long-term debt at March 28, 2014, because the Company has the ability to draw on the Amended and Restated Revolving Credit Facility to finance the conversion of the CODES.
	L-3 Holdings
	Under select conditions, including if L-3 Holdings’ common stock price is more than 120% (currently $106.90) of the then current conversion price (currently $89.08) 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. The current conversion rate is 11.2259 shares of common stock per $1,000 aggregate principal amount of CODES, which is equal to a conversion price of approximately $89.08 per share. At the current conversion price, the aggregate consideration to be delivered upon conversion would be determined based on 7.7 million shares of L-3 Holdings’ common stock. See Note 11 to the audited consolidated financial statements for the year ended December 31, 2013, included in the Company’s Annual Report on Form 10-K/A, filed on October 10, 2014, for the fiscal year ended December 31, 2013, for additional information regarding the CODES, including conditions for conversion.
	On March 31, 2014, the Company notified holders of the CODES that they are currently entitled to convert all or a portion of their CODES. The CODES are convertible because the closing price of L-3 Holdings common stock, for at least 20 trading days during the 30 consecutive trading-day period ended on March 28, 2014 (the last trading day of the previous fiscal quarter), was greater than $106.90 (120% of the then current conversion price of $89.08) (the “trading price condition”). Holders’ right to convert pursuant to the trading price condition began March 31, 2014 and ends on June 27, 2014. As previously announced, the Company intends to settle the entire conversion payment obligation with respect to converted CODES, if any, in cash.
	Interest expense recognized was $5 million for both quarterly periods ended March 28, 2014 and March 29, 2013. The carrying amount of the equity component (conversion feature) of the CODES was $64 million at March 28, 2014 and December 31, 2013.

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 28, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	11.  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 March 28, 2014, 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) commenced audits of the Company’s U.S. Federal income tax returns for 2011 and 2010. The Company cannot predict the outcome of the audits at this time.
	The effective tax rate for the quarter ended March 28, 2014 increased to 30.6% from 28.9% for the quarter ended March 29, 2013. The increase was primarily due to a tax benefit in the quarter ended March 29, 2013 of $12 million related to the U.S. Federal research and experimentation tax credit for 2012 and 2013, which did not recur in the quarter ended March 28, 2014. This increase was partially offset by a lower effective tax rate on foreign earnings.
	As of March 28, 2014, the Company anticipates that unrecognized tax benefits will decrease by approximately $20 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 $12 million ($7 million after income taxes) at March 28, 2014 and $11 million ($7 million after income taxes) at December 31, 2013, and potential penalties of $7 million at March 28, 2014 and $8 million at December 31, 2013.

Amounts_Reclassified_Out_of_Ac

Amounts Reclassified Out of Accumulated Other Comprehensive (Loss) Income	3 Months Ended
	Mar. 28, 2014
Text Block [Abstract]	'
Amounts Reclassified Out of Accumulated Other Comprehensive (Loss) Income	'
	12.  Amounts Reclassified Out of Accumulated Other Comprehensive (Loss) Income
	The amounts reclassified from Accumulated Other Comprehensive (Loss) Income (AOCI) for the quarters ended March 28, 2014 and March 29, 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			(34	)		(3	)		—			(37	)
	Amounts reclassified from other comprehensive income, net of tax			—			—			13			13
	Net current period other comprehensive (loss) income		$	(34	)	$	(3	)	$	13		$	(24	)
	Balance at March 29, 2013		$	133		$	—		$	(707	)	$	(574	)
	Balance at December 31, 2013		$	142		$	1		$	(253	)	$	(110	)
	Other comprehensive loss before reclassifications, net of tax			(16	)		(2	)		—			(18	)
	Amounts reclassified from other comprehensive (loss) income, net of tax			—			(3	)		3			—
	Net current period other comprehensive (loss) income			(16	)		(5	)		3			(18	)
	Balance at March 28, 2014		$	126		$	(4	)	$	(250	)	$	(128	)
	Further details regarding the amounts reclassified from AOCI for the quarter ended March 28, 2014 are presented in the table below.
			Amount Reclassified from AOCI						Affected Line Item in the
			First Quarter Ended						Unaudited Condensed Consolidated
	Details About AOCI		March 28,			March 29,			Statements of  Operations
			2014			2013
			(in millions)			(in millions)
	Loss on hedging instruments		$	(5	)	$	—		Cost of sales-products
				(5	)		—		Income before income taxes
				2			—		Benefit for income taxes
			$	(3	)	$	—		Net income
	Amortization of defined benefit pension items:
	Net loss		$	4		$	22		(a)
				4			22		Income before income taxes
				(1	)		(9	)	Provision for income taxes
			$	3		$	13		Net Income
	Total reclassification for the period		$	—		$	13		Net Income
	(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 19 for additional information).

Equity

Equity	3 Months Ended
	Mar. 28, 2014
Text Block [Abstract]	'
Equity	'
	13.  Equity
	On February 5, 2013, L-3 Holdings’ Board of Directors approved a share repurchase program that authorizes L-3 Holdings to repurchase up to $1.5 billion of its common stock through June 30, 2015. Repurchases of L-3 Holdings’ common stock under the 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, but not limited to, the Company’s financial position, earnings, legal requirements, other investment opportunities (including acquisitions), and market conditions. L-3 Holdings repurchased 1.2 million shares of its common stock at an average price of $109.43 per share for an aggregate amount of $133 million from January 1, 2014 through March 28, 2014. All share repurchases of L-3 Holdings’ common stock have been recorded as treasury shares.
	At March 28, 2014, the remaining dollar value of authorization under the share repurchase program was $735 million. From March 29, 2014 through April 23, 2014, L-3 Holdings repurchased 307,692 shares of its common stock at an average price of $116.98 per share for an aggregate amount of $36 million.
	On February 11, 2014, L-3 Holdings’ Board of Directors declared a cash dividend of $0.60 per share, which resulted in the Company paying total cash dividends of $52 million on March 17, 2014. In addition, during the quarter ended March 28, 2014, the Company paid $3 million of previously accrued dividends for employee held stock-awards.

L3_Holdings_Earnings_Per_Commo

L-3 Holdings' Earnings Per Common Share	3 Months Ended
	Mar. 28, 2014
Earnings Per Share [Abstract]	'
L-3 Holdings' Earnings Per Common Share	'
	14.  L-3 Holdings’ Earnings Per Common Share
	A reconciliation of basic and diluted earnings per share (EPS) is presented in the table below.
			First Quarter Ended
			March 28,			March 29,
			2014			2013
			(in millions, except per share data)
	Reconciliation of net income:
	Net income		$	172		$	192
	Net income attributable to noncontrolling interests			(2	)		(1	)
	Net income attributable to L-3 Holdings’ common shareholders		$	170		$	191
	Earnings per share attributable to L-3 Holdings’ common shareholders:
	Basic:
	Weighted average common shares outstanding			86.1			90.3
	Basic earnings per share:
	Net income		$	1.97		$	2.12
	Diluted:
	Common and potential common shares:
	Weighted average common shares outstanding			86.1			90.3
	Assumed exercise of stock options			3.4			3.4
	Unvested restricted stock awards			1.7			1.7
	Employee stock purchase plan contributions			—			0.2
	Performance unit awards			0.2			0.1
	Assumed purchase of common shares for treasury			(3.5	)		(4.2	)
	Assumed conversion of the CODES(1)			1.5			—
	Common and potential common shares			89.4			91.5
	Diluted earnings per share:
	Net income		$	1.9		$	2.09
	(1)	L-3 Holdings’ CODES had no impact on diluted EPS for the quarterly period ended March 29, 2013 as the average market price of L-3 Holdings’ common stock during this period was less than the price at which the CODES would have been convertible into L-3 Holdings common stock. As of March 28, 2014, the conversion price was $89.08.
	The computation of diluted EPS excluded shares for stock options and employee stock purchase plan contributions of 0.4 million and shares for stock options of 1.8 million for the quarterly periods ended March 28, 2014 and March 29, 2013, respectively, as they were anti-dilutive.

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 28, 2014
Fair Value Disclosures [Abstract]	'
Fair Value Measurements	'
	15.  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.
			March 28, 2014						December 31, 2013
	Description		Level 1(1)		Level 2(2)		Level 3(3)		Level 1(1)		Level 2(2)		Level 3(3)
			(in millions)
	Assets
	Cash equivalents		$	22	$	—	$	—	$	299	$	—	$	—
	Derivatives (foreign currency forward contracts)			—		5		—		—		6		—
	Total Assets		$	22	$	5	$	—	$	299	$	6	$	—
	Liabilities
	Derivatives (foreign currency forward contracts)		$	—	$	10	$	—	$	—	$	5	$	—
	(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	3 Months Ended
	Mar. 28, 2014
Investments, All Other Investments [Abstract]	'
Financial Instruments	'
	16.  Financial Instruments
	At March 28, 2014 and December 31, 2013, 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 other financial instruments are presented in the table below.
			March 28, 2014						December 31, 2013
			Carrying			Estimated			Carrying		Estimated
			Amount			Fair Value			Amount		Fair Value
			(in millions)
	Senior Notes(1)		$	2,942		$	3,168		$	2,941	$	3,121
	CODES(1)			689			911			689		830
	Foreign currency forward contracts(2)			(5	)		(5	)		1		1
	(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 17 for additional disclosures regarding the notional amounts and fair values of foreign currency forward contracts.

Derivative_Financial_Instrumen

Derivative Financial Instruments	3 Months Ended
	Mar. 28, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Derivative Financial Instruments	'
	17.  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 March 28, 2014.
	Currency		Notional Amounts
			(in millions)
	Canadian dollar		$	222
	U.S. dollar			115
	Euro			83
	British pound			13
	Other			2
	Total		$	435
	At March 28, 2014, 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 March 28, 2014 and December 31, 2013.
	The table below presents the location of the Company’s derivative instruments recorded at fair value on the condensed consolidated balance sheets.
			March 28, 2014								December 31, 2013
			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)		$	4	$	1	$	7	$	3	$	5	$	1	$	3	$	2
	Derivatives not designated as hedging instruments:
	Foreign currency forward contracts(1)			—		—		—		—		—		—		—		—
	Embedded derivative related to the CODES			—		—		—		—		—		—		—		—
	Total derivative instruments		$	4	$	1	$	7	$	3	$	5	$	1	$	3	$	2
	(1)	See Note 15 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 periods ended March 28, 2014 and March 29, 2013. At March 28, 2014, the estimated amount of existing gains that are expected to be reclassified into income within the next 12 months is $4 million.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 28, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	18.  Commitments and Contingencies
	Guarantees
	In connection with the spin-off of Engility Holdings, Inc. (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 international 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. International government contracts generally include comparable provisions relating to terminations for convenience or default, as well as other procurement clauses relevant to the international 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 9. Amounts recoverable from insurance contracts or third parties are recorded as assets when deemed probable. At March 28, 2014, 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, which ruled against Kalitta Air and affirmed the trial court’s judgment on November 25, 2013. The Court of Appeals subsequently denied Kalitta Air’s motion for a rehearing of its appeal. On April 3, 2014, Kalitta Air filed a petition with the U.S. Supreme Court seeking review of the Court of Appeals’ November 25, 2013 decision. L-3 IS intends to file a brief with the U.S. Supreme Court opposing Kalitta Air’s petition for review.
	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	3 Months Ended
	Mar. 28, 2014
Compensation and Retirement Disclosure [Abstract]	'
Pension and Other Postretirement Benefits	'
	19.  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
		First Quarter Ended						First Quarter Ended
		March 28,			March 29,			March 28,			March 29,
		2014			2013			2014			2013
		(in millions)
	Components of net periodic benefit cost:
	Service cost	$	27		$	32		$	1		$	1
	Interest cost		36			33			2			2
	Expected return on plan assets		(48	)		(42	)		(1	)		(1	)
	Amortization of prior service costs (credits)		1			—			(1	)		1
	Amortization of net loss (gain)		4			22			—			(1	)
	Curtailment loss		1			—			—			—
	Net periodic benefit cost	$	21		$	45		$	1		$	2
	Contributions. The Company contributed cash of $14 million to its pension plans and $2 million to its other postretirement benefit plans during the quarter ended March 28, 2014. The Company expects to contribute an additional $83 million to its pension plans and $8 million to its other postretirement benefit plans during the remainder of 2014.

StockBased_Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 28, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Stock-Based Compensation	'
	20.  Stock-Based Compensation
	On February 19, 2014, 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 472,992 stock options with an exercise price of $113.67 per option, which was 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 of $20.02 per option 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)	5.5
	Expected volatility	24.4	%
	Expected dividend yield	2.7	%
	Risk-free interest rate	1.7	%
	Restricted Stock Units. The Company granted 402,870 restricted stock units with a weighted average grant date fair value of $113.67 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 47,467 performance units with a weighted average grant date fair value per unit of $113.67. 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, 2016. 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	3 Months Ended
	Mar. 28, 2014
Supplemental Cash Flow Elements [Abstract]	'
Supplemental Cash Flow Information	'
	21.  Supplemental Cash Flow Information
		First Quarter Ended
		March 28,		March 29,
		2014		2013
		(in millions)
	Interest paid on outstanding debt	$	48	$	48
	Income tax payments		26		19
	Income tax refunds		1		10

Segment_Information

Segment Information	3 Months Ended
	Mar. 28, 2014
Segment Reporting [Abstract]	'
Segment Information	'
	22.  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.
	The tables below present net sales, operating income, depreciation and amortization and total assets by reportable segment.
		First Quarter Ended
		March 28,			March 29,
		2014			2013
		(in millions)
	Net Sales:
	Aerospace Systems	$	1,074		$	1,191
	Electronic Systems		1,098			1,137
	Communication Systems		517			575
	NSS		305			331
	Elimination of intercompany sales		(37	)		(37	)
	Consolidated total	$	2,957		$	3,197
	Operating Income:
	Aerospace Systems	$	93		$	127
	Electronic Systems		125			117
	Communication Systems		50			45
	NSS		18			21
	Consolidated total	$	286		$	310
	Depreciation and amortization:
	Aerospace Systems	$	10		$	9
	Electronic Systems		29			30
	Communication Systems		12			12
	NSS		3			3
	Consolidated total	$	54		$	54
		March 28,			December 31,
		2014			2013
		(in millions)
	Total Assets:
	Aerospace Systems	$	3,148		$	3,087
	Electronic Systems		7,027			6,928
	Communication Systems		2,128			2,130
	NSS		1,338			1,247
	Corporate		386			596
	Consolidated total	$	14,027		$	13,988

Employee_Severance_and_Termina

Employee Severance and Termination Costs	3 Months Ended
	Mar. 28, 2014
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 $8 million in employee severance and other termination costs with respect to approximately 570 employees during the quarter period ended March 28, 2014. During the year ended December 31, 2013, the Company recorded a total of $29 million in employee severance and other termination costs with respect to approximately 2,000 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 $13 million at March 28, 2014 and $11 million at December 31, 2013. Employee severance and other termination costs incurred by reportable segment for the quarterly periods ended March 28, 2014 and March 29, 2013 are presented in the table below.
		First Quarter Ended
		March 28,		March 29,
		2014		2013
		(in millions)
	Reportable Segment
	Aerospace Systems	$	—	$	—
	Electronic Systems		4		3
	Communication Systems		3		1
	NSS		1		1
	Consolidated	$	8	$	5

