BUSINESS SEGMENT INFORMATION - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 28, 2025	Mar. 29, 2024
Disaggregation of Revenue [Line Items]
Revenue	$ 5,132	$ 5,211
CS | United States
Disaggregation of Revenue [Line Items]
Revenue	844	925
CS | International
Disaggregation of Revenue [Line Items]
Revenue	496	355
CS | Fixed-price
Disaggregation of Revenue [Line Items]
Revenue	1,161	1,065
CS | Cost-reimbursable
Disaggregation of Revenue [Line Items]
Revenue	179	215
CS | Operating segments
Disaggregation of Revenue [Line Items]
Revenue	1,352	1,294
CS | Intersegment
Disaggregation of Revenue [Line Items]
Revenue	(12)	(14)
IMS | United States
Disaggregation of Revenue [Line Items]
Revenue	1,147	1,166
IMS | International
Disaggregation of Revenue [Line Items]
Revenue	432	450
IMS | Fixed-price
Disaggregation of Revenue [Line Items]
Revenue	1,255	1,245
IMS | Cost-reimbursable
Disaggregation of Revenue [Line Items]
Revenue	324	371
IMS | Operating segments
Disaggregation of Revenue [Line Items]
Revenue	1,592	1,627
IMS | Intersegment
Disaggregation of Revenue [Line Items]
Revenue	(13)	(11)
SAS | United States
Disaggregation of Revenue [Line Items]
Revenue	1,376	1,507
SAS | International
Disaggregation of Revenue [Line Items]
Revenue	218	229
SAS | Fixed-price
Disaggregation of Revenue [Line Items]
Revenue	994	1,108
SAS | Cost-reimbursable
Disaggregation of Revenue [Line Items]
Revenue	600	628
SAS | Operating segments
Disaggregation of Revenue [Line Items]
Revenue	1,611	1,751
SAS | Intersegment
Disaggregation of Revenue [Line Items]
Revenue	(17)	(15)
AR | United States
Disaggregation of Revenue [Line Items]
Revenue	609	564
AR | International
Disaggregation of Revenue [Line Items]
Revenue	10	15
AR | Fixed-price
Disaggregation of Revenue [Line Items]
Revenue	392	335
AR | Cost-reimbursable
Disaggregation of Revenue [Line Items]
Revenue	227	244
AR | Operating segments
Disaggregation of Revenue [Line Items]
Revenue	629	584
AR | Intersegment
Disaggregation of Revenue [Line Items]
Revenue	(10)	(5)
Prime contractor | CS
Disaggregation of Revenue [Line Items]
Revenue	995	913
Prime contractor | IMS
Disaggregation of Revenue [Line Items]
Revenue	1,049	1,056
Prime contractor | SAS
Disaggregation of Revenue [Line Items]
Revenue	1,008	1,108
Prime contractor | AR
Disaggregation of Revenue [Line Items]
Revenue	139	163
Subcontractor | CS
Disaggregation of Revenue [Line Items]
Revenue	345	367
Subcontractor | IMS
Disaggregation of Revenue [Line Items]
Revenue	530	560
Subcontractor | SAS
Disaggregation of Revenue [Line Items]
Revenue	586	628
Subcontractor | AR
Disaggregation of Revenue [Line Items]
Revenue	$ 480	$ 416