BUSINESS SEGMENTS - Disaggregation of Revenue (Details) $ in Millions	3 Months Ended		12 Months Ended
	Jan. 02, 2026 USD ($)	Jan. 03, 2025 USD ($)	Jan. 02, 2026 USD ($) segment	Jan. 03, 2025 USD ($)	Dec. 29, 2023 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment			4
Number of reportable segments | segment			4
Disaggregation of Revenue [Line Items]
Revenue	$ 21,865	$ 21,325		$ 21,325	$ 19,419
Intersegment
Disaggregation of Revenue [Line Items]
Revenue	(229)	(201)			(196)
CS | Prime contractor
Disaggregation of Revenue [Line Items]
Revenue			$ 4,287	3,801	3,420
CS | Subcontractor
Disaggregation of Revenue [Line Items]
Revenue			1,324	1,589	1,597
CS | United States
Disaggregation of Revenue [Line Items]
Revenue			3,609	3,741	3,482
CS | International
Disaggregation of Revenue [Line Items]
Revenue			2,002	1,649	1,535
CS | Fixed-price
Disaggregation of Revenue [Line Items]
Revenue			4,825	4,566	4,289
CS | Cost-type
Disaggregation of Revenue [Line Items]
Revenue			786	824	728
CS | Intersegment
Disaggregation of Revenue [Line Items]
Revenue			(62)	(69)	(53)
CS | Operating segments
Disaggregation of Revenue [Line Items]
Revenue	5,673	5,459	5,673	5,459	5,070
IMS | Prime contractor
Disaggregation of Revenue [Line Items]
Revenue			4,598	4,279	4,152
IMS | Subcontractor
Disaggregation of Revenue [Line Items]
Revenue			1,957	2,286	2,220
IMS | United States
Disaggregation of Revenue [Line Items]
Revenue			4,852	4,721	4,646
IMS | International
Disaggregation of Revenue [Line Items]
Revenue			1,703	1,844	1,726
IMS | Fixed-price
Disaggregation of Revenue [Line Items]
Revenue			5,050	5,199	4,869
IMS | Cost-type
Disaggregation of Revenue [Line Items]
Revenue			1,505	1,366	1,503
IMS | Intersegment
Disaggregation of Revenue [Line Items]
Revenue			(75)	(53)	(74)
IMS | Operating segments
Disaggregation of Revenue [Line Items]
Revenue	6,630	6,618	6,630	6,618	6,446
SAS | Prime contractor
Disaggregation of Revenue [Line Items]
Revenue			4,307	4,307	4,252
SAS | Subcontractor
Disaggregation of Revenue [Line Items]
Revenue			2,575	2,511	2,555
SAS | United States
Disaggregation of Revenue [Line Items]
Revenue			6,045	5,971	5,933
SAS | International
Disaggregation of Revenue [Line Items]
Revenue			837	847	874
SAS | Fixed-price
Disaggregation of Revenue [Line Items]
Revenue			4,619	4,293	4,257
SAS | Cost-type
Disaggregation of Revenue [Line Items]
Revenue			2,263	2,525	2,550
SAS | Intersegment
Disaggregation of Revenue [Line Items]
Revenue			(64)	(51)	(49)
SAS | Operating segments
Disaggregation of Revenue [Line Items]
Revenue	6,946	6,869	6,946	6,869	6,856
AR | Prime contractor
Disaggregation of Revenue [Line Items]
Revenue			650	664	294
AR | Subcontractor
Disaggregation of Revenue [Line Items]
Revenue			2,167	1,888	929
AR | United States
Disaggregation of Revenue [Line Items]
Revenue			2,545	2,504	1,184
AR | International
Disaggregation of Revenue [Line Items]
Revenue			272	48	39
AR | Fixed-price
Disaggregation of Revenue [Line Items]
Revenue			1,850	1,568	783
AR | Cost-type
Disaggregation of Revenue [Line Items]
Revenue			967	984	440
AR | Intersegment
Disaggregation of Revenue [Line Items]
Revenue			(28)	(28)	(20)
AR | Operating segments
Disaggregation of Revenue [Line Items]
Revenue	$ 2,845	$ 2,580	$ 2,845	$ 2,580	$ 1,243