Segment Information - Schedule of Segment Revenues, Depreciation and Amortization, and Operating (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 01, 2017	Sep. 25, 2016	Oct. 01, 2017	Sep. 25, 2016
Revenues:
Service revenues	$ 86.7	$ 87.2	$ 263.3	$ 258.0
Product sales	109.5	78.2	286.4	228.6
Total revenues	196.2	165.4	549.7	486.6
Depreciation & amortization:
Total depreciation and amortization	6.0	5.6	17.0	17.3
Operating income (loss) from continuing operations:
Total operating income (loss) from continuing operations	3.1	(13.0)	7.4	(23.2)
Kratos Government Solutions
Revenues:
Service revenues	47.5	52.9	149.4	163.1
Product sales	67.9	59.9	207.0	178.3
Total revenues	115.4	112.8	356.4	341.4
Depreciation & amortization:
Total depreciation and amortization	3.5	3.6	10.7	11.3
Public Safety & Security
Revenues:
Service revenues	39.2	34.3	113.9	94.9
Product sales	0.0	0.0	0.0	0.0
Total revenues	39.2	34.3	113.9	94.9
Depreciation & amortization:
Total depreciation and amortization	0.1	0.1	0.3	0.4
Unmanned Systems
Revenues:
Service revenues	0.0	0.0	0.0	0.0
Product sales	41.6	18.3	79.4	50.3
Total revenues	41.6	18.3	79.4	50.3
Depreciation & amortization:
Total depreciation and amortization	2.4	1.9	6.0	5.6
Reportable Segments | Kratos Government Solutions
Operating income (loss) from continuing operations:
Total operating income (loss) from continuing operations	1.7	7.7	17.0	10.4
Reportable Segments | Public Safety & Security
Operating income (loss) from continuing operations:
Total operating income (loss) from continuing operations	2.5	0.8	2.8	(1.7)
Reportable Segments | Unmanned Systems
Operating income (loss) from continuing operations:
Total operating income (loss) from continuing operations	1.7	(20.4)	(5.1)	(27.6)
Unallocated corporate expense, net
Operating income (loss) from continuing operations:
Total operating income (loss) from continuing operations	$ (2.8)	$ (1.1)	$ (7.3)	$ (4.3)