Condensed_Combining_Financial_

Condensed Combining Financial Information of L-3 Communications and Its Subsidiaries	3 Months Ended
	Mar. 28, 2014
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 100% 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 11 to the audited consolidated financial statements for the year ended December 31, 2013, included in the Company’s Annual Report on Form 10-K/A, filed on October 10, 2014, for the fiscal year ended December 31, 2013. 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.
	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.
	As discussed in Note 3, the Company is revising its previously issued financial statements. As part of that revision, the Company has revised the accompanying condensed combining financial statements contained herein. The adjustments related to the internal review of the Aerospace Systems segment, excluding certain adjustments related to the Platform Systems segment, were recorded as adjustments to the Guarantor Subsidiaries financial statement amounts. Adjustments from the internal review that related to a foreign subsidiary of the Platform Systems segment, with a cumulative operating impact through March 28, 2014 of $14 million, were recorded to the Non-Guarantor Subsidiaries financial statement amounts. The adjustments for the accounting related to a sales-type lease transaction for flight simulator systems within its Electronic Systems segment have been recorded as adjustments to the L-3 Communications financial statement amounts. The adjustments for the previously identified immaterial errors were recorded as adjustments to the Guarantor Subsidiaries financial statement amounts.
		L-3			L-3			Guarantor			Non-			Eliminations			Consolidated
		Holdings			Communications			Subsidiaries			Guarantor						L-3
		(Parent)									Subsidiaries
		(in millions)
	Condensed Combining Balance Sheets:
	At March 28, 2014:
	Current assets:
	Cash and cash equivalents	$	—		$	57		$	—		$	182		$	(12	)	$	227
	Billed receivables, net		—			343			458			267			—			1,068
	Contracts in process		—			996			1,260			392			—			2,648
	Other current assets		—			357			147			175			—			679
	Total current assets		—			1,753			1,865			1,016			(12	)		4,622
	Goodwill		—			2,307			4,327			1,187			—			7,821
	Other assets		—			821			522			241			—			1,584
	Investment in and amounts due from consolidated subsidiaries		6,749			7,203			3,661			—			(17,613	)		—
	Total assets	$	6,749		$	12,084		$	10,375		$	2,444		$	(17,625	)	$	14,027
	Current liabilities	$	—		$	921		$	932		$	636		$	(12	)	$	2,477
	Amounts due to consolidated subsidiaries		—			—			—			380			(380	)		—
	Other long-term liabilities		—			1,472			191			121			—			1,784
	Long-term debt		689			3,631			—			—			(689	)		3,631
	Total liabilities		689			6,024			1,123			1,137			(1,081	)		7,892
	L-3 shareholders’ equity		6,060			6,060			9,252			1,307			(16,619	)		6,060
	Noncontrolling interests		—			—			—			—			75			75
	Total equity		6,060			6,060			9,252			1,307			(16,544	)		6,135
	Total liabilities and equity	$	6,749		$	12,084		$	10,375		$	2,444		$	(17,625	)	$	14,027
	At December 31, 2013:
	Current assets:
	Cash and cash equivalents	$	—		$	258		$	—		$	261		$	(19	)	$	500
	Billed receivables, net		—			364			401			226			—			991
	Contracts in process		—			925			1,152			354			—			2,431
	Other current assets		—			344			159			169			—			672
	Total current assets		—			1,891			1,712			1,010			(19	)		4,594
	Goodwill		—			2,307			4,326			1,163			—			7,796
	Other assets		—			838			532			228			—			1,598
	Investment in and amounts due from consolidated subsidiaries		6,670			6,940			3,744			—			(17,354	)		—
	Total assets	$	6,670		$	11,976		$	10,314		$	2,401		$	(17,373	)	$	13,988
	Current liabilities	$	—		$	914		$	1,011		$	628		$	(19	)	$	2,534
	Amounts due to consolidated subsidiaries		—			—			—			270			(270	)		—
	Other long-term liabilities		—			1,451			193			124			—			1,768
	Long-term debt		689			3,630			—			—			(689	)		3,630
	Total liabilities		689			5,995			1,204			1,022			(978	)		7,932
	L-3 shareholders’ equity		5,981			5,981			9,110			1,379			(16,470	)		5,981
	Noncontrolling interests		—			—			—			—			75			75
	Total equity		5,981			5,981			9,110			1,379			(16,395	)		6,056
	Total liabilities and equity	$	6,670		$	11,976		$			$	2,401		$	(17,373	)	$	13,988
									10,314
		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 March 28, 2014:
	Total net sales	$	—		$	863		$	1,625		$	543		$	(74	)	$	2,957
	Total cost of sales		(15	)		(769	)		(1,481	)		(495	)		89			(2,671	)
	Operating (loss) income		(15	)		94			144			48			15			286
	Interest expense		(5	)		(43	)		—			—			5			(43	)
	Interest and other income, net		—			5			—			—			—			5
	(Loss) income before income taxes		(20	)		56			144			48			20			248
Benefit (provision) for income taxes		6			(15	)		(45	)		(16	)		(6	)		(76	)
Equity in net income of consolidated subsidiaries		184			129			—			—			(313	)		—
Net income		170			170			99			32			(299	)		172
Net income attributable to noncontrolling interests		—			—			—			—			(2	)		(2	)
Net income attributable to L-3	$	170		$	170		$	99		$	32		$	(301	)	$	170
Comprehensive income attributable to L-3	$	152		$	152		$	96		$	15		$	(263	)	$	152
For the quarter ended March 29, 2013:
Total net sales	$	—		$	946		$	1,740		$	590		$	(79	)	$	3,197
Total cost of sales		(14	)		(864	)		(1,571	)		(531	)		93			(2,887	)
Operating (loss) income		(14	)		82			169			59			14			310
Interest expense		(5	)		(43	)		—			—			5			(43	)
Interest and other income, net		—			3			(1	)		1			—			3
(Loss) income before income taxes		(19	)		42			168			60			19			270
Benefit (provision) for income taxes		5			(12	)		(48	)		(18	)		(5	)		(78	)
Equity in net income of consolidated subsidiaries		205			161			—			—			(366	)		—
Net income		191			191			120			42			(352	)		192
Net income attributable to noncontrolling interests		—			—			—			—			(1	)		(1	)
Net income attributable to L-3	$	191		$	191		$	120		$	42		$	(353	)	$	191
Comprehensive income attributable to L-3	$	167		$	167		$	120		$	5		$	(292	)	$	167
	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 quarter ended March 28, 2014:
Operating activities:
Net cash from (used in) operating activities	$	188		$	80		$	(61	)	$	(34	)	$	(235	)	$	(62	)
Investing activities:
Business acquisitions, net of cash acquired		—			(57	)		—			—			—			(57	)
Investments in L-3 Communications		(51	)		—			—			—			51			—
Other investing activities		—			(13	)		(15	)		(1	)		—			(29	)
Net cash used in investing activities		(51	)		(70	)		(15	)		(1	)		51			(86	)
Financing activities:
Common stock repurchased		(133	)		—			—			—			—			(133	)
Dividends paid on L-3 Holdings common stock		(55	)		—			—			—			—			(55	)
Dividends paid to L-3 Holdings		—			(188	)		—			—			188			—
Investments from L-3 Holdings		—			51			—			—			(51	)		—
Other financing activities		51			(74	)		76			(43	)		54			64
Net cash (used in) from financing activities		(137	)		(211	)		76			(43	)		191			(124	)
Effect of foreign currency exchange rate changes on cash		—			—			—			(1	)		—			(1	)
Net decrease in cash		—			(201	)		—			(79	)		7			(273	)
Cash and cash equivalents, beginning of the period		—			258			—			261			(19	)		500
Cash and cash equivalents, end of the period	$	—		$	57		$	—		$	182		$	(12	)	$	227
For the quarter ended March 29, 2013:
Operating activities:
Net cash from operating activities	$	174		$	92		$	73		$	24		$	(217	)	$	146
Investing activities:
Investments in L-3 Communications		(13	)		—			—			—			13			—
Other investing activities		—			(25	)		(25	)		(4	)		—			(54	)
Net cash used in investing activities		(13	)		(25	)		(25	)		(4	)		13			(54	)
Financing activities:
Common stock repurchased		(122	)		—			—			—			—			(122	)
Dividends paid on L-3 Holdings common stock		(52	)		—			—			—			—			(52	)
Dividends paid to L-3 Holdings		—			(174	)		—			—			174			—
Investments from L-3 Holdings		—			13			—			—			(13	)		—
Other financing activities		13			(86	)		(48	)		(32	)		169			16
Net cash used in financing activities		(161	)		(247	)		(48	)		(32	)		330			(158	)
Effect of foreign currency exchange rate changes on cash		—			—			—			(7	)		—			(7	)
Net decrease in cash		—			(180	)		—			(19	)		126			(73	)
Cash and cash equivalents, beginning of the period		—			246			—			242			(139	)		349
Cash and cash equivalents, end of the period	$	—		$	66		$	—		$	223		$	(13	)	$	276

Basis_of_Presentation_Policies

Basis of Presentation (Policies)	3 Months Ended
	Mar. 28, 2014
Accounting Changes and Error Corrections [Abstract]	'
Principles of Consolidation and Reporting	'
	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/A 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, 2013 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	'
	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 47% of the Company’s net sales in 2013 were accounted for under contract accounting standards, of which approximately 38% 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 $32 million, or 11%, for the quarterly period ended March 28, 2014 and $17 million, or 5%, for the quarterly period ended March 29, 2013.
	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/A for the fiscal year ended December 31, 2013, filed on October 10, 2014.
Adoption of New Accounting Standards	'
	Effective January 1, 2014, the Company adopted Financial Accounting Standards Board (FASB) issued amendments to an accounting standard that require 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 adoption of this standard did not impact the Company’s financial position, results of operations or cash flows.
	In April 2014, the FASB issued an accounting standards update that provides new guidance on the accounting and reporting of discontinued operations. Under the new guidance, only disposals representing a strategic shift in operations should be presented as discontinued operations. Those strategic shifts should have a major effect on the organization’s operations and financial results. Additionally, the new guidance requires additional disclosures about discontinued operations. The update is effective for the Company for interim and annual periods beginning January 1, 2015. The adoption of this standard is not expected to impact the Company’s financial position, results of operations or cash flows and will only affect the treatment of future discontinued operations.

Revisions_to_Previously_Issued1

Revisions to Previously Issued Financial Statements (Tables)	3 Months Ended
	Mar. 28, 2014
Accounting Changes and Error Corrections [Abstract]	'
Schedule of Nature of Adjustments, Applicable Segment, Amount of Increase (or Decrease) to Sales and Operating Income, Period Recorded and Correct Period	'
	With respect to each of these immaterial out of period amounts included in the Company’s previously issued financial statements, the table below presents the: (1) nature of the adjustments, (2) applicable segment and (3) amount of increase (or decrease) to sales and operating income for the quarters ended December 31, September 27, June 28, and March 29, 2013.
					December 31,								September 27,								June 28,								March 29,
					2013								2013								2013								2013
	Nature of Adjustment		Applicable		Sales				Operating				Sales				Operating				Sales				Operating				Sales				Operating
			Segment						Income								Income								Income								Income
					($ in millions)
	Higher development and material costs for networked communications systems		Communication Systems		$	—			$	—			$	—			$	—			$	—			$	—			$	10			$	10
	Sub-contractor subscription deposit		Aerospace Systems			5				—				7				1				7				1				7				1
	Costs accruals for goods/services received		Aerospace Systems			—				—				—				—				—				—				5				1
	Unrecorded liabilities		Aerospace Systems			—				—				—				—				—				—				(2	)			—
	Accrued vacation		Aerospace Systems			—				6				—				(2	)			—				(2	)			—				(2	)
	Overstated revenue		Aerospace Systems			4				—				(4	)			—				—				—				—				—
	Warranty reserve		Electronic Systems			—				—				—				—				—				—				—				—
	Total				$	9			$	6			$	3			$	(1	)		$	7			$	(1	)		$	20			$	10
Schedule of Impact on Sales and Pre-tax Income	'
	The table below presents the impact of the matters discussed above on sales and pre-tax income for the years ended December 31, 2013, 2012 and 2011, and for the years ended prior to December 31, 2011.
			2013								2012								2011								Prior to 2011
			Sales				Pre-tax				Sales				Pre-tax				Sales				Pre-tax				Sales				Pre-tax
							Income								Income								Income								Income
			(in millions)
	Army C-12 Contract		$	(25	)		$	(35	)		$	(3	)		$	(16	)		$	(1	)		$	(3	)		$	—			$	—
	Other Logistics Support Contracts			(2	)			(11	)			(2	)			(11	)			—				(2	)			(1	)			(4	)
	Logistics Solutions		$	(27	)		$	(46	)		$	(5	)		$	(27	)		$	(1	)		$	(5	)		$	(1	)		$	(4	)
	Platform Systems			(12	)			(14	)			3				2				—				—				—				—
	Total Internal Review of Aerospace		$	(39	)		$	(60	)		$	(2	)		$	(25	)		$	(1	)		$	(5	)		$	(1	)		$	(4	)
	Systems Segment
	Sales-Type Lease Transaction			(7	)			5				—				3				—				3				—				17
	Out of Period Amounts			39				14				(36	)			(18	)			(3	)			4				—				—
	Total Revisions		$	(7	)		$	(41	)		$	(38	)		$	(40	)		$	(4	)		$	2			$	(1	)		$	13
	The table below presents the impact of the matters discussed above on sales and pre-tax income for the quarters ended March 28, 2014, December 31, September 27, June 28, and March 29, 2013.
			March 28, 2014								December 31, 2013								September 27, 2013								28-Jun-13								March 29, 2013
			Sales				Pre-tax				Sales				Pre-tax				Sales				Pre-tax				Sales				Pre-tax				Sales			Pre-tax
							Income								Income								Income								Income							Income
			(in millions)
	Army C-12 Contract		$	(2	)		$	(4	)		$	(24	)		$	(20	)		$	3			$	(2	)		$	(3	)		$	(7	)		$	(1	)	$	(6	)
	Other Logistics Support Contracts			—				(5	)			(1	)			(2	)			(1	)			(5	)			—				(2	)			—			(2	)
	Logistics Solutions			(2	)			(9	)			(25	)			(22	)			2				(7	)			(3	)			(9	)			(1	)		(8	)
	Platform Systems			(6	)			(11	)			(2	)			(2	)			1				—				(6	)			(6	)			(5	)		(6	)
	Total Internal Review of Aerospace Systems Segment			(8	)			(20	)			(27	)			(24	)			3				(7	)			(9	)			(15	)			(6	)		(14	)
	Sales-Type Lease Transaction			(5	)			—				(3	)			1				(1	)			2				(1	)			1				(2	)		1
	Out of Period Amounts			—				—				9				6				3				(1	)			7				(1	)			20			10
	Total Revisions		$	(13	)		$	(20	)		$	(21	)		$	(17	)		$	5			$	(6	)		$	(3	)		$	(15	)		$	12		$	(3	)
Schedule of As Previously Reported, Adjustments and As Currently Reported Financial Statements	'
	The tables below present the Company’s: (1) As Previously Reported, (2) Adjustments, and (3) As Currently Reported Condensed Consolidated Balance Sheets as of March 28, 2014, Statements of Operations for the quarterly periods ended March 28, 2014 and March 29, 2013 and the Operating Activities for the Statement of Cash Flows for the period ended March 29, 2013. The Adjustments correct for: (1) the results of the Aerospace Systems internal review, (2) the accounting related to a sales-type lease transaction within the Company’s Electronic Systems segment and (3) immaterial out of period amounts previously recorded in the Company’s financial statements but not recorded in the appropriate period to reflect them in the appropriate period.
							Adjustments for:
			As				Aerospace				Sales-Type				Out of Period				As
			Previously				Systems				Lease				Amounts				Revised
			Reported				Segment				Transaction
							Internal
							Review
			(in millions)
	Unaudited Condensed Consolidated Balance Sheet as of March 28, 2014:
	ASSETS
	Current Assets:
	Cash and cash equivalents		$	227			$	—			$	—			$	—			$	227
	Billed receivables, net of allowances of $24 in 2014			1,093				(25	)			—				—				1,068
	Contracts in process			2,763				(82	)			(33	)			—				2,648
	Inventories			375				—				—				—				375
	Deferred income taxes			118				26				—				—				144
	Other current assets			126				8				30				(4	)			160
	Total current assets			4,702				(73	)			(3	)			(4	)			4,622
	Property, plant and equipment, net			1,028				5				—				—				1,033
	Goodwill			7,821				—				—				—				7,821
	Identifiable intangible assets			283				—				—				—				283
	Deferred debt issue costs			23				—				—				—				23
	Other assets			208				—				37				—				245
	Total assets		$	14,065			$	(68	)		$	34			$	(4	)		$	14,027
	LIABILITIES AND EQUITY
	Current Liabilities:
	Accounts payable, trade		$	590			$	—			$	—			$	—			$	590
	Accrued employment costs			538				5				—				—				543
	Accrued expenses			403				1				—				—				404
	Advance payments and billings in excess of costs incurred			523				1				5				—				529
	Income taxes			22				(10	)			—				17				29
	Other current liabilities			380				2				—				—				382
	Total current liabilities			2,456				(1	)			5				17				2,477
	Pension and postretirement benefits			729				—				—				—				729
	Deferred income taxes			679				3				—				(21	)			661
	Other liabilities			382				—				12				—				394
	Long-term debt			3,631				—				—				—				3,631
	Total liabilities			7,877				2				17				(4	)			7,892
	Equity:
	L-3 shareholders’ equity:
	L-3 Communications Holdings, Inc.’s common stock			5,767				—				—				—				5,767
	L-3 Communications Holdings, Inc.’s treasury stock at cost			(5,421	)			—				—				—				(5,421	)
	Retained earnings			5,895				(73	)			18				2				5,842
	Accumulated other comprehensive loss			(128	)			—				—				—				(128	)
	Total L-3 shareholders’ equity			6,113				(73	)			18				2				6,060
	Noncontrolling interests			75				—				—				—				75
	Total equity			6,188				(73	)			18				2				6,135
	Total liabilities and equity		$	14,065			$	(71	)		$	35			$	(2	)		$	14,027
			As				Adjustments for:												As
			Previously																Revised
			Reported				Aerospace				Sales-Type				Out of Period
							Systems				Lease				Amounts
							Segment				Transaction
							Internal
							Review
			(in millions, except per share data)
	Unaudited Condensed Consolidated Statement of Operations, for the quarter ended March 28, 2014:
	Net sales:
	Products		$	1,661			$	(7	)		$	(5	)		$	—			$	1,649
	Services			1,310				(2	)			—				—				1,308
	Total net sales			2,971				(9	)			(5	)			—				2,957
	Cost of sales:
	Products			(1,467	)			(4	)			5				—				(1,466	)
Services			(1,197	)			(7	)			—				(1	)			(1,205	)
Total cost of sales			(2,664	)			(11	)			5				(1	)			(2,671	)
Operating income			307				(20	)			—				(1	)			286
Interest expense			(43	)			—				—				—				(43	)
Interest and other income, net			3				—				2				—				5
Income before income taxes			267				(20	)			2				(1	)			248
Provision for income taxes			(85	)			9				—				—				(76	)
Net income		$	182			$	(11	)		$	2			$	(1	)		$	172
Net income attributable to noncontrolling interests			(2	)			—				—				—				(2	)
Net income attributable to L-3		$	180			$	(11	)		$	2			$	(1	)		$	170
Earnings per share attributable to L-3 Holdings’ common shareholders:
Basic		$	2.09			$	(0.13	)		$	0.02			$	(0.01	)		$	1.97
Diluted		$	2.01			$	(0.12	)		$	0.02			$	(0.01	)		$	1.9
Cash dividends paid per common share		$	0.6			$	—			$	—			$	—			$	0.6
L-3 Holdings’ weighted average common shares outstanding:
Basic			86.1				—				—				—				86.1
Diluted			89.4				—				—				—				89.4
		As				Adjustments for:												As
		Previously																Revised
		Reported				Aerospace				Sales-Type				Out of Period
						Systems				Lease				Amounts
						Segment				Transaction
						Internal
						Review
		(in millions, except per share data)
Unaudited Condensed Consolidated Statement of Operations, for the quarter ended March 29, 2013:
Net sales:
Products		$	1,813			$	(4	)		$	(2	)		$	14			$	1,821
Services			1,372				(1	)			—				5				1,376
Total net sales			3,185				(5	)			(2	)			19	(1)			3,197
Cost of sales:
Products			(1,620	)			(1	)			2				(3	)			(1,622	)
Services			(1,252	)			(7	)			—				(6	)			(1,265	)
Total cost of sales			(2,872	)			(8	)			2				(9	)			(2,887	)
Operating income			313				(13	)			—				10				310
Interest expense			(43	)			—				—				—				(43	)
Interest and other income, net			3				—				1				(1	)			3
Income before income taxes			273				(13	)			1				9				270
Provision for income taxes			(79	)			4				—				(3	)			(78	)
Net income		$	194			$	(9	)		$	1			$	6			$	192
Net income attributable to noncontrolling interests			(1	)			—				—				—				(1	)
Net income attributable to L-3		$	193			$	(9	)		$	1			$	6			$	191
Earnings per share attributable to L-3 Holdings’ common shareholders:
Basic		$	2.14			$	(0.10	)		$	0.01			$	0.07			$	2.12
Diluted		$	2.11			$	(0.10	)		$	0.01			$	0.07			$	2.09
Cash dividends paid per common share		$	0.55			$	—			$	—			$	—			$	0.55
L-3 Holdings’ weighted average common shares outstanding:
Basic			90.3				—				—				—				90.3
Diluted			91.5				—				—				—				91.5
(1)	Includes rounding of $1 million.
		As				Net				As
		Previously				Adjustments				Revised
		Reported
		(in millions)
Unaudited Condensed Consolidated Statement of Cash Flows for the quarter ended March 28, 2014:
Operating activities:
Net income		$	182			$	(10	)		$	172
Depreciation of property, plant and equipment			42				—				42
Amortization of intangibles and other assets			12				—				12
Deferred income tax provision			22				1				23
Stock-based employee compensation expense			15				—				15
Contributions to employee savings plans in L-3 Holdings’ common stock			44				—				44
Amortization of pension and postretirement benefit plans net loss and prior service cost			4				—				4
Amortization of bond discounts and deferred debt issue costs (included in interest expense)			2				—				2
Other non-cash items			1				—				1
Changes in operating assets and liabilities, excluding amounts from acquisitions and divestitures:
Billed receivables			(74	)			1				(73	)
Contracts in process			(236	)			22				(214	)
Inventories			(16	)			—				(16	)
Other assets			(4	)			(6	)			(10	)
Accounts payable, trade			49				—				49
Accrued employment costs			(12	)			2				(10	)
Accrued expenses			(49	)			(2	)			(51	)
Advance payments and billings in excess of costs incurred			(46	)			—				(46	)
Income taxes			38				(10	)			28
Excess income tax benefits related to share-based payment arrangements			(14	)			—				(14	)
Other current liabilities			(8	)			2				(6	)
Pension and postretirement benefits			(2	)			—				(2	)
All other operating activities			(12	)			—				(12	)
Net cash (used in) from operating activities		$	(62	)		$	—			$	(62	)
		As				Net				As
		Previously				Adjustments				Revised
		Reported
		(in millions)
Unaudited Condensed Consolidated Statement of Cash Flows for the quarter ended March 29, 2013:
Operating activities:
Net income		$	194			$	(2	)		$	192
Depreciation of property, plant and equipment			42				—				42
Amortization of intangibles and other assets			12				—				12
Deferred income tax provision			19				(1	)			18
Stock-based employee compensation expense			14				—				14
Contributions to employee savings plans in L-3 Holdings’ common stock			32				—				32
Amortization of pension and postretirement benefit plans net loss and prior service cost			22				—				22
Amortization of bond discounts and deferred debt issue costs (included in interest expense)			2				—				2
Other non-cash items			3				—				3
Changes in operating assets and liabilities, excluding amounts from acquisitions and divestitures:
Billed receivables			(146	)			—				(146	)
Contracts in process			(145	)			20				(125	)
Inventories			8				—				8
Other assets			49				(2	)			47
Accounts payable, trade			105				(11	)			94
Accrued employment costs			13				4				17
Accrued expenses			(41	)			—				(41	)
Advance payments and billings in excess of costs incurred			(37	)			—				(37	)
Income taxes			51				—				51
Excess income tax benefits related to share-based payment arrangements			(2	)			—				(2	)
Other current liabilities			4				—				4
Pension and postretirement benefits			4				—				4
All other operating activities			(57	)			(8	)			(65	)
Net cash (used in) from operating activities		$	146			$	—			$	146

