Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Revenues	$ 3,648	$ 3,234	$ 2,826
Intersegment sales
Disaggregation of Revenue [Line Items]
Revenues	(14)	(22)	(26)
ASC \| Prime contractor
Disaggregation of Revenue [Line Items]
Revenues	1,056	925	858
ASC \| Subcontractor
Disaggregation of Revenue [Line Items]
Revenues	1,287	1,172	948
ASC \| Firm-fixed price
Disaggregation of Revenue [Line Items]
Revenues	2,056	1,762	1,522
ASC \| Flexibly Priced
Disaggregation of Revenue [Line Items]
Revenues	287	335	284
ASC \| Intersegment sales
Disaggregation of Revenue [Line Items]
Revenues	(12)	(21)	(25)
ASC \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	2,355	2,118	1,831
IMS \| Prime contractor
Disaggregation of Revenue [Line Items]
Revenues	351	259	252
IMS \| Subcontractor
Disaggregation of Revenue [Line Items]
Revenues	954	878	768
IMS \| Firm-fixed price
Disaggregation of Revenue [Line Items]
Revenues	1,149	948	851
IMS \| Flexibly Priced
Disaggregation of Revenue [Line Items]
Revenues	156	189	169
IMS \| Intersegment sales
Disaggregation of Revenue [Line Items]
Revenues	(2)	(1)	(1)
IMS \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	1,307	1,138	1,021
United States \| ASC
Disaggregation of Revenue [Line Items]
Revenues	2,018	1,685	1,537
United States \| IMS
Disaggregation of Revenue [Line Items]
Revenues	1,326	1,117	1,006
International \| ASC
Disaggregation of Revenue [Line Items]
Revenues	325	412	269
International \| IMS
Disaggregation of Revenue [Line Items]
Revenues	$ (21)	$ 20	$ 14