Business Acquisition (Unaudited) (Details 4) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Business Acquisition [Line Items]
Sales	$ 8,085	$ 6,569	$ 21,939	$ 19,452
Pro forma sales	7,744		24,163	22,783
Pro forma net earnings	$ 655		$ 2,749	$ 1,868
Pro forma basic earnings per share	$ 3.76		$ 15.77	$ 10.70
Pro forma diluted earnings per share	$ 3.74		$ 15.69	$ 10.64
Pro Forma Adjustments, Orbital ATK ASC606 Sales adjustment		2		$ 23
Pro Forma Adjustments, Orbital ATK ASC606 Cost of Sales adjustment		(9)		(18)
Pro Forma Adjustments, Orbital ATK intercompany sales elimination		(43)	$ (80)	(108)
Pro Forma Adjustments, Orbital ATK intercompany cost of sales elimination		43	80	108
Pro Forma Adjustments, Elimination of nonrecurring transaction costs			71
Pro Forma Adjustments, Additional depreciation expense, net of removal of historical depreciation		(7)	(10)	(21)
Pro Forma Adjustments, Additional interest expense due to debt issued to finance merger		(66)		(199)
Pro Forma Adjustments, Additional amortization expense, net of removal of historical amortization expense		(73)	(101)	(217)
Pro Forma Adjustments, Elimination of Orbital ATK’s amortization on net actuarial losses and prior service costs and pension/post-retirement costs		27	51	81
Income Tax Effects of Pro Forma Adjustments		$ 42	$ (2)	$ 124