Acquisitions_Tables

Acquisitions (Tables)	3 Months Ended
	Mar. 28, 2014
Business Combinations [Abstract]	'
Unaudited Pro Forma Statements of Operations Data	'
	The following unaudited pro forma Statements of Operations data presents the combined results of the Company and its business acquisitions completed during the quarter ended March 28, 2014 and the year ended December 31, 2013, in each case assuming that the business acquisitions completed during these periods had occurred on January 1, 2013.
		First Quarter Ended
		March 28,		March 29,
		2014		2013
		(in millions, except per share data)
	Pro forma net sales	$	2,964	$	3,215
	Pro forma net income attributable to L-3	$	169	$	191
	Pro forma diluted earnings per share	$	1.89	$	2.09

Contracts_in_Process_Tables

Contracts in Process (Tables)	3 Months Ended
	Mar. 28, 2014
Text Block [Abstract]	'
Components of Contracts in Process	'
	The components of contracts in process are presented in the table below.
		March 28,			December 31,
		2014			2013
		(in millions)
	Unbilled contract receivables, gross	$	2,626		$	2,502
	Unliquidated progress payments		(990	)		(1,035	)
	Unbilled contract receivables, net		1,636			1,467
	Inventoried contract costs, gross		1,088			1,044
	Unliquidated progress payments		(76	)		(80	)
	Inventoried contract costs, net		1,012			964
	Total contracts in process	$	2,648		$	2,431
General and Administrative, Independent Research and Development and Bids 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.
		First Quarter Ended
		March 28,			March 29,
		2014			2013
		(in millions)
	Amounts included in inventoried contract costs at beginning of the period	$	138		$	110
	IRAD and B&P costs		72			73
	Other G&A costs		204			205
	Total contract costs incurred		276			278
	Amounts charged to cost of sales		(273	)		(275	)
	Amounts included in inventoried contract costs at end of the period	$	141		$	113
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.
		First Quarter Ended
		March 28,			March 29,
		2014			2013
		(in millions)
	Selling, general and administrative expenses	$	71		$	72
	Research and development expenses		17			20
	Total	$	88		$	92

Inventories_Tables

Inventories (Tables)	3 Months Ended
	Mar. 28, 2014
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.
		March 28,		December 31,
		2014		2013
		(in millions)
	Raw materials, components and sub-assemblies	$	166	$	160
	Work in process		128		125
	Finished goods		81		74
	Total	$	375	$	359

Goodwill_and_Identifiable_Inta1

Goodwill and Identifiable Intangible Assets (Tables)	3 Months Ended
	Mar. 28, 2014
Goodwill and Intangible Assets Disclosure [Abstract]	'
Changes in Goodwill by Segment	'
	The table below presents the changes in goodwill by segment for the quarter ended March 28, 2014.
			Aerospace			Electronic			Communication		NSS		Consolidated
			Systems			Systems			Systems				Total
			(in millions)
	Balance at December 31, 2013		$	1,751		$	4,085		$	992	$	968	$	7,796
	Business acquisition(1)			—			—			—		40		40
	Foreign currency translation adjustments(2)			(9	)		(6	)		—		—		(15	)
	Balance at March 28, 2014		$	1,742		$	4,079		$	992	$	1,008	$	7,821
	(1)	The increase in goodwill for the NSS segment is due to the L-3 Data Tactics business acquisition.
	(2)	The decrease in goodwill presented in the Aerospace Systems and Electronic Systems segments was primarily due to the strengthening of the U.S. dollar against the Canadian dollar during the quarter ended March 28, 2014.
Identifiable Intangible Assets	'
	The table below presents information for the Company’s identifiable intangible assets that are subject to amortization.
			March 28, 2014										December 31, 2013
			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		$	474		$	261	$	213	$	466		$	253	$	213
	Technology			11			168			110		58		168			108		60
	Other			17			27			15		12		27			15		12
	Total			17		$	669		$	386	$	283	$	661		$	376	$	285
Amortization Expense	'
	The table below presents amortization expense recorded by the Company for its identifiable intangible assets.
			First Quarter Ended
			March 28,			March 29,
			2014			2013
			(in millions)
	Amortization Expense		$	10		$	9
Estimated Amortization Expense	'
	Based on gross carrying amounts at March 28, 2014, the Company’s estimate of amortization expense for identifiable intangible assets for the years ending December 31, 2014 through 2018 is presented in the table below.
			Year Ending December 31,
			2014			2015			2016		2017		2018
			(in millions)
	Estimated amortization expense		$	43		$	41		$	34	$	32	$	26

Other_Current_Liabilities_and_1

Other Current Liabilities and Other Liabilities (Tables)	3 Months Ended
	Mar. 28, 2014
Text Block [Abstract]	'
Other Current Liabilities	'
	The table below presents the components of other current liabilities.
			March 28,			December 31,
			2014			2013
			(in millions)
	Other Current Liabilities:
	Accruals for pending and threatened litigation (see Note 18)		$	7		$	6
	Accrued product warranty costs			76			75
	Estimated costs in excess of estimated contract value to complete contracts in process in a loss position			75			78
	Accrued interest			46			52
	Deferred revenues			40			35
	Other			138			137
	Total other current liabilities		$	382		$	383
Other Liabilities	'
	The table below presents the components of other liabilities.
			March 28,			December 31,
			2014			2013
			(in millions)
	Other Liabilities:
	Non-current income taxes payable (see Note 11)		$	177		$	177
	Deferred compensation			47			45
	Accrued workers’ compensation			42			46
	Accrued product warranty costs			21			24
	Notes payable and capital lease obligations			12			15
	Other			95			99
	Total other liabilities		$	394		$	406
Changes in Company's Accrued Product Warranty Costs	'
	The table below presents the changes in the Company’s accrued product warranty costs.
			First Quarter Ended
			March 28,			March 29,
			2014			2013
			(in millions)
	Accrued product warranty costs:(1)
	Balance at January 1		$	99		$	99
	Accruals for product warranties issued during the period			17			19
	Settlements made during the period			(19	)		(20	)
	Foreign currency translation adjustments			—			(1	)
	Balance at end of period		$	97		$	97
	(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)	3 Months Ended
	Mar. 28, 2014
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.
			March 28,			December 31,
			2014			2013
			(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 (CODES)(2)			689			689
	Principal amount of long-term debt			3,639			3,639
	Unamortized discounts			(8	)		(9	)
	Carrying amount of long-term debt		$	3,631		$	3,630
	(1)	During the quarter ended March 28, 2014, L-3 Communications’ aggregate borrowings and repayments under the Amended and Restated Revolving Credit Facility were $524 million. At March 28, 2014, L-3 Communications had the availability of all of its $1 billion Amended and Restated Revolving Credit Facility, which expires on February 3, 2017.
	(2)	The CODES have been classified as long-term debt at March 28, 2014, because the Company has the ability to draw on the Amended and Restated Revolving Credit Facility to finance the conversion of the CODES.

Amounts_Reclassified_Out_of_Ac1

Amounts Reclassified Out of Accumulated Other Comprehensive (Loss) Income (Tables)	3 Months Ended
	Mar. 28, 2014
Text Block [Abstract]	'
Summary of Amounts Reclassified Out of Accumulated Other Comprehensive (Loss) Income	'
	The amounts reclassified from Accumulated Other Comprehensive (Loss) Income (AOCI) for the quarters ended March 28, 2014 and March 29, 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			(34	)		(3	)		—			(37	)
	Amounts reclassified from other comprehensive income, net of tax			—			—			13			13
	Net current period other comprehensive (loss) income		$	(34	)	$	(3	)	$	13		$	(24	)
	Balance at March 29, 2013		$	133		$	—		$	(707	)	$	(574	)
	Balance at December 31, 2013		$	142		$	1		$	(253	)	$	(110	)
	Other comprehensive loss before reclassifications, net of tax			(16	)		(2	)		—			(18	)
	Amounts reclassified from other comprehensive (loss) income, net of tax			—			(3	)		3			—
	Net current period other comprehensive (loss) income			(16	)		(5	)		3			(18	)
	Balance at March 28, 2014		$	126		$	(4	)	$	(250	)	$	(128	)
	Further details regarding the amounts reclassified from AOCI for the quarter ended March 28, 2014 are presented in the table below.
			Amount Reclassified from AOCI						Affected Line Item in the
			First Quarter Ended						Unaudited Condensed Consolidated
	Details About AOCI		March 28,			March 29,			Statements of  Operations
			2014			2013
			(in millions)			(in millions)
	Loss on hedging instruments		$	(5	)	$	—		Cost of sales-products
				(5	)		—		Income before income taxes
				2			—		Benefit for income taxes
			$	(3	)	$	—		Net income
	Amortization of defined benefit pension items:
	Net loss		$	4		$	22		(a)
				4			22		Income before income taxes
				(1	)		(9	)	Provision for income taxes
			$	3		$	13		Net Income
	Total reclassification for the period		$	—		$	13		Net Income
	(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 19 for additional information).

L3_Holdings_Earnings_Per_Commo1

L-3 Holdings' Earnings Per Common Share (Tables)	3 Months Ended
	Mar. 28, 2014
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.
			First Quarter Ended
			March 28,			March 29,
			2014			2013
			(in millions, except per share data)
	Reconciliation of net income:
	Net income		$	172		$	192
	Net income attributable to noncontrolling interests			(2	)		(1	)
	Net income attributable to L-3 Holdings’ common shareholders		$	170		$	191
	Earnings per share attributable to L-3 Holdings’ common shareholders:
	Basic:
	Weighted average common shares outstanding			86.1			90.3
	Basic earnings per share:
	Net income		$	1.97		$	2.12
	Diluted:
	Common and potential common shares:
	Weighted average common shares outstanding			86.1			90.3
	Assumed exercise of stock options			3.4			3.4
	Unvested restricted stock awards			1.7			1.7
	Employee stock purchase plan contributions			—			0.2
	Performance unit awards			0.2			0.1
	Assumed purchase of common shares for treasury			(3.5	)		(4.2	)
	Assumed conversion of the CODES(1)			1.5			—
	Common and potential common shares			89.4			91.5
	Diluted earnings per share:
	Net income		$	1.9		$	2.09
	(1)	L-3 Holdings’ CODES had no impact on diluted EPS for the quarterly period ended March 29, 2013 as the average market price of L-3 Holdings’ common stock during this period was less than the price at which the CODES would have been convertible into L-3 Holdings common stock. As of March 28, 2014, the conversion price was $89.08.

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 28, 2014
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.
			March 28, 2014						December 31, 2013
	Description		Level 1(1)		Level 2(2)		Level 3(3)		Level 1(1)		Level 2(2)		Level 3(3)
			(in millions)
	Assets
	Cash equivalents		$	22	$	—	$	—	$	299	$	—	$	—
	Derivatives (foreign currency forward contracts)			—		5		—		—		6		—
	Total Assets		$	22	$	5	$	—	$	299	$	6	$	—
	Liabilities
	Derivatives (foreign currency forward contracts)		$	—	$	10	$	—	$	—	$	5	$	—
	(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)	3 Months Ended
	Mar. 28, 2014
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 other financial instruments are presented in the table below.
			March 28, 2014						December 31, 2013
			Carrying			Estimated			Carrying		Estimated
			Amount			Fair Value			Amount		Fair Value
			(in millions)
	Senior Notes(1)		$	2,942		$	3,168		$	2,941	$	3,121
	CODES(1)			689			911			689		830
	Foreign currency forward contracts(2)			(5	)		(5	)		1		1
	(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 17 for additional disclosures regarding the notional amounts and fair values of foreign currency forward contracts.

