Significant Accounting Policies - Schedule of Effect of Adoption of ASU 606 on Cash Flow (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 24, 2018	Mar. 25, 2018	Dec. 31, 2017	Sep. 24, 2017	Jun. 25, 2017	Mar. 26, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities
Net earnings	$ 1,253	$ 1,473	$ 1,163	$ 1,157	$ (744)	$ 963	$ 955	$ 789	$ 5,046	$ 1,963	$ 5,173
Adjustments to reconcile net earnings to net cash provided by operating activities
Depreciation and amortization									1,161	1,195	1,215
Stock-based compensation									173	158	149
Deferred income taxes									(244)	3,448	(193)
Severance and restructuring charges									96	0	99
Gain on property sale									0	(198)	0
Gain on divestiture of IS&GS business									0	(73)	(1,201)
Gain on step acquisition of AWE									0	0	(104)
Changes in assets and liabilities
Receivables, net									(179)	(902)	598
Contract assets									(1,480)	390	(1,246)
Inventories									(119)	(79)	173
Accounts payable									914	(189)	(188)
Contract liabilities									(537)	353	(163)
Postretirement benefit plans									(3,574)	1,316	1,028
Income taxes									1,077	(1,210)	146
Other, net									804	304	(297)
Net cash provided by operating activities									$ 3,138	6,476	5,189
Historical
Operating activities
Net earnings										2,002	5,302
Adjustments to reconcile net earnings to net cash provided by operating activities
Depreciation and amortization										1,195	1,215
Stock-based compensation										158	149
Deferred income taxes										3,432	(152)
Severance and restructuring charges											99
Gain on property sale										(198)
Gain on divestiture of IS&GS business										(73)	(1,242)
Gain on step acquisition of AWE											(104)
Changes in assets and liabilities
Receivables, net										(401)	(811)
Contract assets										0	0
Inventories										183	(46)
Accounts payable										(189)	(188)
Contract liabilities										(24)	3
Postretirement benefit plans										1,316	1,028
Income taxes										(1,210)	146
Other, net										285	(210)
Net cash provided by operating activities										6,476	5,189
ASC 606 | Adjustments for
Operating activities
Net earnings										(39)	(129)
Adjustments to reconcile net earnings to net cash provided by operating activities
Depreciation and amortization										0	0
Stock-based compensation										0	0
Deferred income taxes										16	(41)
Severance and restructuring charges											0
Gain on property sale										0
Gain on divestiture of IS&GS business										0	41
Gain on step acquisition of AWE											0
Changes in assets and liabilities
Receivables, net										(501)	1,409
Contract assets										390	(1,246)
Inventories										(262)	219
Accounts payable										0	0
Contract liabilities										377	(166)
Postretirement benefit plans										0	0
Income taxes										0	0
Other, net										19	(87)
Net cash provided by operating activities										$ 0	$ 0