Subsequent Events (Details) - USD ($) shares in Millions, $ in Millions	Jan. 26, 2016	Jan. 01, 2016	Jan. 30, 2015	Jan. 02, 2015	Jan. 31, 2014
Subsequent Event [Line Items]
Accrued dividends declared		$ 2.0	$ 0.0	$ 25.0	$ 0.0
Lockheed Martin Merger | Subsequent Event
Subsequent Event [Line Items]
Number of shares Lockheed Martin shareholders will receive from Leidos, as a percentage of Leidos common stock (in percentage)	50.50%
Percentage of common stock retained by the Leidos ( in percentage)	49.50%
Termination fees	$ 150.0
Reimbursement of expense, if termination of merger is due to rejection from shareholders'	37.5
Lockheed Martin Merger | Scenario, Forecast | Subsequent Event
Subsequent Event [Line Items]
Accrued dividends declared	1,030.0
Spinco | Lockheed Martin Merger | Scenario, Forecast | Subsequent Event
Subsequent Event [Line Items]
Debt financing	1,800.0
Payments to Parent, Special Payment	$ 1,800.0
Lockheed Martin Shareholders' | Lockheed Martin Merger | Subsequent Event
Subsequent Event [Line Items]
Number of shares Lockheed Martin shareholders will receive from Leidos	77