Basis of Presentation and Preparation (Details 3)	12 Months Ended
	Sep. 27, 2015 item
Concentration of Credit Risk
Financial institutions, in any such number of which investment exposure is limited	1
Accounts receivable due from various agencies of the U.S. federal government (as a percent)	25.00%
International
Concentration of Credit Risk
Revenue from customers (as a percent)	24.60%
U.S. commercial
Concentration of Credit Risk
Revenue from customers (as a percent)	32.00%
U.S. federal government
Concentration of Credit Risk
Revenue from customers (as a percent)	43.40%
Minimum
Goodwill and Intangible Assets.
Period for contingent earn-out payments	2 years
Maximum
Goodwill and Intangible Assets.
Period for contingent earn-out payments	3 years