Derivative_Financial_Instrumen1

Derivative Financial Instruments (Tables)	3 Months Ended
	Mar. 28, 2014
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 March 28, 2014.
	Currency		Notional Amounts
			(in millions)
	Canadian dollar		$	222
	U.S. dollar			115
	Euro			83
	British pound			13
	Other			2
	Total		$	435
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.
			March 28, 2014								December 31, 2013
			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)		$	4	$	1	$	7	$	3	$	5	$	1	$	3	$	2
	Derivatives not designated as hedging instruments:
	Foreign currency forward contracts(1)			—		—		—		—		—		—		—		—
	Embedded derivative related to the CODES			—		—		—		—		—		—		—		—
	Total derivative instruments		$	4	$	1	$	7	$	3	$	5	$	1	$	3	$	2
	(1)	See Note 15 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)	3 Months Ended
	Mar. 28, 2014
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
		First Quarter Ended						First Quarter Ended
		March 28,			March 29,			March 28,			March 29,
		2014			2013			2014			2013
		(in millions)
	Components of net periodic benefit cost:
	Service cost	$	27		$	32		$	1		$	1
	Interest cost		36			33			2			2
	Expected return on plan assets		(48	)		(42	)		(1	)		(1	)
	Amortization of prior service costs (credits)		1			—			(1	)		1
	Amortization of net loss (gain)		4			22			—			(1	)
	Curtailment loss		1			—			—			—
	Net periodic benefit cost	$	21		$	45		$	1		$	2

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 28, 2014
Disclosure of Compensation Related Costs, Share-based 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)	5.5
	Expected volatility	24.4	%
	Expected dividend yield	2.7	%
	Risk-free interest rate	1.7	%

Supplemental_Cash_Flow_Informa1

Supplemental Cash Flow Information (Tables)	3 Months Ended
	Mar. 28, 2014
Supplemental Cash Flow Elements [Abstract]	'
Supplemental Cash Flow Information	'
		First Quarter Ended
		March 28,		March 29,
		2014		2013
		(in millions)
	Interest paid on outstanding debt	$	48	$	48
	Income tax payments		26		19
	Income tax refunds		1		10

Segment_Information_Tables

Segment Information (Tables)	3 Months Ended
	Mar. 28, 2014
Segment Reporting [Abstract]	'
Summary of Segment Information	'
	The tables below present net sales, operating income, depreciation and amortization and total assets by reportable segment.
		First Quarter Ended
		March 28,			March 29,
		2014			2013
		(in millions)
	Net Sales:
	Aerospace Systems	$	1,074		$	1,191
	Electronic Systems		1,098			1,137
	Communication Systems		517			575
	NSS		305			331
	Elimination of intercompany sales		(37	)		(37	)
	Consolidated total	$	2,957		$	3,197
	Operating Income:
	Aerospace Systems	$	93		$	127
	Electronic Systems		125			117
	Communication Systems		50			45
	NSS		18			21
	Consolidated total	$	286		$	310
	Depreciation and amortization:
	Aerospace Systems	$	10		$	9
	Electronic Systems		29			30
	Communication Systems		12			12
	NSS		3			3
	Consolidated total	$	54		$	54
		March 28,			December 31,
		2014			2013
		(in millions)
	Total Assets:
	Aerospace Systems	$	3,148		$	3,087
	Electronic Systems		7,027			6,928
	Communication Systems		2,128			2,130
	NSS		1,338			1,247
	Corporate		386			596
	Consolidated total	$	14,027		$	13,988

Employee_Severance_and_Termina1

Employee Severance and Termination Costs (Tables)	3 Months Ended
	Mar. 28, 2014
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 quarterly periods ended March 28, 2014 and March 29, 2013 are presented in the table below.
		First Quarter Ended
		March 28,		March 29,
		2014		2013
		(in millions)
	Reportable Segment
	Aerospace Systems	$	—	$	—
	Electronic Systems		4		3
	Communication Systems		3		1
	NSS		1		1
	Consolidated	$	8	$	5

Condensed_Combining_Financial_1

Condensed Combining Financial Information of L-3 Communications and Its Subsidiaries (Tables)	3 Months Ended
	Mar. 28, 2014
Text Block [Abstract]	'
Condensed Combining Balance Sheets	'
	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.
	As discussed in Note 3, the Company is revising its previously issued financial statements. As part of that revision, the Company has revised the accompanying condensed combining financial statements contained herein. The adjustments related to the internal review of the Aerospace Systems segment, excluding certain adjustments related to the Platform Systems segment, were recorded as adjustments to the Guarantor Subsidiaries financial statement amounts. Adjustments from the internal review that related to a foreign subsidiary of the Platform Systems segment, with a cumulative operating impact through March 28, 2014 of $14 million, were recorded to the Non-Guarantor Subsidiaries financial statement amounts. The adjustments for the accounting related to a sales-type lease transaction for flight simulator systems within its Electronic Systems segment have been recorded as adjustments to the L-3 Communications financial statement amounts. The adjustments for the previously identified immaterial errors were recorded as adjustments to the Guarantor Subsidiaries financial statement amounts.
			L-3				L-3				Guarantor				Non-				Eliminations				Consolidated
			Holdings				Communications				Subsidiaries				Guarantor								L-3
			(Parent)												Subsidiaries
			(in millions)
	Condensed Combining Balance Sheets:
	At March 28, 2014:
	Current assets:
	Cash and cash equivalents		$	—			$	57			$	—			$	182			$	(12	)		$	227
	Billed receivables, net			—				343				458				267				—				1,068
	Contracts in process			—				996				1,260				392				—				2,648
	Other current assets			—				357				147				175				—				679
	Total current assets			—				1,753				1,865				1,016				(12	)			4,622
	Goodwill			—				2,307				4,327				1,187				—				7,821
	Other assets			—				821				522				241				—				1,584
	Investment in and amounts due from consolidated subsidiaries			6,749				7,203				3,661				—				(17,613	)			—
	Total assets		$	6,749			$	12,084			$	10,375			$	2,444			$	(17,625	)		$	14,027
	Current liabilities		$	—			$	921			$	932			$	636			$	(12	)		$	2,477
	Amounts due to consolidated subsidiaries			—				—				—				380				(380	)			—
	Other long-term liabilities			—				1,472				191				121				—				1,784
	Long-term debt			689				3,631				—				—				(689	)			3,631
	Total liabilities			689				6,024				1,123				1,137				(1,081	)			7,892
	L-3 shareholders’ equity			6,060				6,060				9,252				1,307				(16,619	)			6,060
	Noncontrolling interests			—				—				—				—				75				75
	Total equity			6,060				6,060				9,252				1,307				(16,544	)			6,135
	Total liabilities and equity		$	6,749			$	12,084			$	10,375			$	2,444			$	(17,625	)		$	14,027
	At December 31, 2013:
	Current assets:
	Cash and cash equivalents		$	—			$	258			$	—			$	261			$	(19	)		$	500
	Billed receivables, net			—				364				401				226				—				991
	Contracts in process			—				925				1,152				354				—				2,431
	Other current assets			—				344				159				169				—				672
	Total current assets			—				1,891				1,712				1,010				(19	)			4,594
	Goodwill			—				2,307				4,326				1,163				—				7,796
	Other assets			—				838				532				228				—				1,598
	Investment in and amounts due from consolidated subsidiaries			6,670				6,940				3,744				—				(17,354	)			—
	Total assets		$	6,670			$	11,976			$	10,314			$	2,401			$	(17,373	)		$	13,988
	Current liabilities		$	—			$	914			$	1,011			$	628			$	(19	)		$	2,534
	Amounts due to consolidated subsidiaries			—				—				—				270				(270	)			—
	Other long-term liabilities			—				1,451				193				124				—				1,768
	Long-term debt			689				3,630				—				—				(689	)			3,630
	Total liabilities			689				5,995				1,204				1,022				(978	)			7,932
	L-3 shareholders’ equity			5,981				5,981				9,110				1,379				(16,470	)			5,981
	Noncontrolling interests			—				—				—				—				75				75
	Total equity			5,981				5,981				9,110				1,379				(16,395	)			6,056
	Total liabilities and equity		$	6,670			$	11,976			$				$	2,401			$	(17,373	)		$	13,988
												10,314
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 March 28, 2014:
	Total net sales		$	—			$	863			$	1,625			$	543			$	(74	)		$	2,957
	Total cost of sales			(15	)			(769	)			(1,481	)			(495	)			89				(2,671	)
	Operating (loss) income			(15	)			94				144				48				15				286
	Interest expense			(5	)			(43	)			—				—				5				(43	)
	Interest and other income, net			—				5				—				—				—				5
	(Loss) income before income taxes			(20	)			56				144				48				20				248
	Benefit (provision) for income taxes			6				(15	)			(45	)			(16	)			(6	)			(76	)
	Equity in net income of consolidated subsidiaries			184				129				—				—				(313	)			—
	Net income			170				170				99				32				(299	)			172
	Net income attributable to noncontrolling interests			—				—				—				—				(2	)			(2	)
	Net income attributable to L-3		$	170			$	170			$	99			$	32			$	(301	)		$	170
	Comprehensive income attributable to L-3		$	152			$	152			$	96			$	15			$	(263	)		$	152
	For the quarter ended March 29, 2013:
	Total net sales		$	—			$	946			$	1,740			$	590			$	(79	)		$	3,197
	Total cost of sales			(14	)			(864	)			(1,571	)			(531	)			93				(2,887	)
	Operating (loss) income			(14	)			82				169				59				14				310
	Interest expense			(5	)			(43	)			—				—				5				(43	)
	Interest and other income, net			—				3				(1	)			1				—				3
	(Loss) income before income taxes			(19	)			42				168				60				19				270
	Benefit (provision) for income taxes			5				(12	)			(48	)			(18	)			(5	)			(78	)
	Equity in net income of consolidated subsidiaries			205				161				—				—				(366	)			—
	Net income			191				191				120				42				(352	)			192
	Net income attributable to noncontrolling interests			—				—				—				—				(1	)			(1	)
	Net income attributable to L-3		$	191			$	191			$	120			$	42			$	(353	)		$	191
	Comprehensive income attributable to L-3		$	167			$	167			$	120			$	5			$	(292	)		$	167
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 quarter ended March 28, 2014:
	Operating activities:
	Net cash from (used in) operating activities		$	188			$	80			$	(61	)		$	(34	)		$	(235	)		$	(62	)
	Investing activities:
	Business acquisitions, net of cash acquired			—				(57	)			—				—				—				(57	)
	Investments in L-3 Communications			(51	)			—				—				—				51				—
	Other investing activities			—				(13	)			(15	)			(1	)			—				(29	)
	Net cash used in investing activities			(51	)			(70	)			(15	)			(1	)			51				(86	)
	Financing activities:
	Common stock repurchased			(133	)			—				—				—				—				(133	)
	Dividends paid on L-3 Holdings common stock			(55	)			—				—				—				—				(55	)
	Dividends paid to L-3 Holdings			—				(188	)			—				—				188				—
	Investments from L-3 Holdings			—				51				—				—				(51	)			—
	Other financing activities			51				(74	)			76				(43	)			54				64
	Net cash (used in) from financing activities			(137	)			(211	)			76				(43	)			191				(124	)
	Effect of foreign currency exchange rate changes on cash			—				—				—				(1	)			—				(1	)
	Net decrease in cash			—				(201	)			—				(79	)			7				(273	)
	Cash and cash equivalents, beginning of the period			—				258				—				261				(19	)			500
	Cash and cash equivalents, end of the period		$	—			$	57			$	—			$	182			$	(12	)		$	227
	For the quarter ended March 29, 2013:
	Operating activities:
	Net cash from operating activities		$	174			$	92			$	73			$	24			$	(217	)		$	146
	Investing activities:
	Investments in L-3 Communications			(13	)			—				—				—				13				—
	Other investing activities			—				(25	)			(25	)			(4	)			—				(54	)
	Net cash used in investing activities			(13	)			(25	)			(25	)			(4	)			13				(54	)
	Financing activities:
	Common stock repurchased			(122	)			—				—				—				—				(122	)
	Dividends paid on L-3 Holdings common stock			(52	)			—				—				—				—				(52	)
	Dividends paid to L-3 Holdings			—				(174	)			—				—				174				—
	Investments from L-3 Holdings			—				13				—				—				(13	)			—
	Other financing activities			13				(86	)			(48	)			(32	)			169				16
	Net cash used in financing activities			(161	)			(247	)			(48	)			(32	)			330				(158	)
	Effect of foreign currency exchange rate changes on cash			—				—				—				(7	)			—				(7	)
	Net decrease in cash			—				(180	)			—				(19	)			126				(73	)
	Cash and cash equivalents, beginning of the period			—				246				—				242				(139	)			349
	Cash and cash equivalents, end of the period		$	—			$	66			$	—			$	223			$	(13	)		$	276

Description_of_Business_Additi

Description of Business - Additional Information (Detail)	3 Months Ended
	Mar. 28, 2014
	Segment
Disclosure Description Of Business Additional Information [Abstract]	'
Number of segments	4

Basis_of_Presentation_Addition

Basis of Presentation - Additional Information (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 28, 2014	Mar. 29, 2013
Summary Of Significant Accounting Policies [Line Items]	'	'
Percentage of sales accounted for under contract accounting standards	47.00%	'
Percentage of fixed-price type contracts	38.00%	'
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 operating income due to changes in contract estimates	$32	$17
Percentage of increase in operating income due to changes in contract estimates	11.00%	5.00%
CODES Due 2035 [Member]	'	'
Summary Of Significant Accounting Policies [Line Items]	'	'
Interest rate on debt instruments	3.00%	'
Debt instruments, maturity year	'2035	'

Revisions_to_Previously_Issued2

Revisions to Previously Issued Financial Statements - Additional Information (Detail) (USD $)

3 Months Ended

12 Months Ended

3 Months Ended

12 Months Ended

3 Months Ended

12 Months Ended

3 Months Ended

12 Months Ended

3 Months Ended

12 Months Ended

3 Months Ended

12 Months Ended

3 Months Ended

12 Months Ended

3 Months Ended

12 Months Ended

In Millions, unless otherwise specified

Mar. 28, 2014

Mar. 29, 2013

Mar. 28, 2014

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Mar. 28, 2014

Dec. 31, 2013

Sep. 27, 2013

Jun. 28, 2013

Mar. 29, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Mar. 28, 2014

Dec. 31, 2013

Sep. 27, 2013

Jun. 28, 2013

Mar. 29, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Mar. 28, 2014

Dec. 31, 2013

Sep. 27, 2013

Jun. 28, 2013

Mar. 29, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Mar. 28, 2014

Dec. 31, 2013

Sep. 27, 2013

Jun. 28, 2013

Mar. 29, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Mar. 28, 2014

Dec. 31, 2013

Sep. 27, 2013

Jun. 28, 2013

Mar. 29, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Mar. 28, 2014

Dec. 31, 2013

Sep. 27, 2013

Jun. 28, 2013

Mar. 29, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Mar. 28, 2014

Dec. 31, 2013

Sep. 27, 2013

Jun. 28, 2013

Mar. 29, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Dec. 31, 2010

Dec. 31, 2010

Dec. 31, 2010

Dec. 31, 2010

Dec. 31, 2010

Dec. 31, 2010

Dec. 31, 2010

Sales-Type Lease Transaction [Member]

Sales-Type Lease Transaction [Member]

Sales-Type Lease Transaction [Member]

Sales-Type Lease Transaction [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Prior to 2011 [Member]

Prior to 2011 [Member]

Prior to 2011 [Member]

Prior to 2011 [Member]

Prior to 2011 [Member]

Prior to 2011 [Member]

Prior to 2011 [Member]

Prior to 2011 [Member]

Total Internal Review of Aerospace Systems Segment [Member]

Total Internal Review of Aerospace Systems Segment [Member]

Total Internal Review of Aerospace Systems Segment [Member]

Total Internal Review of Aerospace Systems Segment [Member]

Total Internal Review of Aerospace Systems Segment [Member]

Total Internal Review of Aerospace Systems Segment [Member]

Total Internal Review of Aerospace Systems Segment [Member]

Total Internal Review of Aerospace Systems Segment [Member]

Logistics Solutions [Member]

Logistics Solutions [Member]

Logistics Solutions [Member]

Logistics Solutions [Member]

Logistics Solutions [Member]

Logistics Solutions [Member]

Logistics Solutions [Member]

Logistics Solutions [Member]

Platform Systems [Member]

Platform Systems [Member]

Platform Systems [Member]

Platform Systems [Member]

Platform Systems [Member]

Platform Systems [Member]

Platform Systems [Member]

Platform Systems [Member]

Army C-12 Contract [Member]

Army C-12 Contract [Member]

Army C-12 Contract [Member]

Army C-12 Contract [Member]

Army C-12 Contract [Member]

Army C-12 Contract [Member]

Army C-12 Contract [Member]

Army C-12 Contract [Member]

Other Logistics Support Contracts [Member]

Other Logistics Support Contracts [Member]

Other Logistics Support Contracts [Member]

Other Logistics Support Contracts [Member]

Other Logistics Support Contracts [Member]

Other Logistics Support Contracts [Member]

Other Logistics Support Contracts [Member]

Other Logistics Support Contracts [Member]

Sales-Type Lease Transaction [Member]

Sales-Type Lease Transaction [Member]

Sales-Type Lease Transaction [Member]

Sales-Type Lease Transaction [Member]

Sales-Type Lease Transaction [Member]

Sales-Type Lease Transaction [Member]

Sales-Type Lease Transaction [Member]

Sales-Type Lease Transaction [Member]

Sales-Type Lease Transaction [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Total Internal Review of Aerospace Systems Segment [Member]

Logistics Solutions [Member]

Platform Systems [Member]

Army C-12 Contract [Member]

Other Logistics Support Contracts [Member]

Sales-Type Lease Transaction [Member]

Change in Accounting Estimate [Line Items]

'

'

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Aggregate pre-tax charge as a result of internal review

$248

$270

'

'

'

'

($20)

($17)

($6)

($15)

($3)

($41)

($40)

$2

($20)

($24)

($7)

($15)

($14)

($60)

($25)

($5)

($9)

($22)

($7)

($9)

($8)

($46)

($27)

($5)

($11)

($2)

'

($6)

($6)

($14)

$2

'

($4)

($20)

($2)

($7)

($6)

($35)

($16)

($3)

($5)

($2)

($5)

($2)

($2)

($11)

($11)

($2)

'

$1

$2

$1

$1

$5

$3

$3

'

$13

($4)

($4)

'

'

($4)

$17

Cumulative aggregate adjustments, net

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-91

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-23

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Cumulative aggregate adjustments losses

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11

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58

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33

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Adjustment description

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'The Platform Systems sector adjustments are primarily due to: (1) losses of $xx million on two aircraft modification contracts and two contracts for rotary wing sub-assemblies and parts, and (2) write-offs of deferred costs of $xx million to design and test aerostructures for a new commercial aircraft.

