Segment Information (Details 2) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Intersegment sales and operating income (Table Amounts) [Abstract]
Total sales	$ 6,634	$ 6,527	$ 6,375	$ 6,267	$ 6,397	$ 6,155	$ 6,000	$ 5,956	$ 25,803	$ 24,508	$ 23,526
Operating income	$ 767	$ 845	$ 855	$ 832	$ 831	$ 826	$ 797	$ 739	3,299	3,193	3,076
Intersegment Eliminations [Member]
Intersegment sales and operating income (Table Amounts) [Abstract]
Total sales									2,284	2,073	1,907
Operating income									277	258	209
Intersegment Eliminations [Member] | Aerospace Systems
Intersegment sales and operating income (Table Amounts) [Abstract]
Total sales									295	239	221
Operating income									33	28	27
Intersegment Eliminations [Member] | Mission Systems
Intersegment sales and operating income (Table Amounts) [Abstract]
Total sales									954	875	781
Operating income									141	136	97
Intersegment Eliminations [Member] | Technology Services
Intersegment sales and operating income (Table Amounts) [Abstract]
Total sales									1,035	959	905
Operating income									$ 103	$ 94	$ 85