Revisions to Previously Issued Financial Statements - Schedule of Condensed Consolidated Statement of Cash Flows (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 26, 2014	Sep. 27, 2013
Operating activities:
Net income	$ 470	$ 572
Depreciation of property, plant and equipment	127	122
Amortization of intangibles and other assets	38	36
Deferred income tax provision	91	38
Stock-based employee compensation expense	39	42
Contributions to employee savings plans in L-3 Holdings' common stock	105	90
Amortization of pension and postretirement benefit plans net loss and prior service cost	11	63
Amortization of bond discounts and deferred debt issue costs (included in interest expense)	5	5
Other non-cash items	(5)	1
Changes in operating assets and liabilities, excluding amounts from acquisitions and divestitures:
Billed receivables	118	(117)
Contracts in process	(157)	(70)
Inventories	(17)	(60)
Other assets		(48)
Accounts payable, trade	(125)	54
Accrued employment costs	26	37
Accrued expenses	(51)	(45)
Advance payments and billings in excess of costs incurred	39	(61)
Income taxes	(4)	31
Excess income tax benefits related to share-based payment arrangements	(16)	(3)
Other current liabilities	(21)	(5)
Pension and postretirement benefits	(40)	(23)
All other operating activities	(28)	(42)
Net cash from operating activities	605	617
As Previously Reported [Member]
Operating activities:
Net income		588
Depreciation of property, plant and equipment		122
Amortization of intangibles and other assets		36
Deferred income tax provision		45
Stock-based employee compensation expense		42
Contributions to employee savings plans in L-3 Holdings' common stock		90
Amortization of pension and postretirement benefit plans net loss and prior service cost		63
Amortization of bond discounts and deferred debt issue costs (included in interest expense)		5
Other non-cash items		1
Changes in operating assets and liabilities, excluding amounts from acquisitions and divestitures:
Billed receivables		(117)
Contracts in process		(36)
Inventories		(55)
Other assets		(45)
Accounts payable, trade		65
Accrued employment costs		27
Accrued expenses		(41)
Advance payments and billings in excess of costs incurred		(109)
Income taxes		32
Excess income tax benefits related to share-based payment arrangements		(3)
Other current liabilities		(8)
Pension and postretirement benefits		(23)
All other operating activities		(62)
Net cash from operating activities		617
Restatement Adjustments [Member]
Operating activities:
Net income		(16)
Depreciation of property, plant and equipment
Amortization of intangibles and other assets
Deferred income tax provision		(7)
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
Contracts in process		(34)
Inventories		(5)
Other assets		(3)
Accounts payable, trade		(11)
Accrued employment costs		10
Accrued expenses		(4)
Advance payments and billings in excess of costs incurred		48
Income taxes		(1)
Excess income tax benefits related to share-based payment arrangements
Other current liabilities		3
Pension and postretirement benefits
All other operating activities		20
Net cash from operating activities