'

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Write-offs of deferred costs

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12

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Lease period

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'The period of performance under this contract began in 2004 and ends in 2023.

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Increase in interest income

'

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5

3

3

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12

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Decrease in sales

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-5

-7

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Decrease in cost of sales

'

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($5)

($7)

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($5)

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'

Revisions_to_Previously_Issued3

Revisions to Previously Issued Financial Statements - Schedule of Nature of Adjustments, Applicable Segment, Amount of Increase (or Decrease) to Sales and Operating Income, Period Recorded and Correct Period (Detail) (USD $)	3 Months Ended					12 Months Ended
In Millions, unless otherwise specified	Mar. 28, 2014	Dec. 31, 2013	Sep. 27, 2013	Jun. 28, 2013	Mar. 29, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quantifying Misstatement in Current Year Financial Statements [Line Items]	'	'	'	'	'	'	'	'
Sales	$2,957	'	'	'	$3,197	'	'	'
Operating income	286	'	'	'	310	'	'	'
Aerospace Systems [Member]	'	'	'	'	'	'	'	'
Quantifying Misstatement in Current Year Financial Statements [Line Items]	'	'	'	'	'	'	'	'
Sales	-13	-21	5	-3	12	-7	-38	-4
Out of Period Amounts [Member]	'	'	'	'	'	'	'	'
Quantifying Misstatement in Current Year Financial Statements [Line Items]	'	'	'	'	'	'	'	'
Sales	'	9	3	7	20	'	'	'
Operating income	'	6	-1	-1	10	'	'	'
Out of Period Amounts [Member] | Communication Systems [Member] | Higher Development and Material Costs for Networked Communications Systems [Member]	'	'	'	'	'	'	'	'
Quantifying Misstatement in Current Year Financial Statements [Line Items]	'	'	'	'	'	'	'	'
Sales	'	'	'	'	10	'	'	'
Operating income	'	'	'	'	10	'	'	'
Out of Period Amounts [Member] | Aerospace Systems [Member]	'	'	'	'	'	'	'	'
Quantifying Misstatement in Current Year Financial Statements [Line Items]	'	'	'	'	'	'	'	'
Sales	'	9	3	7	20	39	-36	-3
Out of Period Amounts [Member] | Aerospace Systems [Member] | Sub-Contractor Subscription Deposit [Member]	'	'	'	'	'	'	'	'
Quantifying Misstatement in Current Year Financial Statements [Line Items]	'	'	'	'	'	'	'	'
Sales	'	5	7	7	7	'	'	'
Operating income	'	'	1	1	1	'	'	'
Out of Period Amounts [Member] | Aerospace Systems [Member] | Costs Accruals for Goods/Services Received [Member]	'	'	'	'	'	'	'	'
Quantifying Misstatement in Current Year Financial Statements [Line Items]	'	'	'	'	'	'	'	'
Sales	'	'	'	'	5	'	'	'
Operating income	'	'	'	'	1	'	'	'
Out of Period Amounts [Member] | Aerospace Systems [Member] | Unrecorded Liabilities [Member]	'	'	'	'	'	'	'	'
Quantifying Misstatement in Current Year Financial Statements [Line Items]	'	'	'	'	'	'	'	'
Sales	'	'	'	'	-2	'	'	'
Operating income	'	'	'	'	'	'	'	'
Out of Period Amounts [Member] | Aerospace Systems [Member] | Accrued Vacation [Member]	'	'	'	'	'	'	'	'
Quantifying Misstatement in Current Year Financial Statements [Line Items]	'	'	'	'	'	'	'	'
Sales	'	'	'	'	'	'	'	'
Operating income	'	6	-2	-2	-2	'	'	'
Out of Period Amounts [Member] | Aerospace Systems [Member] | Overstated Revenue [Member]	'	'	'	'	'	'	'	'
Quantifying Misstatement in Current Year Financial Statements [Line Items]	'	'	'	'	'	'	'	'
Sales	'	4	-4	'	'	'	'	'
Operating income	'	'	'	'	'	'	'	'
Out of Period Amounts [Member] | Electronic Systems [Member] | Warranty Reserve [Member]	'	'	'	'	'	'	'	'
Quantifying Misstatement in Current Year Financial Statements [Line Items]	'	'	'	'	'	'	'	'
Sales	'	'	'	'	'	'	'	'
Operating income	'	'	'	'	'	'	'	'

Revisions_to_Previously_Issued4

Revisions to Previously Issued Financial Statements - Schedule of Impact on Sales and Pre-tax Income (Detail) (USD $)

3 Months Ended

12 Months Ended

3 Months Ended

12 Months Ended

3 Months Ended

12 Months Ended

3 Months Ended

12 Months Ended

3 Months Ended

12 Months Ended

3 Months Ended

12 Months Ended

3 Months Ended

12 Months Ended

3 Months Ended

12 Months Ended

In Millions, unless otherwise specified

Mar. 28, 2014

Mar. 29, 2013

Dec. 31, 2013

Sep. 27, 2013

Jun. 28, 2013

Mar. 29, 2013

Mar. 28, 2014

Dec. 31, 2013

Sep. 27, 2013

Jun. 28, 2013

Mar. 29, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Mar. 28, 2014

Dec. 31, 2013

Sep. 27, 2013

Jun. 28, 2013

Mar. 29, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Mar. 28, 2014

Dec. 31, 2013

Sep. 27, 2013

Jun. 28, 2013

Mar. 29, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Mar. 28, 2014

Dec. 31, 2013

Sep. 27, 2013

Jun. 28, 2013

Mar. 29, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Mar. 28, 2014

Dec. 31, 2013

Sep. 27, 2013

Jun. 28, 2013

Mar. 29, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Mar. 28, 2014

Dec. 31, 2013

Sep. 27, 2013

Jun. 28, 2013

Mar. 29, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Mar. 28, 2014

Dec. 31, 2013

Sep. 27, 2013

Jun. 28, 2013

Mar. 29, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Mar. 28, 2014

Dec. 31, 2013

Sep. 27, 2013

Jun. 28, 2013

Mar. 29, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Dec. 31, 2010

Dec. 31, 2010

Dec. 31, 2010

Dec. 31, 2010

Dec. 31, 2010

Dec. 31, 2010

Dec. 31, 2010

Out of Period Amounts [Member]

Out of Period Amounts [Member]

Out of Period Amounts [Member]

Out of Period Amounts [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Prior to 2011 [Member]

Prior to 2011 [Member]

Prior to 2011 [Member]

Prior to 2011 [Member]

Prior to 2011 [Member]

Prior to 2011 [Member]

Prior to 2011 [Member]

Prior to 2011 [Member]

Army C-12 Contract [Member]

Army C-12 Contract [Member]

Army C-12 Contract [Member]

Army C-12 Contract [Member]

Army C-12 Contract [Member]

Army C-12 Contract [Member]

Army C-12 Contract [Member]

Army C-12 Contract [Member]

Other Logistics Support Contracts [Member]

Other Logistics Support Contracts [Member]

Other Logistics Support Contracts [Member]

Other Logistics Support Contracts [Member]

Other Logistics Support Contracts [Member]

Other Logistics Support Contracts [Member]

Other Logistics Support Contracts [Member]

Other Logistics Support Contracts [Member]

Logistics Solutions [Member]

Logistics Solutions [Member]

Logistics Solutions [Member]

Logistics Solutions [Member]

Logistics Solutions [Member]

Logistics Solutions [Member]

Logistics Solutions [Member]

Logistics Solutions [Member]

Platform Systems [Member]

Platform Systems [Member]

Platform Systems [Member]

Platform Systems [Member]

Platform Systems [Member]

Platform Systems [Member]

Platform Systems [Member]

Platform Systems [Member]

Total Internal Review of Aerospace Systems Segment [Member]

Total Internal Review of Aerospace Systems Segment [Member]

Total Internal Review of Aerospace Systems Segment [Member]

Total Internal Review of Aerospace Systems Segment [Member]

Total Internal Review of Aerospace Systems Segment [Member]

Total Internal Review of Aerospace Systems Segment [Member]

Total Internal Review of Aerospace Systems Segment [Member]

Total Internal Review of Aerospace Systems Segment [Member]

Sales-Type Lease Transaction [Member]

Sales-Type Lease Transaction [Member]

Sales-Type Lease Transaction [Member]

Sales-Type Lease Transaction [Member]

Sales-Type Lease Transaction [Member]

Sales-Type Lease Transaction [Member]

Sales-Type Lease Transaction [Member]

Sales-Type Lease Transaction [Member]

Out of Period Amounts [Member]

Out of Period Amounts [Member]

Out of Period Amounts [Member]

Out of Period Amounts [Member]

Out of Period Amounts [Member]

Out of Period Amounts [Member]

Out of Period Amounts [Member]

Out of Period Amounts [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Aerospace Systems [Member]

Army C-12 Contract [Member]

Other Logistics Support Contracts [Member]

Logistics Solutions [Member]

Platform Systems [Member]

Total Internal Review of Aerospace Systems Segment [Member]

Sales-Type Lease Transaction [Member]

Out of Period Amounts [Member]

Quantifying Misstatement in Current Year Financial Statements [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Sales

$2,957

$3,197

$9

$3

$7

$20

($13)

($21)

$5

($3)

$12

($7)

($38)

($4)

($2)

($24)

$3

($3)

($1)

($25)

($3)

($1)

'

($1)

($1)

'

'

($2)

($2)

'

($2)

($25)

$2

($3)

($1)

($27)

($5)

($1)

($6)

($2)

$1

($6)

($5)

($12)

$3

'

($8)

($27)

$3

($9)

($6)

($39)

($2)

($1)

($5)

($3)

($1)

($1)

($2)

($7)

'

'

'

$9

$3

$7

$20

$39

($36)

($3)

($1)

'

($1)

($1)

'

($1)

'

'

Pre-tax Income

$248

$270

'

'

'

'

($20)

($17)

($6)

($15)

($3)

($41)

($40)

$2

($4)

($20)

($2)

($7)

($6)

($35)

($16)

($3)

($5)

($2)

($5)

($2)

($2)

($11)

($11)

($2)

($9)

($22)

($7)

($9)

($8)

($46)

($27)

($5)

($11)

($2)

'

($6)

($6)

($14)

$2

'

($20)

($24)

($7)

($15)

($14)

($60)

($25)

($5)

'

$1

$2

$1

$1

$5

$3

$3

'

$6

($1)

($1)

$10

$14

($18)

$4

$13

'

($4)

($4)

'

($4)

$17

'

Revisions_to_Previously_Issued5

Revisions to Previously Issued Financial Statements - Schedule of Condensed Consolidated Balance Sheet (Detail) (USD $)	Mar. 28, 2014	Dec. 31, 2013	Mar. 29, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Current assets:	'	'	'	'
Cash and cash equivalents	$227	$500	$276	$349
Billed receivables, net of allowances of $24 in 2014	1,068	991	'	'
Contracts in process	2,648	2,431	'	'
Inventories	375	359	'	'
Deferred income taxes	144	147	'	'
Other current assets	160	166	'	'
Total current assets	4,622	4,594	'	'
Property, plant and equipment, net	1,033	1,042	'	'
Goodwill	7,821	7,796	'	'
Identifiable intangible assets	283	285	'	'
Deferred debt issue costs	23	24	'	'
Other assets	245	247	'	'
Total assets	14,027	13,988	'	'
Current liabilities:	'	'	'	'
Accounts payable, trade	590	541	'	'
Accrued employment costs	543	545	'	'
Accrued expenses	404	458	'	'
Advance payments and billings in excess of costs incurred	529	576	'	'
Income taxes	29	31	'	'
Other current liabilities	382	383	'	'
Total current liabilities	2,477	2,534	'	'
Pension and postretirement benefits	729	727	'	'
Deferred income taxes	661	635	'	'
Other liabilities	394	406	'	'
Long-term debt	3,631	3,630	'	'
Total liabilities	7,892	7,932	'	'
L-3 shareholders' equity:	'	'	'	'
L-3 Communications Holdings, Inc.'s common stock	5,767	5,653	'	'
L-3 Communications Holdings, Inc.'s treasury stock at cost	-5,421	-5,288	'	'
Retained earnings	5,842	5,726	'	'
Accumulated other comprehensive loss	-128	-110	-574	-550
Total L-3 shareholders' equity	6,060	5,981	'	'
Noncontrolling interests	75	75	'	'
Total equity	6,135	6,056	5,574	5,527
Total liabilities and equity	14,027	13,988	'	'
As Previously Reported [Member]	'	'	'	'
Current assets:	'	'	'	'
Cash and cash equivalents	227	'	'	'
Billed receivables, net of allowances of $24 in 2014	1,093	'	'	'
Contracts in process	2,763	'	'	'
Inventories	375	'	'	'
Deferred income taxes	118	'	'	'
Other current assets	126	'	'	'
Total current assets	4,702	'	'	'
Property, plant and equipment, net	1,028	'	'	'
Goodwill	7,821	'	'	'
Identifiable intangible assets	283	'	'	'
Deferred debt issue costs	23	'	'	'
Other assets	208	'	'	'
Total assets	14,065	'	'	'
Current liabilities:	'	'	'	'
Accounts payable, trade	590	'	'	'
Accrued employment costs	538	'	'	'
Accrued expenses	403	'	'	'
Advance payments and billings in excess of costs incurred	523	'	'	'
Income taxes	22	'	'	'
Other current liabilities	380	'	'	'
Total current liabilities	2,456	'	'	'
Pension and postretirement benefits	729	'	'	'
Deferred income taxes	679	'	'	'
Other liabilities	382	'	'	'
Long-term debt	3,631	'	'	'
Total liabilities	7,877	'	'	'
L-3 shareholders' equity:	'	'	'	'
L-3 Communications Holdings, Inc.'s common stock	5,767	'	'	'
L-3 Communications Holdings, Inc.'s treasury stock at cost	-5,421	'	'	'
Retained earnings	5,895	'	'	'
Accumulated other comprehensive loss	-128	'	'	'
Total L-3 shareholders' equity	6,113	'	'	'
Noncontrolling interests	75	'	'	'
Total equity	6,188	'	'	'
Total liabilities and equity	14,065	'	'	'
Restatement Adjustments [Member] | Aerospace Systems Segment Internal Review [Member ]	'	'	'	'
Current assets:	'	'	'	'
Cash and cash equivalents	'	'	'	'
Billed receivables, net of allowances of $24 in 2014	-25	'	'	'
Contracts in process	-82	'	'	'
Inventories	'	'	'	'
Deferred income taxes	26	'	'	'
Other current assets	8	'	'	'
Total current assets	-73	'	'	'
Property, plant and equipment, net	5	'	'	'
Goodwill	'	'	'	'
Identifiable intangible assets	'	'	'	'
Deferred debt issue costs	'	'	'	'
Other assets	'	'	'	'
Total assets	-68	'	'	'
Current liabilities:	'	'	'	'
Accounts payable, trade	'	'	'	'
Accrued employment costs	5	'	'	'
Accrued expenses	1	'	'	'
Advance payments and billings in excess of costs incurred	1	'	'	'
Income taxes	-10	'	'	'
Other current liabilities	2	'	'	'
Total current liabilities	-1	'	'	'
Pension and postretirement benefits	'	'	'	'
Deferred income taxes	3	'	'	'
Other liabilities	'	'	'	'
Long-term debt	'	'	'	'
Total liabilities	2	'	'	'
L-3 shareholders' equity:	'	'	'	'
L-3 Communications Holdings, Inc.'s common stock	'	'	'	'
L-3 Communications Holdings, Inc.'s treasury stock at cost	'	'	'	'
Retained earnings	-73	'	'	'
Accumulated other comprehensive loss	'	'	'	'
Total L-3 shareholders' equity	-73	'	'	'
Noncontrolling interests	'	'	'	'
Total equity	-73	'	'	'
Total liabilities and equity	-71	'	'	'
Restatement Adjustments [Member] | Sales-Type Lease Transaction [Member]	'	'	'	'
Current assets:	'	'	'	'
Cash and cash equivalents	'	'	'	'
Billed receivables, net of allowances of $24 in 2014	'	'	'	'
Contracts in process	-33	'	'	'
Inventories	'	'	'	'
Deferred income taxes	'	'	'	'
Other current assets	30	'	'	'
Total current assets	-3	'	'	'
Property, plant and equipment, net	'	'	'	'
Goodwill	'	'	'	'
Identifiable intangible assets	'	'	'	'
Deferred debt issue costs	'	'	'	'
Other assets	37	'	'	'
Total assets	34	'	'	'
Current liabilities:	'	'	'	'
Accounts payable, trade	'	'	'	'
Accrued employment costs	'	'	'	'
Accrued expenses	'	'	'	'
Advance payments and billings in excess of costs incurred	5	'	'	'
Income taxes	'	'	'	'
Other current liabilities	'	'	'	'
Total current liabilities	5	'	'	'
Pension and postretirement benefits	'	'	'	'
Deferred income taxes	'	'	'	'
Other liabilities	12	'	'	'
Long-term debt	'	'	'	'
Total liabilities	17	'	'	'
L-3 shareholders' equity:	'	'	'	'
L-3 Communications Holdings, Inc.'s common stock	'	'	'	'
L-3 Communications Holdings, Inc.'s treasury stock at cost	'	'	'	'
Retained earnings	18	'	'	'
Accumulated other comprehensive loss	'	'	'	'
Total L-3 shareholders' equity	18	'	'	'
Noncontrolling interests	'	'	'	'
Total equity	18	'	'	'
Total liabilities and equity	35	'	'	'
Restatement Adjustments [Member] | Out of Period Amounts [Member]	'	'	'	'
Current assets:	'	'	'	'
Cash and cash equivalents	'	'	'	'
Billed receivables, net of allowances of $24 in 2014	'	'	'	'
Contracts in process	'	'	'	'
Inventories	'	'	'	'
Deferred income taxes	'	'	'	'
Other current assets	-4	'	'	'
Total current assets	-4	'	'	'
Property, plant and equipment, net	'	'	'	'
Goodwill	'	'	'	'
Identifiable intangible assets	'	'	'	'
Deferred debt issue costs	'	'	'	'
Other assets	'	'	'	'
Total assets	-4	'	'	'
Current liabilities:	'	'	'	'
Accounts payable, trade	'	'	'	'
Accrued employment costs	'	'	'	'
Accrued expenses	'	'	'	'
Advance payments and billings in excess of costs incurred	'	'	'	'
Income taxes	17	'	'	'
Other current liabilities	'	'	'	'
Total current liabilities	17	'	'	'
Pension and postretirement benefits	'	'	'	'
Deferred income taxes	-21	'	'	'
Other liabilities	'	'	'	'
Long-term debt	'	'	'	'
Total liabilities	-4	'	'	'
L-3 shareholders' equity:	'	'	'	'
L-3 Communications Holdings, Inc.'s common stock	'	'	'	'
L-3 Communications Holdings, Inc.'s treasury stock at cost	'	'	'	'
Retained earnings	2	'	'	'
Accumulated other comprehensive loss	'	'	'	'
Total L-3 shareholders' equity	2	'	'	'
Noncontrolling interests	'	'	'	'
Total equity	2	'	'	'
Total liabilities and equity	($2)	'	'	'

