Consolidated Statements of Earnings and Comprehensive Income - USD ($) shares in Millions, $ 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
Revenues	$ 8,156	$ 8,085	$ 7,119	$ 6,735	$ 6,552	$ 6,569	$ 6,473	$ 6,410	$ 30,095	$ 26,004	$ 24,706
Operating costs and expenses
General and administrative expenses									3,011	2,712	2,632
Operating income	943	1,172	817	848	672	829	864	853	3,780	3,218	3,277
Other (expense) income
Interest expense									(562)	(360)	(301)
Net FAS (non-service) pension benefit									1,049	699	611
Mark-to-market pension and OPB (expense) benefit									(655)	536	(950)
Other, net									130	136	44
Earnings before income taxes									3,742	4,229	2,681
Federal and foreign income tax expense									513	1,360	638
Net earnings	$ 356	$ 1,244	$ 789	$ 840	$ 672	$ 750	$ 677	$ 770	$ 3,229	$ 2,869	$ 2,043
Basic earnings per share
Basic earnings per share	$ 2.07	$ 7.15	$ 4.52	$ 4.82	$ 3.86	$ 4.31	$ 3.88	$ 4.41	$ 18.59	$ 16.45	$ 11.42
Weighted-average common shares outstanding, in millions	171.8	174.1	174.5	174.3	174.2	174.2	174.5	174.8	173.7	174.4	178.9
Diluted earnings per share
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
Weighted-average diluted shares outstanding, in millions	172.6	174.9	175.4	175.4	175.5	175.3	175.5	176.1	174.6	175.6	180.5
Net earnings (from above)	$ 356	$ 1,244	$ 789	$ 840	$ 672	$ 750	$ 677	$ 770	$ 3,229	$ 2,869	$ 2,043
Other comprehensive loss
Change in unamortized prior service credit, net of tax expense of $19 in 2018, $35 in 2017 and $20 in 2016									(60)	(44)	(62)
Change in cumulative translation adjustment									(8)	(4)	(50)
Other, net									(6)	2	(1)
Other comprehensive loss, net of tax									(74)	(46)	(113)
Comprehensive income									3,155	2,823	1,930
Product [Member]
Cost of Goods and Services Sold									15,785	12,527	11,197
Revenues									20,469	16,364	15,080
Service [Member]
Cost of Goods and Services Sold									7,519	7,547	7,600
Revenues									$ 9,626	$ 9,640	$ 9,626