Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Revenue and operating earnings	$ 3,234	$ 2,826	$ 2,693
Intersegment Sales
Disaggregation of Revenue [Line Items]
Revenue and operating earnings	(22)	(26)	(23)
ASC | Prime contractor
Disaggregation of Revenue [Line Items]
Revenue and operating earnings	925	858	918
ASC | Subcontractor
Disaggregation of Revenue [Line Items]
Revenue and operating earnings	1,172	948	794
ASC | Firm-Fixed Price
Disaggregation of Revenue [Line Items]
Revenue and operating earnings	1,762	1,522	1,494
ASC | Flexibly Priced
Disaggregation of Revenue [Line Items]
Revenue and operating earnings	335	284	218
ASC | Intersegment Sales
Disaggregation of Revenue [Line Items]
Revenue and operating earnings	(21)	(25)	(21)
ASC | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue and operating earnings	2,118	1,831	1,733
IMS | Prime contractor
Disaggregation of Revenue [Line Items]
Revenue and operating earnings	259	252	186
IMS | Subcontractor
Disaggregation of Revenue [Line Items]
Revenue and operating earnings	878	768	795
IMS | Firm-Fixed Price
Disaggregation of Revenue [Line Items]
Revenue and operating earnings	948	851	853
IMS | Flexibly Priced
Disaggregation of Revenue [Line Items]
Revenue and operating earnings	189	169	128
IMS | Intersegment Sales
Disaggregation of Revenue [Line Items]
Revenue and operating earnings	(1)	(1)	(2)
IMS | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue and operating earnings	1,138	1,021	983
United States | ASC
Disaggregation of Revenue [Line Items]
Revenue and operating earnings	1,685	1,537	1,543
United States | IMS
Disaggregation of Revenue [Line Items]
Revenue and operating earnings	1,117	1,006	956
International | ASC
Disaggregation of Revenue [Line Items]
Revenue and operating earnings	412	269	169
International | IMS
Disaggregation of Revenue [Line Items]
Revenue and operating earnings	$ 20	$ 14	$ 25