Segment Information Intersegment Sales and Operating Income (Details 5) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Sales	$ 10,212	$ 9,083	$ 8,884	$ 8,620	$ 8,721	$ 8,475	$ 8,456	$ 8,189	$ 36,799	$ 33,841	$ 30,095
Intersegment sales and operating income (Table Amounts) [Abstract]
Operating income	$ 1,152	$ 985	$ 994	$ 934	$ 1,136	$ 951	$ 946	$ 936	4,065	3,969	3,780
Intersegment sales
Segment Reporting Information [Line Items]
Sales									1,737	1,605	1,604
Intersegment sales and operating income (Table Amounts) [Abstract]
Operating income									216	205	200
Intersegment sales | Aeronautics Systems
Segment Reporting Information [Line Items]
Sales									122	103	73
Intersegment sales and operating income (Table Amounts) [Abstract]
Operating income									11	10	8
Intersegment sales | Defense Systems
Segment Reporting Information [Line Items]
Sales									728	691	750
Intersegment sales and operating income (Table Amounts) [Abstract]
Operating income									76	74	74
Intersegment sales | Mission Systems
Segment Reporting Information [Line Items]
Sales									779	728	718
Intersegment sales and operating income (Table Amounts) [Abstract]
Operating income									116	113	115
Intersegment sales | Space Systems
Segment Reporting Information [Line Items]
Sales									108	83	63
Intersegment sales and operating income (Table Amounts) [Abstract]
Operating income									$ 13	$ 8	$ 3