Revisions_to_Previously_Issued6

Revisions to Previously Issued Financial Statements - Schedule of Condensed Consolidated Balance Sheet (Parenthetical) (Detail) (USD $)	Mar. 28, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Accounting Changes and Error Corrections [Abstract]	'	'
Net allowances for billed receivables	$24	$26

Revisions_to_Previously_Issued7

Revisions to Previously Issued Financial Statements - Schedule of Condensed Consolidated Statement of Operations (Detail) (USD $)

3 Months Ended

In Millions, except Per Share data, unless otherwise specified

Mar. 28, 2014

Mar. 29, 2013

Dec. 31, 2013

Sep. 27, 2013

Jun. 28, 2013

Mar. 29, 2013

Mar. 28, 2014

Mar. 29, 2013

Mar. 28, 2014

Mar. 29, 2013

Mar. 28, 2014

Mar. 29, 2013

Mar. 28, 2014

Mar. 29, 2013

Mar. 28, 2014

Mar. 29, 2013

Out of Period Amounts [Member]

Out of Period Amounts [Member]

Out of Period Amounts [Member]

Out of Period Amounts [Member]

As Previously Reported [Member]

As Previously Reported [Member]

Restatement Adjustments [Member]

Restatement Adjustments [Member]

Restatement Adjustments [Member]

Restatement Adjustments [Member]

Restatement Adjustments [Member]

Restatement Adjustments [Member]

Restatement Adjustments [Member]

Restatement Adjustments [Member]

Aerospace Systems Segment Internal Review [Member ]

Aerospace Systems Segment Internal Review [Member ]

Sales-Type Lease Transaction [Member]

Sales-Type Lease Transaction [Member]

Out of Period Amounts [Member]

Out of Period Amounts [Member]

Net sales:

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Products

$1,649

$1,821

'

'

'

'

$1,661

$1,813

'

'

($7)

($4)

($5)

($2)

'

$14

Services

1,308

1,376

'

'

'

'

1,310

1,372

'

'

-2

-1

'

'

'

5

Total net sales

2,957

3,197

9

3

7

20

2,971

3,185

'

'

-9

-5

-5

-2

'

19

Cost of sales:

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Products

-1,466

-1,622

'

'

'

'

-1,467

-1,620

'

'

-4

-1

5

2

'

-3

Services

-1,205

-1,265

'

'

'

'

-1,197

-1,252

'

'

-7

-7

'

'

-1

-6

Total cost of sales

-2,671

-2,887

'

'

'

'

-2,664

-2,872

'

'

-11

-8

5

2

-1

-9

Operating income

286

310

6

-1

-1

10

307

313

'

'

-20

-13

'

'

-1

10

Interest expense

-43

-43

'

'

'

'

-43

-43

'

'

'

'

'

'

'

'

Interest and other income, net

5

3

'

'

'

'

3

3

'

'

'

'

2

1

'

-1

Income before income taxes

248

270

'

'

'

'

267

273

'

'

-20

-13

2

1

-1

9

Provision for income taxes

-76

-78

'

'

'

'

-85

-79

'

'

9

4

'

'

'

-3

Net income

172

192

'

'

'

'

182

194

-10

-2

-11

-9

2

1

-1

6

Net income attributable to noncontrolling interests

-2

-1

'

'

'

'

-2

-1

'

'

'

'

'

'

'

'

Net income attributable to L-3

$170

$191

'

'

'

'

$180

$193

'

'

($11)

($9)

$2

$1

($1)

$6

Earnings per share attributable to L-3 Holdings' common shareholders:

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Basic

$1.97

$2.12

'

'

'

'

$2.09

$2.14

'

'

($0.13)

($0.10)

$0.02

$0.01

($0.01)

$0.07

Diluted

$1.90

$2.09

'

'

'

'

$2.01

$2.11

'

'

($0.12)

($0.10)

$0.02

$0.01

($0.01)

$0.07

Cash dividends paid per common share

$0.60

$0.55

'

'

'

'

$0.60

$0.55

'

'

'

'

'

'

'

'

L-3 Holdings' weighted average common shares outstanding:

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Basic

86.1

90.3

'

'

'

'

86.1

90.3

'

'

'

'

'

'

'

'

Diluted

89.4

91.5

'

'

'

'

89.4

91.5

'

'

'

'

'

'

'

'

Revisions_to_Previously_Issued8

Revisions to Previously Issued Financial Statements - Schedule of Condensed Consolidated Statement of Cash Flows (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 28, 2014	Mar. 29, 2013
Operating activities:	'	'
Net income	$172	$192
Depreciation of property, plant and equipment	42	42
Amortization of intangibles and other assets	12	12
Deferred income tax provision	23	18
Stock-based employee compensation expense	15	14
Contributions to employee savings plans in L-3 Holdings' common stock	44	32
Amortization of pension and postretirement benefit plans net loss and prior service cost	4	22
Amortization of bond discounts and deferred debt issue costs (included in interest expense)	2	2
Other non-cash items	1	3
Changes in operating assets and liabilities, excluding amounts from acquisitions and divestitures:	'	'
Billed receivables	-73	-146
Contracts in process	-214	-125
Inventories	-16	8
Other assets	-10	47
Accounts payable, trade	49	94
Accrued employment costs	-10	17
Accrued expenses	-51	-41
Advance payments and billings in excess of costs incurred	-46	-37
Income taxes	28	51
Excess income tax benefits related to share-based payment arrangements	-14	-2
Other current liabilities	-6	4
Pension and postretirement benefits	-2	4
All other operating activities	-12	-65
Net cash (used in) from operating activities	-62	146
As Previously Reported [Member]	'	'
Operating activities:	'	'
Net income	182	194
Depreciation of property, plant and equipment	42	42
Amortization of intangibles and other assets	12	12
Deferred income tax provision	22	19
Stock-based employee compensation expense	15	14
Contributions to employee savings plans in L-3 Holdings' common stock	44	32
Amortization of pension and postretirement benefit plans net loss and prior service cost	4	22
Amortization of bond discounts and deferred debt issue costs (included in interest expense)	2	2
Other non-cash items	1	3
Changes in operating assets and liabilities, excluding amounts from acquisitions and divestitures:	'	'
Billed receivables	-74	-146
Contracts in process	-236	-145
Inventories	-16	8
Other assets	-4	49
Accounts payable, trade	49	105
Accrued employment costs	-12	13
Accrued expenses	-49	-41
Advance payments and billings in excess of costs incurred	-46	-37
Income taxes	38	51
Excess income tax benefits related to share-based payment arrangements	-14	-2
Other current liabilities	-8	4
Pension and postretirement benefits	-2	4
All other operating activities	-12	-57
Net cash (used in) from operating activities	-62	146
Restatement Adjustments [Member]	'	'
Operating activities:	'	'
Net income	-10	-2
Depreciation of property, plant and equipment	'	'
Amortization of intangibles and other assets	'	'
Deferred income tax provision	1	-1
Stock-based employee compensation expense	'	'
Contributions to employee savings plans in L-3 Holdings' common stock	'	'
Amortization of pension and postretirement benefit plans net loss and prior service cost	'	'
Amortization of bond discounts and deferred debt issue costs (included in interest expense)	'	'
Other non-cash items	'	'
Changes in operating assets and liabilities, excluding amounts from acquisitions and divestitures:	'	'
Billed receivables	1	'
Contracts in process	22	20
Inventories	'	'
Other assets	-6	-2
Accounts payable, trade	'	-11
Accrued employment costs	2	4
Accrued expenses	-2	'
Advance payments and billings in excess of costs incurred	'	'
Income taxes	-10	'
Excess income tax benefits related to share-based payment arrangements	'	'
Other current liabilities	2	'
Pension and postretirement benefits	'	'
All other operating activities	'	-8
Net cash (used in) from operating activities	'	'

Acquisitions_Additional_Inform

Acquisitions - Additional Information (Detail) (USD $)	Mar. 28, 2014	Dec. 31, 2013	Dec. 19, 2013	Mar. 04, 2014
In Millions, unless otherwise specified			2013 Business Acquisition [Member]	2014 Business Acquisition [Member]
Acquisitions And Discontinued Operations [Line Items]	'	'	'	'
Purchase price of acquisition	'	'	$54	$57
Amount of goodwill recognized	7,821	7,796	44	40
Goodwill deductible for income tax purposes	'	'	$44	$40

Acquisitions_Unaudited_Pro_For

Acquisitions - Unaudited Pro Forma Statements of Operations Data (Detail) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 28, 2014	Mar. 29, 2013
Business Combinations [Abstract]	'	'
Pro forma net sales	$2,964	$3,215
Pro forma net income attributable to L-3	$169	$191
Pro forma diluted earnings per share	$1.89	$2.09

Contracts_in_Process_Component

Contracts in Process - Components of Contracts in Process (Detail) (USD $)	Mar. 28, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Components of contracts in process	'	'
Unbilled contract receivables, gross	$2,626	$2,502
Unliquidated progress payments	-990	-1,035
Unbilled contract receivables, net	1,636	1,467
Inventoried contract costs, gross	1,088	1,044
Unliquidated progress payments	-76	-80
Inventoried contract costs, net	1,012	964
Total contracts in process	$2,648	$2,431

Contracts_in_Process_General_a

Contracts in Process - General and Administrative, Independent Research and Development and Bids and Proposal Costs (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 28, 2014	Mar. 29, 2013
Inventory Disclosure [Abstract]	'	'
Amounts included in inventoried contract costs at beginning of the period	$138	$110
IRAD and B&P costs	72	73
Other G&A costs	204	205
Total contract costs incurred	276	278
Amounts charged to cost of sales	-273	-275
Amounts included in inventoried contract costs at end of the period	$141	$113

Contracts_in_Process_Selling_G

Contracts in Process - Selling, General and Administrative Expenses and Research and Development Expenses (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 28, 2014	Mar. 29, 2013
Inventory Disclosure [Abstract]	'	'
Selling, general and administrative expenses	$71	$72
Research and development expenses	17	20
Total	$88	$92

Inventories_Inventories_at_Low

Inventories - Inventories at Lower of Cost or Market (Detail) (USD $)	Mar. 28, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Inventory Disclosure [Abstract]	'	'
Raw materials, components and sub-assemblies	$166	$160
Work in process	128	125
Finished goods	81	74
Total	$375	$359

Goodwill_and_Identifiable_Inta2

Goodwill and Identifiable Intangible Assets - Changes in Goodwill by Segment (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 28, 2014
Goodwill [Line Items]	'
Balance, Beginning	$7,796
Business acquisition	40
Foreign currency translation adjustments	-15
Balance, Ending	7,821
Aerospace Systems [Member]	'
Goodwill [Line Items]	'
Balance, Beginning	1,751
Business acquisition	'
Foreign currency translation adjustments	-9
Balance, Ending	1,742
Electronic Systems [Member]	'
Goodwill [Line Items]	'
Balance, Beginning	4,085
Business acquisition	'
Foreign currency translation adjustments	-6
Balance, Ending	4,079
Communication Systems [Member]	'
Goodwill [Line Items]	'
Balance, Beginning	992
Business acquisition	'
Foreign currency translation adjustments	'
Balance, Ending	992
NSS [Member]	'
Goodwill [Line Items]	'
Balance, Beginning	968
Business acquisition	40
Foreign currency translation adjustments	'
Balance, Ending	$1,008

Goodwill_and_Identifiable_Inta3

Goodwill and Identifiable Intangible Assets - Additional Information (Detail) (USD $)	Mar. 28, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Goodwill [Line Items]	'	'
Accumulated goodwill impairment losses	$58	$58
Electronic Systems [Member]	'	'
Goodwill [Line Items]	'	'
Accumulated goodwill impairment losses	43	43
Communication Systems [Member]	'	'
Goodwill [Line Items]	'	'
Accumulated goodwill impairment losses	$15	$15

Goodwill_and_Identifiable_Inta4

Goodwill and Identifiable Intangible Assets - Identifiable Intangible Assets (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 28, 2014	Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]	'	'
Weighted Average Amortization Period (in years)	'17 years	'
Gross Carrying Amount	$669	$661
Accumulated Amortization	386	376
Net Carrying Amount	283	285
Customer Contractual Relationships [Member]	'	'
Finite-Lived Intangible Assets [Line Items]	'	'
Weighted Average Amortization Period (in years)	'19 years	'
Gross Carrying Amount	474	466
Accumulated Amortization	261	253
Net Carrying Amount	213	213
Technology [Member]	'	'
Finite-Lived Intangible Assets [Line Items]	'	'
Weighted Average Amortization Period (in years)	'11 years	'
Gross Carrying Amount	168	168
Accumulated Amortization	110	108
Net Carrying Amount	58	60
Other [Member]	'	'
Finite-Lived Intangible Assets [Line Items]	'	'
Weighted Average Amortization Period (in years)	'17 years	'
Gross Carrying Amount	27	27
Accumulated Amortization	15	15
Net Carrying Amount	$12	$12

Goodwill_and_Identifiable_Inta5

Goodwill and Identifiable Intangible Assets - Amortization Expense (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 28, 2014	Mar. 29, 2013
Goodwill and Intangible Assets Disclosure [Abstract]	'	'
Amortization Expense	$10	$9

Goodwill_and_Identifiable_Inta6

Goodwill and Identifiable Intangible Assets - Estimated Amortization Expense (Detail) (USD $)	Mar. 28, 2014
In Millions, unless otherwise specified
Goodwill and Intangible Assets Disclosure [Abstract]	'
Estimated amortization expense, 2014	$43
Estimated amortization expense, 2015	41
Estimated amortization expense, 2016	34
Estimated amortization expense, 2017	32
Estimated amortization expense, 2018	$26

Other_Current_Liabilities_and_2

Other Current Liabilities and Other Liabilities - Other Current Liabilities (Detail) (USD $)	Mar. 28, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Other Current Liabilities:	'	'
Accruals for pending and threatened litigation (see Note 18)	$7	$6
Accrued product warranty costs	76	75
Estimated costs in excess of estimated contract value to complete contracts in process in a loss position	75	78
Accrued interest	46	52
Deferred revenues	40	35
Other	138	137
Total other current liabilities	$382	$383

Other_Current_Liabilities_and_3

Other Current Liabilities and Other Liabilities - Other Liabilities (Detail) (USD $)	Mar. 28, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Other Liabilities:	'	'
Non-current income taxes payable (see Note 11)	$177	$177
Deferred compensation	47	45
Accrued workers' compensation	42	46
Accrued product warranty costs	21	24
Notes payable and capital lease obligations	12	15
Other	95	99
Total other liabilities	$394	$406

