Revenue - Revenue by Contract Type (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Oct. 01, 2017	Sep. 30, 2018	Oct. 01, 2017
Revenue [Line Items]
Revenue	$ 9,094	$ 7,580	$ 25,815	$ 22,696
Aerospace
Revenue [Line Items]
Revenue	2,031	1,995	5,751	6,147
Combat Systems
Revenue [Line Items]
Revenue	1,523	1,500	4,497	4,201
Information Technology
Revenue [Line Items]
Revenue	2,307	1,068	5,887	3,178
Mission Systems
Revenue [Line Items]
Revenue	1,230	1,086	3,475	3,226
Marine Systems
Revenue [Line Items]
Revenue	2,003	1,931	6,205	5,944
Fixed-price
Revenue [Line Items]
Revenue	6,036	5,195	17,384	15,495
Fixed-price | Aerospace
Revenue [Line Items]
Revenue	1,807	1,835	5,171	5,650
Fixed-price | Combat Systems
Revenue [Line Items]
Revenue	1,309	1,258	3,892	3,538
Fixed-price | Information Technology
Revenue [Line Items]
Revenue	941	359	2,387	1,049
Fixed-price | Mission Systems
Revenue [Line Items]
Revenue	695	612	1,973	1,744
Fixed-price | Marine Systems
Revenue [Line Items]
Revenue	1,284	1,131	3,961	3,514
Cost-reimbursement
Revenue [Line Items]
Revenue	2,376	2,019	6,673	6,075
Cost-reimbursement | Aerospace
Revenue [Line Items]
Revenue	0	0	0	0
Cost-reimbursement | Combat Systems
Revenue [Line Items]
Revenue	204	233	580	636
Cost-reimbursement | Information Technology
Revenue [Line Items]
Revenue	955	552	2,462	1,660
Cost-reimbursement | Mission Systems
Revenue [Line Items]
Revenue	499	437	1,390	1,357
Cost-reimbursement | Marine Systems
Revenue [Line Items]
Revenue	718	797	2,241	2,422
Time-and-materials
Revenue [Line Items]
Revenue	682	366	1,758	1,126
Time-and-materials | Aerospace
Revenue [Line Items]
Revenue	224	160	580	497
Time-and-materials | Combat Systems
Revenue [Line Items]
Revenue	10	9	25	27
Time-and-materials | Information Technology
Revenue [Line Items]
Revenue	411	157	1,038	469
Time-and-materials | Mission Systems
Revenue [Line Items]
Revenue	36	37	112	125
Time-and-materials | Marine Systems
Revenue [Line Items]
Revenue	$ 1	$ 3	$ 3	$ 8