Revenues from Contracts with Customers (Disaggregation of Revenue) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Oct. 01, 2021	Sep. 30, 2022	Oct. 01, 2021
Disaggregation of Revenue [Line Items]
Revenues	$ 3,579	$ 3,449	$ 10,624	$ 10,157
United States
Disaggregation of Revenue [Line Items]
Revenues	3,295	3,185	9,761	9,312
International
Disaggregation of Revenue [Line Items]
Revenues	284	264	863	845
Cost-reimbursement and fixed-price-incentive-fee
Disaggregation of Revenue [Line Items]
Revenues	1,808	1,764	5,320	5,164
Firm-fixed-price
Disaggregation of Revenue [Line Items]
Revenues	1,336	1,228	4,002	3,628
Time-and-materials and fixed-price-level-of-effort
Disaggregation of Revenue [Line Items]
Revenues	435	457	1,302	1,365
DoD and U.S. Intelligence Community
Disaggregation of Revenue [Line Items]
Revenues	1,836	1,735	5,414	4,976
Other U.S. government agencies
Disaggregation of Revenue [Line Items]
Revenues	1,284	1,284	3,812	3,865
Commercial and non-U.S. customers
Disaggregation of Revenue [Line Items]
Revenues	459	430	1,398	1,316
Defense Solutions
Disaggregation of Revenue [Line Items]
Revenues	2,075	2,009	6,175	5,969
Defense Solutions \| United States
Disaggregation of Revenue [Line Items]
Revenues	1,830	1,778	5,429	5,237
Defense Solutions \| International
Disaggregation of Revenue [Line Items]
Revenues	245	231	746	732
Defense Solutions \| Cost-reimbursement and fixed-price-incentive-fee
Disaggregation of Revenue [Line Items]
Revenues	1,166	1,230	3,493	3,627
Defense Solutions \| Firm-fixed-price
Disaggregation of Revenue [Line Items]
Revenues	668	540	1,950	1,619
Defense Solutions \| Time-and-materials and fixed-price-level-of-effort
Disaggregation of Revenue [Line Items]
Revenues	241	239	732	723
Defense Solutions \| DoD and U.S. Intelligence Community
Disaggregation of Revenue [Line Items]
Revenues	1,559	1,513	4,620	4,386
Defense Solutions \| Other U.S. government agencies
Disaggregation of Revenue [Line Items]
Revenues	236	215	686	724
Defense Solutions \| Commercial and non-U.S. customers
Disaggregation of Revenue [Line Items]
Revenues	280	281	869	859
Civil
Disaggregation of Revenue [Line Items]
Revenues	849	759	2,457	2,271
Civil \| United States
Disaggregation of Revenue [Line Items]
Revenues	810	726	2,340	2,158
Civil \| International
Disaggregation of Revenue [Line Items]
Revenues	39	33	117	113
Civil \| Cost-reimbursement and fixed-price-incentive-fee
Disaggregation of Revenue [Line Items]
Revenues	442	397	1,293	1,176
Civil \| Firm-fixed-price
Disaggregation of Revenue [Line Items]
Revenues	279	245	792	755
Civil \| Time-and-materials and fixed-price-level-of-effort
Disaggregation of Revenue [Line Items]
Revenues	128	117	372	340
Civil \| DoD and U.S. Intelligence Community
Disaggregation of Revenue [Line Items]
Revenues	22	19	62	45
Civil \| Other U.S. government agencies
Disaggregation of Revenue [Line Items]
Revenues	676	619	1,949	1,849
Civil \| Commercial and non-U.S. customers
Disaggregation of Revenue [Line Items]
Revenues	151	121	446	377
Health
Disaggregation of Revenue [Line Items]
Revenues	655	681	1,992	1,917
Health \| United States
Disaggregation of Revenue [Line Items]
Revenues	655	681	1,992	1,917
Health \| International
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Health \| Cost-reimbursement and fixed-price-incentive-fee
Disaggregation of Revenue [Line Items]
Revenues	200	137	534	361
Health \| Firm-fixed-price
Disaggregation of Revenue [Line Items]
Revenues	389	443	1,260	1,254
Health \| Time-and-materials and fixed-price-level-of-effort
Disaggregation of Revenue [Line Items]
Revenues	66	101	198	302
Health \| DoD and U.S. Intelligence Community
Disaggregation of Revenue [Line Items]
Revenues	255	203	732	545
Health \| Other U.S. government agencies
Disaggregation of Revenue [Line Items]
Revenues	372	450	1,177	1,292
Health \| Commercial and non-U.S. customers
Disaggregation of Revenue [Line Items]
Revenues	$ 28	$ 28	$ 83	$ 80