Other_Current_Liabilities_and_4

Other Current Liabilities and Other Liabilities - Changes in Company's Accrued Product Warranty Costs (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 28, 2014	Mar. 29, 2013
Accrued product warranty costs:	'	'
Balance at January 1	$99	$99
Accruals for product warranties issued during the period	17	19
Settlements made during the period	-19	-20
Foreign currency translation adjustments	'	-1
Balance at end of period	$97	$97

Debt_Components_of_Debt_and_Re

Debt - Components of Debt and Reconciliation to Carrying Amount of Long-Term Debt (Detail) (USD $)	Mar. 28, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
L-3 Communications Corporation [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 (CODES)	689	689
Principal amount of long-term debt	3,639	3,639
Unamortized discounts	-8	-9
Carrying amount of long-term debt	$3,631	$3,630

Debt_Components_of_Debt_and_Re1

Debt - Components of Debt and Reconciliation to Carrying Amount of Long-Term Debt (Parenthetical) (Detail) (USD $)	Mar. 28, 2014	Dec. 31, 2013
Debt Instrument [Line Items]	'	'
Aggregate borrowings and repayments under the Amended and Restated Revolving Credit Facility	524,000,000	'
Borrowings under Amended and Restated Revolving Credit Facility	1,000,000,000	'
CODES Due 2035 [Member]	'	'
Debt Instrument [Line Items]	'	'
Interest rate on Senior Notes	3.00%	'
L-3 Communications Corporation [Member] | 3.95% Senior Notes due 2016 [Member]	'	'
Debt Instrument [Line Items]	'	'
Interest rate on Senior Notes	3.95%	3.95%
L-3 Communications Corporation [Member] | 5.20% Senior Notes due 2019 [Member]	'	'
Debt Instrument [Line Items]	'	'
Interest rate on Senior Notes	5.20%	5.20%
L-3 Communications Corporation [Member] | 4.75% Senior Notes due 2020 [Member]	'	'
Debt Instrument [Line Items]	'	'
Interest rate on Senior Notes	4.75%	4.75%
L-3 Communications Corporation [Member] | 4.95% Senior Notes due 2021 [Member]	'	'
Debt Instrument [Line Items]	'	'
Interest rate on Senior Notes	4.95%	4.95%
L-3 Communications Holdings, Inc. [Member] | CODES Due 2035 [Member]	'	'
Debt Instrument [Line Items]	'	'
Interest rate on Senior Notes	3.00%	3.00%

Debt_Additional_Information_De

Debt - Additional Information (Detail) (USD $)	3 Months Ended
Share data in Millions, except Per Share data, unless otherwise specified	Mar. 28, 2014	Mar. 29, 2013	Dec. 31, 2013
Debt Instrument [Line Items]	'	'	'
Excess of current common stock price over common stock conversion price	120.00%	'	'
Common stock, shares	7.7	'	'
Conversion price of L-3 Holdings' CODES	$89.08	'	'
Number of trading days for conversion, minimum	'20 days	'	'
Number of consecutive trading-day period ending on the last trading day of the previous fiscal quarter	'30 days	'	'
L-3 Communications Holdings, Inc. [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Conversion rate of CODES, shares	11.2259	'	'
Settlement amount upon conversion of the CODES	$1,000	'	'
Interest expense recognized	5,000,000	5,000,000	'
Carrying amount of the equity component (conversion feature)	$64,000,000	'	$64,000,000
L-3 Communications Holdings, Inc. [Member] | CODES Due 2035 [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Current common stock price	$106.90	'	'
Conversion price of L-3 Holdings' CODES	$89.08	'	'

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 28, 2014	Mar. 29, 2013	Dec. 31, 2013
Tax Credit Carryforward [Line Items]	'	'	'
Effective tax rate	30.60%	28.90%	'
Anticipated decrease in unrecognized tax benefits over the next 12 months	$20	'	'
Accrued potential interest included within non-current income taxes payable	12	'	11
Accrued potential interest included within non-current income taxes payable, after income taxes	7	'	7
Potential penalties	7	'	8
U.S. Federal Research and Experimentation Tax Credit [Member]	'	'	'
Tax Credit Carryforward [Line Items]	'	'	'
Tax benefit	'	12	'

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
In Millions, unless otherwise specified	Mar. 28, 2014	Mar. 29, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'
Beginning Balance	($110)	($550)
Other comprehensive loss before reclassifications, net of tax	-18	-37
Amounts reclassified from other comprehensive (loss) income, net of tax	'	13
Net current period other comprehensive (loss) income	-18	-24
Ending Balance	-128	-574
Cost of sales-products	1,466	1,622
Income before income taxes	248	270
(Provision) benefit for income taxes	-76	-78
Reclassification out of Accumulated Other Comprehensive Income [Member]	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'
Net income	'	13
Foreign Currency Translation [Member]	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'
Beginning Balance	142	167
Other comprehensive loss before reclassifications, net of tax	-16	-34
Amounts reclassified from other comprehensive (loss) income, net of tax	'	'
Net current period other comprehensive (loss) income	-16	-34
Ending Balance	126	133
Unrealized Gains (Losses) on Hedging Instruments [Member]	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'
Beginning Balance	1	3
Other comprehensive loss before reclassifications, net of tax	-2	-3
Amounts reclassified from other comprehensive (loss) income, net of tax	-3	'
Net current period other comprehensive (loss) income	-5	-3
Ending Balance	-4	'
Unrealized Gains (Losses) on Hedging Instruments [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'
Cost of sales-products	-5	'
Income before income taxes	-5	'
(Provision) benefit for income taxes	2	'
Net income	-3	'
Unrecognized (Losses) Gains and Prior Service Cost, Net [Member]	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'
Beginning Balance	-253	-720
Other comprehensive loss before reclassifications, net of tax	'	'
Amounts reclassified from other comprehensive (loss) income, net of tax	3	13
Net current period other comprehensive (loss) income	3	13
Ending Balance	-250	-707
Accumulated Defined Benefit Plans Adjustment [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'
Net loss	4	22
Income before income taxes	4	22
(Provision) benefit for income taxes	-1	-9
Net income	$3	$13

Equity_Additional_Information_

Equity - Additional Information (Detail) (USD $)	0 Months Ended			3 Months Ended			1 Months Ended	3 Months Ended		1 Months Ended
	Mar. 17, 2014	Feb. 11, 2014	Feb. 05, 2013	Mar. 28, 2014	Mar. 29, 2013	Mar. 28, 2014	Apr. 23, 2014	Mar. 28, 2014	Mar. 29, 2013	Apr. 23, 2014
						February 5, 2013 Share Repurchase Program [Member]	February 5, 2013 Share Repurchase Program [Member]	Common Stock [Member]	Common Stock [Member]	Common Stock [Member]
							Subsequent Event [Member]			February 5, 2013 Share Repurchase Program [Member]
										Subsequent Event [Member]
Class of Stock [Line Items]	'	'	'	'	'	'	'	'	'	'
Amount of shares authorized to be repurchased	'	'	$1,500,000,000	'	'	'	'	'	'	'
Average price per share of repurchased shares	'	'	'	$109.43	'	'	$116.98	'	'	'
Number of common shares repurchased	'	'	'	'	'	'	'	1,200,000	1,600,000	307,692
Aggregate amount of repurchased shares	'	'	'	133,000,000	122,000,000	'	36,000,000	'	'	'
Remaining value under share repurchase program	'	'	'	'	'	735,000,000	'	'	'	'
Cash dividend, declared per share	'	$0.60	'	'	'	'	'	'	'	'
Total cash dividends	52,000,000	'	'	52,000,000	50,000,000	'	'	'	'	'
Payment of accrued dividends	'	'	'	$3,000,000	'	'	'	'	'	'

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
In Millions, except Per Share data, unless otherwise specified	Mar. 28, 2014	Mar. 29, 2013
Reconciliation of net income:	'	'
Net income	$172	$192
Net income attributable to noncontrolling interests	-2	-1
Net income attributable to L-3 Holdings' common shareholders	$170	$191
Basic:	'	'
Weighted average common shares outstanding	86.1	90.3
Basic earnings per share:	'	'
Net income	$1.97	$2.12
Common and potential common shares:	'	'
Weighted average common shares outstanding	86.1	90.3
Assumed purchase of common shares for treasury	-3.5	-4.2
Assumed conversion of the CODES	1.5	'
Common and potential common shares	89.4	91.5
Diluted earnings per share:	'	'
Net income	$1.90	$2.09
Stock Options [Member]	'	'
Common and potential common shares:	'	'
Common and potential common shares	3.4	3.4
Unvested Restricted Stock Awards [Member]	'	'
Common and potential common shares:	'	'
Common and potential common shares	1.7	1.7
Employee Stock Purchase Plan Contributions [Member]	'	'
Common and potential common shares:	'	'
Common and potential common shares	'	0.2
Performance Unit Awards [Member]	'	'
Common and potential common shares:	'	'
Common and potential common shares	0.2	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 $)	Mar. 28, 2014
Earnings Per Share [Abstract]	'
Conversion price of L-3 Holdings' CODES	$89.08

L3_Holdings_Earnings_Per_Commo4

L-3 Holdings' Earnings Per Common Share - Additional Information (Detail)	3 Months Ended
In Millions, unless otherwise specified	Mar. 28, 2014	Mar. 29, 2013
Earnings Per Share [Abstract]	'	'
Shares excluded from computation of diluted earnings per share and employee stock purchase plan contributions	0.4	1.8

Fair_Value_Measurements_Compan

Fair Value Measurements - Company's Assets and Liabilities at Fair Value on Recurring Basis (Detail) (USD $)	Mar. 28, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Level 1 [Member]	'	'
Assets	'	'
Cash equivalents	$22	$299
Derivatives (foreign currency forward contracts)	'	'
Total Assets	22	299
Liabilities	'	'
Derivatives (foreign currency forward contracts)	'	'
Level 2 [Member]	'	'
Assets	'	'
Cash equivalents	'	'
Derivatives (foreign currency forward contracts)	5	6
Total Assets	5	6
Liabilities	'	'
Derivatives (foreign currency forward contracts)	10	5
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 $)	Mar. 28, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Senior Notes, Carrying Amount	$2,942	$2,941
CODES, Carrying Amount	689	689
Senior Notes, Estimated Fair Value	3,168	3,121
CODES, Estimated Fair Value	911	830
Estimated Fair Value [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Foreign currency forward contracts	-5	1
Carrying Amount [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Foreign currency forward contracts	($5)	$1

Derivative_Financial_Instrumen2

Derivative Financial Instruments - Notional Amounts of Company's Outstanding Foreign Currency Forward Contracts by Currency (Detail) (USD $)	Mar. 28, 2014
In Millions, unless otherwise specified
Derivative [Line Items]	'
Notional amounts of foreign currency forward contracts	$435
Canadian Dollar [Member]	'
Derivative [Line Items]	'
Notional amounts of foreign currency forward contracts	222
U.S. Dollar [Member]	'
Derivative [Line Items]	'
Notional amounts of foreign currency forward contracts	115
Euro [Member]	'
Derivative [Line Items]	'
Notional amounts of foreign currency forward contracts	83
British Pound [Member]	'
Derivative [Line Items]	'
Notional amounts of foreign currency forward contracts	13
Other [Member]	'
Derivative [Line Items]	'
Notional amounts of foreign currency forward contracts	$2

Derivative_Financial_Instrumen3

Derivative Financial Instruments - Additional Information (Detail) (USD $)	Mar. 28, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Derivative [Line Items]	'	'
Estimated amount of existing gains expected to be reclassified into income within the next 12 months	$4	'
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 $)	Mar. 28, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Other Current Liabilities [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Total derivative instruments, assets	$7	$3
Other Current Liabilities [Member] | Foreign Currency Forward Contracts [Member] | Designated as Hedging Instruments [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Total derivative instruments, assets	7	3
Other Current Liabilities [Member] | Foreign Currency Forward Contracts [Member] | Not Designated as Hedging Instruments [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Total derivative instruments, assets	'	'
Other Current Liabilities [Member] | CODES Due 2035 [Member] | Not Designated as Hedging Instruments [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Total derivative instruments, assets	'	'
Other Liabilities [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Total derivative instruments, assets	3	2
Other Liabilities [Member] | Foreign Currency Forward Contracts [Member] | Designated as Hedging Instruments [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Total derivative instruments, assets	3	2
Other Liabilities [Member] | Foreign Currency Forward Contracts [Member] | Not Designated as Hedging Instruments [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Total derivative instruments, assets	'	'
Other Liabilities [Member] | CODES Due 2035 [Member] | Not Designated as Hedging Instruments [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Total derivative instruments, assets	'	'
Other Current Assets [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Total derivative instruments, liabilities	4	5
Other Current Assets [Member] | Foreign Currency Forward Contracts [Member] | Designated as Hedging Instruments [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Total derivative instruments, liabilities	4	5
Other Current Assets [Member] | Foreign Currency Forward Contracts [Member] | Not Designated as Hedging Instruments [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Total derivative instruments, liabilities	'	'
Other Current Assets [Member] | CODES Due 2035 [Member] | Not Designated as Hedging Instruments [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Total derivative instruments, liabilities	'	'
Other Assets [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Total derivative instruments, liabilities	1	1
Other Assets [Member] | Foreign Currency Forward Contracts [Member] | Designated as Hedging Instruments [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Total derivative instruments, liabilities	1	1
Other Assets [Member] | Foreign Currency Forward Contracts [Member] | Not Designated as Hedging Instruments [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Total derivative instruments, liabilities	'	'
Other Assets [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 $)	Mar. 28, 2014	31-May-12	Mar. 09, 2010	Jul. 01, 2004
In Millions, unless otherwise specified
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_Employee_Ben

Pension and Other Employee Benefits - Components of Net Periodic Benefit Cost (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 28, 2014	Mar. 29, 2013
Pension Plans [Member]	'	'
Components of net periodic benefit cost:	'	'
Service cost	$27	$32
Interest cost	36	33
Expected return on plan assets	-48	-42
Amortization of prior service costs (credits)	1	'
Amortization of net loss (gain)	4	22
Curtailment loss	1	'
Net periodic benefit cost	21	45
Postretirement Benefit Plans [Member]	'	'
Components of net periodic benefit cost:	'	'
Service cost	1	1
Interest cost	2	2
Expected return on plan assets	-1	-1
Amortization of prior service costs (credits)	-1	1
Amortization of net loss (gain)	'	-1
Curtailment loss	'	'
Net periodic benefit cost	$1	$2

Pension_and_Other_Employee_Ben1

Pension and Other Employee Benefits - Additional Information (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 28, 2014
Pension Plans [Member]	'
Defined Benefit Plan Disclosure [Line Items]	'
Contribution to pension plans	$14
Expected contributions to plans	83
Postretirement Benefit Plans [Member]	'
Defined Benefit Plan Disclosure [Line Items]	'
Contribution to other postretirement benefit plans	2
Expected contributions to plans	$8

StockBased_Compensation_Additi

Stock-Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 28, 2014
Employee Restricted Equity Awards And Performance Stock Awards Vesting Activity [Line Items]	'
Exercise price	$113.67
Stock options granted	472,992
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	$20.02
Restricted Stock Units [Member]	'
Employee Restricted Equity Awards And Performance Stock Awards Vesting Activity [Line Items]	'
Vesting period	'3 years
Units granted	402,870
Weighted average grant date fair value	$113.67
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	47,467
Weighted average grant date fair value	$113.67
Length of service after grant date	'3 years
Minimum payout range	0.00%
Maximum payout range	200.00%

StockBased_Compensation_Weight

Stock-Based Compensation - Weighted Average Assumptions in Valuation Model (Detail) (Stock Options [Member])	3 Months Ended
	Mar. 28, 2014
Stock Options [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Expected holding period (in years)	'5 years 6 months
Expected volatility	24.40%
Expected dividend yield	2.70%
Risk-free interest rate	1.70%

Supplemental_Cash_Flow_Informa2

Supplemental Cash Flow Information - Supplemental Cash Flow Information (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 28, 2014	Mar. 29, 2013
Additional Cash Flow Elements and Supplemental Cash Flow Information [Abstract]	'	'
Interest paid on outstanding debt	$48	$48
Income tax payments	26	19
Income tax refunds	$1	$10

Segment_Information_Additional

Segment Information - Additional Information (Detail)	3 Months Ended
	Mar. 28, 2014
	Segment
Segment Reporting [Abstract]	'
Number of segments	4

