Acquisitions - Assets Acquired and Liabilities Assumed (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 25, 2011	Jul. 02, 2012 Composite Engineering, Inc.	Dec. 30, 2011 Critical Infrastructure Business	Nov. 15, 2011 SecureInfo Corporation	Jul. 27, 2011 Integral Systems, Inc.	Mar. 25, 2011 Herley Industries, Inc.
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Cash			$ 8.9
Accounts receivable			9.3
Inventoried costs			12.5
Other current assets			8.8
Property and equipment			7.8
Intangible assets			38.0
Goodwill	678.5	571.6	103.2
Total assets			188.5
Current liabilities			(25.0)
Net assets acquired			163.5
Business Acquisition, Purchase Price Allocation [Abstract]
Cash					1.4	6.8	21.8
Accounts receivable				23.4		68.4	39.1
Inventoried costs						15.8	42.8
Deferred tax assets						36.4	17.3
Other assets				0.5	3.0	3.5	7.2
Property and equipment					0.1	12.9	34.2
Intangible assets				2.0	4.5	32.0	37.0
Goodwill				3.8	12.2	187.8	146.4
Total assets				29.7	21.2	363.6	345.8
Current liabilities				(9.7)	(0.9)	(84.5)	(40.8)
Deferred tax liabilities						(19.5)	(16.8)
Debt							(9.5)
Long-term liabilities						(18.5)	(6.2)
Net assets acquired				$ 20.0	$ 20.3	$ 241.1	$ 272.5