BUSINESS SEGMENTS - Disaggregation of Revenue (Details) $ in Millions	12 Months Ended
	Jan. 03, 2025 USD ($) segment	Dec. 29, 2023 USD ($)	Dec. 30, 2022 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment	4
Number of reportable segments | segment	4
Disaggregation of Revenue [Line Items]
Revenue	$ 21,325	$ 19,419	$ 17,062
United States
Disaggregation of Revenue [Line Items]
Revenue	19,614	17,537	15,373
International
Disaggregation of Revenue [Line Items]
Revenue	1,711	1,882	1,689
Other
Disaggregation of Revenue [Line Items]
Revenue	(192)	(189)	(165)
SAS | United States
Disaggregation of Revenue [Line Items]
Revenue	5,971	5,933	5,623
SAS | International
Disaggregation of Revenue [Line Items]
Revenue	847	874	712
SAS | Fixed-price
Disaggregation of Revenue [Line Items]
Revenue	4,293	4,257	3,811
SAS | Cost-reimbursable
Disaggregation of Revenue [Line Items]
Revenue	2,525	2,550	2,524
SAS | Prime contractor
Disaggregation of Revenue [Line Items]
Revenue	4,307	4,252	4,005
SAS | Subcontractor
Disaggregation of Revenue [Line Items]
Revenue	2,511	2,555	2,330
SAS | Other
Disaggregation of Revenue [Line Items]
Revenue	51	49	49
SAS | Operating segments
Disaggregation of Revenue [Line Items]
Revenue	6,869	6,856	6,384
IMS | United States
Disaggregation of Revenue [Line Items]
Revenue	4,926	4,816	4,796
IMS | International
Disaggregation of Revenue [Line Items]
Revenue	1,844	1,727	1,759
IMS | Fixed-price
Disaggregation of Revenue [Line Items]
Revenue	5,378	5,020	5,060
IMS | Cost-reimbursable
Disaggregation of Revenue [Line Items]
Revenue	1,392	1,523	1,495
IMS | Prime contractor
Disaggregation of Revenue [Line Items]
Revenue	4,341	4,196	4,301
IMS | Subcontractor
Disaggregation of Revenue [Line Items]
Revenue	2,429	2,347	2,254
IMS | Other
Disaggregation of Revenue [Line Items]
Revenue	72	87	71
IMS | Operating segments
Disaggregation of Revenue [Line Items]
Revenue	6,842	6,630	6,626
CS | United States
Disaggregation of Revenue [Line Items]
Revenue	3,741	3,482	2,735
CS | International
Disaggregation of Revenue [Line Items]
Revenue	1,649	1,535	1,437
CS | Fixed-price
Disaggregation of Revenue [Line Items]
Revenue	4,566	4,289	3,552
CS | Cost-reimbursable
Disaggregation of Revenue [Line Items]
Revenue	824	728	620
CS | Prime contractor
Disaggregation of Revenue [Line Items]
Revenue	3,801	3,420	2,829
CS | Subcontractor
Disaggregation of Revenue [Line Items]
Revenue	1,589	1,597	1,343
CS | Other
Disaggregation of Revenue [Line Items]
Revenue	69	53	45
CS | Operating segments
Disaggregation of Revenue [Line Items]
Revenue	5,459	5,070	4,217
AR | United States
Disaggregation of Revenue [Line Items]
Revenue	2,299	1,015
AR | International
Disaggregation of Revenue [Line Items]
Revenue	48	37
AR | Fixed-price
Disaggregation of Revenue [Line Items]
Revenue	1,389	632
AR | Cost-reimbursable
Disaggregation of Revenue [Line Items]
Revenue	958	420
AR | Prime contractor
Disaggregation of Revenue [Line Items]
Revenue	602	250
AR | Subcontractor
Disaggregation of Revenue [Line Items]
Revenue	1,745	802
AR | Other
Disaggregation of Revenue [Line Items]
Revenue	0	0
AR | Operating segments
Disaggregation of Revenue [Line Items]
Revenue	$ 2,347	$ 1,052	$ 0