BUSINESS SEGMENT INFORMATION - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 27, 2024	Sep. 29, 2023	Sep. 27, 2024	Sep. 29, 2023
Disaggregation of Revenue [Line Items]
Revenue	$ 5,292	$ 4,915	$ 15,802	$ 14,079
Intersegment
Disaggregation of Revenue [Line Items]
Revenue	(40)	(49)	(149)	(142)
SAS | United States
Disaggregation of Revenue [Line Items]
Revenue	1,484	1,478	4,479	4,407
SAS | International
Disaggregation of Revenue [Line Items]
Revenue	187	195	622	613
SAS | Fixed-price
Disaggregation of Revenue [Line Items]
Revenue	1,012	1,039	3,192	3,160
SAS | Cost-reimbursable
Disaggregation of Revenue [Line Items]
Revenue	659	634	1,909	1,860
SAS | Operating segments
Disaggregation of Revenue [Line Items]
Revenue	1,683	1,686	5,141	5,056
SAS | Intersegment
Disaggregation of Revenue [Line Items]
Revenue	(12)	(13)	(40)	(36)
IMS | United States
Disaggregation of Revenue [Line Items]
Revenue	1,217	1,141	3,683	3,679
IMS | International
Disaggregation of Revenue [Line Items]
Revenue	443	406	1,330	1,258
IMS | Fixed-price
Disaggregation of Revenue [Line Items]
Revenue	1,258	1,164	3,876	3,767
IMS | Cost-reimbursable
Disaggregation of Revenue [Line Items]
Revenue	402	383	1,137	1,170
IMS | Operating segments
Disaggregation of Revenue [Line Items]
Revenue	1,671	1,568	5,069	5,003
IMS | Intersegment
Disaggregation of Revenue [Line Items]
Revenue	(11)	(21)	(56)	(66)
CS | United States
Disaggregation of Revenue [Line Items]
Revenue	975	874	2,786	2,499
CS | International
Disaggregation of Revenue [Line Items]
Revenue	390	366	1,183	1,168
CS | Fixed-price
Disaggregation of Revenue [Line Items]
Revenue	1,146	1,047	3,329	3,127
CS | Cost-reimbursable
Disaggregation of Revenue [Line Items]
Revenue	219	193	640	540
CS | Operating segments
Disaggregation of Revenue [Line Items]
Revenue	1,382	1,255	4,022	3,707
CS | Intersegment
Disaggregation of Revenue [Line Items]
Revenue	(17)	(15)	(53)	(40)
AR | United States
Disaggregation of Revenue [Line Items]
Revenue	584	443	1,682	443
AR | International
Disaggregation of Revenue [Line Items]
Revenue	12	12	37	12
AR | Fixed-price
Disaggregation of Revenue [Line Items]
Revenue	361	272	1,007	272
AR | Cost-reimbursable
Disaggregation of Revenue [Line Items]
Revenue	235	183	712	183
AR | Operating segments
Disaggregation of Revenue [Line Items]
Revenue	596	455	1,719	455
AR | Intersegment
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Prime contractor | SAS
Disaggregation of Revenue [Line Items]
Revenue	1,008	1,081	3,192	3,175
Prime contractor | IMS
Disaggregation of Revenue [Line Items]
Revenue	1,051	962	3,214	3,243
Prime contractor | CS
Disaggregation of Revenue [Line Items]
Revenue	977	866	2,805	2,471
Prime contractor | AR
Disaggregation of Revenue [Line Items]
Revenue	149	113	457	113
Subcontractor | SAS
Disaggregation of Revenue [Line Items]
Revenue	663	592	1,909	1,845
Subcontractor | IMS
Disaggregation of Revenue [Line Items]
Revenue	609	585	1,799	1,694
Subcontractor | CS
Disaggregation of Revenue [Line Items]
Revenue	388	374	1,164	1,196
Subcontractor | AR
Disaggregation of Revenue [Line Items]
Revenue	$ 447	$ 342	$ 1,262	$ 342