Description of Business	12 Months Ended
Dec. 31, 2011
Description of Business [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 Command, Control, Communications, Intelligence, Surveillance and Reconnaissance (C³ ISR) systems, aircraft modernization and maintenance, and government services. L-3 is also a leading provider of a broad range of electronic systems used on military and commercial platforms. The Company’s customers include the United States (U.S.) Department of Defense (DoD) and its prime contractors, U.S. Government intelligence agencies, the U.S. Department of Homeland Security (DHS), U.S. Department of State (DoS), U.S. Department of Justice (DoJ), allied foreign governments, domestic and foreign commercial customers and select other U.S. federal, state and local government agencies. The Company has the following four reportable segments: (1) C ³ISR, (2) Government Services, (3) Aircraft Modernization and Maintenance (AM&M), and (4) Electronic Systems. Financial information with respect to each of the Company’s segments is included in Note 22. C³ISR provides products and services for the global ISR market, C³ systems, networked communications systems and secure communications products. The Company believes that these products and services are critical elements for a substantial number of major command, control and communication, intelligence gathering and space systems. These products and services are used to connect a variety of airborne, space, ground and sea-based communication systems and are used in the transmission, processing, recording, monitoring, and dissemination functions of these communication systems. Government Services provides a full range of systems engineering and technical assistance (SETA), training, operational support, cyber security, intelligence, enterprise information technology (IT) and security solutions services to the DoD, DoS, DoJ, and U.S. Government intelligence agencies and allied foreign governments. AM&M provides modernization, upgrades and sustainment, maintenance and logistics support services for military and various government aircraft and other platforms. The Company sells these services primarily to the DoD, the Canadian Department of Defense and other allied foreign governments. Electronic Systems provides a broad range of products and services, including components, products, subsystems and systems and related services to military and commercial customers in several niche markets across several business areas, including microwave, power & control systems, integrated sensor systems, aviation products, simulation & training, warrior systems, precision engagement, security & detection, space & propulsion, undersea warfare and marine services. On July 28, 2011, the Company announced that its Board of Directors approved a plan to spin-off a new, independent government services company that will be publicly traded. The new public company will be named Engility Holdings, Inc. (Engility). The spin-off, which is intended to be tax-free to L-3 and its shareholders, is expected to be completed in the first half of 2012. Upon completion, L-3 shareholders will own 100% of the shares of both L-3 and Engility. The spin-off is not subject to a shareholder vote. Under the plan, Engility will include the SETA, training and operational support services businesses that are currently part of L-3’s Government Services segment. L-3 will retain the cyber security, intelligence, enterprise IT and security solutions businesses that are also part of L-3’s Government Services segment. The Government Services segment will be renamed National Security Solutions upon completion of the spin-off. The completion of the spin-off is subject to certain customary conditions, including filing of required documents with the U.S. Securities and Exchange Commission, and an opinion of counsel as to the satisfaction of certain requirements necessary for the spin-off to receive tax-free treatment upon which the Internal Revenue Service does not rule, which is expected to be received immediately prior to the completion of the spin-off transaction. There can be no assurance that any separation transaction will ultimately occur, or if one does occur, its terms or timing.

Description of Business

12 Months Ended

Dec. 31, 2011

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 Command, Control, Communications, Intelligence, Surveillance and Reconnaissance (C³ ISR) systems, aircraft modernization and maintenance, and government services. L-3 is also a leading provider of a broad range of electronic systems used on military and commercial platforms. The Company’s customers include the United States (U.S.) Department of Defense (DoD) and its prime contractors, U.S. Government intelligence agencies, the U.S. Department of Homeland Security (DHS), U.S. Department of State (DoS), U.S. Department of Justice (DoJ), allied foreign governments, domestic and foreign commercial customers and select other U.S. federal, state and local government agencies.

The Company has the following four reportable segments: (1) C ³ISR, (2) Government Services, (3) Aircraft Modernization and Maintenance (AM&M), and (4) Electronic Systems. Financial information with respect to each of the Company’s segments is included in Note 22. C³ISR provides products and services for the global ISR market, C³ systems, networked communications systems and secure communications products. The Company believes that these products and services are critical elements for a substantial number of major command, control and communication, intelligence gathering and space systems. These products and services are used to connect a variety of airborne, space, ground and sea-based communication systems and are used in the transmission, processing, recording, monitoring, and dissemination functions of these communication systems. Government Services provides a full range of systems engineering and technical assistance (SETA), training, operational support, cyber security, intelligence, enterprise information technology (IT) and security solutions services to the DoD, DoS, DoJ, and U.S. Government intelligence agencies and allied foreign governments. AM&M provides modernization, upgrades and sustainment, maintenance and logistics support services for military and various government aircraft and other platforms. The Company sells these services primarily to the DoD, the Canadian Department of Defense and other allied foreign governments. Electronic Systems provides a broad range of products and services, including components, products, subsystems and systems and related services to military and commercial customers in several niche markets across several business areas, including microwave, power & control systems, integrated sensor systems, aviation products, simulation & training, warrior systems, precision engagement, security & detection, space & propulsion, undersea warfare and marine services.

On July 28, 2011, the Company announced that its Board of Directors approved a plan to spin-off a new, independent government services company that will be publicly traded. The new public company will be named Engility Holdings, Inc. (Engility). The spin-off, which is intended to be tax-free to L-3 and its shareholders, is expected to be completed in the first half of 2012. Upon completion, L-3 shareholders will own 100% of the shares of both L-3 and Engility. The spin-off is not subject to a shareholder vote.

Under the plan, Engility will include the SETA, training and operational support services businesses that are currently part of L-3’s Government Services segment. L-3 will retain the cyber security, intelligence, enterprise IT and security solutions businesses that are also part of L-3’s Government Services segment. The Government Services segment will be renamed National Security Solutions upon completion of the spin-off.

The completion of the spin-off is subject to certain customary conditions, including filing of required documents with the U.S. Securities and Exchange Commission, and an opinion of counsel as to the satisfaction of certain requirements necessary for the spin-off to receive tax-free treatment upon which the Internal Revenue Service does not rule, which is expected to be received immediately prior to the completion of the spin-off transaction. There can be no assurance that any separation transaction will ultimately occur, or if one does occur, its terms or timing.