Comprehensive Income (Details) (USD $) In Millions	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 24, 2010	Sep. 24, 2010	Sep. 30, 2011
Reconciliation of net income to comprehensive income attributable to L-3
Net income	$ 238	$ 241	$ 694	$ 691
Other comprehensive income (loss):
Foreign currency translation adjustments	(81)	44	(14)	(14)
Unrealized (losses) gains on hedging instruments	(9)	1	2	(11)
Net gain from pension and postretirement benefit plans arising during the period		1	3
Amortization of pension and postretirement benefit plans net loss and prior service cost	6	7	19	22
Total comprehensive income	154	294	704	688
Less: Comprehensive income attributable to noncontrolling interests	3	3	7	9
Comprehensive income attributable to L-3	151	291	697	679
Comprehensive Income (Textuals)
Income tax effect on unrealized gains (losses) on hedging instruments	(5)		2	(7)
Income tax effect on amortization of pension and postretirement benefit plans net loss and prior service cost	$ 4	$ 5	$ 12	$ 14

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Tax effect on the amortization of pension and postretirement benefit plans net loss and prior service cost.

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The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the reporting entity. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, but excludes any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

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The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to noncontrolling interests, if any. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

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The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the economic entity, including both controlling (parent) and noncontrolling interests. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, including any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

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The accumulated change in the value of either the projected benefit obligation or the plans assets resulting from experience different from that assumed or from a change in an actuarial assumption that has not been recognized in net periodic benefit cost pursuant to FAS 87 and 106, after tax.

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Adjustment that results from the process of translating subsidiary financial statements and foreign equity investments into functional currency of the reporting entity, net of tax.

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The adjustment out of other comprehensive income for actuarial gains (losses) recognized as a component of net periodic benefit cost during the period, after tax

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Change in accumulated gains and losses from derivative instrument designated and qualifying as the effective portion of cash flow hedges, net of tax effect. The after tax effect change includes an entity's share of an equity investee's increase (decrease) in deferred hedging gains or losses.

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Tax effect on the change in accumulated gains and losses from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Includes an entity's share of an equity investee's increase (decrease) in deferred hedging gains or losses.

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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