BUSINESS SEGMENTS - Disaggregation of Revenue (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jan. 03, 2020	Dec. 28, 2018	Jun. 28, 2019	Jun. 29, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue	$ 9,263	$ 3,208	$ 6,801	$ 6,168	$ 5,897
United States
Disaggregation of Revenue [Line Items]
Revenue	8,485		6,530	5,854	5,637
International
Disaggregation of Revenue [Line Items]
Revenue	778		271	314	260
Integrated Mission Systems
Disaggregation of Revenue [Line Items]
Revenue	2,774		48	45	38
Integrated Mission Systems | United States
Disaggregation of Revenue [Line Items]
Revenue	2,300		30	39	27
Integrated Mission Systems | International
Disaggregation of Revenue [Line Items]
Revenue	474		18	6	11
Integrated Mission Systems | Fixed-price
Disaggregation of Revenue [Line Items]
Revenue	2,138		48	45	37
Integrated Mission Systems | Cost-reimbursable
Disaggregation of Revenue [Line Items]
Revenue	636		0	0	1
Integrated Mission Systems | Prime contractor
Disaggregation of Revenue [Line Items]
Revenue	1,904		25	20	24
Integrated Mission Systems | Subcontractor
Disaggregation of Revenue [Line Items]
Revenue	870		23	25	14
Communication Systems
Disaggregation of Revenue [Line Items]
Revenue	2,151		2,208	2,015	1,891
Communication Systems | United States
Disaggregation of Revenue [Line Items]
Revenue	1,518		1,281	1,031	880
Communication Systems | International
Disaggregation of Revenue [Line Items]
Revenue	633		927	984	1,011
Communication Systems | Fixed-price
Disaggregation of Revenue [Line Items]
Revenue	1,849
Communication Systems | Cost-reimbursable
Disaggregation of Revenue [Line Items]
Revenue	302
Communication Systems | Prime contractor
Disaggregation of Revenue [Line Items]
Revenue	1,406
Communication Systems | Subcontractor
Disaggregation of Revenue [Line Items]
Revenue	745
Aviation Systems
Disaggregation of Revenue [Line Items]
Revenue	2,038		672	668	697
Aviation Systems | United States
Disaggregation of Revenue [Line Items]
Revenue	1,514		644	627	647
Aviation Systems | International
Disaggregation of Revenue [Line Items]
Revenue	524		28	41	50
Aviation Systems | Fixed-price
Disaggregation of Revenue [Line Items]
Revenue	1,688		587	582	636
Aviation Systems | Cost-reimbursable
Disaggregation of Revenue [Line Items]
Revenue	350		85	86	61
Aviation Systems | Prime contractor
Disaggregation of Revenue [Line Items]
Revenue	1,246		654	656	697
Aviation Systems | Subcontractor
Disaggregation of Revenue [Line Items]
Revenue	792		18	12	0
Transferred over Time | Space and Airborne Systems
Disaggregation of Revenue [Line Items]
Revenue	2,360		3,715	3,304	3,156
Transferred over Time | Space and Airborne Systems | United States
Disaggregation of Revenue [Line Items]
Revenue	2,037		3,255	2,937	2,782
Transferred over Time | Space and Airborne Systems | International
Disaggregation of Revenue [Line Items]
Revenue	323		460	367	374
Transferred over Time | Space and Airborne Systems | Fixed-price
Disaggregation of Revenue [Line Items]
Revenue	1,367		2,097	1,634	1,390
Transferred over Time | Space and Airborne Systems | Cost-reimbursable
Disaggregation of Revenue [Line Items]
Revenue	993		1,618	1,670	1,766
Transferred over Time | Space and Airborne Systems | Prime contractor
Disaggregation of Revenue [Line Items]
Revenue	1,337		2,246	2,159	2,067
Transferred over Time | Space and Airborne Systems | Subcontractor
Disaggregation of Revenue [Line Items]
Revenue	$ 1,023		$ 1,469	$ 1,145	$ 1,089