Assumed purchase of common shares for treasury.

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Net Income Loss From Discontinued Operations Attributable To Noncontrolling Interest

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Amount of income (loss) from continuing operations attributable to the parent. Also defined as revenue less expenses and taxes from ongoing operations before extraordinary items but after deduction of those portions of income or loss from continuing operations that are allocable to noncontrolling interests.

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Amount of income (loss) from continuing operations attributable to the noncontrolling interest. Also defined as revenue less expenses and taxes from ongoing operations before extraordinary items but after deduction of those portions of income or loss from continuing operations that are allocable to noncontrolling interests.

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The amount of net income (loss) from continuing operations per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) derived from continuing operations during the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Amount of income (loss) from a disposal group, net of income tax, reported as a separate component of income before extraordinary items after deduction or consideration of the amount allocable to noncontrolling interests. Includes, net of tax, income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

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Per basic share amount, after tax, of income (loss) from the day-to-day business activities of the discontinued operation and gain (loss) from the disposal of the discontinued operation.

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Per diluted share amount, after tax, of income (loss) from the day-to-day business activities of the discontinued operation and gain (loss) from the disposal of the discontinued operation.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of convertible debt securities using the if-converted method.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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Net income after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period).

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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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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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L-3 Holdings' Earnings Per Share - Reconciliation of Basic and Diluted Earnings per Share (EPS) (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation of net income:
Net income	$ 207us-gaap_ProfitLoss	$ 157us-gaap_ProfitLoss	$ 141us-gaap_ProfitLoss	$ 172us-gaap_ProfitLoss	$ 188us-gaap_ProfitLoss	$ 204us-gaap_ProfitLoss	$ 176us-gaap_ProfitLoss	$ 192us-gaap_ProfitLoss	$ 677us-gaap_ProfitLoss	$ 760us-gaap_ProfitLoss	$ 794us-gaap_ProfitLoss
Net income from continuing operations attributable to noncontrolling interests									(13)	(9)	(6)
Net income from discontinued operations attributable to noncontrolling interests											(4)
Net income attributable to L-3 Holdings common shareholders									664	751	784
Earnings attributable to L-3 Holdings' common shareholders:
Continuing operations									664	751	756
Discontinued operations, net of income tax											28
Net income attributable to L-3 Holdings common shareholders									$ 664	$ 751	$ 784
Basic:
Weighted average common shares outstanding									85.4	89.4	96.3
Basic earnings per share attributable to L-3 Holdings' common shareholders:
Continuing operations									$ 7.78	$ 8.40	$ 7.85
Discontinued operations, net of income tax											$ 0.29
Basic earnings per share	$ 2.41us-gaap_EarningsPerShareBasic	$ 1.81us-gaap_EarningsPerShareBasic	$ 1.59us-gaap_EarningsPerShareBasic	$ 1.97us-gaap_EarningsPerShareBasic	$ 2.10us-gaap_EarningsPerShareBasic	$ 2.23us-gaap_EarningsPerShareBasic	$ 1.95us-gaap_EarningsPerShareBasic	$ 2.12us-gaap_EarningsPerShareBasic	$ 7.78us-gaap_EarningsPerShareBasic	$ 8.40us-gaap_EarningsPerShareBasic	$ 8.14us-gaap_EarningsPerShareBasic
Common and potential common shares:
Weighted average common shares outstanding									85.4	89.4	96.3
Assumed purchase of common shares for treasury									(3.1)	(4.5)	(3.0)
Assumed conversion of the CODES									0.8	0.2
Common and potential common shares									87.8	91.1	97.6
Diluted earnings per share attributable to L-3 Holdings' common shareholders:
Continuing operations									$ 7.56	$ 8.24	$ 7.74
Discontinued operations, net of income tax											$ 0.29
Diluted earnings per share	$ 2.36us-gaap_EarningsPerShareDiluted	$ 1.78us-gaap_EarningsPerShareDiluted	$ 1.53us-gaap_EarningsPerShareDiluted	$ 1.90us-gaap_EarningsPerShareDiluted	$ 2.04us-gaap_EarningsPerShareDiluted	$ 2.19us-gaap_EarningsPerShareDiluted	$ 1.92us-gaap_EarningsPerShareDiluted	$ 2.09us-gaap_EarningsPerShareDiluted	$ 7.56us-gaap_EarningsPerShareDiluted	$ 8.24us-gaap_EarningsPerShareDiluted	$ 8.03us-gaap_EarningsPerShareDiluted
Stock Options [Member]
Common and potential common shares:
Common and potential common shares									3.0	3.9	1.9
Unvested Restricted Stock Awards [Member]
Common and potential common shares:
Common and potential common shares									1.6	1.8	2.0
Employee Stock Purchase Plan Contributions [Member]
Common and potential common shares:
Common and potential common shares										0.2	0.3
Performance Unit Awards [Member]
Common and potential common shares:
Common and potential common shares									0.1	0.1	0.1