Acquisition and Divestitures - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions			3 Months Ended			6 Months Ended
	Jan. 26, 2016	Nov. 06, 2015	Jun. 26, 2016	Dec. 31, 2015	Jun. 28, 2015	Jun. 26, 2016	Jun. 28, 2015
Acquisitions And Divestitures [Line Items]
Goodwill			$ 13,621	$ 13,576		$ 13,621
Amortization of intangible assets			70		$ 20	$ 139	$ 41
Special dividend per share to be paid to Leidos stockholders						$ 13.64
Leidos
Acquisitions And Divestitures [Line Items]
Outstanding equity to be received by stockholders, percentage	50.50%
Conversion ratio of Abacus common stock held by Lockheed Martin stockholders upon completing the merger	1
Outstanding equity to be received by stockholders, shares	77
Outstanding equity to be held by Leidos stockholders, percentage	49.50%
One-time special cash receipt	$ 1,800
Sikorsky Aircraft Corporation
Acquisitions And Divestitures [Line Items]
Acquisitions of businesses and investments in affiliates		$ 9,000
Cash on hand		2,000
Proceeds from Issuance of Commercial Paper		$ 1,000
Repayment of commercial paper				1,000
Inventories			(10)			$ (60)
Deferred income tax assets			(30)			(20)
Customer advances and amounts in excess of costs incurred						10
Goodwill			45			45
Intangible assets weighted-average useful life		15 years
Customer contractual obligations		$ 480
Customer contractual obligations remaining in 2016			40			40
Customer contractual obligations due in 2017			90			90
Customer contractual obligations due in 2018			70			70
Customer contractual obligations due in 2019			70			70
Customer contractual obligations due in 2020			70			70
Customer contractual obligations due in 2021			50			50
Customer contractual obligations due after 2021			40			40
Sales related to customer contractual obligations, to date			50			50
Goodwill		2,807
Sikorsky Aircraft Corporation | Three Hundred And Sixty Four Day Revolving Credit Facility And Five Year Revolving Credit Facility
Acquisitions And Divestitures [Line Items]
Proceeds from borrowings under revolving credit facilities		$ 6,000
Sikorsky Aircraft Corporation | November 2015 Notes
Acquisitions And Divestitures [Line Items]
Proceeds from issuance of fixed interest-rate long-term notes				$ 7,000
Sikorsky Aircraft Corporation | Pro Forma Adjustment
Acquisitions And Divestitures [Line Items]
Amortization of intangible assets			40				80
Interest expense, debt			$ 45				$ 90
Sikorsky Aircraft Corporation | Customer Programs
Acquisitions And Divestitures [Line Items]
Intangible assets						(30)
Sikorsky Aircraft Corporation | Trademarks
Acquisitions And Divestitures [Line Items]
Intangible assets						$ 70