Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Disaggregation of Revenue [Line Items]
Total revenues	$ 812	$ 703	$ 2,253	$ 1,900
Intersegment Sales
Disaggregation of Revenue [Line Items]
Total revenues	(6)	(5)	(17)	(18)
ASC | Firm-Fixed Price
Disaggregation of Revenue [Line Items]
Total revenues	446	356	1,198	1,015
ASC | Flexibly Priced
Disaggregation of Revenue [Line Items]
Total revenues	81	70	243	193
ASC | Prime contractor
Disaggregation of Revenue [Line Items]
Total revenues	200	227	616	570
ASC | Subcontractor
Disaggregation of Revenue [Line Items]
Total revenues	327	199	825	638
ASC | Intersegment Sales
Disaggregation of Revenue [Line Items]
Total revenues	(6)	(5)	(17)	(18)
ASC | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	533	431	1,458	1,226
ASC | United States
Disaggregation of Revenue [Line Items]
Total revenues	426	376	1,159	1,046
ASC | International
Disaggregation of Revenue [Line Items]
Total revenues	101	50	282	162
IMS | Firm-Fixed Price
Disaggregation of Revenue [Line Items]
Total revenues	238	234	670	572
IMS | Flexibly Priced
Disaggregation of Revenue [Line Items]
Total revenues	47	43	142	120
IMS | Prime contractor
Disaggregation of Revenue [Line Items]
Total revenues	58	62	182	156
IMS | Subcontractor
Disaggregation of Revenue [Line Items]
Total revenues	227	215	630	536
IMS | Intersegment Sales
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
IMS | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	285	277	812	692
IMS | United States
Disaggregation of Revenue [Line Items]
Total revenues	277	272	796	680
IMS | International
Disaggregation of Revenue [Line Items]
Total revenues	$ 8	$ 5	$ 16	$ 12