Acquisitions, Divestitures and Discontinued Operations, Business Acquisitions (Details) £ in Millions, $ in Millions																	3 Months Ended								12 Months Ended
	Sep. 20, 2018 USD ($)	Sep. 18, 2018 USD ($)	Sep. 18, 2018 GBP (£)	Aug. 31, 2018 USD ($) shares	Aug. 31, 2018 AUD ($) shares	Jun. 29, 2018 USD ($)	Jun. 28, 2018 USD ($)	Dec. 18, 2017 USD ($)	Oct. 27, 2017 USD ($)	Sep. 08, 2017 USD ($)	May 19, 2017 USD ($)	Jan. 05, 2017 USD ($)	Nov. 22, 2016 USD ($)	Nov. 22, 2016 GBP (£)	Sep. 30, 2016 USD ($)	Jan. 22, 2016 USD ($)	Dec. 31, 2018 USD ($)	Sep. 28, 2018 USD ($)	Jun. 29, 2018 USD ($)	Mar. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 29, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Aug. 31, 2018 AUD ($)	Feb. 16, 2018 USD ($)	Sep. 12, 2017 USD ($)	Mar. 17, 2017 USD ($)	Nov. 22, 2016 GBP (£)
Business Acquisition [Line Items]
Gain on sale of the Crestview Aerospace and TCS businesses																									$ 42,000,000	$ 0	$ 0
Goodwill recognized																	$ 6,808,000,000				$ 6,615,000,000				6,808,000,000	6,615,000,000	6,374,000,000
Fair value of liability, contingent consideration																	20,000,000				31,000,000				20,000,000	31,000,000
Net sales																	2,771,000,000	$ 2,519,000,000	$ 2,583,000,000	$ 2,371,000,000	2,574,000,000	$ 2,293,000,000	$ 2,385,000,000	$ 2,321,000,000	10,244,000,000	9,573,000,000	9,210,000,000
Loss before income taxes																									924,000,000	871,000,000	804,000,000
Amortization expense																									$ 49,000,000	43,000,000	33,000,000
Technology [Member]
Business Acquisition [Line Items]
Finite lived intangible assets, weighted average amortization period																									9 years
Customer Relationships [Member]
Business Acquisition [Line Items]
Finite lived intangible assets, weighted average amortization period																									16 years
2018 Business Acquisitions [Member]
Business Acquisition [Line Items]
Net sales																									$ 46,000,000
Loss before income taxes																									(7,000,000)
Amortization expense																									7,000,000
IRAD expense																									1,000,000
ASV Global LLC [Member]
Business Acquisition [Line Items]
Purchase price of acquisition	$ 94,000,000
Cash acquired from acquisition	1,000,000
C.K. Industrial Engineers Limited [Member]
Business Acquisition [Line Items]
Purchase price of acquisition		$ 24,000,000	£ 18
Cash acquired from acquisition		5,000,000	£ 4
Goodwill recognized		$ 13,000,000
Azimuth Security and Linchpin Labs [Member]
Business Acquisition [Line Items]
Purchase price of acquisition				$ 185,000,000	$ 249
Cash acquired from acquisition				15,000,000	$ 21
Fair value of liability, contingent consideration				$ 31,000,000																								$ 43
Contingent consideration (shares) | shares				161,087	161,087
Increase to equity for fair value of contingent consideration				$ 6,000,000
Applied Defense Solutions [Member]
Business Acquisition [Line Items]
Purchase price of acquisition						$ 53,000,000
Cash acquired from acquisition						$ 1,000,000
Goodwill recognized																	40,000,000								40,000,000
L3 Latitude Engineering [Member]
Business Acquisition [Line Items]
Purchase price of acquisition							$ 15,000,000
Fair value of liability, contingent consideration							20,000,000
Increase to equity for fair value of contingent consideration							6,000,000
Kigre, Inc [Member]
Business Acquisition [Line Items]
Purchase price of acquisition								$ 13,000,000
Goodwill recognized								9,000,000
Goodwill deductible for income tax purposes								$ 0
Escola De Aviacao Aerocondor, S.A [Member]
Business Acquisition [Line Items]
Purchase price of acquisition									$ 13,000,000
Goodwill recognized									12,000,000
Goodwill deductible for income tax purposes									$ 0
Doss Aviation, Inc. [Member]
Business Acquisition [Line Items]
Goodwill recognized																														$ 37,000,000
Goodwill deductible for income tax purposes																														$ 13,000,000
Adaptive Methods, Inc. [Member]
Business Acquisition [Line Items]
Purchase price of acquisition										$ 33,000,000
Goodwill recognized										28,000,000
Goodwill deductible for income tax purposes										$ 28,000,000
Open Water Power, Inc. [Member]
Business Acquisition [Line Items]
Purchase price of acquisition											$ 17,000,000
Goodwill recognized											25,000,000
Goodwill deductible for income tax purposes											0
Fair value of liability, contingent consideration											14,000,000
Open Water Power, Inc. [Member] | IPR&D [Member]
Business Acquisition [Line Items]
Identifiable intangible assets											$ 65,000,000
OceanServer Technology, Inc. [Member]