Segment_Information_Summary_of

Segment Information - Summary of Segment Information (Detail) (USD $)	3 Months Ended					12 Months Ended
In Millions, unless otherwise specified	Mar. 28, 2014	Dec. 31, 2013	Sep. 27, 2013	Jun. 28, 2013	Mar. 29, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net Sales:	'	'	'	'	'	'	'	'
Net Sales	$2,957	'	'	'	$3,197	'	'	'
Operating Income:	'	'	'	'	'	'	'	'
Operating income	286	'	'	'	310	'	'	'
Depreciation and amortization:	'	'	'	'	'	'	'	'
Depreciation and amortization	54	'	'	'	54	'	'	'
Total Assets:	'	'	'	'	'	'	'	'
Total assets	14,027	13,988	'	'	'	13,988	'	'
Aerospace Systems [Member]	'	'	'	'	'	'	'	'
Net Sales:	'	'	'	'	'	'	'	'
Net Sales	-13	-21	5	-3	12	-7	-38	-4
Operating Segments [Member] | Aerospace Systems [Member]	'	'	'	'	'	'	'	'
Net Sales:	'	'	'	'	'	'	'	'
Net Sales	1,074	'	'	'	1,191	'	'	'
Operating Income:	'	'	'	'	'	'	'	'
Operating income	93	'	'	'	127	'	'	'
Depreciation and amortization:	'	'	'	'	'	'	'	'
Depreciation and amortization	10	'	'	'	9	'	'	'
Total Assets:	'	'	'	'	'	'	'	'
Total assets	3,148	3,087	'	'	'	3,087	'	'
Operating Segments [Member] | Electronic Systems [Member]	'	'	'	'	'	'	'	'
Net Sales:	'	'	'	'	'	'	'	'
Net Sales	1,098	'	'	'	1,137	'	'	'
Operating Income:	'	'	'	'	'	'	'	'
Operating income	125	'	'	'	117	'	'	'
Depreciation and amortization:	'	'	'	'	'	'	'	'
Depreciation and amortization	29	'	'	'	30	'	'	'
Total Assets:	'	'	'	'	'	'	'	'
Total assets	7,027	6,928	'	'	'	6,928	'	'
Operating Segments [Member] | Communication Systems [Member]	'	'	'	'	'	'	'	'
Net Sales:	'	'	'	'	'	'	'	'
Net Sales	517	'	'	'	575	'	'	'
Operating Income:	'	'	'	'	'	'	'	'
Operating income	50	'	'	'	45	'	'	'
Depreciation and amortization:	'	'	'	'	'	'	'	'
Depreciation and amortization	12	'	'	'	12	'	'	'
Total Assets:	'	'	'	'	'	'	'	'
Total assets	2,128	2,130	'	'	'	2,130	'	'
Operating Segments [Member] | NSS [Member]	'	'	'	'	'	'	'	'
Net Sales:	'	'	'	'	'	'	'	'
Net Sales	305	'	'	'	331	'	'	'
Operating Income:	'	'	'	'	'	'	'	'
Operating income	18	'	'	'	21	'	'	'
Depreciation and amortization:	'	'	'	'	'	'	'	'
Depreciation and amortization	3	'	'	'	3	'	'	'
Total Assets:	'	'	'	'	'	'	'	'
Total assets	1,338	1,247	'	'	'	1,247	'	'
Elimination of Intercompany Sales [Member]	'	'	'	'	'	'	'	'
Net Sales:	'	'	'	'	'	'	'	'
Net Sales	-37	'	'	'	-37	'	'	'
Corporate [Member]	'	'	'	'	'	'	'	'
Total Assets:	'	'	'	'	'	'	'	'
Total assets	$386	$596	'	'	'	$596	'	'

Employee_Severance_and_Termina2

Employee Severance and Termination Costs - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Mar. 28, 2014	Mar. 29, 2013	Dec. 31, 2013
	Employees		Employees
Restructuring and Related Activities [Abstract]	'	'	'
Employee severance and other related termination costs	$8	$5	$29
Number of employees terminated	570	'	2,000
Remaining balance of employee termination costs	$13	'	$11

Employee_Severance_and_Termina3

Employee Severance and Termination Costs - Employee Severance and Other Termination Costs Incurred by Reportable Segment (Detail) (USD $)	3 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Mar. 28, 2014	Mar. 29, 2013	Dec. 31, 2013
Restructuring Cost and Reserve [Line Items]	'	'	'
Employee severance and other related termination costs	$8	$5	$29
Aerospace Systems [Member]	'	'	'
Restructuring Cost and Reserve [Line Items]	'	'	'
Employee severance and other related termination costs	'	'	'
Electronic Systems [Member]	'	'	'
Restructuring Cost and Reserve [Line Items]	'	'	'
Employee severance and other related termination costs	4	3	'
Communication Systems [Member]	'	'	'
Restructuring Cost and Reserve [Line Items]	'	'	'
Employee severance and other related termination costs	3	1	'
NSS [Member]	'	'	'
Restructuring Cost and Reserve [Line Items]	'	'	'
Employee severance and other related termination costs	$1	$1	'

Condensed_Combining_Financial_2

Condensed Combining Financial Information of L-3 Communications and Its Subsidiaries - Additional Information (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 28, 2014
Condensed Financial Statements, Captions [Line Items]	'
Ownership percentage held in subsidiary	100.00%
Non-Guarantor Subsidiaries [Member]	'
Condensed Financial Statements, Captions [Line Items]	'
Cumulative aggregate adjustments, net	$14

Condensed_Combining_Financial_3

Condensed Combining Financial Information of L-3 Communications and Its Subsidiaries - Condensed Combining Balance Sheets (Detail) (USD $)	Mar. 28, 2014	Dec. 31, 2013	Mar. 29, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Current assets:	'	'	'	'
Cash and cash equivalents	$227	$500	$276	$349
Billed receivables, net	1,068	991	'	'
Contracts in process	2,648	2,431	'	'
Other current assets	679	672	'	'
Total current assets	4,622	4,594	'	'
Goodwill	7,821	7,796	'	'
Other assets	1,584	1,598	'	'
Investment in and amounts due from consolidated subsidiaries	'	'	'	'
Total assets	14,027	13,988	'	'
Current liabilities	2,477	2,534	'	'
Amounts due to consolidated subsidiaries	'	'	'	'
Other long-term liabilities	1,784	1,768	'	'
Long-term debt	3,631	3,630	'	'
Total liabilities	7,892	7,932	'	'
L-3 shareholders' equity	6,060	5,981	'	'
Noncontrolling interests	75	75	'	'
Total equity	6,135	6,056	5,574	5,527
Total liabilities and equity	14,027	13,988	'	'
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	6,749	6,670	'	'
Total assets	6,749	6,670	'	'
Current liabilities	'	'	'	'
Amounts due to consolidated subsidiaries	'	'	'	'
Other long-term liabilities	'	'	'	'
Long-term debt	689	689	'	'
Total liabilities	689	689	'	'
L-3 shareholders' equity	6,060	5,981	'	'
Noncontrolling interests	'	'	'	'
Total equity	6,060	5,981	'	'
Total liabilities and equity	6,749	6,670	'	'
L-3 Communications Corporation [Member]	'	'	'	'
Current assets:	'	'	'	'
Cash and cash equivalents	57	258	66	246
Billed receivables, net	343	364	'	'
Contracts in process	996	925	'	'
Other current assets	357	344	'	'
Total current assets	1,753	1,891	'	'
Goodwill	2,307	2,307	'	'
Other assets	821	838	'	'
Investment in and amounts due from consolidated subsidiaries	7,203	6,940	'	'
Total assets	12,084	11,976	'	'
Current liabilities	921	914	'	'
Amounts due to consolidated subsidiaries	'	'	'	'
Other long-term liabilities	1,472	1,451	'	'
Long-term debt	3,631	3,630	'	'
Total liabilities	6,024	5,995	'	'
L-3 shareholders' equity	6,060	5,981	'	'
Noncontrolling interests	'	'	'	'
Total equity	6,060	5,981	'	'
Total liabilities and equity	12,084	11,976	'	'
Guarantor Subsidiaries [Member]	'	'	'	'
Current assets:	'	'	'	'
Cash and cash equivalents	'	'	'	'
Billed receivables, net	458	401	'	'
Contracts in process	1,260	1,152	'	'
Other current assets	147	159	'	'
Total current assets	1,865	1,712	'	'
Goodwill	4,327	4,326	'	'
Other assets	522	532	'	'
Investment in and amounts due from consolidated subsidiaries	3,661	3,744	'	'
Total assets	10,375	10,314	'	'
Current liabilities	932	1,011	'	'
Amounts due to consolidated subsidiaries	'	'	'	'
Other long-term liabilities	191	193	'	'
Long-term debt	'	'	'	'
Total liabilities	1,123	1,204	'	'
L-3 shareholders' equity	9,252	9,110	'	'
Noncontrolling interests	'	'	'	'
Total equity	9,252	9,110	'	'
Total liabilities and equity	10,375	10,314	'	'
Non-Guarantor Subsidiaries [Member]	'	'	'	'
Current assets:	'	'	'	'
Cash and cash equivalents	182	261	223	242
Billed receivables, net	267	226	'	'
Contracts in process	392	354	'	'
Other current assets	175	169	'	'
Total current assets	1,016	1,010	'	'
Goodwill	1,187	1,163	'	'
Other assets	241	228	'	'
Investment in and amounts due from consolidated subsidiaries	'	'	'	'
Total assets	2,444	2,401	'	'
Current liabilities	636	628	'	'
Amounts due to consolidated subsidiaries	380	270	'	'
Other long-term liabilities	121	124	'	'
Long-term debt	'	'	'	'
Total liabilities	1,137	1,022	'	'
L-3 shareholders' equity	1,307	1,379	'	'
Noncontrolling interests	'	'	'	'
Total equity	1,307	1,379	'	'
Total liabilities and equity	2,444	2,401	'	'
Eliminations [Member]	'	'	'	'
Current assets:	'	'	'	'
Cash and cash equivalents	-12	-19	'	'
Billed receivables, net	'	'	'	'
Contracts in process	'	'	'	'
Other current assets	'	'	'	'
Total current assets	-12	-19	'	'
Goodwill	'	'	'	'
Other assets	'	'	'	'
Investment in and amounts due from consolidated subsidiaries	-17,613	-17,354	'	'
Total assets	-17,625	17,373	'	'
Current liabilities	-12	-19	'	'
Amounts due to consolidated subsidiaries	-380	-270	'	'
Other long-term liabilities	'	'	'	'
Long-term debt	-689	-689	'	'
Total liabilities	-1,081	-978	'	'
L-3 shareholders' equity	-16,619	-16,470	'	'
Noncontrolling interests	75	75	'	'
Total equity	-16,544	-16,395	'	'
Total liabilities and equity	($17,625)	($17,373)	'	'

Condensed_Combining_Financial_4

Condensed Combining Financial Information of L-3 Communications and Its Subsidiaries - Condensed Combining Statements of Operations (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 28, 2014	Mar. 29, 2013
Condensed Financial Statements, Captions [Line Items]	'	'
Total net sales	$2,957	$3,197
Total cost of sales	-2,671	-2,887
Operating (loss) income	286	310
Interest expense	-43	-43
Interest and other income, net	5	3
(Loss) income before income taxes	248	270
(Provision) benefit for income taxes	-76	-78
Equity in net income of consolidated subsidiaries	'	'
Net income	172	192
Net income attributable to noncontrolling interests	-2	-1
Net income attributable to L-3	170	191
Comprehensive income attributable to L-3	152	167
L-3 Communications Holdings, Inc. [Member]	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Total net sales	'	'
Total cost of sales	-15	-14
Operating (loss) income	-15	-14
Interest expense	-5	-5
Interest and other income, net	'	'
(Loss) income before income taxes	-20	-19
(Provision) benefit for income taxes	6	5
Equity in net income of consolidated subsidiaries	184	205
Net income	170	191
Net income attributable to noncontrolling interests	'	'
Net income attributable to L-3	170	191
Comprehensive income attributable to L-3	152	167
L-3 Communications Corporation [Member]	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Total net sales	863	946
Total cost of sales	-769	-864
Operating (loss) income	94	82
Interest expense	-43	-43
Interest and other income, net	5	3
(Loss) income before income taxes	56	42
(Provision) benefit for income taxes	-15	-12
Equity in net income of consolidated subsidiaries	129	161
Net income	170	191
Net income attributable to noncontrolling interests	'	'
Net income attributable to L-3	170	191
Comprehensive income attributable to L-3	152	167
Guarantor Subsidiaries [Member]	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Total net sales	1,625	1,740
Total cost of sales	-1,481	-1,571
Operating (loss) income	144	169
Interest expense	'	'
Interest and other income, net	'	-1
(Loss) income before income taxes	144	168
(Provision) benefit for income taxes	-45	-48
Equity in net income of consolidated subsidiaries	'	'
Net income	99	120
Net income attributable to noncontrolling interests	'	'
Net income attributable to L-3	99	120
Comprehensive income attributable to L-3	96	120
Non-Guarantor Subsidiaries [Member]	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Total net sales	543	590
Total cost of sales	-495	-531
Operating (loss) income	48	59
Interest expense	'	'
Interest and other income, net	'	1
(Loss) income before income taxes	48	60
(Provision) benefit for income taxes	-16	-18
Equity in net income of consolidated subsidiaries	'	'
Net income	32	42
Net income attributable to noncontrolling interests	'	'
Net income attributable to L-3	32	42
Comprehensive income attributable to L-3	15	5
Eliminations [Member]	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Total net sales	-74	-79
Total cost of sales	89	93
Operating (loss) income	15	14
Interest expense	5	5
Interest and other income, net	'	'
(Loss) income before income taxes	20	19
(Provision) benefit for income taxes	-6	-5
Equity in net income of consolidated subsidiaries	-313	-366
Net income	-299	-352
Net income attributable to noncontrolling interests	-2	-1
Net income attributable to L-3	-301	-353
Comprehensive income attributable to L-3	($263)	($292)

Condensed_Combining_Financial_5

Condensed Combining Financial Information of L-3 Communications and Its Subsidiaries - Condensed Combining Statements of Cash Flows (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 28, 2014	Mar. 29, 2013
Operating activities:	'	'
Net cash from (used in) operating activities	($62)	$146
Investing activities:	'	'
Business acquisitions, net of cash acquired	-57	'
Investments in L-3 Communications	'	'
Other investing activities	-29	-54
Net cash used in investing activities	-86	-54
Financing activities:	'	'
Common stock repurchased	-133	-122
Dividends paid on L-3 Holdings common stock	-55	-52
Dividends paid to L-3 Holdings	'	'
Investments from L-3 Holdings	'	'
Other financing activities	64	16
Net cash used in financing activities	-124	-158
Effect of foreign currency exchange rate changes on cash	-1	-7
Net decrease in cash and cash equivalents	-273	-73
Cash and cash equivalents, beginning of the period	500	349
Cash and cash equivalents, end of the period	227	276
L-3 Communications Holdings, Inc. [Member]	'	'
Operating activities:	'	'
Net cash from (used in) operating activities	188	174
Investing activities:	'	'
Business acquisitions, net of cash acquired	'	'
Investments in L-3 Communications	-51	-13
Other investing activities	'	'
Net cash used in investing activities	-51	-13
Financing activities:	'	'
Common stock repurchased	-133	-122
Dividends paid on L-3 Holdings common stock	-55	-52
Dividends paid to L-3 Holdings	'	'
Investments from L-3 Holdings	'	'
Other financing activities	51	13
Net cash used in financing activities	-137	-161
Effect of foreign currency exchange rate changes on cash	'	'
Net 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 [Member]	'	'
Operating activities:	'	'
Net cash from (used in) operating activities	80	92
Investing activities:	'	'
Business acquisitions, net of cash acquired	-57	'
Investments in L-3 Communications	'	'
Other investing activities	-13	-25
Net cash used in investing activities	-70	-25
Financing activities:	'	'
Common stock repurchased	'	'
Dividends paid on L-3 Holdings common stock	'	'
Dividends paid to L-3 Holdings	-188	-174
Investments from L-3 Holdings	51	13
Other financing activities	-74	-86
Net cash used in financing activities	-211	-247
Effect of foreign currency exchange rate changes on cash	'	'
Net decrease in cash and cash equivalents	-201	-180
Cash and cash equivalents, beginning of the period	258	246
Cash and cash equivalents, end of the period	57	66
Guarantor Subsidiaries [Member]	'	'
Operating activities:	'	'
Net cash from (used in) operating activities	-61	73
Investing activities:	'	'
Business acquisitions, net of cash acquired	'	'
Investments in L-3 Communications	'	'
Other investing activities	-15	-25
Net cash used in investing activities	-15	-25
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	76	-48
Net cash used in financing activities	76	-48
Effect of foreign currency exchange rate changes on cash	'	'
Net decrease in cash and cash equivalents	'	'
Cash and cash equivalents, beginning of the period	'	'
Cash and cash equivalents, end of the period	'	'
Non-Guarantor Subsidiaries [Member]	'	'
Operating activities:	'	'
Net cash from (used in) operating activities	-34	24
Investing activities:	'	'
Business acquisitions, net of cash acquired	'	'
Investments in L-3 Communications	'	'
Other investing activities	-1	-4
Net cash used in investing activities	-1	-4
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	-43	-32
Net cash used in financing activities	-43	-32
Effect of foreign currency exchange rate changes on cash	-1	-7
Net decrease in cash and cash equivalents	-79	-19
Cash and cash equivalents, beginning of the period	261	242
Cash and cash equivalents, end of the period	182	223
Eliminations [Member]	'	'
Operating activities:	'	'
Net cash from (used in) operating activities	-235	-217
Investing activities:	'	'
Business acquisitions, net of cash acquired	'	'
Investments in L-3 Communications	51	13
Other investing activities	'	'
Net cash used in investing activities	51	13
Financing activities:	'	'
Common stock repurchased	'	'
Dividends paid on L-3 Holdings common stock	'	'
Dividends paid to L-3 Holdings	188	174
Investments from L-3 Holdings	-51	-13
Other financing activities	54	169
Net cash used in financing activities	191	330
Effect of foreign currency exchange rate changes on cash	'	'
Net decrease in cash and cash equivalents	7	126
Cash and cash equivalents, beginning of the period	-19	-139
Cash and cash equivalents, end of the period	($12)	($13)