Summary of Significant Accounting Policies (Additional Information) (Detail)	1 Months Ended	3 Months Ended		6 Months Ended
	Jan. 30, 2015 USD ($)	Jul. 03, 2015 USD ($) $ / shares	Aug. 01, 2014 USD ($) $ / shares	Jul. 03, 2015 USD ($) $ / shares	Aug. 01, 2014 USD ($) $ / shares	Sep. 19, 2013
Significant Accounting Policies [Line Items]
Reverse stock split				0.25
Revenues	$ 373,000,000	$ 1,257,000,000	$ 1,306,000,000	$ 2,503,000,000	$ 2,618,000,000
Net income (loss)	(23,000,000)	64,000,000	(410,000,000)	102,000,000	(323,000,000)
Increase (decrease) in income due to contract estimates		$ 5,000,000	$ 6,000,000	$ 10,000,000	$ 18,000,000
Increase (decrease) in income due to contract estimates per diluted share | $ / shares		$ 0.04	$ 0.06	$ 0.08	$ 0.15
Total adjustment to cash flow	16,000,000			$ (94,000,000)	$ (72,000,000)
Cash flow from operating activities	11,000,000			109,000,000	115,000,000
Financing activities	47,000,000			206,000,000	256,000,000
Cash flow from discontinued operations	$ 20,000,000			$ 19,000,000	11,000,000
Leidos, Inc.
Significant Accounting Policies [Line Items]
Ownership interest		100.00%		100.00%
Revenues		$ 1,257,000,000	$ 1,306,000,000	$ 2,503,000,000	2,618,000,000
Net income (loss)		64,000,000	$ (410,000,000)	102,000,000	(323,000,000)
Total adjustment to cash flow				(94,000,000)	(72,000,000)
Cash flow from operating activities				109,000,000	115,000,000
Financing activities				47,000,000	1,000,000
Cash flow from discontinued operations				19,000,000	11,000,000
SAIC
Significant Accounting Policies [Line Items]
Stock issued to Leidos shareholder upon divestiture of SAIC, ratio						1.4285
Facility Closing
Significant Accounting Policies [Line Items]
Restructuring charges, net				2,000,000	$ 1,000,000
Notes payable and long-term debt, net of current portion | Notes Which Mature In December 2020 | Designated as Hedging Instrument | Interest rate swaps
Significant Accounting Policies [Line Items]
Hedged instrument, face amount		$ 450,000,000		$ 450,000,000
Stated interest rate		4.45%		4.45%