Summary of Significant Accounting Policies (Details 4) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Change in Accounting Estimate [Line Items]
Contract with Customer, Performance Obligation Satisfied in Previous Period									$ 631	$ 374	$ 463
Operating income	$ 943	$ 1,172	$ 817	$ 848	$ 672	$ 829	$ 864	$ 853	3,780	3,218	3,277
Net earnings	$ 356	$ 1,244	$ 789	$ 840	$ 672	$ 750	$ 677	$ 770	$ 3,229	$ 2,869	$ 2,043
Diluted earnings per share	$ 2.06	$ 7.11	$ 4.50	$ 4.79	$ 3.83	$ 4.28	$ 3.86	$ 4.37	$ 18.49	$ 16.34	$ 11.32
Contracts Accounted for under Percentage of Completion [Member]
Change in Accounting Estimate [Line Items]
Operating income									$ 577	$ 360	$ 443
Net earnings									$ 456	$ 234	$ 288
Diluted earnings per share									$ 2.61	$ 1.33	$ 1.60
Aerospace Systems [Member] | Contracts Accounted for under Percentage of Completion [Member]
Change in Accounting Estimate [Line Items]
Operating income			$ 69			$ 56