Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Disaggregation of Revenue [Line Items]
Revenues	$ 829	$ 753	$ 1,628	$ 1,441
Intersegment Sales
Disaggregation of Revenue [Line Items]
Revenues	(3)	(5)	(6)	(11)
ASC | Firm-Fixed Price
Disaggregation of Revenue [Line Items]
Revenues	468	402	905	752
ASC | Flexibly Priced
Disaggregation of Revenue [Line Items]
Revenues	71	85	142	162
ASC | Prime contractor
Disaggregation of Revenue [Line Items]
Revenues	238	253	462	416
ASC | Subcontractor
Disaggregation of Revenue [Line Items]
Revenues	301	234	585	498
ASC | Intersegment Sales
Disaggregation of Revenue [Line Items]
Revenues	(3)	(5)	(6)	(11)
ASC | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	542	492	1,053	925
ASC | United States
Disaggregation of Revenue [Line Items]
Revenues	465	396	911	733
ASC | International
Disaggregation of Revenue [Line Items]
Revenues	74	91	136	181
IMS | Firm-Fixed Price
Disaggregation of Revenue [Line Items]
Revenues	242	214	496	432
IMS | Flexibly Priced
Disaggregation of Revenue [Line Items]
Revenues	48	52	85	95
IMS | Prime contractor
Disaggregation of Revenue [Line Items]
Revenues	54	59	100	124
IMS | Subcontractor
Disaggregation of Revenue [Line Items]
Revenues	236	207	481	403
IMS | Intersegment Sales
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
IMS | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	290	266	581	527
IMS | United States
Disaggregation of Revenue [Line Items]
Revenues	296	262	590	519
IMS | International
Disaggregation of Revenue [Line Items]
Revenues	$ (6)	$ 4	$ (9)	$ 8