Segment Information (Unaudited) (Details 4) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue, Geographic Location [Line Items]
Sales	$ 8,085	$ 6,569	$ 21,939	$ 19,452
Concentration Risk, Percentage	100.00%	100.00%	100.00%	100.00%
United States
Revenue, Geographic Location [Line Items]
Sales	$ 6,981	$ 5,703	$ 18,845	$ 16,923
Concentration Risk, Percentage	86.00%	87.00%	86.00%	87.00%
United States | Aerospace Systems [Member]
Revenue, Geographic Location [Line Items]
Sales	$ 2,970	$ 2,760	$ 8,757	$ 8,007
Concentration Risk, Percentage	92.00%	90.00%	90.00%	90.00%
United States | Innovation Systems [Member]
Revenue, Geographic Location [Line Items]
Sales	$ 1,105	$ 0	$ 1,401	$ 0
Concentration Risk, Percentage	80.00%	0.00%	79.00%	0.00%
United States | Mission Systems [Member]
Revenue, Geographic Location [Line Items]
Sales	$ 2,253	$ 2,220	$ 6,666	$ 6,688
Concentration Risk, Percentage	86.00%	85.00%	85.00%	86.00%
United States | Technology Services [Member]
Revenue, Geographic Location [Line Items]
Sales	$ 653	$ 723	$ 2,021	$ 2,228
Concentration Risk, Percentage	78.00%	79.00%	77.00%	80.00%
Asia/Pacific
Revenue, Geographic Location [Line Items]
Sales	$ 446	$ 344	$ 1,229	$ 1,072
Concentration Risk, Percentage	6.00%	5.00%	6.00%	6.00%
Asia/Pacific | Aerospace Systems [Member]
Revenue, Geographic Location [Line Items]
Sales	$ 121	$ 155	$ 499	$ 500
Concentration Risk, Percentage	4.00%	5.00%	5.00%	6.00%
Asia/Pacific | Innovation Systems [Member]
Revenue, Geographic Location [Line Items]
Sales	$ 72	$ 0	$ 96	$ 0
Concentration Risk, Percentage	5.00%	0.00%	6.00%	0.00%
Asia/Pacific | Mission Systems [Member]
Revenue, Geographic Location [Line Items]
Sales	$ 208	$ 161	$ 521	$ 470
Concentration Risk, Percentage	8.00%	6.00%	7.00%	6.00%
Asia/Pacific | Technology Services [Member]
Revenue, Geographic Location [Line Items]
Sales	$ 45	$ 28	$ 113	$ 102
Concentration Risk, Percentage	5.00%	3.00%	4.00%	4.00%
All other
Revenue, Geographic Location [Line Items]
Sales	$ 658	$ 522	$ 1,865	$ 1,457
Concentration Risk, Percentage	8.00%	8.00%	8.00%	7.00%
All other | Aerospace Systems [Member]
Revenue, Geographic Location [Line Items]
Sales	$ 149	$ 140	$ 491	$ 376
Concentration Risk, Percentage	4.00%	5.00%	5.00%	4.00%
All other | Innovation Systems [Member]
Revenue, Geographic Location [Line Items]
Sales	$ 201	$ 0	$ 268	$ 0
Concentration Risk, Percentage	15.00%	0.00%	15.00%	0.00%
All other | Mission Systems [Member]
Revenue, Geographic Location [Line Items]
Sales	$ 170	$ 222	$ 623	$ 619
Concentration Risk, Percentage	6.00%	9.00%	8.00%	8.00%
All other | Technology Services [Member]
Revenue, Geographic Location [Line Items]
Sales	$ 138	$ 160	$ 483	$ 462
Concentration Risk, Percentage	17.00%	18.00%	19.00%	16.00%
Intersegment Eliminations [Member] | Aerospace Systems [Member]
Revenue, Geographic Location [Line Items]
Sales	$ 42	$ 70	$ 152	$ 229
Intersegment Eliminations [Member] | Innovation Systems [Member]
Revenue, Geographic Location [Line Items]
Sales	37	0	50	0
Intersegment Eliminations [Member] | Mission Systems [Member]
Revenue, Geographic Location [Line Items]
Sales	280	233	858	718
Intersegment Eliminations [Member] | Technology Services [Member]
Revenue, Geographic Location [Line Items]
Sales	204	272	615	743
Operating Segments [Member] | Aerospace Systems [Member]
Revenue, Geographic Location [Line Items]
Sales	$ 3,282	$ 3,125	$ 9,899	$ 9,112
Concentration Risk, Percentage	100.00%	100.00%	100.00%	100.00%
Operating Segments [Member] | Innovation Systems [Member]
Revenue, Geographic Location [Line Items]
Sales	$ 1,415	$ 0	$ 1,815	$ 0
Concentration Risk, Percentage	100.00%	0.00%	100.00%	0.00%
Operating Segments [Member] | Mission Systems [Member]
Revenue, Geographic Location [Line Items]
Sales	$ 2,911	$ 2,836	$ 8,668	$ 8,495
Concentration Risk, Percentage	100.00%	100.00%	100.00%	100.00%
Operating Segments [Member] | Technology Services [Member]
Revenue, Geographic Location [Line Items]
Sales	$ 1,040	$ 1,183	$ 3,232	$ 3,535
Concentration Risk, Percentage	100.00%	100.00%	100.00%	100.00%