Business Acquisition [Line Items]
Goodwill recognized																															$ 19,000,000
Goodwill deductible for income tax purposes																															$ 19,000,000
Explosive Trace Detection Business of Implant Sciences [Member]
Business Acquisition [Line Items]
Purchase price of acquisition												$ 118,000,000
Goodwill recognized												80,000,000
Goodwill deductible for income tax purposes												$ 80,000,000	$ 0
MacDonald Humfrey (Automation) Limited [Member]
Business Acquisition [Line Items]
Purchase price of acquisition													327,000,000	£ 263
Goodwill recognized													255,000,000																			£ 204
Identifiable intangible assets													$ 56,000,000																			45
Finite lived intangible assets, weighted average amortization period													10 years	10 years
Fair value of liability, contingent consideration													$ 26,000,000																			21
Contingent consideration													38,000,000																			30
MacDonald Humfrey (Automation) Limited [Member] | Technology [Member]
Business Acquisition [Line Items]
Identifiable intangible assets													12,000,000																			10
MacDonald Humfrey (Automation) Limited [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Identifiable intangible assets													36,000,000																			29
MacDonald Humfrey (Automation) Limited [Member] | Trade Name [Member]
Business Acquisition [Line Items]
Identifiable intangible assets													$ 8,000,000																			£ 6
Micreo Limited And Aerosim Technologies Inc [Member]
Business Acquisition [Line Items]
Purchase price of acquisition															$ 86,000,000
Goodwill recognized															59,000,000
Goodwill deductible for income tax purposes															$ 6,000,000
Advanced Technical Materials Incorporation [Member]
Business Acquisition [Line Items]
Purchase price of acquisition																$ 27,000,000
Goodwill recognized																20,000,000
Goodwill deductible for income tax purposes																$ 20,000,000
C&NS [Member]
Business Acquisition [Line Items]
Goodwill recognized																	2,007,000,000				1,962,000,000				2,007,000,000	1,962,000,000	1,868,000,000
Net sales																									3,059,000,000
C&NS [Member] | ASV Global LLC [Member]
Business Acquisition [Line Items]
Goodwill recognized	54,000,000
Goodwill deductible for income tax purposes	16,000,000
C&NS [Member] | ASV Global LLC [Member] | Technology [Member]
Business Acquisition [Line Items]
Identifiable intangible assets	$ 30,000,000
ISR Systems [Member]
Business Acquisition [Line Items]
Goodwill recognized																	2,596,000,000				2,458,000,000				2,596,000,000	2,458,000,000	2,466,000,000
Net sales																									4,441,000,000
ISR Systems [Member] | Azimuth Security and Linchpin Labs [Member]
Business Acquisition [Line Items]
Goodwill recognized				117,000,000
Goodwill deductible for income tax purposes				20,000,000
Identifiable intangible assets				$ 90,000,000
ISR Systems [Member] | Azimuth Security and Linchpin Labs [Member] | Technology [Member]
Business Acquisition [Line Items]
Finite lived intangible assets, weighted average amortization period				4 years	4 years
ISR Systems [Member] | Azimuth Security and Linchpin Labs [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Finite lived intangible assets, weighted average amortization period				20 years	20 years
Electronic Systems [Member]
Business Acquisition [Line Items]
Goodwill recognized																	$ 2,205,000,000				$ 2,195,000,000				2,205,000,000	$ 2,195,000,000	$ 2,040,000,000
Net sales																									$ 2,744,000,000
Electronic Systems [Member] | L3 Latitude Engineering [Member]
Business Acquisition [Line Items]
Goodwill recognized							15,000,000
Post-acquisition Performance through December 2021 [Member] | L3 Latitude Engineering [Member]
Business Acquisition [Line Items]
Fair value of liability, contingent consideration							15,000,000
Post-acquisition Milestone Achievements through December 2020 [Member] | L3 Latitude Engineering [Member]
Business Acquisition [Line Items]
Fair value of liability, contingent consideration							$ 5,000,000
Peak Nano Optics, LLC [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Business Acquisition [Line Items]
Goodwill recognized																													$ 11,000,000
Ownership interest (percent)																													25.00%
Equity method investments																													$ 20,000,000
Peak Nano Optics, LLC [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] | IPR&D [Member]
Business Acquisition [Line Items]
Intangible assets acquired																													$ 13,000,000