Reportable Segments (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Sep. 28, 2014	Jun. 29, 2014	Mar. 30, 2014	Dec. 29, 2013	Sep. 29, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 30, 2012	Sep. 28, 2014	Sep. 29, 2013	Sep. 30, 2012
Revenue by client sector
Threshold percentage for disclosure of revenue from a single client									10.00%	10.00%	10.00%
Revenue	$ 622,179	$ 629,502	$ 586,285	$ 645,848	$ 698,376	$ 614,835	$ 641,999	$ 658,545	$ 2,483,814	$ 2,613,755	$ 2,711,075
International
Revenue by client sector
Revenue									643,685	697,975	664,375
U.S. commercial
Revenue by client sector
Revenue									719,006	693,677	718,457
U.S. federal government
Revenue by client sector
Revenue									766,514	829,790	1,008,424
U.S. state and local government
Revenue by client sector
Revenue									$ 354,609	$ 392,313	$ 319,819
Accounts Receivable
Revenue by client sector
Number of clients exceeding threshold									0	0	0