BUSINESS SEGMENTS - Revenues and Income From Continuing Operations by Segment (Details) - USD ($)		6 Months Ended		12 Months Ended
	Jun. 29, 2019	Jan. 03, 2020	Dec. 28, 2018	Dec. 31, 2021	Jan. 01, 2021	Jan. 03, 2020	Jun. 28, 2019
Segment Reporting Information [Line Items]
Revenue		$ 9,263,000,000	$ 3,208,000,000	$ 17,814,000,000	$ 18,194,000,000	$ 12,856,000,000	$ 6,801,000,000
Income from Continuing Operations before Income Taxes
Segment Operating Income (Loss)		1,600,000,000		3,342,000,000	2,686,000,000		1,446,000,000
Unallocated Items [Abstract]
Unallocated corporate department expense, net		3,000,000		(57,000,000)	(69,000,000)		(2,000,000)
L3Harris Merger-related transaction, integration and other expenses and losses		(390,000,000)		(128,000,000)	(140,000,000)		(65,000,000)
Amortization of acquisition-related intangibles		(289,000,000)		(627,000,000)	(709,000,000)		(101,000,000)
Additional cost of sales related to fair value step-up in inventory sold		(142,000,000)		0	(31,000,000)		0
Business divestiture-related gains (losses)		229,000,000	0	220,000,000	(51,000,000)	229,000,000	0
Impairment of goodwill and other assets		0		(125,000,000)	(132,000,000)		0
Other items		0		(71,000,000)	10,000,000		0
Total unallocated expenses		(589,000,000)		(788,000,000)	(1,122,000,000)		(168,000,000)
Pension adjustment		(172,000,000)		(445,000,000)	(389,000,000)		(186,000,000)
Non-operating income		192,000,000		439,000,000	401,000,000		188,000,000
Net interest expense		(123,000,000)	(86,000,000)	(265,000,000)	(254,000,000)	(204,000,000)	(167,000,000)
Income from continuing operations before income taxes		908,000,000	$ 528,000,000	2,283,000,000	1,322,000,000	$ 1,493,000,000	1,113,000,000
Goodwill impairment	$ 0			62,000,000	480,000,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | CPS business
Unallocated Items [Abstract]
Goodwill impairment				62,000,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | CTS
Unallocated Items [Abstract]
Impairment of identifiable assets				63,000,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | VSE disposal group
Unallocated Items [Abstract]
Goodwill impairment					14,000,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Applied Kilovolts Business
Unallocated Items [Abstract]
Goodwill impairment					5,000,000
Integrated Mission Systems
Unallocated Items [Abstract]
Goodwill impairment				0	0
Space & Airborne Systems
Unallocated Items [Abstract]
Goodwill impairment				0	5,000,000
Communication Systems
Unallocated Items [Abstract]
Goodwill impairment				0	0
Aviation Systems
Unallocated Items [Abstract]
Goodwill impairment				62,000,000	475,000,000
Operating segments | Integrated Mission Systems
Segment Reporting Information [Line Items]
Revenue		2,758,000,000		5,839,000,000	5,538,000,000		52,000,000
Income from Continuing Operations before Income Taxes
Segment Operating Income (Loss)		371,000,000		950,000,000	847,000,000		10,000,000
Operating segments | Space & Airborne Systems
Segment Reporting Information [Line Items]
Revenue		2,377,000,000		5,093,000,000	4,946,000,000		3,711,000,000
Income from Continuing Operations before Income Taxes
Segment Operating Income (Loss)		447,000,000		970,000,000	932,000,000		696,000,000
Operating segments | Communication Systems
Segment Reporting Information [Line Items]
Revenue		2,151,000,000		4,287,000,000	4,443,000,000		2,208,000,000
Income from Continuing Operations before Income Taxes
Segment Operating Income (Loss)		493,000,000		1,092,000,000	1,084,000,000		637,000,000
Operating segments | Aviation Systems
Segment Reporting Information [Line Items]
Revenue		2,038,000,000		2,783,000,000	3,448,000,000		672,000,000
Income from Continuing Operations before Income Taxes
Segment Operating Income (Loss)		289,000,000		330,000,000	(177,000,000)		76,000,000
Other non-reportable business segments
Segment Reporting Information [Line Items]
Revenue		23,000,000		0	0		165,000,000
Income from Continuing Operations before Income Taxes
Segment Operating Income (Loss)		0		0	0		27,000,000
Corporate eliminations
Segment Reporting Information [Line Items]
Revenue		$ (84,000,000)		$ (188,000,000)	$ (181,000,000)		$ (7,000,000)