Segment Information - Revenues, Operating Income (Loss) and Assets by Reportable Segments (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 27, 2015	Sep. 27, 2015	Jun. 28, 2015	Mar. 29, 2015	Dec. 28, 2014	Sep. 28, 2014	Jun. 29, 2014	Mar. 30, 2014	Dec. 27, 2015	Dec. 28, 2014	Dec. 29, 2013
Segment Reporting Information [Line Items]
Service revenues									$ 354.2	$ 390.8	$ 443.6
Product sales									302.9	372.2	400.5
Revenues									657.1	763.0	844.1
Depreciation and amortization									25.5	32.4	46.4
Total operating income (loss) from continuing operations	$ 1.5	$ 1.6	$ (3.7)	$ (3.9)	$ 5.6	$ (3.0)	$ 2.3	$ 0.4	(4.5)	5.3	18.2
Assets	903.3				1,131.2				903.3	1,131.2
Corporate activities
Segment Reporting Information [Line Items]
Total operating income (loss) from continuing operations									(7.0)	(4.4)	(2.9)
Assets	37.7				55.2				37.7	55.2
Discontinued operations
Segment Reporting Information [Line Items]
Assets	0.0				190.8				0.0	190.8
Unmanned Systems
Segment Reporting Information [Line Items]
Assets	162.0				166.1				162.0	166.1
Unmanned Systems | Operating Segments
Segment Reporting Information [Line Items]
Service revenues									0.0	0.0	0.0
Product sales									66.3	81.5	121.6
Revenues									66.3	81.5	121.6
Depreciation and amortization									6.7	7.3	20.3
Total operating income (loss) from continuing operations									(16.2)	(9.8)	(17.2)
Kratos Government Solutions
Segment Reporting Information [Line Items]
Assets	606.8				618.9				606.8	618.9
Kratos Government Solutions | Operating Segments
Segment Reporting Information [Line Items]
Service revenues									209.5	207.4	233.9
Product sales									236.6	277.7	278.9
Revenues									446.1	485.1	512.8
Depreciation and amortization									18.2	23.1	22.6
Total operating income (loss) from continuing operations									16.1	24.4	30.5
Public Safety & Security
Segment Reporting Information [Line Items]
Assets	$ 96.8				$ 100.2				96.8	100.2
Public Safety & Security | Operating Segments
Segment Reporting Information [Line Items]
Service revenues									144.7	183.4	209.7
Product sales									0.0	13.0	0.0
Revenues									144.7	196.4	209.7
Depreciation and amortization									0.6	2.0	3.5
Total operating income (loss) from continuing operations									$ 2.6	$ (4.9)	$ 7.8