BUSINESS SEGMENTS - Revenues and Income From Continuing Operations by Segment (Details) - USD ($)		6 Months Ended		9 Months Ended	12 Months Ended
	Jun. 29, 2019	Jan. 03, 2020	Dec. 28, 2018	Oct. 02, 2020	Jan. 01, 2021	Jul. 03, 2020	Jan. 03, 2020	Jun. 28, 2019	Jun. 29, 2018
Segment Reporting Information [Line Items]
Revenue		$ 9,263,000,000	$ 3,208,000,000		$ 18,194,000,000		$ 12,856,000,000	$ 6,801,000,000	$ 6,168,000,000
Income from Continuing Operations before Income Taxes
L3Harris Merger-related transaction, integration and other expenses and losses		(273,000,000)			(130,000,000)			(65,000,000)	0
L3Harris Merger-related restructuring costs		(117,000,000)			(26,000,000)
Amortization of acquisition-related intangibles					(729,000,000)	$ (290,000,000)		(115,000,000)	(117,000,000)
Impairment of identifiable intangible assets		0			(113,000,000)			0	0
Business divestiture-related (losses) gains		229,000,000	0		(51,000,000)		229,000,000	0	0
Pension adjustment		(172,000,000)			(389,000,000)			(186,000,000)	(184,000,000)
Non-operating income		192,000,000			401,000,000			188,000,000	156,000,000
Net interest expense		(123,000,000)			(254,000,000)			(167,000,000)	(168,000,000)
Income from continuing operations before income taxes		908,000,000	528,000,000		1,322,000,000		$ 1,493,000,000	1,113,000,000	908,000,000
Gain on sale of property, plant and equipment		0			22,000,000			0	0
Goodwill impairment loss	$ 0			$ 480,000,000
Operating lease expense								73,000,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income from Continuing Operations before Income Taxes
Business divestiture-related (losses) gains					296,000,000
L3Harris Technologies, Inc. And Exelis
Income from Continuing Operations before Income Taxes
Amortization of acquisition-related intangibles		(289,000,000)			(709,000,000)			(101,000,000)	(101,000,000)
L3Harris
Segment Reporting Information [Line Items]
Revenue			$ 3,208,000,000		12,856,000,000
Income from Continuing Operations before Income Taxes
L3Harris Merger-related restructuring costs		(117,000,000)			(10,000,000)			0	0
Amortization of acquisition-related intangibles		(239,000,000)			(609,000,000)
Integration costs, recognized as incurred		72,000,000			130,000,000			34,000,000
Exelis
Income from Continuing Operations before Income Taxes
L3Harris Merger-related restructuring costs									(5,000,000)
Amortization of acquisition-related intangibles		(50,000,000)			(100,000,000)			(101,000,000)	(101,000,000)
Integrated Mission Systems
Income from Continuing Operations before Income Taxes
Goodwill impairment loss				0
Space and Airborne Systems
Income from Continuing Operations before Income Taxes
Goodwill impairment loss				5,000,000
Communication Systems
Income from Continuing Operations before Income Taxes
Goodwill impairment loss				0
Aviation Systems
Income from Continuing Operations before Income Taxes
Goodwill impairment loss				$ 475,000,000
Operating segments | Integrated Mission Systems
Segment Reporting Information [Line Items]
Revenue		2,758,000,000			5,538,000,000			52,000,000	55,000,000
Income from Continuing Operations before Income Taxes
Net EAC adjustments, before income taxes		371,000,000			847,000,000			10,000,000	9,000,000
Operating segments | Space and Airborne Systems
Segment Reporting Information [Line Items]
Revenue		2,377,000,000			4,946,000,000			3,711,000,000	3,294,000,000
Income from Continuing Operations before Income Taxes
Net EAC adjustments, before income taxes		447,000,000			932,000,000			696,000,000	626,000,000
Operating segments | Communication Systems
Segment Reporting Information [Line Items]
Revenue		2,151,000,000			4,443,000,000			2,208,000,000	2,015,000,000
Income from Continuing Operations before Income Taxes
Net EAC adjustments, before income taxes		493,000,000			1,084,000,000			637,000,000	561,000,000
Operating segments | Aviation Systems
Segment Reporting Information [Line Items]
Revenue		2,038,000,000			3,448,000,000			672,000,000	668,000,000
Income from Continuing Operations before Income Taxes
Net EAC adjustments, before income taxes		289,000,000			(177,000,000)			76,000,000	54,000,000
Operating segments | Other non-reportable business segments
Segment Reporting Information [Line Items]
Revenue		23,000,000			0			165,000,000	148,000,000
Income from Continuing Operations before Income Taxes
Net EAC adjustments, before income taxes		0			0			27,000,000	20,000,000
Corporate eliminations
Segment Reporting Information [Line Items]
Revenue		(84,000,000)			(181,000,000)			(7,000,000)	(12,000,000)
Corporate eliminations
Income from Continuing Operations before Income Taxes
Net EAC adjustments, before income taxes		(139,000,000)			(109,000,000)			$ (2,000,000)	(65,000,000)
Gain on sale of property, plant and equipment					22,000,000
Divestiture-related expenses					13,000,000
Gain on sale of assets		12,000,000
Deferred compensation expense									12,000,000
Corporate eliminations | Disposal Group, Held-for-sale, Not Discontinued Operations
Income from Continuing Operations before Income Taxes
Goodwill impairment loss					14,000,000
Corporate eliminations | Disposal Group, Disposed of by Sale, Not Discontinued Operations | Applied Kilovolts and Analytical Instrumentation Business
Income from Continuing Operations before Income Taxes
Goodwill impairment loss					5,000,000
Corporate eliminations | Restatement Adjustment
Income from Continuing Operations before Income Taxes
Operating lease expense		10,000,000			2,000,000
Corporate eliminations | L3Harris
Income from Continuing Operations before Income Taxes
Additional cost of sales related to fair value step-up in inventory sold		$ 142,000,000			$ 31,000,000
Corporate eliminations | Exelis
Income from Continuing Operations before Income Taxes
Integration costs, recognized as incurred									5,000,000
Corporate eliminations | Commercial Line Business | Business Exit
Income from Continuing Operations before Income Taxes
Divestiture-related expenses									$ 47,000,000