Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Revenue [Line Items]
Total revenues	$ 612	$ 681
Intersegment Sales
Disaggregation of Revenue [Line Items]
Total revenues	(2)	(3)
ASC | Prime contractor
Disaggregation of Revenue [Line Items]
Total revenues	232	277
ASC | Subcontractor
Disaggregation of Revenue [Line Items]
Total revenues	162	203
ASC | Firm Fixed Price
Disaggregation of Revenue [Line Items]
Total revenues	342	426
ASC | Flexibly Priced
Disaggregation of Revenue [Line Items]
Total revenues	52	54
ASC | Intersegment Sales
Disaggregation of Revenue [Line Items]
Total revenues	2	3
ASC | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	396	483
IMS | Prime contractor
Disaggregation of Revenue [Line Items]
Total revenues	33	44
IMS | Subcontractor
Disaggregation of Revenue [Line Items]
Total revenues	185	157
IMS | Firm Fixed Price
Disaggregation of Revenue [Line Items]
Total revenues	193	170
IMS | Flexibly Priced
Disaggregation of Revenue [Line Items]
Total revenues	25	31
IMS | Intersegment Sales
Disaggregation of Revenue [Line Items]
Total revenues	0	0
IMS | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	218	201
United States | ASC
Disaggregation of Revenue [Line Items]
Total revenues	372	445
United States | IMS
Disaggregation of Revenue [Line Items]
Total revenues	212	189
International | ASC
Disaggregation of Revenue [Line Items]
Total revenues	22	35
International | IMS
Disaggregation of Revenue [Line Items]
Total revenues	$ 6	$ 12